New Forest Wetland Restoration Review by New Forest National Park Authority

New Forest Wetland Restoration Review

Jonathan Cox, Martin Janes, Ulrika Ă&#x2026;berg July 2015

FINAL REPORT 29/07/2015

New Forest Wetland Restoration Review

New Forest Wetland Restoration Review Introduction ........................................................................................................................................ 6 Study Approach ................................................................................................................................... 8 Holly Hatch ........................................................................................................................................ 12 Overview ................................................................................................................................................... 12 Project summary...................................................................................................................................... 12 Objectives .................................................................................................................................................. 13 Restoration techniques .......................................................................................................................... 13 Current status ........................................................................................................................................... 14 Ecology ................................................................................................................................................... 14 Hydromorphology ............................................................................................................................... 14 National Vegetation Classification Survey .......................................................................................... 16 Assessment of Wetland Restoration Objectives ................................................................................ 18 Mire Restoration .................................................................................................................................. 18 River Restoration................................................................................................................................. 18 Appropriateness of techniques ............................................................................................................. 19 Lessons learned ....................................................................................................................................... 21 Summary ................................................................................................................................................... 22 White Moor ........................................................................................................................................ 23 Overview ................................................................................................................................................... 23 Project summary...................................................................................................................................... 23 Objectives .................................................................................................................................................. 23 Restoration techniques .......................................................................................................................... 24 Current status ........................................................................................................................................... 25 Ecology ................................................................................................................................................... 25 Hydromorphology ............................................................................................................................... 25 National Vegetation Classification Survey .......................................................................................... 28 Assessment of Wetland Restoration Objectives ................................................................................ 34 Wetland Restoration ........................................................................................................................... 34 River Restoration................................................................................................................................. 34 Appropriateness of techniques ............................................................................................................. 34 Lessons learned ....................................................................................................................................... 35 Summary ................................................................................................................................................... 35 Soldiers Bog ....................................................................................................................................... 36 River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Overview ................................................................................................................................................... 36 Project summary...................................................................................................................................... 37 Objectives .................................................................................................................................................. 37 Restoration techniques .......................................................................................................................... 38 Current status ........................................................................................................................................... 38 Ecology ................................................................................................................................................... 38 Hydromorphology ............................................................................................................................... 38 National Vegetation Classification Survey .......................................................................................... 40 Assessment of Wetland Restoration Objectives ................................................................................ 43 Mire Restoration .................................................................................................................................. 43 River Restoration................................................................................................................................. 43 Appropriateness of techniques ............................................................................................................. 44 Lessons learned ....................................................................................................................................... 44 Summary ................................................................................................................................................... 46 North Oakley ..................................................................................................................................... 47 Overview ................................................................................................................................................... 47 Project summary...................................................................................................................................... 48 Objectives .................................................................................................................................................. 49 Restoration techniques .......................................................................................................................... 49 Current status ........................................................................................................................................... 49 Ecology ................................................................................................................................................... 49 Hydromorphology ............................................................................................................................... 49 National Vegetation Classification Survey .......................................................................................... 53 Assessment of Wetland Restoration Objectives ................................................................................ 55 River Restoration................................................................................................................................. 55 Appropriateness of techniques ............................................................................................................. 55 Lessons learned ....................................................................................................................................... 56 Summary ................................................................................................................................................... 56 Dames Slough Inclosure ................................................................................................................... 58 Overview ................................................................................................................................................... 58 Project summary...................................................................................................................................... 58 Objectives .................................................................................................................................................. 59 Restoration techniques .......................................................................................................................... 59 Current status ........................................................................................................................................... 60 Ecology ................................................................................................................................................... 60

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Hydromorphology ............................................................................................................................... 60 National Vegetation Classification ....................................................................................................... 66 Assessment of Wetland Restoration Objectives ................................................................................ 69 River Restoration................................................................................................................................. 69 Appropriateness of techniques ............................................................................................................. 70 Lessons learned ....................................................................................................................................... 70 Summary ................................................................................................................................................... 71 Fletchers Thorns ............................................................................................................................... 72 Overview ................................................................................................................................................... 72 Project summary...................................................................................................................................... 72 Objectives .................................................................................................................................................. 73 Restoration techniques .......................................................................................................................... 74 Current status ........................................................................................................................................... 75 Ecology ................................................................................................................................................... 75 Hydromorphology ............................................................................................................................... 75 National Vegetation Classification Survey .......................................................................................... 78 Assessment of Wetland Restoration Objectives ................................................................................ 80 Mire Restoration .................................................................................................................................. 80 River Restoration................................................................................................................................. 80 Appropriateness of techniques ............................................................................................................. 81 Lessons learned ....................................................................................................................................... 81 Summary ................................................................................................................................................... 82 Akercome Bottom ............................................................................................................................. 83 Overview ................................................................................................................................................... 83 Project summary...................................................................................................................................... 83 Objectives .................................................................................................................................................. 84 Restoration techniques .......................................................................................................................... 84 Current ecological status........................................................................................................................ 85 Ecology ................................................................................................................................................... 85 Hydromorphology ............................................................................................................................... 85 National Vegetation Classification Survey .......................................................................................... 86 Assessment of Wetland Restoration Objectives ................................................................................ 92 Mire Restoration .................................................................................................................................. 92 River Restoration................................................................................................................................. 92 Appropriateness of techniques ............................................................................................................. 94

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Lessons learned ....................................................................................................................................... 94 Summary ................................................................................................................................................... 95 Penny Moor ....................................................................................................................................... 96 Overview ................................................................................................................................................... 96 Project summary...................................................................................................................................... 96 Objectives .................................................................................................................................................. 98 Restoration techniques .......................................................................................................................... 98 Current ecological status........................................................................................................................ 98 Ecology ................................................................................................................................................... 98 Hydromorphology ............................................................................................................................... 99 National Vegetation Classification Survey ........................................................................................ 101 Assessment of Wetland Restoration Objectives .............................................................................. 107 Mire Restoration ................................................................................................................................ 107 River Restoration............................................................................................................................... 107 Review of Restoration Techniques .................................................................................................... 108 Lessons learned ..................................................................................................................................... 108 Summary ................................................................................................................................................. 108 Summary & Conclusions ................................................................................................................. 110 The following section provides a summary of the key conclusions and proposed recommendations from the review of eight restoration sites. ........................................................................................................ 110 Overview ................................................................................................................................................. 110 Summary of Findings ............................................................................................................................ 110 Holly Hatch .............................................................................................................................................. 110 White Moor ............................................................................................................................................. 110 Soldiers Bog ............................................................................................................................................ 111 North Oakley ........................................................................................................................................... 111 Dames Slough Inclosure ....................................................................................................................... 111 Fletchers Thorns .................................................................................................................................... 111 Akercome Bottom .................................................................................................................................. 111 Penny Moor ............................................................................................................................................. 112 Monitoring .............................................................................................................................................. 118 Biological monitoring ....................................................................................................................... 118 Morphological monitoring ............................................................................................................... 118 References ....................................................................................................................................... 120 Acknowledgements......................................................................................................................... 121

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Introduction The Forestry Commission, together with various partner organisations, have been progressing Wetland Restoration Projects in the New Forest since 1997. It is estimated that nearly 150 wetland sites have been restored. The earliest schemes, funded by the European Union Life 2 programme were focused on mire restoration and developing techniques to repair damaged mire systems, while the Life 3 Programme focused on restoring rivers, lawns and mires to improve wetland habitats. Funding for wetland restoration has continued through successive funding streams such as Pathfinder, Final 4000 and the New Forest Higher Level Stewardship (HLS) Scheme. Over the years various techniques to restore the New Forest Wetlands have been developed, refined or modified based on the experience gained and levels of success. The majority of techniques that have been used are documented in the New Forest Wetland Management Plan1. The Forestry Commission is now required to obtain Town & Country Planning Consent for many of the proposed wetland restoration projects, which involves wide consultation with a range of stakeholders. The River Restoration Centre and Jonathan Cox Associates were commissioned by LUC on behalf of the Forestry Commission to independently review a sample of past wetland restoration projects to determine whether the projects have met their objectives. LUC are currently involved in preparing planning applications on behalf of the Forestry Commission for a number of Wetland Restoration Schemes within the New Forest and the findings of this study will help inform this work and future project designs. The key overall objectives of the wetland restoration schemes since 1997 (as defined by the Forestry Commission) are: Mire Restoration • • •

To stabilise mire systems against further erosion and drying as a result of artificial drainage either in the mire itself or from knick point migration as a result of downstream artificial drainage. Improve water levels and water retention within mire systems. Re-establish/improve the quality of mire habitat communities.

River Restoration Restore the physical functioning of the river system to a more natural system to: • • • • •

Achieve a diverse natural channel morphology comprising pools, riffles and meanders. Reconnect floodplain habitats and re-activate floodplain morphology and function. Stabilise the hydrological system to a more natural, balanced state to reduce excessive scour, overdeepening and headward erosion. Increase the value/quality of in-stream habitat niches for fish and macro-invertebrates. Restore the quality and diversity of floodplain vegetation communities through the effects of natural seasonal flooding and re-activation of floodplain interaction.

Smith, Jane. (2006) New Forest Wetland Management Plan 2006 – 2016 LIFE02/NAT/UK8544 April 2006. Forestry Commission, The Queen’s House, Lyndhurst, Hampshire, SO43 7NH River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

This report sets out the results of this independent review of past wetland restoration schemes. Structure of Report The remainder of this report is structured as follows: Chapter 2: sets out the proposed approach to the study. Chapters 3- 10: set out the findings of the wetland restoration review for the eight sites assessed. Chapter 11: provides a summary of the key conclusions and recommendations.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Study Approach The study involved four main tasks: Task 1. Task 2. Task 3. Task 4.

Desk based review of all potential sites where wetland restoration work has taken place. Identification of a sample of sites to be surveyed. Field survey and assessment. Reporting.

A brief description of these key tasks is provided below: Task 1: Desk based review A spreadsheet of 147 wetland restoration sites in the New Forest was provided by the Forestry Commission to the RRC and Jonathan Cox Associates. The list identified what information was available for each site under the following headings:  Site name.  Project funding.  Year works were undertaken.  Level of Information available.  Availability of Hydrological reports (i.e. was a hydrological report prepared).  River Corridor Survey (RCS) (i.e. was an RCS been undertaken prior to restoration).  Photos (before and after restoration work).  Site map.  Restoration proposal (presence of written restoration proposals).  Vegetation monitoring (any before and after vegetation survey and monitoring).  Invertebrate monitoring (LIFE 3 Technical Report Annex, 20062).  Fish monitoring (LIFE 3 Technical Report Annex, 2006).  Fish Habitat (LIFE 3 Technical Report Annex, 2006).  Hydrolomorphology monitoring (The Geomorphic and Hydrological Response of New Forest streams to river restoration; Ober Water Geomorphological Dynamics Assessment3).  Drain erosion measurements4.  Dipwell monitoring (Dipwell monitoring records).  Infill Materials if known.  Catchment.  Habitats present (information on habitats present at the project site).

Sustainable Wetland Restoration in the New Forest (LIFE 3) (2006). Technical Final Report (Annex 9.1 – 9.25).

GeoData Institute/ School of Geography University of Southampton (2005) Ober Water Geomorphological Dynamics Assessment. Report to the Forestry Commission. 4

Tuckfield, C G (1976) A Geomorphological Appraisal of Some Recent Drainage Work Carried out in the New Forest by The Forestry Commission. Report to the Nature Conservancy Council. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Task 2: Identification of sites to be surveyed. The selection of the sites was undertaken independently by RRC and Jonathan Cox Associates. It was however requested by LUC that these should include a combination of stream/mire sites and large and small sites. The selection from the long list of sites was undertaken using the following steps: The long list of sites was split into two groups; those with or without mire habitat. Each of these two groups was then sorted according to the following criteria: 1. Are before and after photographs available of the site? (Y or N) 2. Is detailed information available on the restoration proposals? (Y or N) 3. What supporting studies (RCS, ditch survey (Tuckfield, 1976), JBA report) are available? (Level of Information ‘score’). Each list was then sorted according to age to give two groups of sites (Mire and Streams). Initially, it was decided that emphasis should be given to older, rather than younger sites, as in theory these might have had longer for restoration work to have had an effect. However, these sites tended to be concentrated in the Inclosure woodlands and consequently are not representative of the open New Forest habitats. Some additional more recent sites were therefore included to give a wider diversity of habitat type and time range. This spread of scheme age range also allowed a better assessment of the evolving approaches that the Forestry Commission (FC) has developed over time. The resulting process produced a ‘shortlist’ of 25 sites with a mix of either predominantly stream or predominantly mire restoration works. The location of these shortlist sites was then mapped and grouped into approximate river catchments. Several catchments contained a number of sites. The final eight sites were then selected to ensure a good spread of geographic and habitat diversity. The shortlist and final selection of survey sites is shown in table 1. No.

Site Name

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16

Akercombe Bottom Picket Bottom Buckherd Roe Inclosure South Broomy Bottom Holly Hatch Slufters Mires Bratley Mire Soldiers Bog North Oakley Dames Slough Rhinefield Fletchers Inclosure Fletchers Lawn Millyford Green Highland Water

River Restoration Centre/Jonathan Cox Associates

Year Works Undertaken 2010-2011 2014-15 2013-14 2011-2012 2004-2005 2004-2005 2004-2006 2005-2006 2013-2014 2003-2004 2006-2007 2003-2004 2010-2011 2011-2012 2005-2006 2004-2005

Main habitat type Mire & Stream Mire Mire Stream Mire Mire and Stream Mire Mire Mire and wet heath Mire and Stream Stream Stream Stream Stream Stream Stream 9

New Forest Wetland Restoration Review

17 18 19 20 21 22 23 24 25

Ditch End Bottom Claypits Bottom Penny Moor Furzey Lodge/Hawkhill Wilverley Bog Holmsely river work Stony Moors White Moor (Emery Down) Red rise/Markway Lawn

2011-2012 2010-2011 2012-2013 2013-2014 2004-2006 2005-2006 2004-2005 2004-2005 2004-2005

Mire Mire and Stream Mire and Stream Mire Mire Stream Mire Mire Mire and lawn

Table 1: Short list of potential survey sites with eight selected survey sites highlighted in green and two reserve sites highlighted in orange.

Task 3: Field Surveys and Assessment Field surveys were undertaken to evaluate: â&#x20AC;˘ Status of existing hydro-geomorphological and restoration features. This included recording areas and progress of renaturalisation, erosion and deposition, habitat development for the overall channel and floodplain development. â&#x20AC;˘ Status of existing vegetation communities. This included a general overview of the NVC communities on the site and a survey of river habitats. The channel form and restoration features assessment used the River Restoration Centre rapid assessment form to record the visual assessment (based on a walkover) made by the RRC staff. The assessment records details of the site and project objectives, the general characteristics of the river and type, hydromorphological impact of the restoration, biological impact, any water quality aspects, vegetation and designated species (here covered by the other NVC recording, see below), and an expert judgement evaluation of the degree of success of the techniques used, incorporating any additional recorded surveys, assessments or finding that are additionally available (to increase the overall confidence of the evaluation). The Assessment forms are included in the supporting file. Vegetation field surveys followed standard vegetation survey techniques, with a walk over survey used to identify and map areas of homogenous vegetation on to an air photograph. Lists of dominant and preferential species were then made of each identified vegetation type with species abundance recorded using DAFOR scale (dominant, abundant, frequent, occasional, rare). At Akercombe Bottom, vegetation composition was also sampled along transects running across the valley where there were well developed transitions in vegetation type. Vegetation communities were assigned to the National Vegetation Classification (NVC) as described by Rodwell (19915) and in the New Forest SAC Management Plan (English Nature, 20016). Photographs of habitat features and vegetation were taken and notes made on habitat and vegetation structure and function. The field survey was undertaken in the autumn of 2014. Most plants have finished flowering by this time of year and the vegetation survey was therefore dependent upon the identification of species from vegetative characteristics. The identification of vegetation types and the structure and functioning of habitats was not unduly compromised by undertaking the survey at this time of year.

5 6

Rodwell, J.S. Ed (1991). British Plant Communities, Volume 2: Mires and Heaths. CUP. Wright, R.N. & Westerhoff, D.V. (2001). New Forest SAC Management Plan. English Nature, Lyndhurst

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Task 4: Reporting The findings of the field surveys and assessment work are set out in Chapters 3-10 of this report for each of the eight sites surveyed. For each site, the findings are structured as follows:  Overview  Project summary  Objectives  Restoration techniques  Current status  Ecology  Hydromorphology  National Vegetation Classification Survey  Assessment of Wetland Restoration Objectives  Mire Restoration  River Restoration  Appropriateness of techniques  Lessons learned  Summary

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Holly Hatch Overview The Holly Hatch stream occupies a small side valley in the Dockens Water catchment that drains west into the River Avon. The upper reaches of the Holly Hatch stream rise from a series of valley side seepages on the north side of Ocknell Plain. The seepages support areas of wet heath and wet Molinia fen meadow grassland. Prior to restoration, attempts had been made to improve drainage by cutting ditches. These had formed erosion knick points that were cutting back into the seepages in the upper part of the Holly Hatch stream valley. The valley side seepages collect on the edge of Holly Hatch Inclosure to form a stream that flows north through an area of A&O woodland known as Anses Wood. In the past, this had been significantly deepened and straightened. The stream confluences with the Dockens Water on the north side of Anses Wood. An artificial drain runs along the edge of Holly Hatch Inclosure and parallel to the Holly Hatch stream. Holly Hatch – extract from LIFE3 final report (2006) Work was undertaken by contractors to infill the badly eroded stream flowing from the adjacent mire, and to re-define the drain along the Inclosure bank and stabilise it with timber dams. Heather bales were used to fill in the drain, and clay and gravel were used to raise the stream bed level. A total of 5.02 ha of mire was restored.

Project summary In 2004 the Stream was badly eroded along most of its course, over deep and wide, with a significant ‘plunge pool’ at the upstream limit of the true stream before it became the exit point from the mire drainage. All of this material had been transported downstream into the Dockens Water, or deposited at the site of a blocked culvert where the gradient flattens out. The 2005 project aimed to reduce the volume of water conveyed by the stream to reduce the erosion pressure and restore width and depth to more appropriate proportions.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.2.1. Map of Holly Hatch site

Objectives The objectives of the restoration works (locations on map) were to:  Re-route the Inclosure boundary ditch (1 & 2) flow away from the stream by removing obstructions in that ditch.  Restore the bed of the stream (4) and address the head cut (3) and gullying.  Reduce excessive erosion of the Inclosure drain (5 & 6) leading to deposition downstream.  Fell Scots Pine encroaching on the mire system (except ‘landscape character’ trees).

Restoration techniques The restoration techniques used included (and are illustrated in the three photos below): 1. Infilling the upper connecting drain using heather bales, recovered gravel and inserting clay plugs. 2. Slowing the flow in the Inclosure ditch by installing wooden posts in the ditch bed. 3. Raising the stream bed with heather bales, imported hoggin and recovered gravel, by inserting wooden retaining boards and clay plugs.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.4.1. Connecting drain (2004)

3.4.2. Wooden posts (2005)

3.4.3. Raised bed (2014)

Current status Ecology The Holly Hatch stream passes through two Natural England condition assessment units. Unit 76 was assessed in May 2013 and was considered to be in favourable condition. The mire restoration works are considered to have restored the watercourse to a shallow stream flowing through close grazed Molinia and sedge dominated grassland. Anses Wood through which the stream then flows is within assessment Natural England SSSI unit 104 and was assessed in June 2010 as being in unfavourable recovering condition. It states that ‘Drain improvements noted. Further management works will maintain and enhance these habitats.’ Hydromorphology The channel proportions are more appropriate to a New Forest stream, rather than a drainage ditch, and the bed is dominated by gravel. The connecting Inclosure ditch remains infilled (and no trace that it existed is visible) and the ditch flows continuously via the new track culvert and obstruction removal. The 2x2m head cut plunge pool has remained filled to the desired 30cm below ground level. Sediment movement is still active, but less extensive than previously, providing morphological adjustment and creating new features Some issues are present at the site after 10 years:  There is now another head cut located approx. 10m downstream of the previous location.  Gravel has been eroded from the bed, without being replaced from upstream (no source available in the mire).  Wooden retaining boards have become exposed and are forming weirs.  The wooden posts in the Inclosure drain have rotted and snapped so the drain bed has eroded to previous levels.  The lower connecting ditch infill has been washed out (gravels, hoggin and heather bales) to previous levels leaving a large drop over the remaining retaining boards.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.5.1. Headcut (2004)

3.5.2. Infilled with hoggin/gravel (2005)

3.5.4. Deeply incised channel with materials ready (2005)

3.5.3. Small headcut reforming (2014)

3.5.5. Bed restored, but 20cm surface erosion (2014)

3.5.6. Confluence of the Holly Hatch stream (left) and inclosure edge drain (right) within Anses Wood (2014)

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

National Vegetation Classification Survey W14 Fagus sylvatica – Rubus fruticosus woodland

The woodland through which the Holly Hatch stream flows is typical of New Forest beech woodlands in which the canopy is composed of a mix of beech Fagus sylvatica and oak Quercus spp. (mostly hybrid oaks Quercus x rosacea). The shrub layer is dominated by holly Ilex aquifolium and the ground flora is very sparse and limited to scattered moss patches. The distinction between this community and the more acidic W15 Fagus sylvatica - Deschampsia flexuosa woodland is determined by the composition of these moss patches, the presence or absence of wavy hair-grass Deschampsia flexuosa and abundance of bramble Rubus fruticosus (although this is heavily browsed in the New Forest and is rarely very abundant). The woodland surrounding the Holly Hatch stream has developed on base-poor brown earths with some impeded drainage typical of W14 but not as acidic as W15. Moss mats include abundant Polytrichum formosum and Thuidium tamariscinum. Other ground flora associates consist of wood sage Teucrium scorodonium, foxglove Digitalis purpurea, wood sorrel Oxalis acetosella and scattered bracken Pteridium aquilinum. M24c Molinia caerulea-Cirsium dissectum Fen meadow - Juncus acutiflorus -Erica tetralix sub community

At the head of the catchment the seepages flow through well grazed areas of wet grassland composed of a mix of Purple moor-grass Molinia caerulea and sharp-flowered rush Juncus acutiflorus with a diverse associated flora including bog pimpernel Anagallis tenella, meadow thistle Cirsium dissectum, bird’s foot trefoil Lotus corniculatus, velvet bent Agrostis canina and sphagnum moss Sphagnum inundatum. U4 Festuca ovina – Agrostis capillaris-Galium saxatile acid grassland

On the edge of Anses Wood the right bank of the Holly Hatch stream has a small area of moist lawn grassland dominated by common bent grass Agrostis capillaris with heath grass Danthonia decumbens, Molinia caerulea, tormentil Potentilla erecta, heath bedstraw Galium saxatile and the sedges Carex panicea and Carex viridula var oedocarpa. This moist acid grassland may have developed from the Molina fen meadow as a consequence of former drainage. A further small acid grassland lawn has developed at the downstream end of the stream by the confluence with the Dockens Water. This is characterised by a sward dominated by Agrostis capillaris with daisy Bellis perennis, creeping buttercup Ranunculus repens, self heal Prunella vulgaris, rough hawkit Leontodon hispidus and lesser celendine Ranunculus ficaria. This is a disturbed flood grassland that is not easily classified within the NVC but has similarities to U4 Festuca ovina-Agrostis capillaris-Galium saxatile grassland.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.6.1. The Holly Hatch stream on the edge of Anses Wood where timber structures have failed and the stream remains incised. Acid grassland lawns on the right bank may reflect the drainage effect of the deepened stream at this point (2014) M29 Potamogeton polygonifolius â&#x20AC;&#x201C; Hypericum eloides soakaway

Flow tracks through the wet Molinia grassland are marked by soakaway vegetation typically composed of bog pondweed Potamogeton polygonifolius and marsh St Johnâ&#x20AC;&#x2122;s wort Hypericum eloides with frequent lesser spearwort Ranunculus flammula and Glyceria fluitans. These soakaways are never more than 1m in width. They terminate in a shallow knick point at the head of the gravel bedded stream on the edge of Anses Wood. A24 Juncus bulbosus stream vegetation

There is very little aquatic vegetation under the heavy shade of the oak and beech woodland below the knick point marking the change from soakaway vegetation to stream. There are scattered patches of Potamogeton polygonifolius with Glyceria fluitans, Juncus bulbosus and occasional Ranunculus omiophyllus. At the confluence with the Dockens Water the stream has created a gravel outwash delta with scattered plants of foxglove Digitalis purpurea, tormentil Potentilla erecta and wavy bitter-cress Cardamine flexuosa. The Dockens Water at this point has banks with fools water-cress Apium nodiflorum and a stream flora typical of permanently flowing New Forest streams with Ranunculus peltatus, Callitriche sp. and Glyceria fluitans. The stream banks here have frequent violet Viola riviniana and Oxalis acetosella and the mosses Atrichum undulatum and some Sphagnum inundatum.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives Mire Restoration The use of heather bales appears to have successfully restored drainage and water levels through the axis of the Molinia fen meadow grassland, with well-developed flow tracks supporting typical soakaway vegetation. There are also good transitions to valley side wet heath communities and localised seepage mires. However, the lower end of the soakaway track (essentially the start of the stream with a defined channel) is marked by a low knick point to the stream. This appears to be relatively stable but will require monitoring and possible further remediation. Objectives To stabilise mire systems against further erosion and drying as a result of artificial drainage either in the mire itself or from knick point migration as a result of downstream artificial drainage. Improve water levels and water retention within mire systems. Re-establish/improve the quality of mire habitat communities.

Evaluation Objective has been largely met although a new knick point is evident at the foot of the mire.

Former drainage has been reversed and the mire system â&#x20AC;&#x201C; in the form of Molinia fen meadow and soakaway communities has good water levels. Molinia fen meadow grassland and associated soakaway communities are in good condition although further erosion of the knick point needs to be monitored to prevent drying.

River Restoration Restore the physical functioning of the river system to a more natural system to: Objectives Evaluation Achieve a diverse natural channel morphology Stream size and flow prohibitive to achieve this comprising pools, riffles and meanders generally. However, retaining boards restrict the ability of the steam to operate naturally (have become weirs). Reconnect floodplain habitats and re-activate The adjacent open woodland is not floodplain floodplain morphology and function woodland per se, but does have a better degree of connectivity now. Stabilise the hydrological system to a more natural, The works have addressed this, but the long term balanced state to reduce excessive scour, sustainability of the methods is doubtful due to the overdeepening and headward erosion. energy gradient of the stream combined with the methods used (specifically the wooden boards). Increase the value/quality of in-stream habitat Hydromorphoplogically this has been successful niches for fish and macro-invertebrates along the majority of the project, however in channel wood and macrophyte growth are both limiting the degree of habitat available to complement the bed morphology. Restore the quality and diversity of floodplain Adjacent woodland inundation now occurs more vegetation communities through the effects of regularly, however this is not floodplain woodland natural seasonal flooding and re-activation of (apart for the very lower confluence with Dockens floodplain interaction. Water). Anses Wood through which the stream River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

flows was assessed in June 2010 as being in unfavourable recovering condition.

Appropriateness of techniques Generally, raising the stream bed with heather bales, imported hoggin and recovered gravel has worked. The clay plugs are noticeable if you venture into the shallow stream, as the bed is soft and a plume of clay enters the water column. Any overlying gravels that were used to ‘dress’ the clay have washed off or been pushed into the clay. A plug not so close to the surface would probably have sufficed to return the watertable and surface flows to the desired levels, and allowed a deeper overlying layer of gravels. The noticeable weak link is the wooden boards that were incorporated to retain the gravels. These initially ‘hidden’ structures have not adjusted with the stream bed (fill material settlement and some gravel movement that would be expected) and have led to erosion and scour at the downstream face. In some places the boards have been outflanked, undermined or washed out.

3.8.1 Board outflanked (2014)

3.8.2 Board undercut (2014)

The best example of the boards not working well is the short ‘return’ drain which takes the stream back into the Inclosure ditch. Here the bed of the ditch was raised from the Inclosure ditch level up to the restored stream bed level. This resulted in a steeper gradient gravel bed than elsewhere. It is unclear how far the heather bale infill extended, but it is likely from a close inspection that these have long since washed out along with the gravel dressing, exposing the upstream boards and creating the current ‘weir’ structure.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.7.1. Before (2005)

3.7.2. During (2005)

3.7.4. ‘Weir’ effect of boards (2015)

3.7.3. After (2015) - Arrow shows ‘weir’.

3.7.5. The channel has scoured the gravel overlay and heather bales (2015)

Slowing the flow in the Inclosure drain by installing vertical wooden posts has not worked well. The posts have rotted, snapped and generally degraded so that they no longer carry out their intended role. The main issue here is that the semi natural ‘stream’ joins back to the artificial and straight Inclosure ditch. The stream restoration acted to undo the scouring influence of the combined flows of the stream and ditch. However, by uncoupling the ditch flow and ‘clearing out’ the ditch route, this has just re energised the exact situation that is the problem all across the New Forest – channelised straight ditch lines with steep gradients and excess energy which results in bed scour and gully creation.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.7.6. three examples of failed wooden posts along the inclosure edge drain (2014)

Lessons learned The work to split the flows by re connecting to the ditch should instead have aimed to retain the flows in the stream, close the ditch, naturalise the lower ditch after the confluence, and introduce more large wood into the stream channel instead of the ‘structural’ wooden boards, to aid in stabilising the imported hoggin and recovered gravel. Stability of headwater reaches is always a much more difficult proposition than middle and lower reaches due to the absence of supply bed material. The mire system provides water only, until the scour pool of the headcut has developed. Thus any work to infill the channel base cannot rely on future supply from upstream (as might be the case at lower sites on the Blackwater (Dames Slough, Fletchers, etc.)). There is a need to review the wooden board structures and plan to replace these with a more long-term solution. Once the lower board fails (which it will do at some point), the weir effect will become a knick point that recedes upstream eroding out the bed infill. The point at which this happens and the rapidity of the erosion is unknown, but it will then become harder to address. The head cut at the top of the stream was infilled with hoggin and recovered gravel. A small headcut has developed close to this location. This is likely to happen. There will at some point be a transition from mire ‘flush’ through vegetation to a defined single main channel which breaks through the surface vegetation layer. The use of felled trees to provide obstructions and flow/habitat complexity should be explored in this location. A good example of the effectiveness of this is the large fallen beech that has blocked the channel and is diffusing flow whilst holding back the gravel bed above far better than the wooden boards visible just downstream.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

3.9.1. Ineffective wooden board (left) below fallen beech that provides an effective method of diffusing flow and holding back the gravel bed (right) (2014).

Summary The works at Holly Hatch are showing their 10 year age. The site is difficult as it is a headwater and has a relatively steep gradient (for a New Forest stream). 10 years on, some of the techniques applied here are no longer deemed best practice (the use of wooden boards) and there are alternatives that are in use elsewhere (e.g. tree limbs and other woody material) to retain bed gravels and add habitat complexity. The gradient has meant that the steady bed slope has become more stepped with the boards acting as weirs in places. A better understanding of the long section profile is required for these steeper stream sections when planning what techniques to use and how to apply them. Surveying the long profile of the stream will enable the team to identify the overall gradient and energy regime of the stream under different flow conditions, as well as the specific gradient down the stream. So identifying breaks of slope where the gradient reduces (areas of deposition) and areas of bed movement and potential erosion /head cutting where the gradient is locally steeper. This then helps specify what techniques and works are best suited to exact locations to achieve the overall New Forest objectives for that specific stream and detailed location plan.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

White Moor Overview There are several areas of the New Forest referred to as White Moor and at least two that have been subject to wetland restoration works. The White Moor considered in this report is located to the west of Emery Down on the eastern side of the Highland Water valley. White Moor consists of a complex of wet heath and wet streamside lawns with some mire habitat, woodland and transitions to dry heath. A system of drainage ditches have been cut through the area taking flow in a generally south-westerly direction to the Highland Water. Restoration works undertaken in 2006 were aimed at restoring wet heath, mire and woodland habitats without having impacts on areas of wet streamside lawns. White Moor – extract from LIFE3 final report (2006) White Moor comprises a mosaic of mire, bog woodland and wet heath that has been significantly damaged by drainage activities in the 1970’s. The drains have suppressed the water table and led to the loss of some mire and the drying out of an area of bog woodland. In the spring of 2006 the works involved the complete infill of some drains (using staked heather bales and adjacent spoil) and bed level raising in others. This has allowed the water table in the mire and the bog woodland to be raised, and works on peripheral drainage have greatly benefited the wet heath community. As such these activities have restored 1.3 hectares of mire, 0.6 hectares of bog woodland and had the wider benefit of reducing the influence of artificial drainage on 11.4 hectares of wet heath.

Project summary Historic maps of the area show the sinuous channel with tributaries flowing through what is now referred to as White Moor to the Highland Water (figure 4.4.2). However, by the publication of the First Edition 6” (circa 1870), the sinuous channels had been straightened and extended up the catchment indicating artificial drainage activity, presumably to improve the quality of grazing for livestock. Work was undertaken in 2006 to remedy the impacts this drainage activity was having on wetland habitats in particular mire, wet heath and wet woodland. However, where historic drainage had produced tangible results for grazing through the generation of wet grassland, these naturalised channels were retained due to Commoners and Verderers requests and therefore a full restoration was not possible.

Objectives The objectives of the restoration works were to:  Restore bed levels in five drains having an adverse effect on areas of mire, wet heath and wet woodland.  Restore bed levels to bank top where drains were damaging wet heath, mire and woodland.  Restore bed levels to within 30cm of bank top where they had developed drain edge wet grassland lawns to allow water to return to the channel following over bank flow events.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Restoration techniques Work was undertaken in five areas shown in figure 4.4.1 and described below. Area 1:

Area 2:

Area 3

Area 4

Area 5

The bed of the straightened and deepened headwater channel was raised with imported gravel but due to the value of the adjacent wet grassland for grazing animals, bed levels were only restored to within 30cm of ground surface to allow water to drain from the streamside grassland lawns following high flow events. A section of some 45m of drain upstream of the track crossing was infilled to within 5m of the track using staked heather bales with the intention of preventing drainage of the adjacent wet heath. The incised and heavily shaded channel through this area had a significant amount of bank spoil and lacked any in channel vegetation. There was also evidence of continued erosion of the bed. The bed was raised with bank spoil, imported gravel and heather bales by 30cm for 20-25m of channel. Alder and willow were coppiced to gain access and some coppiced material was used as live stakes driven into the raised bed to encourage consolidation. This drainage channel was having an adverse effect on the adjacent wet heath. The water table was to be restored by completely infilling the drain for 60m using staked heather bales. It does not appear this was achieved as the drain remains significantly below ground level. A 40m channel that was draining an area of mire was infilled using staked heather bales. In addition some 15m of drainage channel around the edge of an area of wet woodland was infilled with available spoil and heather bales to restore drainage to the wet woodland in the valley bottom.

Figure 4.4.1. White Moor wetland restoration proposals (2006)

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Figure 4.4.2. Extract of ‘Driver’s’ map of 1789 showing the meandering course of the stream through Buck Hill Hole and White Shoot

Current status Ecology White Moor is within a large monitoring unit split into a number of separate parcels and referred to as MA5 WET (341). It is assessed as being in unfavourable recovering condition. The Natural England assessment (dated 05/12/2013) states; ‘Drainage is an issue in several places but in particular at White Moor where several straightened drainage channels cross the wet heath. Some of these are naturally infilling and may be of value as habitat for a variety of Odonata as at Acres Down a known site used by Southern Damselfly. Adjacent to these is a consistently wide strip of species rich molinia meadow which may be artificially created. Some restoration of these drains is needed and hence the unit remains unf. rec.’

Hydromorphology The sinuous channel evident in the late 18th century has not been restored and the central drain through White Moor remains straight and with water flow below bank level. However, on the main drain, bed level raising has prevented further damage to flanking wet heath habitats. On the side drain within Area 4 there is still evidence of drainage of the adjacent wet heathland and bank erosion from lateral flows across the wet heath. It does not appear that the intended infilling of the drain was undertaken as shown in figure 4.4.1 (Area 4).

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

4.5.1-3. Drainage of wet heath within Area 4 with erosion of bank sides (2015)

By contrast infilling of the drain in Area 2 has been very successful and there is good evidence of wet heath and mire vegetation recovering along the course of this drain that was infilled with staked heather bales.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

4.5.4. Staked heather bales blocking the head of drain 2 with consequent restoration of M21 mire and M16 wet heath habitats (date unknown)

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New Forest Wetland Restoration Review

National Vegetation Classification Survey M24c Molinia caerulea-Cirsium dissectum fen meadow - Juncus acutiflorus -Erica tetralix sub community

The excavation of drainage channels through the White Moor valley created raised banks alongside the drains that have been colonised with wet grassland to create streamside lawns. Unlike floodplain lawns found elsewhere in the Forest these are not regularly inundated from the stream or drain along which they occur but receive water from lateral flows from the adjacent wet heath habitats into which they merge. The vegetation of these narrow drain side lawns is however quite diverse. The grassland is dominated by a combination of Molinia caerulea and Agrostis canina commonly with Festuca rubra and Danthonia decumbens. Associated flora includes Potentilla erecta, Cirsium dissectum, Sphagnum inundatum, Carex nigra, Carex panicea, Juncus acutiflorus and occasional Calluna vulgaris. In places, this community occurs as a component of transitional wet heath habitat in which wet heath occurs on low hummocks with Molinia fen meadow grassland between. The flora in these transitional areas is particularly rich with components of both vegetation types occurring as a complex mosaic.

4.6.1. Drain 5 with fringing hummock of wet heath within Molinia fen meadow grassland (Left). Top of drain 3 with well vegetated drain (M29) and fringing fen meadow grassland (M24c) and wet heath (M16a) (date unknown)

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New Forest Wetland Restoration Review

4.6.2. Drain 1 with M24 Molinia fen meadow lawn and sharp transition to wet heath. Drain overgrown with bog myrtle Myrica gale together with grey willow Salix cinerea and downy birch Betula pubescens (date unknown) W5b Alnus glutinosa-Carex paniculata woodland - Lysimachia vulgaris sub-community

The head of drain 5 is marked by an area of alder Alnus glutinosa woodland. This is rather species poor and heavily grazed making an assessment of its NVC community rather difficult. However, the lack of associated tree species and its location on an acid mire system suggest it will conform to W5b community. The only associated species visible at the time of survey were some scattered holly Ilex aquifolium and bramble Rubus fruticosus. W10a Quercus robur – Pteridium aquilinum – Rubus fruticosus woodland

A spinney of oak woodland occurs in the middle of White Moor. This is dominated by even aged mature pendunculate oaks Quercus robur with Ilex aquifolium, Pteridium aquilinum and Rubus fruticosus. It is rather species poor and apparently of recent origin; it is not shown on Driver’s map of 1789 and may have developed following 19th century drainage works. Lower down the system are further areas of younger woodland dominated by silver birch Betula pendula with young oaks that will develop into similar mature oak woodland. M16a Erica tetralix – Sphagnum compactum wet heath – Typical sub-community

Away from the drain edge the vegetation shows a rapid transition to typical wet heath. This is dominated by Erica tetralix and Calluna vulgaris forming a dwarf-shrub canopy over a well grazed Molina caerulea carpet with abundant Sphagnum mosses including tussocks of Sphagnum compactum and Sphagnum tenellum together with Sphagnum inundatum and locally Sphagnum cuspidatum.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Drain 4 cuts through an area of wet heath. The drain has become colonised with a diversity of Sphagnum mosses (see WPT083) whilst the open and slightly poached banks of the drain have locally abundant pale butterwort Pinguicula lusitanica.

4.6.3. The insectivorous pale butterwort Pinguicula lusitanica growing in developing M21 mire at the head of Drain 2, with Rhychospora alba, Sphagnum cuspidatum and some Sphagnum papillosum (date unknown) M21a Narthecium ossifragum-Sphagnum papillosum Valley Mire - Rhynchospora alba-Sphagnum auriculatum sub-community

Above the alder woodland at the head of drain 4 is a small but well developed seepage mire conforming well to the M21a community with community constants; Sphagnum papillosum and Rhynchospora alba together with Sphagnum fallax, Sphagnum denticulatum and Juncus acutiflorus. The axis of the mire supports typical M29 soakaway vegetation.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

4.6.4. Narthecium ossifragum-Sphagnum papillosum Valley Mire - Rhynchospora alba-Sphagnum auriculatum subcommunity (date unknown) M29 Hypericum elodes-Potamogeton polygonifolius soakaway

The most heavily vegetated drains support mixtures of bog pondweed Potamogeton polygonifolius and marsh St Johnâ&#x20AC;&#x2122;s wort Hypericum eloides and conform to this community. As flow rate increases and the vegetation becomes more truly aquatic the M29 community gives way to the A24 Juncus bulbosus community. Associated species in the M29 vegetated drains include Juncus bulbosus, Ranunculus flammula, Sphagnum palustre and Juncus acutiflorus. The best example of the community occurs along the central drainage axis with the M21a mire at the head of Drain 5. A24 Juncus bulbosus aquatic community

Few of the drains have developed a stream flora. Water flow is generally slow and they are becoming well vegetated and reverting to mire and heath habitat. However, the lower reaches of Drain 1 and 2 have more aquatic vegetation that although it has much in common with the M29 soakaway community is better regarded as A24 aquatic community. Potamogeton polygonifolius remains abundant together with Juncus bulbosus, Eleogiton fluitans, Glyceria fluitans and Hypericum eloides.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

4.6.5. Drains with timber barriers to restore water levels. These have been partially effective but water generally flows at between 0.3 and 0.5m below ground level and surface water drainage causes local bank erosion as seen in Drain 4 (date unknown)

Waypoint Number (See White Moor map in Appendix 1) WPT076

WPT077

WPT078 WPT079

Note

Ditch side lawn (2-4m wide) alongside drain through wet heath. Lawn with short wet grass – Molinia caerulea, Agrostis canina, Potentilla erecta, Sphagnum inundatum, Carex nigra, Festuca rubra, Juncus acutiflorus, Calluna vulgaris, Danthonia decumbens. Drain 1.2m wide – partially choked with vegetation – (M29) Hypericum eloides, Juncus bulbosus, Ranunculus flammula, Sphagnum palustre with transition to Wet heath (M16). Wet heath with abundant Sphagnum mosses – Sphagnum denticulatum and Sphagnum tenellum, Molinia, Calluna vulgaris, Erica tetralix (dominant) – Narthecium absent. Drain with 7m wide marginal wet lawn on left bank. Wet heath on right bank. Drain with Potamogeton polygonifolius, Juncus bulbosus, Hypericum eloides. Water to 0.3m from drain top. – Drain becomes more choked downstream with addition of Ranunculus flammula, Juncus acutiflorus, Sphagnum palustre, Sphagnum denticulatum. Wet lawn on left bank 7-8m wide. Some Pteridium aquilinum around woodland edge with Wet Heath. Oak wood/spinney with Ilex aquifolium, Pteridium aquilinum, Rubus fruticosus. Drain with water 0.5m from bank top. Drains wet heath. Choked side drain. Potamogeton polygonifolius, Eleogiton fluitans, Juncus bulbosus, Hypericum eloides, - to Myrica gale dominated wet grassland.

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New Forest Wetland Restoration Review

WPT080

WPT081

WPT082

WPT083

WPT084

WPT085 WPT086

WPT087

Drain below wood choked with Potamogeton polygonifolius, Hypericum eloides, Juncus acutiflorus. At top of drain Juncus bulbosus, Ranunculus flammula, Anagallis tenellum, Agrostis canina. Drain with 6m wide wet grass lawn (M24) with Cirsium dissectum and hummocks. Head of drain with good mire and wet heath transition. Central axis of mire with M29 soakaway through Sphagnum lawn with Sphagnum papillosum, Sphagnum denticulatum, Juncus bulbosus, Molinia caerulea. Timber weirs used to block drain. With transition to M21 mire. Woodland below waypoint Alnus glutinosa, Ilex, Rubus â&#x20AC;&#x201C; very spp poor. Confluence of main drain and drain 4 through wood (W10) with Alnus along stream edge. Stream with some woody/leaf accumulations. Blocked at downstream end of wood with Myrica clump. Drain upstream of WPT082 in need of further infilling. Water level 40-50cm below bank top with local gullies along drain side. Drain with good Sphagnum carpets (S. cuspidatum, S. denticulatum, S. palustre, S. fallax and S. papillosum with Pinguicula lusitanica). Drain mostly full of Myrica gale with Salix cinerea, Betula pubescens. Small sections of open water with Potamogeton polygonifolius, Ranunculus flammula, Juncus bulbosus. Flow rate very slow. Margin of wet grass lawn to 8m wide with local hummocks. Scattered Quercus robur on right bank extending down from larger woodland. Track crossing. Water level 40-50cm below bank top with gentle flow. Infilled drain with water flowing at bank top in shallow gulley. Drain channel with steady flow. Juncus bulbosus, Sphagnum denticulatum, Eleogiton fluitans, Hypericum eloides, Sphagnum fallax. Adjacent wet heath and mire with developing M21. Sphagnum papilosum, Pinguicula lusitanica, Rhychospora alba, Sphagnum cuspidatum, Sphagnum fallax â&#x20AC;&#x201C; Narthecium absent. Downstream of track crossing on Drain 2 in wet heath. Drain plugs at approximately 10m intervals, partially effective but in need of more infill.

Table 2: Way point records (WPT) shown on vegetation map in Appendix 1

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New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives Wetland Restoration Backfilling deepened drains with spoil and heather bales has successfully restored mire, wet woodland and wet heath habitats in the upper reaches of drains where filling has been to bank top. However, where bed level raising has only partially infilled drains, there is evidence of continued drainage of wet heath and erosion of drain banks from lateral surface flows. The sinuous channel formerly in evidence has not been restored but bed raising through a section of wet woodland has prevented further erosion and drainage of adjacent wet heath. There is evidence that vegetation growth within the wooded section of the drain is continuing to restore water levels. Objectives To stabilise mire, wet heath and woodland against further erosion and drying as a result of artificial drainage either in the mire itself or from knick point migration as a result of downstream artificial drainage. Improve water levels and water retention within mire systems.

Re-establish/improve the quality of mire habitat communities.

Evaluation Where drains have been filled to bank top there is evidence of good mire and wet heath habitat restoration. Where bed level raising has not been to bank top there are localised areas of bank erosion but knick point creation or migration is not occurring. Water levels in areas of mire, wet heath and wet woodland appear to have been restored where drains have been fully infilled. Water levels are still below ideal in sections with partial bed level raising (drain 4 and head of drain 3). There is evidence of good mire and wet heath development at the head of drain 2 and on drain 5. It is not clear if drainage is having an adverse effect on areas of wet heath on drain 3 and 4.

River Restoration Wetland restoration at White Moor did not have an objective of restoring natural stream flows. Connection between stream and floodplain appears to have only been partially restored through the level of bed raising undertaken. The drain through the main axis of White Moor is slowly becoming choked with vegetation and wood deposits and within the woodland drain 3 is now flowing at bank level. It is unlikely that these naturalising processes will be sufficient to re-activate stream dynamics and there will continue to be only limited interaction between the drain and its associated floodplain. The objective of allowing out of bank flows to return to the stream by not back-filling the upper reaches of the main drain or much of drain 4 means that the natural downstream transition from mire and wet heath to a gravel bedded stream is not evident.

Appropriateness of techniques The use of staked heather bales and backfilling with spoil and imported gravel has been very successful where this has restored water levels to ground level as seen in the upper reaches of drain 2 and 5. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

However, partial infilling has had only partial success in restoring mire and stream hydromorphology and associated habitat.

Lessons learned The partial infilling of drains to preserve wet grassland vegetation along the drain edges has had partial benefits and may prevent further degradation of associated wet heath and woodland. However, restoration of these habitats and the natural downstream transition from seepage flows to stream flow has not been restored. This is a compromise restoration scheme in which nature conservation objectives have been constrained by the requirements of other stakeholders. There is a need to better understand the effects of wetland and watercourse restoration on wet grassland lawns and forage quality for New Forest stock.

Summary Restoration works at White Moor are now nine years old. Their effect on habitats in the area has been varied. Where drains have been fully backfilled there is good wet woodland, mire and wet heath development. However, partial drain infilling has resulted in only partial habitat restoration and there is some evidence of continued erosion and drainage of wet heath habitat as a consequence. Growth of scrub and vegetation in partially filled drains and deposits of wood are unlikely to re-activate a dynamic stream flow and floodplain interaction. It is more likely that the drain will develop into a linear pond with flow through it.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Soldiers Bog Overview Soldiers Bog is located in the headwaters of the Lymington River. It drains to the south into the Blackensford Brook which flows through North Oakley Inclosure. The water-course then undergoes a series of name changes as it grows in size. The Blackensford Brook confluences with the Bratley Water as it flows south through the inclosures, which in turn confluences with the Black Water at Burley Lodge. The Black Water then flows east through Dames Slough Inclosure and Fletchers Thorns Inclosure to confluence with the Ober Water just west of Brockenhurst where it is finally referred to as Lymington River. Figure 5.1.1 shows that there was a series of channels draining the Bog prior to the drainage works. The vegetation in Soldiers Bog has been significantly affected by past drainage works and now comprises a lower mire dominated by purple moor-grass tussocks with abundant bog myrtle. This shows lateral transitions to wet heath and rush pasture hummock vegetation. Restoration of the mire has restored more natural mire flows through the Bog that now forms developing soakaway channels, however, the restoration works are quite recent and the vegetation is still responding to the improved drainage pattern following the recent restoration. The head of the Bog is marked by an area of reed swamp and on the western side of the central mire is an area of reedmace Typha latifolia swamp. These may be due to naturally raised nutrient levels in ground water or be influenced by past drainage works in the mire. The JBA Report (2013)7 refers to these being ‘an indicator of silting due to erosion further up the system (Jennifer Thomas, Natural England, pers. comm. 23rd April 2013).’

Figure 5.1.1.The figure shows an extract from the OS Six Inch 1888-1913 map series. Prior to the drainage works a braided channel system (east of Stinking Edge Wood) drained Soldiers Bog and joined Brackensford Brook.

JBA report – http://publications.naturalengland.org.uk/file/6101543870791680

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New Forest Wetland Restoration Review

Project summary This mire and river restoration site is contained within SSSI Unit 123 between SU2296007490 and SU2307407035. Prior to restoration, the main drainage channel was running down along the western edge of the valley with an eroding knick-point at about 250m upstream of the footbridge (Figure 5.2.1). The restoration of this site was carried out in 2013/2014 addressing issues of drainage, heavy grazing, spreading grassland, erosion and channel incision. The aim of the restoration was to restore the SSSI site to a favourable condition by restoring the natural meandering course of the river, infilling the drain, raising the bed level of the river and re-connecting it with the floodplain.

Figure 5.2.1. Forestry Commission Restoration Plan for Soldiers Bog

Objectives The objectives of the works were to:  Raise bed level of channel in mire (from knick point to just upstream of footbridge) using heather bales.  Restore old meandering course from end of bed raising section to 250m downstream of the footbridge.  Remove the old concrete culvert over the parallel drain, and relocate the existing wooden footbridge from the artificial channel to the restored stream.  Infill the artificial drain along the western edge.  Raise bed level of the existing channel (downstream to the confluence with Blackensford Brook) using hoggin/rejects and heather bales.  Maintain the gravel ford upstream of the confluence with Blackensford Brook. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

  

Raise bed level in the Blackensford Brook using hoggin/rejects and heather bales. Maintain the gravel ford on Blackensford Brook. Repair localised erosion by bed level raising using hoggin/rejects.

Restoration techniques The restoration techniques used included: 1. Bed level raising using heather bales. 2. Remeandering of the stream. 3. Infilling of old channel using hoggin/clay plugs.

Current status Ecology Soldiers Bog falls within Natural England monitoring unit 123. It was last assessed prior to the most recent restoration works, in December 2013 when it was considered to be in unfavourable recovering condition. The assessment concluded that “The unit is unfavourable due to loss of mire habitat caused by artificial drainage and is included in the wetland restoration programme so considered to be recovering.” The restoration work had been completed by the autumn of 2014 when this current survey was undertaken. The vegetation appears to be in a state of some flux as a consequence. The hydrology of the mire has been restored with the use of heather bales and water levels have been raised. There appears to have been a reduction in the extent of Phragmites swamp (S4) and Typha latifolia (S12) swamp since restoration. This would suggest an improvement in condition probably as a result of more constant water levels and reduced nutrient input. However, the mire remains rather species poor and dominated by Molinia caerulea with little Sphagnum moss. It is likely that the cover of Sphagnum mosses will increase in future and diversify the mire vegetation. The presence and local abundance of Carex echinata in the mire may also indicate a move towards M6 Carex echinata – Sphagnum fallax/denticulatum mire although neither of these mosses was seen in the mire during this survey. The stream vegetation downstream of the mire appears to have naturalised very well following restoration of the stream meanders. The Natural England assessment of the site being in ‘Unfavourable recovering condition’ is based on the assumption that wetland restoration works will be undertaken. Now that these have been completed Soldiers Bog can now be assessed as truly recovering with all elements in place for restoration of the mire and stream system. Hydromorphology The main river channel draining the Bog becomes defined about 250m upstream of the footpath, approximately where the knick point used to be. The river banks are gently sloping and consist mainly of gravel/clay/peat, while the bed material is made up of gravel with some clay/peat outcrops. The water levels were near bank top at the time of survey and there is good connection between river and floodplain with no barriers to prevent out of bank flooding or return of flood water to the channel. Former bank-side deposits have been removed and the stream is now able to flood and retreat into the channel in response to flow. Due to the increased floodplain connection River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

and variation in depth, the restored channel seems to be resilient to depleted flows and the mire naturally provides permanent and temporary wetland features. The restored channel is sinuous with gravel bars, increased flow dynamics and width/depth variability. There is an abundance of macrophytes and good habitat diversity with pools, riffles and gravel bars still developing. This will create spawning habitat for rheophilic fish (brown trout, brook lamprey, bullhead) and good habitat for aquatic invertebrates. The floodplain vegetation is still in a state of flux following restoration works and infilling of the former ditch channel. However, this appears to be developing into an area of rush pasture vegetation and may be considered a component of the Annex 1 habitat type Eu-Molinion for which the New Forest has been designated a SAC. There are also good transitions from the floodplain to the valley side wet heath habitats and in places presence of the hummock vegetation which combines Eu-Molinion rush pasture with wet heath habitats.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

National Vegetation Classification Survey This survey confined itself to the lower section of the valley mire that had been subject to recent restoration works following the JBA survey of 2013. The details of the restoration works are shown in Figure 5.2.1. M25a Molinia caerulea – Potentilla erecta mire Erica tetralix sub-community

Much of the central mire vegetation upstream of the path that crosses the Bog consists of M25a Molinia caerulea-Potentilla erecta mire. This is characterised by large tussocks of Molinia caerulea and an abundance of sharp-flowered rush Juncus acutiflorus. Associated species are few but include the community constants of Potentilla erecta and Erica tetralix. Towards the margins of the mire, bog myrtle Myrica gale forms a distinct transition zone between the mire and the adjacent wet heat/rush pasture community. The mire currently lacks significant Sphagnum growth but there is evidence of a possible transition to poor fen habitat with locally abundant start sedge Carex echinata – a constant species of M6 Carex echinata – Sphagnum recurvum/auriculatum mire. S12 Typha latifolia swamp

An area on the western side of the mire retains an area of Typha latifolia swamp. This can be classed as S12 Typha latifolia swamp. It occupies a relatively small area 20-30m in diameter, shown in Figure 5.6.1. Earlier surveys undertaken by JBA Consulting suggest that the Typha swamp occupied a larger area in 2013 and linked with the Phragmites swamp to the north. S4 Phragmites australis swamp

The upper reaches of the valley supports an area of Phragmites australis swamp growing through the Molinia mire vegetation. This probably conforms to S4c Phragmites australis swamp Menyanthes trifoliata sub-community. The JBA report shows this extending down the valley to link with the area of Typha latifolia swamp. This was not evident in the autumn of 2014 with a distinct break occupied by Molinia mire between the two swamp communities as shown in Figure 5.6.2.

5.6.1. Views to south of Soldiers Bog with Typha latifolia swamp within M25 Molinia mire and transition to wet heath with Narthecium ossifragum in the foreground (date unknown)

5.6.2. Mire with Phragmites swamp to the north of Soldiers Bog (date unknown)

M29 Potamogeton polygonifolius – Hypericum eloides soakaway

This is the typical community formed along water tracks through the mire vegetation. In Soldiers Bog it is dominated by bog pondweed Potamogeton polygonifolius with unusually little Hypericum eloides. This may River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

reflect the recent restoration of these features following the infilling of the drainage channel through the Bog in 2013/14. These soakaway tracks are also marked by the presence of abundant star sedge Carex echinata. M16a Erica tetralix â&#x20AC;&#x201C; Sphagnum compactum wet heath Typical sub-community/M23 Juncus acutiflorus Galium palustre rush pasture - Juncus acutiflorus sub-community

Between the Bog crossing and the edge of North Oakley Inclosure, the stream has been restored to its meandering course through a mosaic of wet heath and rush pasture vegetation. The wet heath occupies the slightly higher ground on the valley sides and forms a typical hummock structure around the Molinia tussocks (Figure 5.6.3). These tussocks are marked by cross-leaved heath Erica tetralix wet heath with the intervening grassland consisting of well grazed marsh grassland with abundant Molina caerulea, Juncus acutiflorus, Potentilla erecta, carnation sedge Carex panicea, yellow sedge Carex viridula oedocarpa and heath grass Danthonia decumbens. Along the stream course, the wet heath element is reduced and a more typical rush pasture lawn is developing along the floodplain. The stream banks are marked by marginal clumps of Myrica gale. A24 Juncus bulbosus stream vegetation

The soakaway vegetation within the restored mire system emerges as a defined stream just above the bridge and stream crossing. At the time of survey this supported a swift flow over a gravel stream bed. The channel supports abundant aquatic macrophyte growth consisting of Potamogeton polygonifolius, Elegiton fluitans, Ranunculus omiophyllus, Glyceria fluitans, Juncus bulbosus and Callitriche sp (Figure 5.6.4). Allocating this community to the NVC is difficult as it does not conform well to any of the described communities. Sanderson (2001) refers to the Juncus bulbosus community being present within slower flowing peaty streams in the New Forest and having a close affinity to the M29 soakaway community. It is likely that flows in the Soldiers Bog stream were significantly enhanced at the time of survey in the autumn of 2014 and will reduce to a much more typical slow flowing seepage in the summer months where A24 Juncus bulbosus community is more typically found.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

5.6.3. Molinia tussock in hummock wet grassland/wet heath mosaic flanking the valley side at the southern end of Soldiers Bog (date unknown)

River Restoration Centre/Jonathan Cox Associates

5.6.4. Well developed aquatic macrophyte vegetation within the restored meandering stream channel to the south of Soldiers Bog (date unknown)

New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives Mire Restoration Objectives To stabilise mire systems against further erosion and drying as a result of artificial drainage either in the mire itself or from knick point migration as a result of downstream artificial drainage.

Improve water levels and water retention within mire systems Re-establish/improve the quality of mire habitat communities

Evaluation Mire restoration has been effective in removing any defined drainage channel through the mire and creating natural soakaways. This mire appears to be responding well with developing soakaway vegetation communities and possibly a reduction in the extent and vigour of Typha and Phragmites swamp communities. Water levels in the mire appear to be high and stable restoring good conditions for restoration of mire vegetation. Restoration of mire communities with the development of Sphagnum dominated vegetation is likely to create examples of the Annex 1 habitat type â&#x20AC;&#x2DC;Depressions in peat substrate with Rhynchosporionâ&#x20AC;&#x2122;; a habitat for which the New Forest has been designated a SAC.

River Restoration Objectives Achieve a diverse natural channel morphology comprising pools, riffles and meanders Reconnect floodplain habitats and re-activate floodplain morphology and function Stabilise the hydrological system to a more natural, balanced state to reduce excessive scour, overdeepening and headward erosion.

Increase the value/quality of in-stream habitat niches for fish and macro-invertebrates

Restore the quality and diversity of floodplain vegetation communities through the effects of natural seasonal flooding and re-activation of floodplain interaction.

River Restoration Centre/Jonathan Cox Associates

Evaluation The restored river has a sinuous plan form and gravel sorting developing pool and riffle sequences. The connection between the adjacent bog and the river has been largely increased by bed level raising and meander restoration. The work has addressed this by raising the bed level of the river in the upper reaches and returning the original meandering course (and infilling old drain). The old eroding knick-point could not be seen at the time of the survey. Hydromorphoplogically the project has been successful and the restored river provides good habitat diversity for rheophile fish and invertebrates including pools, riffles, gravel bars and a diversity of macrophytes. The floodplain vegetation appears to be developing into an area of rush pasture vegetation and may be considered a component of the Annex 1 habitat type Eu-Molinion for which the New Forest has been designated a SAC. There are also good transitions from the 43

New Forest Wetland Restoration Review

floodplain to the valley side wet heath habitats and in places presence of the hummock vegetation which combines Eu-Molinion rush pasture with wet heath habitats.

Appropriateness of techniques Generally, raising the stream bed with heather bales, imported hoggin and recovered gravel has worked well and there was no sign of the knick-point upstream of the footbridge. Restoration of the meandering channel has been successful. It’s very gently sloping, and sometimes undefinable, banks create a very good connectivity to the adjacent mire, especially in the upper reaches. The infill of the drain has worked very well and it is difficult to determine exactly its old outline. There are also no noticeable signs of where any clay plugs have been put in.

Lessons learned Due to the bed level raising, remeandering and increased connectivity with the floodplain it is likely that the current species poor Molinia dominated mire will develop into a more natural mire with increased Sphagnum growth and poor fen species typical of M6 Carex echinata-Sphagnum recurvum mire. Currently there is no Sphagnum at the upstream end of the restoration area. The restoration works have led to increased:  channel sinuosity;  flow and habitat diversity;  macrophyte cover;  marginal vegetation;  a more species rich bog. The infilling of the old drainage channel has worked well, it has blended into the landscape and it is now difficult to spot where the channels once were. For recovery of the mire vegetation it is essential that grazing by New Forest stock is encouraged. This will reduce the dominance of Molinia and encourage a greater diversity of mire species.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

5.9.1. Footbridge (item 3 on Fig 5.2.1) in the restoration before relocation. Photo: JBA (date unknown)

5.9.2. Restored stream with relocated footbridge. (2014)

5.9.3. Channel prior to restoration, localised erosion due to incision. Photo JBA (date unknown)

5.9.4. Channel after bed level raise. (2014)

5.9.5. Old drainage channel being filled in (2013). Photo: Alaska

5.9.6. Same view one year after restoration. (2014)

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Summary Restoration of Soldiers Bog was undertaken in 2013/2014. The vegetation and ecology is still in a state of some flux as a consequence of these recent changes. However, the works undertaken appear to have been very successful with good restoration of mire and stream hydro-morphology. Further monitoring is needed to record restoration of the mire vegetation and associated stream ecology as these habitats reach equilibrium with the restored conditions.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

North Oakley Overview North Oakley was inclosed from the open New Forest in 1853 to create the current plantation. This has been managed to create a mixed woodland composed of both conifer and broadleaved species. Meandering south through the inclosure is the Blackensford Brook. This is fed from Soldiers Bog within Backley Bottom to the north of the inclosure boundary. The Blackensford Brook had been straightened and deepened probably at the time of inclosure to improve drainage and encourage tree growth. Since stream restoration, the Brook has been returned to its former meandering course although this now flows through plantation woodland rather than the open Forest lawn (Blackensford Lawn) that it did prior to the creation of the inclosure. Figure 6.1.1 shows the meandering course of the Blackensford Brook through Backley Bottom, then under the track that crosses Soldiers Bog. North Oakley Inclosure, Blackensford Brook - extract from LIFE3 final report (2006) The majority of this 800m reach is within Forest Inclosures, stretching from the point at which the Blackensford Brook divides from what goes on to become the Bratley Water at SU 237 065, to where there is further division into Blackensford Bottom and Stinking Edge Wood at SU 230 069. This was a straight, artificial channel through floodplain woodland, with bed levels lower than the adjacent palaeochannel, which was evident primarily on the left bank. The deepened nature of this channelised reach had eroded upstream, beyond the Inclosure boundary where the watercourse bifurcates, and was eroding back into headwater mires on each arm. As a result, further work was also proposed outside of the Inclosures, connecting the river restoration works with mire restoration works done under Life 2. This extended some 350m up each river fork into the Open Forest to SU 228 069 in Blackensford Bottom, and SU 230 070 in Stinking Edge Wood.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Figure 6.1.1. Extract from Drivers map of 1789 showing course of the Blackensford Stream through Backley Bottom and Blackensford Lawn. The approximate location of the current inclosure boundary is super-imposed in blue.

The project was an early part of the LIFE 3 New Forest project. The works were undertaken June to August 2005 on 800m of the Blackensford Brook. Information on the works undertaken at North Oakley is limited to the summary in the final LIFE 3 report.

Project summary The river length was increased by upwards of 7% (a conservative estimate rather than a measured length 2010 report) through reconnecting the old paleo channels. From Google Earth, the restored course is around 80% visible and very clear for mapping the length of the current course (895m) and the previous channelised route (740m) both from the lower bridge to the upper joining of tributary channels (Blackensford Bottom and Soldiers Bog). This represents a gain in length and thus sinuosity of 21%.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

6.2.1-2. Restored channel through North Oakley Inclosure with point bars and pool and riffle sequences (2014)

Objectives Specific restoration objectives have not been published but can be interpreted from extracts in the LIFE 3 report (LIFE 3, 2006). These were to:  Prevent further headward erosion into the mire habitats outside of the inclosure.  Restore flows to palaeochannels from deepened and channelised channel.  Create an area of new floodplain woodland. Prior to the creation of North Oakley Inclosure in the 19th century the Blackensford Stream flowed through an area of wet grassland referred to as Blackensford Green. The stream was deepened and straightened to facilitate woodland planting within the silvicultural inclosure, as shown in figure 6.1.1. Restoration of the old meandering channel will create new riverine woodland habitat within the inclosure.

Restoration techniques The restoration techniques used included:  Reconnection of the remnant paleo-channels over a length of approx. 1km.  Raising and narrowing the bed of the existing channelised brook where the two channels merge.  Infilling the existing channel using spoil from on-site (possibly supplemented with imported hoggin).

Current status Ecology North Oakley Inclosure is currently assessed by Natural England as being in unfavourable recovering condition. This assessment was undertaken in October 2011 and is predicated on proposals within the Forest Design Plan to restore the inclosure woodland to semi-natural vegetation and restore more open conditions along the stream floodplain. This work is still ongoing and the compartment remains in unfavourable but recovering condition. Hydromorphology The cleared conifer plantation now consists of areas of mixed deciduous woodland, so drier than would be typical for a floodplain woodland. This is consistent with the Blackensford Brook being towards the top end of the Blackwater, and the site being at the top of the Blackensford Brook. It would be expected that gradients would be steeper when higher in the catchment. Although the site visit was only two days after a significant wet period in the forest (deep flooding of the floodplain at the lower reaches of the Blackwater), it was clear that little overbank flow had taken place at North Oakley (evidenced by undisturbed leaf litter). River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

6.5.1/2. Lower section, the only place where there was evidence (leaf litter washed away) of overland flow between the restored brook and the old channel. Mostly the two courses (restored and old) will have little interaction (2014)

The restored course is, therefore, still somewhat disconnected from its floodplain. Inundation occurs, and most likely on a more frequent basis than prior to the restoration, but the adjacent vegetation is not characteristic of a floodplain habitat. It is unclear if wetland restoration was a key objective for this site but this has not been achieved. However, the reconnection with paleo channels has produced a less incised, more characteristically sinuous course with a variety of bed features and width and depth (thus flow) variation. It appears that some attempt had been made to incorporate in-channel and â&#x20AC;&#x2DC;floodplainâ&#x20AC;&#x2122; flow obstructions from on-site woody material (tree trunks and grubbed out stumps), however, they have not accumulated significant smaller material, so are having only limited effect (principally some scour around the downstream side at high flows).

6.5.3. Cross-channel tree and stumps (2014)

River Restoration Centre/Jonathan Cox Associates

6.5.4. More comprehensive structure showing deep pools and gravel shoals (2014)

New Forest Wetland Restoration Review

One new woody structure (debris dam) has formed (or further developed if it was â&#x20AC;&#x2DC;installedâ&#x20AC;&#x2122;) and this has created complex flow patterns, accreted a large gravel shoal above and offers habitat for invertebrates and fish. The impact is that below this point the restored course has scoured much of the gravel placed in this old channelised section, so that whilst the structure is playing an important role to regulate the transport of bed material (as would naturally occur with multiple long term woody structures), it is also denying the downstream reach from this source material resulting in a short denuded section.

6.5.5. Fallen tree changing the flow pattern and providing habitat (2014)

6.5.6. The structure is stabilising with further leaf and wood input from above (2014)

6.5.7. In-filled old straightened course (2014)

6.5.8. The retained straightened course in the upper part of the reach (possibly retained due to lack of in-fill material) conveying some surface water (2014)

The old straightened reach has been completely in-filled in the middle and upper reaches, and is only really visible as a distinction between the grass cover against the surrounding bracken (plus a 4-5m wide absence of trees). In the lower reach, much of the old channel still remains as a shallow linear pond, which would convey flow in exceptionally wet periods.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

6.5.9. The headcut. Arrow indicates the return to the old course (2014)

6.5.10. Forming a deep pool (1.5m) (2014)

A knick point has developed approx. 30m above the point where the restored course flows back into the old channel. It can be seen that by eroding back upstream, this has dropped the bed level and thus the water level by approx. 20cm, eating into the gravel bed down to the underlying clay. It is assumed that this has travelled around 20-30m in the past 10 years and formed due to a slight steepening of the gradient as the shallow restored course needed to be returned to the deeper straightened brook. The knick point has formed a considerable hole in the bed. Whilst this feature offers a deep holding pool for fish, etc. it could continue upstream (over decades) and leave a denuded clay bottomed bed below it (or the clay may prove stiff enough to withstand further erosion). These features would usually be interrupted by structures such as woody material blockages, forming bed checks to interrupt the movement of bed material. Even in the restored course, without these woody material features there is little to prevent occasional high flows scouring the bed and cutting in to the clay beneath where it is locally less cohesive.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

National Vegetation Classification Survey W14 Fagus sylvatica â&#x20AC;&#x201C; Rubus fruticosus woodland

The woodland through which the Blackensford Stream flows all conforms to a single woodland NVC community with a canopy dominated by planted beech Fagus sylvatica and pedunculate oak Quercus robur. The ground flora is species poor but includes scattered plants of Molinia caerulea and Juncus effusus that are perhaps indicative of its former open lawn habitat with some woodland species such as wood sorrel Oxalis acetosella and violet Viola riviniana. There are also frequent mossy patches with abundant Thuidium tamariscinum and Polytrichum formosum. The restored stream now appears reconnected with its flood plain and there is evidence of out-of-bank flooding with localised grassy lawns with gravel outwash in the stream flood plain. These are species poor and dominated by common bent Agrostis capillaris with some Oxalis acetosella, Stellaria media, Ranunculus repens, Prunella vulgaris, Juncus effusus and Digitalis purpurea. The ground flora away from the stream channel appears to be patterned by flooding with drier areas being dominated by bracken Pteridium aquilinum. This is also species poor but contains some bramble Rubus fruticosus, honeysuckle Lonicera periclymenum, Molinia caerulea and Juncus effusus. The old drain channel has been partially retained in the floodplain although separated from the restored meandering channel with clay infill. This disturbed clay has been colonised by creeping buttercup Ranunculus repens, creeping bent Agrostis stolonifera, self heal Prunella vulgaris, spear thistle Cirsium vulgare, violet Viola riviniana and lesser spearwort Ranunculus flammula.

6.6.1. Restored stream course through North Oakley inclosure with good pool and riffle sequences and side bars under dense canopy of beech and pedunculate oak (2014)

6.6.2. Stream floodplain within North Oakley inclosure showing patterning of ground flora with bracken dominated higher ground and grassy woodland lawns within lower areas of the floodplain (2014)

A24 Juncus bulbosus stream vegetation

The stream channel through much of the inclosure is heavily shaded and supports little aquatic macrophyte growth with only scattered plants of Juncus bulbosus var fluitans, Potamogeton polygonifolius and Callitriche stagnialis. The stream banks are marked by hard fern Blechnum spicant and lady fern Athyrium felix-femina. This sparse community is difficult to assign to the NVC but is probably developing towards the A24 Juncus bulbosus community.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Towards the edge of the inclosure shading is less heavy and a more diverse aquatic flora develops with Eleogiton fluitans occurring together with a greater abundance of Potamogeton polygonifolius, Juncus bulbosus var fluitans and occasional plants of round-leaved water-crowfoot Ranunculus omiophyllus. This suggests a seasonally reduced water level and flow, with significantly increased flow rates during the autumn and winter that perhaps belie the reduced flows and water levels experienced in the summer months.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives No mire restoration was undertaken a this site, but it links seamlessly with the 2012 Soldiers Bog river restoration work to tie in with mire restoration as part of LIFE 2 in the upper Soldiers Bog area. River Restoration Objectives Achieve a diverse natural channel morphology comprising pools, riffles and meanders

Reconnect floodplain habitats and re-activate floodplain morphology and function.

Stabilise the hydrological system to a more natural, balanced state to reduce excessive scour, overdeepening and headward erosion.

Increase the value/quality of in-stream habitat niches for fish and macro-invertebrates

Restore the quality and diversity of floodplain vegetation communities through the effects of natural seasonal flooding and re-activation of floodplain interaction.

Evaluation The morphology is far more diverse than it would have been in the old channelised reach, with a good range of bed forms within a sinuous channel (with an increase in length of 21%). The adjacent open woodland is not floodplain woodland per se, but does have some degree of inundation now. It is unclear if this was an initial objective for this site. The work has addressed this mostly by simply returning the channel to the original meandering course. Areas where there is some excessive scour are the lower â&#x20AC;&#x2DC;returnâ&#x20AC;&#x2122; section (steeper gradient necessary to equalise the bed levels) where a scour pool and headcut has developed, and downstream of a stable woody blockage where sediment supply is being starved. Hydromorphoplogically this has been successful along the majority of the project, however limited presence of in-channel wood and macrophyte growth are both limiting the degree of habitat available to complement the bed morphology. Adjacent woodland inundation now occurs more regularly, however this is not floodplain woodland. The 2011 aim is to restore the inclosure woodland to semi-natural vegetation and restore more open conditions along the stream floodplain. This work is still ongoing and the compartment remains in unfavourable but recovering condition.

Appropriateness of techniques The main technique of reconnecting the existing paleo-channels has been very successful. It has overcome the issues of lack of sinuosity, over-deep and over-wide bed and negated the difficulties associated with inchannel narrowing and shallowing. It was very difficult to discern exactly where the new and old channels crossed paths and, therefore, had required raising and narrowing of the existing channelised course. In itself, this displays that the works have achieved considerable success such that evidence that restoration work has been undertaken is so hard to see, even for the experienced observer. In most cases this is the ultimate definition of success. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

The infill of the old channel has worked well. The sections do demonstrate a different character from the surrounding woodland, not only the obvious lack of mature trees, but also the change in vegetation to grass rather than bracken domination. The greater diversity of channel features has the potential to provide good habitat for fish and macroinvertebrates but this potential is being restricted due to a lack of woody material in the channel and heavy canopy shading. Further thinning of the canopy to create well lit streamside lawns with scattered opengrown oaks and beech and the deposition of more in-stream dead wood would help improve the stream habitat.

Lessons learned The imported clay plugs used to create the initial barrier to water re-entering the old channel, have remained poorly vegetated, very soft when wet and the only obvious sign of the old course where in-filled. In a few instances they are visible where the channel has migrated a short distance and eroded in to the compacted clay. They could be set further back from the new channel edge, such that they provide the hydrological barrier to seepage into the old straight channel. The bulk backfill could be achieved by using excavated material. Local adjustment of the edges would not then expose the clay which is unlikely to colonise with bankside vegetation as quickly.

6.9.1. Clay plug visible on the far bank (2014)

Summary The reconnection work has been very successful, probably due to the obvious paleo-channel needing little additional work. Very minor comments such as those above would be expected on any project after 10 years. Additional work and areas to monitor erosion would be the lower 30m including the headcut and scour pool, to the join with the channelised course. The use of significant quantities of woody material (including whole trees as shown above), to reduce velocities in this scouring section and to accrete gravel should be considered. Thinning of the woodland canopy and restoration of the former Blackensford Lawn would significantly improve the value of the floodplain vegetation communities. These are likely to revert to species rich rush River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

pasture (Annex 1 habitat type Eu-Molinion). The currently heavily shaded floodplain is generally species poor but shows clear patterning between flooded grassy areas and higher bracken dominated areas.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Dames Slough Inclosure Overview Dames Slough Inclosure was created in 1859 (NFA, 2006) from an area of wood pasture and heath (as shown in Driver’s Map of 1789). Following inclosure the Open Forest habitats were planted with a mix of broadleaved and conifer trees. The site includes a 3.0km section of the Blackwater as it begins its final West to East journey prior to joining the Highland Water and the Lymington River. The river restoration work was carried out May to June 2005. The river had been straightened (realigned) and significantly deepened and widened to accommodate increased flows and to drain the 100m wide floodplain for conifer planting. Drainage of the floodplain was also undertaken using open drains. The dense conifer planation had hidden extensive paleo-channels. Dames Slough – extract from LIFE3 final report (2006)

Work was carried out on a 1.56 km channelised reach totally within Forest Inclosures, stretching from the Black Water bridge on the A35 at SU 253 047 upstream to Dog Kennel Bridge at SU 240 050. This reach runs primarily through what was fairly deep conifer plantation with some extensively deepened and straightened channels and many spoil heaps clearly in evidence. Reference to the 1870s maps indicated that the channel had been straightened post this period. River restoration work started on 11 May 2005, and included the following: • Re-instatement of original meanders; • Cutting of new meanders where original channel could not be located; • Installation of 10m clay plugs to divert flow from drainage channel into new meander; • Partial back-fill of drainage channel and re-profiling of banks, leaving backwaters and linear ponds where in-fill material was not sufficient; • Bed-level raising work using locally sourced hoggin where the restored channel occupies the previous drainage channel. This work resulted in an increase of approximately 549 metres of river length, with a total of 2.109 km restored at this site. After the main bulk of work, further refining was made to river and floodplain profiles to optimise results. Large volumes of spoil were evident at the down-stream end of the Inclosure. These were stock-piled to be moved off-site to other areas targeted for restoration. The work carried out may contribute to the re-establishment of the rare cut grass Leersia oryzoides, a priority BAP species. Its extinction is thought to have been brought about through either over-shading, grazing, or re-routing of the channel. Consultation between EA and Neil Sanderson (ecological consultant and WBMF member) Project summary to secureconifer a suitable restoration design, takingtook into place, account its the specific habitatand requirements, Insought 2003 extensive removal from the floodplain with site raked burnt. Then, in which may help with its re-establishment. 2005, the main drains were in-filled with a combination of woody debris material and large logs from the site works and the spoil heaps embanking those drains, from when they were first excavated. Heather bales (a by-product of the Forestry Commission heather cutting work) were used as infill for the deeper sections to reduce the import of quarried hoggin which was then placed over the top. Where the new higher bed level had to cross the previous course, the difference was in-filled with hoggin up to the required bed level. The main drains were completely infilled using hoggin and clay plugs in 2010 due to the River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

partial infill of the main drains being insufficient to maintain floodplain stability (the clay plugs were being eroded). The fence lines were altered to allow access for machinery and also erecting a new section of Inclosure fencing as well as deer exclosure fencing. The current vegetation along the Blackwater through Dames Slough reflects the varied history of the inclosure, with elements of former wet grassland, swamp and heathland habitats becoming re-established together with retained elements of woodland and scrub habitats. These habitats form an intimate mosaic making it impossible to map individual elements of the vegetation. In approximate terms, rush pasture is the dominant vegetation type covering 60-70% of the floodplain. Drier grassland, bracken and scrub patches constitute 20-30% of the vegetation with pools, swamps and open water occupying the remaining 10%. The edges of the floodplain show classic transitions to wet and humid heathland although these are still in early stages of development, following tree clearance, and contain significant areas of bracken and locally dense purple moor-grass Molinia caerulea.

Figure 7.2.1. Extract from Driver’s map of the New Forest (1789) showing the now reinstated meandering course of the Blackwater within riverine woodland through what is now Dames Slough and Fletchers Thorns Inclosures.

Objectives Specific objectives have not been recorded for this individual site although it is assumed that the main objective was to naturalise the river and restore riverine floodplain habitats.

Restoration techniques The restoration techniques used included:  Reconnecting meandering paleochannels where existing.  Cutting new meanders where old course not clearly evident.  Blocking the old straightened channel with clay plugs. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review



Bed level raising where old course retained, using imported hoggin and existing spoil banks (created from drainage channel excavation and subsequent dredging).

Current status Ecology Dames Slough Inclosure was last assessed by Natural England in July 2008. It was then considered to be in unfavourable recovering condition. The inclosure has been returned to New Forest grazing although fences remain in place to manage stock. The assessment is brief but states ‘River restoration carried out successfully, conifers removed and commoners stock now grazing. Fences still in place to assist managing the stock.’ Since 2008 the inclosure has continued to develop and supports a mosaic of floodplain habitats that are not widely found in the New Forest as a result of reduced grazing pressure and presence of abundant early succession scrub. The Blackwater restoration has also been a considerable success with well developed meanders, in channel diversity and good connection between stream and floodplain. The aquatic macrophyte vegetation is well developed and is still developing. Hydromorphology A total of 2,109m of stream has been restored to its meandering course increasing its length by some 549 metres (LIFE III Technical Report, 2006)8. The site can be divided into three roughly similar length reaches (referred to as upper, middle and lower) by the two main forestry track crossing points as shown in Figures 7.5.1 & 7.5.2. The floodplain has remained open, with limited encroachment of bracken after the conifer felling. The reduction in width and depth of the channel (by routing it through the old paleo-channels), combined with the significant increase in length (reduced gradient), has acted to increase the frequency at which water overtops the banks and on to the floodplain in the upper and middle reaches.

Upper reach

Middle reach

Figure 7.5.1. Western end of Dames Slough Inclosure showing restored floodplain of the Blackwater. Map data 8

LIFE 3. Sustainable Wetland Restoration in the New Forest (2006) Technical Final Report. Hampshire County Council

River Restoration Centre/Jonathan Cox Associates

Middle reach

Lower reach

Figure 7.5.2. Eastern end of Dames Slough Inclosure showing restored floodplain of the Blackwater. Map data ©2015 Google Imagery ©2015 , DigitalGlobe, Getmapping plc, Infoterra Ltd & Bluesky Upper reach

From 30m downstream of the Dogkennel Bridge on the Lyndhurst Road, the Blackwater now follows the old course, exactly, as clearly visible on aerial photos (above). This upper reach functions well at just below bank full (as was occurring on the day of the site visit) and just overtopping. The sinuosity of the restored river and the in-channel and marginal vegetation were acting to spill floodwater onto the lowest (lower lying/lower gradient) floodplain areas.

7.5.1-2. Upper reach of the Blackwater in Dames Slough Inclosure (2014)

Aesthetically, the restored channel showed very few signs of being re-routed only 10 years before. There is a good degree of connectivity between the wetland vegetation, marginal plants and the river. Where mature trees occurred pre-restoration, many of these (though not plantation conifers) have been retained, and survive or are now dead wood contributing to the carbon input to the river system. River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

7.5.3. 9 May 2006, prior to reconnection

7.5.4. November 2014, same post same trees.

7.5.5. Paleo-channel with standing water, June 2006

7.5.6. Reconnected as restored course, Nov 2014

Middle reach

This reach clearly followed well defined channels (visible on old air photos) but then also has had to rely on excavation of new â&#x20AC;&#x2DC;connectingâ&#x20AC;&#x2122; channels in places. This reach is, in places, particularly low gradient and this wide wetland area would probably have masked the old course. However, as the gradient is low and the bank height very shallow, these new channels have blended in to the floodplain landscape very well. In some locations the incorporation of tree root structures in the bank and bed (through the precise location of the restored/new channel) has added a degree of complexity to the morphology, creating nearsurface (riffle) gravel deposition.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

7.5.7-8. Low lying adjacent banks, backwater (still water) and marginal habitat (2014)

The final 100m flows along the same course as the pre restored channel, but it is clear that the working of material from the 1km above, as well as that transported material from further up the catchment, has maintained the raised bed that was in-filled as part of the scheme.

7.5.9. Effects of bed raising still apparent (2014). Lower reach

The bed-raised old course also continues into the lower reach for approx. 150m. The course is not as sinuous as it is in the upper and middle reaches where old relic channels existed, but neither is it totally straight.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

7.5.10. 2005 - removal of gravel spoil banks and bed raising

7.5.11. 2014 â&#x20AC;&#x201C; channel narrowing and floodplain lawn re-growth

The main change is the return of the channel to a large meander, which was still open due to the input of a small tributary. From old maps (1st Edition OS - 1890s) it is clear that additional meanders could have been added to the restored course. These were not incorporated due to the potential presence of freshwater mud snail Lymnaea glabra, a rare species which was present in similar habitat at Black Water (Rhinefield Drive). This final reach does still appear to be less well integrated in to the restored character of the river. The channel remains wider and deeper, with a much greater bank height (around 50cm above being in contact with the floodplain when the upper and middle reaches are at bank-full).

7.5.12. The channel is still wide and incised compared to upstream (2014)

River Restoration Centre/Jonathan Cox Associates

7.5.13. Diverted off into the old loop (the clay plug is on the right bank) (2014)

New Forest Wetland Restoration Review

7.5.14. Just upstream of the A35, the channel is shallow but 10m wide (2014)

The A35 forms the lower boundary to this site, and floodplain flows would route overland flow towards this road if it were actively encouraged.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

National Vegetation Classification The floodplain habitats of the restored Blackwater stream remain within the fenced Dames Slough Inclosure and are not subject to the grazing pressure experienced in the Open Forest where commonersâ&#x20AC;&#x2122; livestock has free access. Although this inclosure has been thrown open, grazing pressure appears to be lower in the inclosure as much of the former fencing has been retained for stock management reasons. There are significant numbers of deer within the Inclosure fences. These provide a level of browsing and grazing pressure but this is visibly less than in the Open Forest. The cleared conifer plantations from the floodplain of the Blackwater have permitted the development of a complex mosaic of habitats consisting of rush pasture, grassy lawns, bracken, scrub, scattered trees, ponds, pools and swamps.

7.6.1. Mosaic of rush pasture, pools, bracken, scrub and scattered trees in the Blackwater floodplain, upper reaches of Dames Slough Inclosure (2014)

7.6.2. June 2006. The vegetation community at the same location prior to reconnection

M23 Juncus effusus/Juncus acutiflorus â&#x20AC;&#x201C; Galium palustre rush pasture

Marshy rush pasture is a dominant vegetation type in the floodplain mosaic. This consists of Juncus effusus, Juncus acutiflorus, Festuca rubra, Poa trivialis, Holcus lanatus, Agrostis stolonifera, Ranunculus repens, Senecio aquatiticus, Mentha aquatica, Prunella vulgaris and Trifolium sp. Floodplain puddles have some Glyceria fluitans and Ranunculus flammula. This mix of species suggests comparatively mesotrophic soil conditions than other examples of this community in the New Forest. This reflects the recent and disturbed nature of the habitat and is likely to develop more species diversity and lose some of the more mesotrophic species over time. A large cleared lawn occurs midway along the restored stream section where a large area of rush pasture is developing. This still conforms to M23 but includes a greater diversity of species including greater abundance of Galium palustre, Potentilla erecta, Carex panicea, Agrostis canina and Carex viridula var oedocarpa. This is a more typical combination of species of this community. The northern edge of the floodplain also shows transitions to wet heath (M16a) with a greater abundance of Molinia caerulea and Erica tetralix. U4 Festuca ovina-Agrostis capillaris-Galium saxatile grassland

On slightly raised parts of the floodplain not covered with bracken are patches of U4 moist acid grassland conforming to U4. These areas are dominated by the fine leaved common bent grass Agrostis stolonifera River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

with a varied associated flora including Holcus lanatus, Potentilla erecta, tufted hair-grass Deschampsia cespitosa, Lotus corniculatus and occasional trailing St John’s wort Hypericum humifusum. S12 Typha latifolium and S14 Sparganium erectum Swamps

There are numerous side channels and marginal swamps within the floodplain. These are all small in scale occupying patches of 10-20 metres in diameter. They are dominated by combinations of branched burreed Sparganium erectum and reed mace Typha latifolia. The former constitutes S14 Sparganium erectum swamp, the latter S12 Typha latifolia swamp but in reality the swamps are a mix of these two communities with Typha dominating in the slower flowing and still water and the Sparganium as marginal swamp in the slightly faster flowing water. Associated species include Purple loose-strife Lythrum salicaria, water plantain Alisma plantago-aquatica, water mint Mentha aquatica, fool’s water-cress Apium nodiflorum and soft rush Juncus effusus. Swamps such as this are uncommon in the New Forest and have developed here on mesotrophic silt and clay substrates within these recently restored wetlands in the absence of significant grazing pressure. It is likely that they will evolve into more typical acid and base poor mire communities over time or become colonised by scrub. Some evidence of this is shown by the presence of occasional patches of bog myrtle Myrica gale growing on the stream banks. However, in their current state they provide unusual New Forest habitat and are likely to support a good diversity of wetland invertebrates.

7.6.3. Marginal branched bur-reed Sparganum erectum swamp with bog myrtle Myrica gale on the banks of the Blackwater (2014) W25b Pteridium aquilinum-Rubus fruticosus underscrub

Slightly raised mounds in the floodplain have isolated patches of bracken Pteridium aquilinum dominated vegetation with honeysuckle Lonicera periclymenum, bugle Ajuga reptans, bird’s foot trefoil Lotus corniculatus, wood sage Teucrium scorodonium and bramble Rubus fruticosus. This mix of species fits within W25a of the NVC. This bracken type was classified as Group 5; Bracken with Bramble, Honeysuckle and Litter community by Cox and Bealey (2013). It is a common bracken vegetation type in the New Forest where it often occurs at the edges of woodlands and can act as a nurse to regenerating woodland. W10 Quercus robur – Pteridium aquilinum – Rubus fruticosus woodland

Thinning of the inclosure plantations has left a scatter of pedunculate oaks across the floodplain creating a park-like structure. At its lower end, the stream also links with more dense oak-ash woodland on its northern side. This is ancient woodland that has survived the inclosure planting. It slopes gently away from River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

the stream on the valley side. The canopy is dominated by a mix of Quercus robur and Fraxinus excelsior with a mix of beech Fagus sylvatica and some silver birch Betula pendula. The shrub layer is very sparse but includes some scattered hawthorn Crataegus monogyna. The ground flora includes a number of woodland species including butcher’s broom Ruscus aculeatus, wood sorrel Oxalis acetosella. Where the woodland is flushed by occasional floodplain flows there is some evidence of base enrichment with the presence of forget-me-not Veronica montana and wood false-broom Brachypodium sylvaticum. W1 Salix cinerea – Galium palustre woodland

The floodplain also contains many patches of scrub. These form part of a complex mosaic of vegetation types with cover of scrub ranging from up to 30% in places but more often forming discrete patches occupying 10-20% cover. Scrub species vary with soil moisture levels and range from the bramble clumps associated with bracken patches (W24) to more dense patches of grey willow Salix cinerea/silver birch Betula pendula scrub (W1 Salix cinerea-Galium palustre woodland). Associated species include downy birch Betula pubescens, alder Alnus glutinosa, bramble Rubus fruticosus, hawthorn Crataegus monogyna and field maple Acer campestre over a ground flora of Yorkshire Holcus lanatus and creeping bent Agrostis stolonifera. A24 Juncus bulbosus & A14 Myriophyllum alterniflorum stream vegetation

The restored course of the Blackwater meanders through the floodplain over a gravel stream bed. It supports a good aquatic macrophyte flora that appears to become more diverse towards the eastern, lower, end of the section. The upper reaches of the stream support regular patches of Glyceria fluitans with Potamogeton polygonifolius, Eleogiton fluitans, Juncus bulbosus var fluitans, Ranunculus omiophyllus and Callitriche stagnalis. Lower down the restored section (Lower Reach) are also some well developed beds of Myriophyllum alterniflorum with Juncus bulbosus var fluitans, Glyceria fluitans and Potamogeton polygonifolius. These sections of stream are probably referable to the A14 Myriophyllum alterniflorum community. This is characteristic of faster flowing, somewhat les acidic streams of the New Forest. Gravel bars within the stream support emergent vegetation consisting of Apium nodiflorum with Ranunculus flammula. This may be considered a small stand of S23 ‘Other water-margin vegetation’. 7.6.4. Beds of Juncus bulbosus var fluitans with Myriophyllum alterniflorum in the lower reaches of the Blackwater within Dames Slough Inclosure (A14 Myriophyllum alterniflorum community) (2014)

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives No mire restoration was undertaken at this site. River Restoration Objectives Achieve a diverse natural channel morphology comprising pools, riffles and meanders

Evaluation Pools and riffles are subtle as the gradient is very flat in places. The channel is maintaining a good gravel bed, with diversity of bed forms and cross sectional profiles. The use of the old remnant meanders means that there was already wetland vegetation on the banks, so bare bank erosion issues were limited and do not appear an issue now. In the sections where bed material was in-filled, the geometry of the channel is still over-large, and the river is confined within comparatively high (50cm) banks. This agrees with the summary of benefits and concerns of Sear et al (2012)9.

Reconnect floodplain habitats and re-activate floodplain morphology and function.

This has been very successful in the re-meandered sections.

Stabilise the hydrological system to a more natural, balanced state to reduce excessive scour, overdeepening and headward erosion.

The far greater sinuosity, increase in length and consequent decrease in gradient has reduced flow velocities. This has reduced the likelihood of scour (bed and bank). The restored course is also consolidated by tree roots, scrub and marginal vegetation, and has the added â&#x20AC;&#x2DC;balanceâ&#x20AC;&#x2122; that this was the natural course of the river which existed in equilibrium within its floodplain prior to being realigned.

Increase the value/quality of in-stream habitat niches for fish and macro-invertebrates

Hydromorphoplogically this has been successful along the majority of the project, however limited presence of in-channel wood and riparian cover are both limiting the degree of habitat available to complement the bed morphology. River restoration has reconnected the Blackwater with its floodplain which now supports a complex mosaic of wetland habitats including scrub, rush pasture, swamps, pools and ponds. These are being well maintained by grazing of New Forest stock although grazing pressure appears to be less than in the adjacent areas of Open Forest.

Restore the quality and diversity of floodplain vegetation communities through the effects of natural seasonal overspill and re-activation of floodplain interaction.

Sear, D. E. (2012). New Forest Hydrogeomorphology, University of Southampton.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Appropriateness of techniques    

Reconnecting meandering paleochannels where existing; Cutting new meanders where old course not clearly evident; Blocking the old straightened channel with clay plugs; Bed level raising where old course retained, using imported hoggin and existing spoil banks (created from drainage channel excavation and subsequent dredging).

Reconnection of the paleo-channels has been very successful, especially in the upper and middle reaches. The significant reduction in size when compared to the channelised course has improved connectivity with the surrounding extensive floodplain. There were only a few sections where entirely new channels needed to be dug to connect to the paleochannels, as most of the old course was still visible. For this reason there was a clear ‘template’ for any such new routes from the adjacent area, helping to avoid over or under sizing these new cuts. The 10m clay plugs have taken a long time to establish vegetation, due to the nature of the type of clay required to ‘seal’ the old channel ends. This is compounded by the poaching by pony hooves when the clay is saturated. The result is boggy clay areas with poor vegetation development. These areas also invite more grazing pressure as effectively open grassed ‘lawns’ without dense vegetation to hinder movement. Bed level raising has not been as effective as the re-meandering, at the lower end of the site, mostly due to still retaining the previous width (unaffected by just bed raising). This is less effective at increasing the desired frequency of overbank flow, and so concentrates flow within the channel which acts to scour the introduced bed material. Floodplain habitats (especially the upper three quarters of the site) have been transformed since the restoration work. The current diverse mosaic of habitats has replaced dense, species poor spruce plantations along much of the length of the Inclosure. The River Corridor Survey (1996)10 describes these as follows;‘This stretch of river has undergone extensive deepening and straightening at some time in the past and no longer has any real meanders remaining. It has subsequently lost the majority of its geomorphological interest with most of the channel being square in cross section. In addition, the lack of any flow in the channel makes it difficult to assess flow types. During periods of better flow it is likely that these will consist largely of riffles and runs. Only a few shallow pools remained in the channel bottom during the time of survey. The adjacent habitat consists largely of coniferous woodland with occasional areas of broad leaved wood on the left bank. Some overhang on the left bank, plus the recesses channel gives the river an enclosed feel.’

Lessons learned Achieving a more comprehensive restoration of the size of channel (at the lower end of the site) and the river’s connectivity with the floodplain, would require redesign of the road bridge to accommodate a wider floodplain flow path and raised bridge.

Holzer, T. (1996) Strategic River Corridor Survey of the New Forest Catchment Report Two Volume 6 - Tributaries of the Lymington - the Blackwater and Oberwater. Report to the Environment Agency, Bugle Ecological Services River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Clay plug sections, where there is a propensity for the clay to remain soft and vegetation establishment to be slow, could be protected more from the pressure of grazing animals (in particular hoof damage) by placing any excess brushwood, felled trees, root balls, etc. on these areas. This approach has been used by the contractors at Fletchers Thorns (see Chapter 8). This would detract from animals grazing and poaching the banks and provide a less disturbed area for vegetation growth and gradual settlement and compaction of the clay plug with time. The plugs could alternatively be set further back from the new channel edge, such that they provide the hydrological barrier to seepage into the old straight channel. The bulk backfill could be achieved by using excavated material. Local adjustment of the edges would not then expose the clay which is unlikely to colonise with bankside vegetation as quickly.

7.9.1. Clay plug showing the impact of hoof trampling and poor vegetation growth after 10 years (2014)

Downstream of the access bridge (1st section of the lower reach) could have been narrowed using woody material and additional gravel to restrict the size of the channel further. However towards the lower end this would not be possible due to the proximity of the A35 bridge.

Summary The upper two thirds of the restored River Blackwater at North Oakley Inclosure are functioning better as a meandering floodplain stream than the lower third. Comparison of the 1996 River Corridor Survey shows the magnitude of structural change that has occurred. The increased length and diversity of structure in the Blackwater have significantly improved it as a habitat for aquatic macrophytes, invertebrates and fish. The high sinuosity and comparatively small depth and width both combine to allow the river to spill out onto the floodplain in periods of high rainfall. Whilst still visible as an absence of trees in most places, the old in-filled channel is vegetating well (except the clay plugs, see above).

River Restoration Centre/Jonathan Cox Associates

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Fletchers Thorns Overview At its upstream end, this stretch of the Blackwater emerges from a forestry inclosure known as Fletchers Thorns Inclosure. The restored stream now follows a meandering course across an area of stream-side lawn with fringing heathland before entering an area of riverine woodland and scrub through which the stream flows to its confluence with the Highland Water. Prior to restoration, the river had been realigned to a wide artificial drainage channel dug in a straight course from the Inclosure to Queen Bower. The drain had a uniform cross section with poor habitat diversity, little or no gravel and spoil banks limiting interaction with the floodplain and leaving large areas of standing water not draining back into the channel.

Figure 8.1.1. The meandering course of the Blackwater through Fletchers Green at the end of the 18 century. The current inclosure boundary incorporates the woodland along Fletchers Water and much of the former Pound Hill Heath

Project summary The river restoration at Fletchers Thorns covers a stretch of approximately 1.3km from the gravel track at SU2759604327 to the confluence with Highland Water at SU2886604333 (Figure 8.2.1). The restoration was carried out in summer 2011 and the restored reach can be roughly divided into three sections: 1. Open grassland section without tree cover or riparian vegetation SU2759604327 - SU2776604245 2. Semi-open section partly covered by dense thorn scrub SU2759604327 - SU2799604255 3. Woodland section which becomes increasingly mature towards the downstream end SU2799604255 - SU2886604333 Prior to the restoration this SSSI unit was in unfavourable declining condition due to the effects of the artificial straight drainage channel, which caused increased erosion of the river bed and limited channel habitat diversity. As a result of this incised channel, there was no seasonal inundation of the surrounding land.

River Restoration Centre/Jonathan Cox Associates

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Figure 8.2.1. Restoration scheme for the Blackwater through Fletchers Thorns showing straightened course and restored meandering course

The aim of the restoration was to re-establish a more natural riverine system and improve the SSSI to a favourable condition. To achieve this, the straight artificial drain was infilled and flow diverted back through the river’s old meandering course. Evidence of over-bank flows was observed over two survey days in November 2014 and showed the restored river to be in good connection with its floodplain. The restored river is still in a young state and has yet to develop a mature macrophyte vegetation community.

Objectives The objectives of the restoration were:  Translocate rare plants.  Undertake localised scrub clearance.  Restore remnant meanders (still visible in the field).  Raise bed level at concrete ford.  Maintain gravel ford.  Protect pond at passageway crossing with a low bund and upgrade bridge.  Maintain ford for access.  Create transitional bed levels at confluence with Highland Water.  Infill redundant drains (use as access route for materials).  Remove redundant bridge. 

Infill drains in the section through Queen Bower Scheduled Ancient Monument (a 15th century medieval hunting lodge).

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Restoration techniques The straight artificial 1190m drainage channel was replaced by approximately 2085m of restored meander. The existing bed level was graded for approximately 50m upstream of the first meander and for 50m before the confluence with the Highland Water. Specific techniques included: 1. Bed level raising of existing channel using hoggin and/or rejects as the infill material. 2. Bed level raising of drain where new meandering channel crosses over using hoggin and/or rejects as the infill material. 3. Clay plugs inserted both upstream and downstream of the drain/meander crossing points. 4. Excavation of identified meander route to achieve sufficient dimensions to take flow, clearing out obstructions (e.g. stumps in channel) and significant accumulations of organic material. 5. Existing surface layer removed and used for infilling the drain. 6. Pedestrian crossing point constructed using a simple structure of oak boards and hoggin. 7. Bed material from the drain channel bottom recovered and dispersed along the restored meanders 8. Infilling of the drain with a combination of imported hoggin (packed down in layers), rejects, tree trunks felled during the restoration work (no more than 15% of infill), held in position with clay plugs every 15-20 metres. 9. Infill materials built up to bank height in manageable layers, and dynamically compacted using the excavator bucket. 10. Infill surface dressed with any adjacent bankside spoil, and organic material from the original meander excavation. To create a steady gradient into the first meander, the bed level had to be raised both upstream and downstream of the concrete ford, starting from approximately 50m upstream of the first meander. In order to maintain both operational and public access, the surface of the concrete ford was raised (Figure 8.5.1). The bed level in the drain required raising to the meander level. Hoggin and rejects were placed in the dry channel in manageable layers and dynamically compacted using an excavator bucket with a clay plug to deflect flow into the next meander section. The meander route was restored following the dimensions and contours of the visible remnant channel. The identified meander route was cleared out or excavated where needed, and turf temporarily stored to be used for surface dressing of the infilled drain. Where the meander route approaches the passageway (at SU280042), the restored route was directed around the edge of the pond area with a low bund built up to protect the standing water habitat and rare plants within it, whilst allowing for overtopping during high flow events. A pedestrian ford was created across the restored meander route in the lawn clearing to maintain access. Bed material was recovered from the existing channel bottom and dispersed along the restored meanders. The work was undertaken during the summer months, to minimise the impact on migratory fish (sea trout). Fish rescue was undertaken by the Environment Agencyâ&#x20AC;&#x2122;s Fisheries team immediately prior to the commencement of works. Immediately prior to diversion of flow, gravel from the drain bed was excavated and placed in the new channel to help the process of aquatic invertebrate re-colonisation. Infilling of the drain was achieved using various materials held in position with clay plugs at periodic intervals. Large pieces of naturally occurring deadwood were placed on the surface dressing to make it blend in better with the surroundings. A pedestrian bridge and concrete abutments over the drain channel were removed. River Restoration Centre/Jonathan Cox Associates

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Current status Ecology Fletchers Thorns/Green is within Natural England condition assessment unit 476. This was assessed in December 2013 as being in unfavourable recovering condition. A significant component of the recovering assessment is the restoration of the stream through the unit. The assessment comments state â&#x20AC;&#x2DC;Recent restoration of the watercourse to its old meandering channel is naturalising well and the old straight channel is vegetating wellâ&#x20AC;&#x2122;. Floodplain habitats are still adapting to the new conditions and it is likely that with more frequent winter inundation there will be a transition from streamside lawn to hummock and bracken. However, greater frequency of inundation is also likely to reduce the abundance of bracken both within woodland and grassland areas. Hydromorphology The reinstated meandering river looks natural and has good connectivity with the floodplain throughout. Evidence from two visits in November 2014 showed how the Blackwater is able to store water on considerable areas of the floodplain after heavy rain events which then subside back into the channel. The restored meandering river channel offers considerably improved habitat for fish and aquatic invertebrates. This will be provided by the significantly increased length of water course as well as the substantially improved diversity of in-stream features including pool and riffle sequences, side bars and shoals. The restored river can be divided into three main sections the upstream open grassland, the mid-stream semi-open section partly covered by dense thorn scrub and the downstream woodland section. In the upstream section there is a lack of riparian vegetation due to heavy grazing. Due to the lack of shading there is a higher macrophyte growth (Figure 8.5.2). The bed consists mainly of gravel deposits and the banks of clay and gravel. The imported gravel has been reworked and instream features such as bars and pools-riffles have developed naturally (Figure 8.5.3). The grading in the transition between the old and new channel is smooth and there are few visible signs of the point where the restored river crosses the old drain (Figure 8.5.4).

8.5.1. Concrete ford at upstream end of restoration scheme. (2014)

River Restoration Centre/Jonathan Cox Associates

8.5.2. Macrophytes in upstream open section of restored river. (2014)

New Forest Wetland Restoration Review

8.5.3. Gravel bars and flow diversity in restored river. (2014)

8.5.4. Crossing point between the infilled old drain and the restored river. Dashed lines showing approximate outline of the old drain. (2014)

The clearance of scrub has opened up sections in the middle sections (Figure 8.5.5). In high flow a number of side channels and back waters develop (Figures 8.5.6, 8.5.7). Linkages between river and floodplain are very good and inundation of the floodplain is likely to have slowed flows and decreased flood peaks. The river has a high sinuosity with a good diversity of habitat types. Grazing is less intense and there is more bankside vegetation. In the downstream wooded section there is a good amount of wood in the river and there are several woody dams of various sizes (Figure 8.5.9). The grading towards the confluence with Highland Water is smooth (Figure 8.5.10). There is a good width and depth variability. There are gravel deposits throughout the length of the channel with some larger areas of clay bed and macrophyte cover where the tree cover is less dense.

8.5.5. Scrub clearance - before (spring 2011)

River Restoration Centre/Jonathan Cox Associates

8.5.6. After (autumn 2014)

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8.5.7. The middle section has several side channels and some islands and backwaters are forming during high flows. (2014)

8.5.8. New bridge and pond feature to the right in the photo. (2014)

Highland Water

8.5.9. Collection of large wood and smaller branches creates flow and habitat diversity in the channel. (2014)

River Restoration Centre/Jonathan Cox Associates

8.5.10. Confluence with Highland Water, the restored channel graded to meet the level of Highland Water. (2014)

New Forest Wetland Restoration Review

National Vegetation Classification Survey The terrestrial vegetation along the course of the stream is relatively simple, although shows some structural complexity. U4 Festuca ovina - Agrostis capillaris – Galium saxatile grassland

At its western end the restored stream flows through a streamside lawn composed of well grazed short acid grassland. These are described by Sanderson (2001) who states – ‘moist acid grasslands are referable to U4, the ubiquitous grassland of the north wet uplands.’ In the New Forest these tend to be rather species poor, tightly grazed grass dominated swards. At Fletchers Thorns there are two distinct areas of this grassland type. Within the Inclosure fence is an area that appears to have been managed by mowing or cutting. This is very species poor and dominated by common bent grass Agrostis capillaris with associated creeping bent Agrostis stolonifera, soft rush Juncus effusus, sharp flowered rush Juncus acutiflorus and tufted hair grass Deschampsia cespitosa. This is developing grassland following removal of plantation woodland but will develop into more typical moist acid grassland or humid heathland with appropriate management. Outside of the Inclosure fence, the streamside lawn shows a well-developed transition from the restored stream edge to a hummock lawn to humid heathland (Figure 8.6.1). The streamside lawn is well grazed and also dominated by Agrostis capillaris, but with a greater diversity of species including heath grass Danthonia decumbens, red fescue Festuca rubra, carnation sedge Carex panicea glaucous sedge Carex flacca, rough hawkbit Lentodon hispidus, ribwort plantain Plantago lanceolata, creeping buttercup Ranunculus repens, birds foot trefoil Lotus corniculatus, tormentil Potentilla erecta and daisy Bellis perennis. The transition to hummock lawn is not marked by any obvious or distinct change in the vegetation. The hummocks appear to have a greater abundance of broadleaved species including Lotus corniculatus, Potentilla erecta and Plantago lanceolata but are otherwise part of the same relatively species poor moist acid grassland found on the adjacent streamside lawns. The history of hummock lawn development is in some debate but Tubbs (2001) suggests that these distinctive features of the New Forest are derived from former wet heathland through grazing. It may be that the hummock lawns at Fletchers Thorns are historic features derived from wet heath prior to the straightening of the stream course at the time of Inclosure. Subsequent drying following drainage has changed the vegetation of the hummocks from wet heath and Molinia caerulea grassland to the moist acid grassland found today. The line of the old back-filled channel is re-vegetating well, but remains species poor and with several species indicative of disturbed ground conditions including creeping buttercup Ranunculus repens and spear thistle Cirsium vulgare. U20 Pteridium aquilinum-Galium saxatile community

Set within the floodplain are localised patches of bracken dominated vegetation. These are open bracken stands with a well developed grassy understorey dominated by Agrostis capillaris. Bracken cover within these patches is approximately 50%. This grassy form of bracken conforms to the Anthoxanthum oderatum sub-community of U20 (U20a). It is described for the New Forest by Cox and Bealey (2013) as Group 2 wet grassland with bracken.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review W8 Quercus robur – Fraxinus excelsior – Mercurialis perennis woodland

Mature riverine woodland occurs along the course of the restored meandering stream. Assigning this to an NVC community in autumn is problematical due to the absence of spring flowering plants and the recent history of drainage and more recent restoration of the meandering. The canopy is dominated by mixtures of pedunculate oak Quercus robur and ash Fraxinus excelsior with occasional field maple Acer campestre. There are variable amounts of thorny under-scrub composed of hawthorn Crataegus monogyna and blackthorn Prunus avium. The ground flora is indistinct following recent high flows at the time of survey (Figure 8.6.2). The ground shows considerable micro-topographic variation with high areas dominated by bracken Pteridium aquilinum with bramble Rubus fruticosus. Lower flood prone areas support Agrostis capillaris, wood sorrel Oxalis acetosella, violet Viola riviniana, wood false brome Brachypodium sylvaticum and mossy carpets dominated by Thiudium tamariscinum. In spring it is likely that these woodlands will also support a diverse woodland ground flora including species such as wood anemone Anemone nemorialis, primrose Primula vulgaris and sanicle Sanicula europea. This will confirm the classification as the Anemone nemorosa sub-community of W8 (W8b).

8.6.1. Classic hummock grassland on Fletchers Lawn with transitions to bracken, scrub and riverine woodland

8.6.2. Fletchers lawn in flood conditions, 14 November 2014

W22 Prunus spinosa scrub

The riverine woodland shows a gradual transition to the west to streamside scrub dominated by scattered thickets of blackthorn Prunus spinosa with hawthorn Crataegus monogyna. This open scrub is set within the humid grassland of the lawn into which it merges. This is complex vegetation with many small glades, thickets of dense scrub and scattered mature trees. A24 Juncus bulbosus stream vegetation

The stream vegetation varies along the course of the restored Blackwater. In areas of more light particularly to the west there is a better macrophyte growth in places occupying 50-60% of the stream bed. Further to the east the stream becomes more heavily shaded and macrophyte growth consequently diminishes in abundance. At elsewhere on the Blackwater, the stream vegetation is dominated by mixes of bog pondweed Potamogeton polygonifolius, bulbous rush Juncus bulbosus, floating club-rush Eleogiton fluitans and Glyceria fluitans with occasional Callitriche brutia var hamulata. Marginal slacks have frequent Calitriche stagnals and occasional Ranunculus omiophyllus and Myosotus scorpioides. Un-rooted plants of Apium inundatum were also recorded – these may have been washed from higher in the catchment following recent flooding.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review H2 Calluna vulgaris â&#x20AC;&#x201C; Ulex minor heathland

Away from the floodplain the humid grassland streamside lawns and humock grassland shows transitions to humid heathland. This is typically dominated by well grazed heather Calluna vulgaris with cross-leaved heath Erica tetralix, Molinia caerulea and scattered plants of dwarf gorse Ulex minor.

Assessment of Wetland Restoration Objectives Mire Restoration No mire restoration was undertaken at this site. River Restoration Objectives Achieve a diverse natural channel morphology comprising pools, riffles and meanders

Reconnect floodplain habitats and re-activate floodplain morphology and function.

Stabilise the hydrological system to a more natural, balanced state to reduce excessive scour, overdeepening and headward erosion.

Increase the value/quality of in-stream habitat niches for fish and macro-invertebrates.

Restore the quality and diversity of floodplain vegetation communities through the effects of natural seasonal flooding and re-activation of floodplain interaction.

River Restoration Centre/Jonathan Cox Associates

Evaluation Restoring the old meandering channel has increased channel length by 75%. The old drain was straight, incised, had low hydromorphological and habitat diversity and no lateral connectivity. The restored channel is highly sinuous with a diverse morphology including gravel bars, pools, riffles and woody dams. The restored river has good connectivity with the floodplain along the whole length with mainly gently sloping banks. In high flows side channels and backwaters are created which provide refuge. In the lower reaches the forest provides woody material to the stream. The work has addressed this by returning the channel to the original meandering course. The drain was over-deepened with a constantly eroding bed. The restored river has a natural depth-width ratio and in spate the water spills over onto the floodplain where it slowly seeps back to the river, not causing any erosion. The restored channel has increased the length of channel and has a high diversity of in-stream habitats including gravel bars, pools, riffles, sidechannels and back waters important for both fish and invertebrates. Collections of large wood also create localised flow and habitat diversity. A good macrophyte community is developing (more prominent in the upper reaches). Floodplain habitats are still adapting to the new conditions and it is likely that transitions from streamside lawn to hummock and bracken will adjust with more frequent winter flooding events. Riverine woodland and scrub communities may also be in the process of adjustment although this is difficult to assess in the absence of more detailed survey of ground flora during the spring. Greater 80

New Forest Wetland Restoration Review

innundation frequency is however likely to reduce the abundance of bracken both within woodland and grassland areas.

Appropriateness of techniques The main technique of reconnecting the meandering channels has been very successful. The abandoned meandering channel was in most places still visible in the field and could therefore be restored by clearing out accumulated organic material. The imported gravel, both that moved from the drain and imported from off-site, has been important in creating good habitat diversity. In the upstream open section the channel had to be excavated and the turf was successfully used to dress the infilled drain. The infill of the drain has worked very well. Except for the lack of mature trees there are no obvious signs of the drain, and the dressing blends very well into the surroundings. There are also no noticeable signs of where the clay plugs have been put in. Where the restored channel crossed the old drain both bed level raising and infilling to create the banks of the restored channel has been successfully achieved.

Lessons learned This process based restoration has been very successful in restoring the old, largely abandoned, meandering stretch of the Black Water at Fletchers Thorns. Although only three years have passed since the restoration, there are no visible signs of any negative impacts or techniques that have been inappropriate or not worked. Compared with the straight, incised drainage channel, the restored river has greatly increased sinuosity, habitat diversity and lateral connectivity (Figures 74-76). Restoration of the river by clearing out and reconnecting the old meandering course combined with placement of imported gravel has created a hydromorphologically diverse system providing a number of ecosystem services such as natural flood management, habitats for many species and a popular recreational area. The grading of the channel both at the upstream and downstream end has worked well. The flow in the channel was fairly high at the time of the survey, but the bed level raising, both upstream and downstream of the concrete ford, seems to have worked well. At the point where the restored river crosses the old drain (in the upstream section close to the ford) is hardly visible (Figure 8.9.2). The infilling of the old drainage channel has worked well and it is blending into the landscape. The clay plugs are less prominent and have not created the sort of ground with limited vegetation growth as noticed at e.g. North Oakley.

8.9.1. Before (spring 2011)

River Restoration Centre/Jonathan Cox Associates

8.9.2. After (autumn 2014)

New Forest Wetland Restoration Review

8.9.3. During construction (summer 2011)

8.9.4. After (autumn 2014)

8.9.5. Drainage channel - before (spring 2011)

8.9.6. After (autumn 2014)

Summary The river restoration at Fletchers Thorns has naturalised and achieved significant nature conservation and ecosystem service benefits in a very short period of time. The restored meandering channel of the Blackwater through Fletchers Thorns has restored connection between the river and its floodplain. The flora and vegetation of the area is still responding to these changes but is likely to be substantially improved. The old channel is re-vegetating well and can only be recognised by the discerning eye.

River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Akercome Bottom Overview Akercome Bottom occupies a side valley tributary to the east of the Linford Brook. It rises as a series of valley side mires to the north-east of the main A31 that confluence at a small artificially constructed pond at the head of a typical New Forest valley mire with transitions through wet lawn and wet heath to flanking areas of dry heathland. At its western end the valley mire flow becomes sufficient to create a defined stream-course. The stream descends west through Pinnick Wood, an area of ancient semi-natural old growth woodland. West of Pinnick Wood it meanders across an area of wet grassland or lawn with flanking wet and dry heathland transitions. The Akercome Bottom stream confluences within Linford Brook within riverine woodland that extends south west from Pinnick Wood along the floodplain.

Project summary Prior to restoration the system of mire, woodland stream and streamside lawn was badly damaged by drainage works that had created a deep and straight ditch through the centre of Akercome Bottom leading to damaging erosion and drainage of a number of important wetland habitats. The SSSI assessment unit that covers Akercome Bottom was in unfavourable declining condition due to the effects of the artificial drain, causing erosion within the woodland and mire habitats and gravel deposition on the lawn. As a result of the deeply incised channel, there was no seasonal inundation of the woodland and inconsistent interaction with the floodplain with consequent negative effects on floodplain habitats. Restoration work was undertaken in 2010 to rectify the damage. This followed on from earlier restoration attempts in the upper reaches of the mire. This comprised the following:   

Bed level raising of the eroded vegetated channel through the mire using staked heather bales. Grading of the mire into remnant stream meanders and infill of the drain through the woodland and lawn habitat. Linking of the meander route at its downstream end with the Linford Brook and replace a footbridge with a gravel ford.

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New Forest Wetland Restoration Review

Figure 9.2.1. Akercome Bottom restoration plan

Objectives The objective of this restoration scheme was to restore the SSSI Unit to favourable condition, by; ď&#x201A;ˇ Reversing the erosion effects of the artificial drain that was causing erosion of woodland and mire habitats and gravel deposition on the lawn. ď&#x201A;ˇ Restoring hydrological interaction of the stream with its floodplain.

Restoration techniques The following work was undertaken within Akercome Bottom to restore the wetland system: 1. 2.

The poached and eroded transition from mire to pond at the top of the mire was consolidated using staked heather bales. Channel restoration was a continuation from earlier restoration work undertaken along the line of the drain as it flows through the mire. Downstream of the bridge crossing, the remaining section of eroded vegetated channel through the mire had its bed level raised for approximately 75m using staked heather bales. The existing vegetation on the line of the channel was removed and temporarily stored for final habitat reinstatement. The excavated channel was in-filled with a layer of compacted hoggin topped with staked heather bales prior to re-instatement of mire vegetation. The restored channel route through the woodland followed the dimensions and contours of the visible meander remnants. The excavated material and any vegetation removed along the line of the meander route were stored for use as drain infill and surface dressing. Clay plugs were placed on either side of where the meanders crossed the drain. Two side drains fed into the meanders within the woodland, the western-most of these was infilled. The easternmost required a short stretch (20m) of bed level raising to grade in to the restored meander level.

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New Forest Wetland Restoration Review

6. 7.

Across the lawn, turf was carefully removed and stored to be used in reinstatement works to minimise habitat loss. Following meander preparation, a substantial clay plug was required to send the water away from the drain and into the restored meander system. Clay plugs were also put in on either side of where meanders crossed the old drain. Bed material was recovered from the existing drainage channel bottom, and dispersed along the restored meanders, to help with the stream recolonisation process. The old drain was then infilled. Infill was undertaken using rejects and hoggin, held in position with clay plugs. This was finally surface dressed with stored excavated material and the retained turves/vegetation, up to the level of the surrounding ground. At the eastern end of the lawn accumulated gravel-outwash was removed and a new boarded ford crossing to allow access across the stream. At the downstream end of the site the meander route was linked to the Linford Brook and the causeway to the footbridge was replaced with a gravel ford for pedestrian access.

Current ecological status Ecology The Akercome Bottom stream flows through three Natural England monitoring units. The upper unit, above Pinnick Wood was assessed in 2012 as being unfavourable recovering condition. Pinnick Wood was assessed in 2010 as being in favourable condition. The lower reaches of the stream before its confluence with the Linford Brook is included within a heathland monitoring unit which is assessed as being in favourable condition. However, the vegetation of the stream is more closely associated with that of the adjacent monitoring unit that extends along the valley of the Linford Brook. This is assessed as being in unfavourable recovering condition, with recovery being secured through restoration of the drainage system. Hydromorphology The wetland system in Akercome Bottom falls into three distinct hydrological sections. The upper part of the system consists of a mire system in which water flows through the mire vegetation with no clear channel. This natural drainage pattern is interrupted by an artificial pond located midway down the mire. At the bottom of the mire, water flow accumulates sufficiently to create a defined gravel bedded stream channel. This flows across a short section of wet grassland lawn before entering Pinnick Wood. The deeply incised drain through the wood has been infilled and the stream restored to a meandering channel. Gradients vary through the wood with corresponding variation in flow. In steeper sections, the channel is still slightly incised. The lower reaches of the stream now follow a natural meandering course across a wide streamside lawn. The stream appears to have good connection with its floodplain with out of bank flow soon returning to the channel.

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New Forest Wetland Restoration Review

9.5.1 Stream channel through Pinnick Wood (August 2010). Before restoration.

9.5.2. After restoration (November 2014)

9.5.3. Stream channel through Pinnick Wood (August 2010). Before restoration.

9.5.4. After restoration (November 2014)

National Vegetation Classification Survey W10a Quercus robur â&#x20AC;&#x201C; Pteridium aquilinum â&#x20AC;&#x201C; Rubus fruticosus Woodland Typical Sub-community

Although located within the valley bottom the woodland at the confluence of the Akercome Bottom stream and Linford Brook is not riverine woodland but conforms to typical oak woodland with a tree and shrub layer consisting of a mix of Pedunculate oak Quercus robur, some ash Fraxinus excelsior, holly Ilex aquifolium, grey willow Salix cinerea and bramble Rubus fruticosus. The ground flora is typical of grazed woodlands in the New Forest consisting of a mix of bracken Pteridium aquilinum, Yorkshire fog Holcus

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New Forest Wetland Restoration Review

lanatus, creeping buttercup Ranunculus repens, wood sage Teucrium scorodonium, violet Viola riviniana, honeysuckle Lonicera periclymenum and bugle Ajuga reptans. The main block of woodland forming Pinnick Wood has been disturbed by felling and stream restoration works. The canopy is overwhelmingly dominated by pedunculate and hybrid oaks Quercus robur, Quercus x rosacea with a scatter of scots pine Pinus sylvestris and silver birch Betula pendula. The ground flora comprises a mix of wet grassland (70%), bracken (20%) and scattered bramble, blackthorn and hawthorn scrub (10%). It is difficult to survey woodland late in the year due to the lack of vernal ground flora species present only in spring but it would appear that this area of woodland is generally rather species poor and conforms to the typical sub-community (W10a). M23a Juncus acutiflorus-Galium palustre rush pasture Typical sub-community

The lower floodplain of the Akercome Bottom stream is dominated by wet grassland referable to the typical sub-community of Juncus acutiflorus-Galium palustre rush pasture. However, the examples of this vegetation in the New Forest are heavily grazed which limits the dominance of the rushes in the vegetation and promotes the development of a more diverse species rich sward. This is typically dominated with velvet bent Agrostis canina and red fescue Festuca rubra, commonly with sharp-flowered rush Juncus acutiflorus, purple moor-grass Molinia caerulea, common sedge Carex nigra, devilâ&#x20AC;&#x2122;s bit scabious Succisa pratensis, tormentil Potentilla erecta and yellow sedge Carex viridula spp oedocarpa. Variation within the community is evident in relation to levels of inundation. Along the stream edge, there is a clear flood line marked by a line of deposited leaf-litter extending 1-2m from the stream edge. This inundation zone is marked with an increase in the abundance of Juncus acutiflorus, lesser spearwort Ranunculus flammula, birdâ&#x20AC;&#x2122;s foot trefoil Lotus corniculatus and Molinia caerulea. Away from the stream edge the lawn also shows some micro-topographical variation with slightly raised mounds supporting a greater abundance of heath grass Danthonia decumbens, Succisa pratensis, Carex nigra and glaucous sedge Carex panicea.

9.6.1. Restored meanders within M23 rush pasture with deposits of leaves on meander bend marking recent high flow extent (date unknown)

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New Forest Wetland Restoration Review

9.6.2. Erosion point upstream of the restored boarded ford within rush pasture lawn and open bracken grassland (date unknown)

The vegetation on the line of the old back-filled drain has recovered well but still shows evidence of disturbance with a dominance of common bent Agrostis capillaris and occasional rough hawkbit Leontodon hispidus, dandelion Taraxicum officinale, selfheal Prunella vulgaris and spear thistle Cirsium vulgare. With these indicators of disturbance and bare ground are typical species of rush pasture (M23) including Lotus corniculatus, Danthonia decumbens, Succisa pratensis, Juncus acutiflorus and the mosses Sphagnum denticulatum, Rhytidiadelphus squarrosus and Pseudoscleropodium purum. There are also some seedlings of heather Calluna vulgaris and bramble Rubus fruticosus. U20 Pteridium aquilinum-Galium saxatile community

On the south side of the Akercome Bottom stream there is a transition from wet grassland to bracken dominated vegetation on the valley side. Bracken Pteridium aquilinum cover is about 60% with purple moor-grass Molinia caerulea being abundant together with frequent Calluna vulgaris, Festuca rubra, Agrostis capillaris, heath bedstraw Galium saxatile, Carex panicea, Agrostis canina, Cerastium fontanum and Potentilla erecta. Although generally falling within this NVC community grazed examples of this habitat in the New Forest are far more diverse than and generally less heavily bracken dominated than the community described. Cox and Bealey (2013) developed a unique bracken classification for New Forest bracken dominated vegetation types. The open bracken stand found here with frequent Calluna vulgaris conforms to the humid heath and bracken community described by Cox and Bealey (2013) for the New Forest. H3a Calluna vulgaris â&#x20AC;&#x201C; Agrostis curtisii heath Typical sub-community

To the south of the bracken dominated vegetation and in places forming a mosaic with the bracken are areas of dry heath. These are dominated by Calluna vulgaris with abundant Molina caerulea and occasional Erica cinerea, Erica tetralix, Genista anglica, Agrostis curtisii, Festuca rubra, Carex pilulifera, Potentilla erecta and Ulex minor. Mire communities (M25a Molinia caerulea-Potentilla erecta mire - Erica tetralix sub-community and M29 Hypericum eloides-Potamogeton polygonifolius Soakaway community)

The defined stream channel extends some 340m upstream of the edge of Pinnick Wood. It then merges into the valley mire. This supports complex mosaics of mire vegetation consisting of two vegetation communities (M25a Molinia caerulea-Potentilla erecta mire - Erica tetralix sub-community and M29 River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

Hypericum eloides-Potamogeton polygonifolius Soakaway community). The majority of the mire is composed of M25a Molinia caerulea-Potentilla erecta mire - Erica tetralix sub-community. This tends to be quite a tall, tussocky wet vegetation. It is dominated by tussocks of Molinia caerulea with an abundance of Juncus acutiflorus and frequent cotton-grass Eriophorum angustifolium and rarely some white-beak sedge Rhynchospora alba. Occurring within this are local tussocks of sphagnum moss. These are mostly of Sphagnum inundatum with locally some Sphagnum palustre, Sphagnum subnitens and Sphagnum papillosum. Bog pimpernel Anagallis tenella is common creeping over the Sphagnum tussocks as is Potentilla erecta. Weaving its way through this taller vegetation are tracks of water where flow is concentrated. These tracks or soakaways support a distinctive vegetation community dominated by bog pondweed Potamogeton polygonifolius and marsh St Johnâ&#x20AC;&#x2122;s wort Hypericum eloides. Species associated with this community include Juncus bulbosus, Sphagnum inundatum, Eriophorum angustifolium, Carex echinata and Anagallis tenella. A transitional zone occurs along much of the edge of the main mire which is characterised by an abundance of bog myrtle Myrica gale. This forms a rather tall shrubby vegetation between the mire and associated wet heath. Myrica gale also occurs forming a bank-side variant of the M25 mire community along much of the course of the stream. M21a Narthecium ossifragum - Sphagnum papillosum mire Rhychospora alba sub-community

At the head of the main valley mire is an artificially constructed pond. Much work has been undertaken to stabilise the transition from the pond to the mire communities upstream of it. The pond also marks a distinct change in the vegetation. Upstream of the pond the vegetation undergoes a transition from M25 mire to M21a Narthecium ossifragum - Sphagnum papillosum mire. This is the typical sub-community in which Rhychospora alba is common. This is a much shorter vegetation than the M25 mire with carpets of Sphagnum papillosum, frequent Rhychospora alba and bog asphodel Narthecium ossifragum. At the head of the mire there are also stunted shoots of common reed Phragmites australis. M29 soakaway vegetation marks the main axis of the mire which occupies an increasingly narrow and steep sided valley with transitions to wet heath on either side. M16 Erica tetralix â&#x20AC;&#x201C; Sphagnum compactum wet heath

Wet heath occurs commonly on the valley sides in the transition from mire to dry heath. In places this transition is marked by an abundance of Myrica gale. Wet heath is characterised by an abundance of Erica tetralix with frequent Molinia caerulea. It is species rich wet heath with Succisa pratensis, meadow thistle Cirsium dissectum and sphagnum mosses Sphagnum denticulatum and Sphagnum palustre being frequent.

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New Forest Wetland Restoration Review

9.6.3. M21a Narthecium ossifragum - Sphagnum papillosum mire (date unknown)

9.6.4. M16 Erica tetralix â&#x20AC;&#x201C; Sphagnum compactum wet heath (date unknown)

A24 Juncus bulbosus stream vegetation

The aquatic macrophyte vegetation was sampled at several locations along the length of the stream after it emerged from the valley mire as a defined channel. These point samples are summarised in Table 3. It follows a meandering route with well developed pool and riffle sequences, good macrophyte growth and gravel bars. Water levels at the time of survey were good and where it crosses the lawn in its lower reaches was often within a few centimetres of bank top. Flow was swift and there was evidence of recent out of bank flooding with leaf-litter deposits on the banks for 1-2m from the stream edge. The bed is generally of flint gravel although there are some sections of exposed clay bedrock. Banks are also mostly of clay. In places there are signs of some erosion of the soft infill of the old channel on the outside of new meanders as shown in Figure 9.7.4. The vegetation is abundant in the lower reaches of the stream reaching 90% cover. It is much less abundant through the woodland where cover values drop to <5%. In terms of the NVC, the stream vegetation is probably best considered as a component of A24 Juncus bulbosus community, but this is generally a community of still bog pools or slow flowing streams and not the swiftly flowing gravel bedded stream that has developed at Akercome Bottom. It may be that this vegetation is still in the process of maturing and in time it will develop into a typical swift flowing stream community such as the A14 Myriophyllum alterniflorum community, but this species is currently absent from the stream. Species present also have affinities with OV35 Lythrum portula-Ranunculus flammula community but this is typically a vegetation of ephemeral pond and pool margins that is widespread in the New Forest but not typical of swiftly flowing streams of this sort. It is likely that stream flows decline significantly in midRiver Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

summer and hence the presence of still and slow flowing water habitats. At present it is difficult to place this stream vegetation community within the NVC, but this may become more evident as the vegetation matures. The absence of a stream vegetation survey prior to the restoration work taking places also makes determination of current macrophyte changes difficult to assess. Photographs of the stream in August 2010 show it to be virtually dry in a deeply incised channel through the woodland and a still or slow flowing boggy stream across the lower lawn. Justification of the restoration works refer to frequent flooding and deposition of gravel on the lawn suggesting winter spate flows. Waypoint Number (See Appendix 1 for map) WPT035

WPT036

WPT046 WPT047

WPT052

Notes Stream meanders with abundant in-channel vegetation (90% macrophyte cover, <5% bare gravel) with Eleogiton fluitans, Peplis portula, Glyceria fluitans, Ranunculus fluitans. Marginal mire with Myrica gale (dominant), Juncus acutiflorus, Agrostis canina and Carex viridula var oedocarpa. Knick point upstream of old stream crossing with remnant timber shuttering. Stream now in old channel to south side of floodplain. Macrophyte vegetation abundant with Eleogiton fluitans, Juncus bulbosus and Ranunculus flammula. Stream below ford. Riffle pool sequence with 90% vegetation cover in riffles and 20% in pools. Riffles 8-15m apart. Stream above ford. Steeper gradient, very little macrophyte vegetation (<5% cover) with Galium palustre, Agrostis canina, Juncus bulbosus and Eleogiton fluitans. Knick point at head of eroding section. Upstream of knick gradient more gentle with pool and riffle sequence. 80% macrophyte cover on riffles, 20% in pools. Eleogiton fluitans (dominant), Peplis portula Glyceria fluitans, Ranunculus flammula, Galium palustre, (frequent), Potamogeton polygonifolius (occasional), Apium inundatum (rare).

Table 3: Aquatic macrophyte samples from the Akercome Bottom stream Pond

The pond located in the mire system has an interesting flora that does not conform to any particular NVC community. It is dominated by Potamogeton polygonifolius and Hypericum eloides and is therefore related to M29 soakaway community found in the mires. However, the pond also contains an abundance of bog bean Menyanthes trifoliata growing as an emergent. This can be a feature of M21 mires in the New Forest as well as poor fen swamp communities. Water levels in the pond are maintained by an earth bund at its lower end. A large number of heather bales have been placed at its upstream end to stabilise the mire that flows into it. These appear to have been successful and M21 mire vegetation is now developing down to the pond edge.

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New Forest Wetland Restoration Review

Assessment of Wetland Restoration Objectives Mire Restoration Mire restoration appears to have been very successful. There is an apparently natural transition from stream to mire with no obvious erosion knick point. Water levels are maintained in the mire with well developed soakaway tracks supporting M29 vegetation. The pond located midway up the mire is a significant interruption to the natural sequence of vegetation. The restoration work upstream of the pond seems to be maintaining water levels in the upper part of the mire but it remains to be seen how stable these restoration works will be. The pond currently marks a transition from M25 to M21 community. It may be that the mire downstream of the pond is undergoing a change following restoration work and it is possible that species of M21 will extend down the mire in future years now that conditions have been restored. In terms of the New Forest SAC features, the M21a Rhynchospora alba-Sphagnum auriculatum sub-community conforms to the Annex 1 habitat type â&#x20AC;&#x2DC;Depressions on peat substrates of the Rhynchosporionâ&#x20AC;&#x2122;. The M25a community does not conform to any of the Annex 1 habitat types. It is hoped that following restoration work the mire below the pond will develop into a good example of the Annex 1 habitat type. River Restoration Work on the stream below the mire, through Pinnick Wood and across the lawn to its confluence with Linford Brook appears to have been largely successful. In its upper reaches the stream now flows at or near bank level through the woodland although there are sections where is cuts through a slightly more incised channel, possibly reflecting local topographical variation in the woodland. There is also evidence of some erosion into the softer infill material in the old stream channel. Below the wood, the stream now meanders across its floodplain and appears to have good connection with its floodplain. There is one small knick point that has developed upstream of an old stream crossing. This will need to be monitored in future to ensure it does not develop into a significant erosion feature. Instream habitats are in good condition with abundant macrophyte vegetation, good autumn flows and well structured gravel bed. This is likely to support typical New Forest stream fish and macro-invertebrate communities although this will depend to a degree on summer low flow levels. Mire restoration works will assist in reducing this impact by maintaining summer flows. There is some evidence that stream-side vegetation receives some degree of autumn and winter flooding that has an effect on the vegetation composition. This is not sufficient to move the lawn into a different NVC community but changes the relative abundance of some of the typical wet grassland species. Further monitoring is required to determine if these changes are still dynamic or stable and if there has been any effect on grassland productivity as a result of the restoration works.

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9.7.1. Stream flow within slightly incised channel through Pinnick Wood (date unknown)

9.7.2. Stream with good meanders, flow variation and gravel side bars within restored section (date unknown)

9.7.3. Local shoot flow causing bed erosion due to gradiant variation within Pinnick Wood (date unknown)

9.7.4. Erosion of clay plug where restored channel crosses the old drain (date unknown)

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9.7.5. Heather bales staked across the bottom of the mire upstream of the artificial pond (date unknown)

9.7.6. Stake tops protruding from the mire vegetation in restored mire channel (date unknown)

Appropriateness of techniques The techniques used were appropriate to the situation and have been developed over several years of wetland restoration in the New Forest. The use of staked heather bales has worked well in restoring mire vegetation in the upper part of the system. Meander re-excavation and backfilling of the old drain through Pinnick Wood and the wet grassland lawn using imported hoggin and rejects has also worked well. Bed levels have been restored although some instability remains due to variations in gradient, particularly within Pinnick Wood. Monitoring and remedial intervention may be required to stabilise these minor instabilities. The use of large wood accumulations would assist in preventing downstream movement of significant quantities of bed material and to dissipate high flows.

Lessons learned A significant lesson has been learned from similar restoration undertaken at Holly Hatch. In Akercome Bottom, the drainage system has been restored in its entirety avoiding the creation of breaks in the hydromorphology that inevitably create instability and consequent erosion. The use of significant quantities of imported hoggin to raise bed levels has been shown to be much more effective than the use of the timber boards used at Holly Hatch. The downstream end of the Akercome Bottom stream now meanders across streamside wet grassland lawns. Flood flows are able to expand and retreat across the floodplain. This contrasts with the partially restored drains at White Moor where attempts were made to preserve streamside wet grassland from deteriorating through excessive inundation. Further monitoring is required to assess the effects of restoration of stream bed levels on streamside lawn vegetation composition and productivity.

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Summary Akercome Bottom restoration scheme demonstrates a wide range of wetland restoration techniques ranging from mire restoration to stream restoration within woodland and across stream side lawn. The resultant system is now largely self-sustaining and operating in sympathy with adjacent habitats. Some minor adjustments may be required to stabilise local erosion features caused by changes in gradient and where clay plugs have been used, but in general the wetland restoration techniques used have succeeded in meeting their objectives. Ecological monitoring is required to assess further changes as habitats and species populations adjust to the restored conditions.

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New Forest Wetland Restoration Review

Penny Moor Overview Penny Moor is located on the southern side of the extensive Denny Bog wetland system. It consists of a complex of wet heath, mire and grassland habitats that have been modified by historic attempts at improving drainage. The central drainage channel and several of the side drains to this have been infilled or restored to a more natural course. Restoration work was undertaken between 2012 and 2013.

Project summary Prior to restoration, the SSSI assessment units containing Penny Moor were in unfavourable and declining condition due to the effects of artificial drainage. In some places this was compromising the integrity of Denny Bog. At the eastern end of Penny Moor drainage works was causing increased erosion of the stream bed and limiting channel habitat diversity. The natural extent of mire habitat was being artificially defined and to the west, inconsistent seasonal inundation of surrounding habitat had reduced interaction of the stream with its floodplain. The main restoration works included: 1 The remaining stretch of artificial side drain through Denny Bog (from SU35480460 to SU35480452) was infilled using a combination of staked heather bales and existing spoil. 2 On Penny Moor, where remnant meanders were evident, the stream was restored to a natural meandering course (at the western end, from SU35040435 to SU35190449, and downstream of Rowbarrow Pond, from SU35830452 to SU36190460). Existing side drains were linked in to the restored route. 3 To achieve full restoration of the Penny Moor SSSI unit, the artificial drainage channel across the middle of the site should have been completely infilled. However, in the face of strong opposition from the Commoners Defence Association (CDA) and Verderers, a compromise was agreed. The wide vegetated drain bordering the edge of the mire was reduced in size for part of its length, to run in parallel to the restored original water course through the lowest point in the mire to the north (from SU35230453 to SU35480452). Continuing eastwards, the drain was retained untouched, but the spoil bank bund on its northern bank was repaired and consolidated to maintain the integrity of the mire habitat of Denny Bog to the north. 4 Sufficient trees and scrub were felled and cleared, along the routes of the drain to be infilled and the meanders to be reinstated, to facilitate working and access. The majority of this was towards the eastern end of the site, consisting of birch and willow along the line of the drain and on spoil heaps, with an additional area of thorn scrub and birch being cleared off lawn habitat. 5 Approximately 1118m of restored meander replaced 653m of artificially straightened channel across Penny Moor. In addition, the wide vegetated drain bordering the edge of the mire was reduced in size (width and depth) for 316m, to run in parallel to the original restored water course through the lowest point in the mire to the north. The remaining 60m of artificial side drain through Denny Bog was infilled.

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Figure 10.2.1. The original restoration plan prepared in June 2012 was subsequently amended following the discovery of significant rare plant assemblages as part of a botanical survey of the site. As a consequence, changes were made to the restoration of the drain at point 8.

Figure 10.2.2. The drain parallel to the meandering channel was consequently left untouched with a partial clay bund erected at its upstream end to divert main water flows along the restored meander route. River Restoration Centre/Jonathan Cox Associates

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Figure 10.2.3. Extract from First Edition OS Map (1871) showing location of Rowbarrow Pond. Subsequent drainage works split the pond leaving the remnant to the north of the new drain.

Objectives The objectives of the restoration works were to:  Prevent further drainage of mire habitat within Denny Bog.  Restore water levels and floodplain connection within Penny Moor including the restoration of rush pasture, fen meadow habitats and mire.  Restore stream meanders and in channel habitat diversity.  Restore stream flows to areas of wet woodland.  Conserve populations of rare wetland plant species.

Restoration techniques The restoration techniques used included:  Restoring meanders through wet grassland following contours of visible meanders where these were evident.  Infilling old drain channel (Figure 10.2.1, points 2, 7 & 11) with hoggin held in position with clay plugs at periodic intervals.  Levelling spoil heaps and using the material as drain infill and surface dressing.  Surface dressing the infilled channel with restored excavated material and retained turves up to the level of the surrounding ground.  Repairing breaches in the spoil bank along the northern side of the main drain and consolidating using hoggin and clay, top dressed with spoil and vegetation.  Clearing obstructions along the route of the original meander course through an area of wet woodland at the eastern end of Penny Moor to restore original channel dimensions.

Current ecological status Ecology The condition assessment for Penny Moor (Natural England unit 428) was last undertaken in December 2013. It assessed the unit as being in unfavourable recovering condition. The assessment is reproduced in Box 1. It suggests that the area is recovering from past drainage activity. Recent restoration works have achieved significant improvements to the alder carr woodland to the east of the wetland system and to the River Restoration Centre/Jonathan Cox Associates

New Forest Wetland Restoration Review

mire communities to the west. Rare plant locations within the drains have also been maintained. Restoration works will also help restore water levels along side drains where it is anticipated that Molinia fen meadow habitats will develop. However, the main channel of Penny Moor remains straight and deep and creates an artificial break between Denny Bog to the north and the partially drained Myrica dominated grasslands to the south. Recent repairs to the stream side bund alongside Rowbarrow Pond have reenforced this split in the hydrology, but maintained the Pond with its associated rich flora. This unit is composed of a range of open habitats including Molinia lawn, acid grassland and wet heath. Rarely small areas of sphagnum poor mire that would appear to be reduced in extent due to colonisation by heather and molinia due to changed water levels. The majority of the unit is wet heath and grassland scrub mosaic with high levels of bog myrtle and molinia with sphagnum only at low levels throughout suggestive of habitat loss. Wet heath mire indicator species are thin on the ground and only include carnation sedge, deer grass, bog asphodel, bog cotton and tormentil. Grassland has patches of bog myrtle and much bare ground, is heavily grazed and poached and has been negatively affected by previously heavy rain and vehicle access for woodland management. Is quite species rich in places with bog pimpernel, carnation sedge, meadow thistle, marsh pennywort, birdâ&#x20AC;&#x2122;s-foot trefoil, tormentil, spearwort and devils-bit scabious. There is extensive drainage with obvious spoil banks in particular between this and the adjacent unit to the North. At Rowbarrow pond the water level in the pond and adjacent mire (unit 427) is a metre higher than in the ditch, separated only by the spoil bank. This area of ditch is however species rich in its own right with pillwort, Hampshire purslane, lesser marshwort and royal fern. Unit is in unfavourable condition due to artificial drainage affecting habitat extent and quality but recovering due to work carried out under the wetland restoration programme. Box 1: Extract from Natural England condition assessment for Penny Moor (dated 06/12/2013).

Hydromorphology Penny Moor remains only partially restored. The lower reaches of the stream through alder carr woodland have been very successfully restored. The upper reaches of the wetland system have also been successfully restored through areas of valley mire. However, the main drain through the moor remains. This separates Denny Bog to the north from the drained southern side of the moor. An earth bund running east-west along the line of the drain prevents flow of water from Denny Bog to the south and causes ponding of water along the southern side of the Bog. Although this bund has the advantage of maintaining water levels in Rowbarrow Pond it is an artificial feature that has a significant impact on the hyrdromorphology of the eastern half of Penny Moor.

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10.5.1. The restored meandering route of the water course through Penny Moor with Denny Bog in background (date unknown)

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10.5.2. Route of restored water course looking to the upstream western end (date unknown)

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National Vegetation Classification Survey W7b Alnus glutinosa-Fraxinus excelsior-Lysimachia nemorum woodland, Carex remota-Cirsium palustre sub-community

The lower end of the main Penny Moor stream flows through a restored meandering course through an area of alder Alnus glutinosa wet woodland with some ash Fraxinus excelsior and holly Ilex aquifolium. Ground flora in this woodland includes violet Viola riviniana, lesser spearwort Ranunculus flammula, creeping buttercup Ranunculus repens, bugle Ajuga reptans, remote sedge Carex remota, yellow iris Iris pseudacorus, broad buckler fern Dryopteris dilitata, butchers broom Ruscus aculeatus, wood sorrel Oxalis acetosella, hard fern Blechnum spicant and royal fern Osmunda regalis. The restored stream channel through the wood appears to be operating well with good meanders, pool and riffle sequences and some lodged woody material.

10.6.1. Penny Moor stream through alder woodland with good gravel bed, pool - riffle sequences and woody material (date unknown) W4b: Betula pubescens-Molinia caerulea woodland - Juncus effusus sub-community

Within the southern arm of Denny Bog are several patches of wet willow dominated mature scrub. This conforms to W4b Betula pubescens-Molinia caerulea woodland - Juncus effusus sub-community. This mature willow scrub woodland is a component of the Bog Woodland priority habitat type for which the New Forest has been designated a SAC. The examples in Penny Moor consist of downy birch Betula pubescens, grey willow Salix cinerea, purple moor grass Molinia caerulea, hard fern Blechnum spicant and tussock sedge Carex paniculata. U4 Festuca ovina-Agrostis capillaris-Galium saxatile grassland

Disturbed areas along the route of backfilled drain and banks alongside the main drain through Penny Moor support narrow belts of species poor moist acid grassland. This consists of a mix of common bent Agrostis capillaris, velvet bent Agrostis canina and heath grass Danthonia decumbens. The disturbed ground along River Restoration Centre/Jonathan Cox Associates

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the route of the backfilled drain also has annual meadow grass Poa annua, creeping buttercup Ranunculus repens, spear thistle Cirsium vulgare and self heal Prunella vulgaris. Puddles have also developed along the route of the restored drain with some bog pondweed Potamogeton polygonifolius.

10.6.2. Infilled drain on the south side of the alder wood with transition to wet heath with abundant bog myrtle Myrica gale (date unknown) M23a Juncus effusus / acutiflorus - Galium palustre rush pasture â&#x20AC;&#x201C; J. acutiflorus sub-community

Areas of rush pasture occur along the southern side of the main Penny Moor drain and are developing along the main north â&#x20AC;&#x201C; south drain that skirts the western side of Denny Bog. The distinction between this community and the related M24 Molinia caerulea fen meadow grassland is slight in the New Forest. Areas of streamside lawn have been placed in M23a where Molinia cover is low and rushes are more dominant. Juncus acutiflorus is the dominant rush with abundant creeping bent Agrostis stolonifera, common bent Agrostis capillaris, carnation sedge Carex panicea, common sedge Carex nigra and Ranunculus flammula. Molinia caerulea is uncommon but increases in abundance towards areas of wet heath. Meadow thistle Cirsium dissectum and some Sphagnum palustre are also present. M24c Molinia caerulea-Cirsium dissectum fen meadow - Juncus acutiflorus fen meadow - Erica tetralix sub community

Two areas of streamside lawn occur along the north flowing side drains at the western and eastern ends of the Penny Moor stream. These are floristically close to areas of M23 rush pasture but are distinguished by a greater abundance of Molinia caerulea and less rush. Included in this area is some classic wet hummock grassland which is transitional to wet heath. These hummocks are thought to be derived from grazing of Molinia tussocks (Tubbs, 2001) and create a distinctive landscape. The vegetation of these areas of wet fen meadow grassland comprises mixed of Molinia caerulea, Juncus acutiflorus, Potentilla erecta, Carex panicea, Anagallis tenella, Cirsium dissectum and some cross-leaved heath Erica tetralix and Sphagnum tenellum where it is transitional to wet heath (M16). River Restoration Centre/Jonathan Cox Associates

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This community is relatively uncommon in the New Forest as it develops where grazing pressure is reduced leading to a build up of Molinia caerulea tussocks and litter. This tends to suppress associated flora and can create rather species poor mire vegetation. The southern extension of Denny Bog to the north of the main Penny Moor drain is dominated by an extensive area of this community. It is particularly and probably artificially wet due to the damming effect of the earth bund that occurs on the northern side of the main Penny Moor drain. Despite the dominance of tall Molinia caerulea, the vegetation has some diversity and includes several species of M21 Sphagnum papillosum mire. The wet area of Denny Bog includes white beaked sedge Rhynchospora alba, cotton grass Eriophorum angustifolium and marsh lousewort Pedicularis palustris. The areas of this community to the west of Penny Moor, by the railway line, have grassy runnels between the Molinia tussocks with a flora similar to M24 fen meadow. Sphagnum moss is present throughout this community particularly Sphagnum denticulatum and some Sphagnum papillosum as is Erica tetralix. An associated vegetation type has been classified as M25 Myrica gale mire. This is not described in the NVC but is a feature of drained wet heath. Some extensive areas of this vegetation type occur within Penny Moor alongside the main Penny Moor drain. They are characterised by an abundance of bog myrtle Myrica gale which forms a low open scrubby vegetation over a grassy sward that is dominated by Molinia caerulea and varying amounts of Erica tetralix and other typical species of M25. Where Erica tetralix is abundant, this vegetation has been classified as M16 wet heath with Myrica gale. M29 Hypericum elodes-Potamogeton polygonifolius soakaway

This community is common throughout Penny Moor and occurs in a variety of situations in association with M25 Molinia mire. The most extensive and well developed examples occur in the very wet mire at the southern edge of Denny Bog where water levels are maintained by an earth bund on the north side of the main Penny Moor drain. In this area the vegetation consists of a mix of bottle sedge Carex rostrata, Sphagnum fallax, Potamogeton polygonifolius, Sphagnum palustre, Hypericum eloides and marsh lousewort Pedicularis palustris. This community shows some affinities to the M6 Carex echinata â&#x20AC;&#x201C; Sphagnum recurvum mire but the absence of Carex echinata (or at least scarcity) and abundance of Carex rostrata suggests it is better regarded as a diverse stand of M29. Elsewhere, M29 vegetation occupies runnels and water tracks through other areas of the tussocky M25 vegetation and can choke smaller and narrow drainage ditches within the streamside lawns.

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10.6.3. Right side of picture shows M29 soakaway vegetation with abundant bottle sedge Carex rostrata on the southern side of Denny Bog. Water levels are maintained by the earth bank alongside the Penny Moor drain on the left of the picture (date unknown)

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New Forest Wetland Restoration Review M16a Erica tetralix â&#x20AC;&#x201C; Sphagnum compactum wet heath Typical sub-community

Wet heath is the natural transitional vegetation from M25/M21 mire towards drier heathland types. It occurs widely on the flanks of Penny Moor. It is typically dominated by Erica tetralix and Molinia caerulea with the constant Sphagnum tenellum and often Sphagnum inundatum. As mentioned above, the wet heath is also locally invaded by bog myrtle Myrica gale giving it a low shrubby appearance. A24 Juncus bulbosus stream vegetation

The aquatic vegetation of the drains and streams within Penny Moor is rich and diverse. It has all been classified within A24 Juncus bulbosus community but in reality it shows considerable variation. In most of the free flowing streams, the vegetation is characterised by a combination of Potamogeton polygonifolius, Eleogiton fluitans, Juncus bulosus var fluitans, Glyceria fluitans, Callitriche sp. and Hypericum eloides. In places a marginal community is evident although this was inundated at the time of survey. This includes the nationally rare pillwort Pilulifera globulifera, mudwort Apium inundatum and purslane Peplis portula. This community is particularly well developed on the north flowing side drain to the west of Penny Moor and alongside the main Penny Moor drain. Also present in this marginal community is the round-leaved water-crowfoot Ranunculus omiophyllus and its hybrid with the nationally rare Ranunculus tripartitus. This hybrid is also rare and has been termed New Forest water-crowfoot Ranunculus x novae-forestae. It was seen at a few locations along the course of the main Penny Moor drain as shown in Figure 10.6.4, but was not recorded during the Penny Moor Rare Plant Survey undertaken in 2012 (Sanderson, 2012)11.

10.6.4. Round-leaved water crowfoot Ranunculus omiophyllus (left) and the nationally rare hybrid referred to as New Forest water crowfoot Ranunculus novae-forestae (right) (date unknown)

The rare Hampshire purslane Ludwigia palustris was also recorded in the drain to the west of Penny Moor (Waypoint WPT097 Appendix 1) and was recorded elsewhere on the main Penny Moor drain in 2012 (Sanderson, 2012).

Sanderson, N.A. (2013) Rare Plant Survey of Penny Moor, New Forest, July 2012. Report to The Forestry Commission

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10.6.5. Junction on north-south drain with Penny Moor stream - blocked with clay plug with Juncus bulbosus, Juncus acutiflorus and Ranunculus flammula (date unknown)

Waypoint Number (See Appendix 1 for location) WPT090

WPT091 WPT092

WPT093

WPT094 WPT095

WPT096

10.6.6. Hummock wet grassland (M24a) with transition to M25 Molinia mire with abundant Bog myrtle Myrica gale (date unknown)

Notes Transition: Alder carr to infill channel to M25 mire (Molinia caerulea, Myrica gale, Calluna vulgaris, Sphagnum fallax, Sphagnum papillosum, Sphagnum palustre) to M16 wet heath Retained side drain with Potamogeton polygonifolius and Pilularia globulifera with Eleogiton fluitans, Callitiche sp., Hypericum eloides Bund on south side of Rowbarrow Pond. Pond full, bunding appears successful. Bund with Osmunda regalis. Pond with Potamogeton polygonifolius, Hypericum eloides, Eleogiton fluitans, Pond edge mire â&#x20AC;&#x201C; M29/M6 Carex rostrata, Sphagnum fallax, Potamogeton polygonifolius, Sphagnum palustre. West of pond, Carex rostrata reduces, increased abundance of Molinia, Rhychospora alba, Eriophorum angustifolium, Pedicularis palustris. Mire M29/M6 Carex rostrata, Potamogeton polygonifolius, Hypericum eloides, Pedicularis palustris, Sphagnum fallax to M25 mire with Molinia (dominant), Myrica gale, very wet. Filled end of drain with swift flow over clay bund and southern end of drain Culvert passage with old cross drain with floating mat of Juncus acutiflorus, Ranunculus flammula and Hypericum eloides. Drain with Glyceria fluitans, Potamogeton polygonifolius, Apium inundatum, Callitriche brutia and Ranunculus x novae-forestae End of infilled drain by Salix cinerea with new meander. Silty bed, 20cm water

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WPT097 WPT098

depth, Glyceria fluitans (dominant) with Ranunculus flammula, Eleogiton fluitans, (frequent) Callitriche brutia, Apium inundatum (occasional) Top of infilled drain with Ludwigia palustris, Glyceria fluitans, Peplis portula, Ranunculus flammula, Juncus bulbosus var fluitans and Apium inundatum Infilled drain in Myrica heath/lawn with Molinia caerulea, Juncus acutiflorus, Carex panicea and Cirsium dissectum

Table 4: Waypoint notes within Penny Moor

Assessment of Wetland Restoration Objectives Mire Restoration Repairs to the side drains into Penny Moor have stabilised areas of streamside wet grassland (M23 and M24) although the clay bund between the side drain and the main Penny Moor stream at Waypoint WPT094 creates a potential erosion point and will need to be monitored. Repairs of the bund along the south side of Rowbarrow Pond are maintaining artificially high water levels in Denny Bog and a sharp division between the bog to the north and the Myrica gale dominated streamside lawns to the south of the stream. These have been affected by drainage and fluctuating water levels. The Penny Moor drain supports an abundance of rare wetland plants and should not be infilled, however the effects of the bund on the south side of Denny Bog could be reduced to allow equalisation of water levels across the valley. This would help restore wet grassland lawns with reduced Myrica cover on the south side of the stream and reduce water levels to encourage better grazing pressure on Denny Bog to the north. Installation of spillways or removal of sections of the bund would have this effect but could threaten the retained water levels in Rowbarrow Pond. The new section of drain that links the restored meandering stream through the alder carr with the main drain through Penny Moor is required to link the original stream section with the later, twentieth century, drainage system. This is a complex site with conflicting nature conservation and livestock management objectives. The current restoration scheme has been partially successful, but further restoration works should be considered to reverse the effects of the drainage works, particularly of the lower eastern reaches of the wetland system. River Restoration Stream restoration has been confined to restoration of flows through the alder woodland to the east of Penny Moor and meander restoration along the stream to the west of the Moor. The infilling of the drain and restoration of flows through the alder woodland has restored floodplain interaction with the stream through the wood. The restoration of meanders through the wet grassland lawns to the west of Penny Moor has also restored good connection between a small side stream and its floodplain. This is rich in aquatic macrophytes including the nationally rare Hampshire purslane Ludwigia palustris and flows through an area of M24 Molinia fen meadow lawn â&#x20AC;&#x201C; an Annex 1 habitat type for which the New Forest has been designated a SAC.

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10.7.1. Restored meandering stream through M24 fen meadow to the west of Penny Moor (date unknown)

Review of Restoration Techniques Restoration techniques used are similar to those that have been tested on a number of other wetland restoration schemes throughout the New Forest. Re-excavation and complementary infilling of drainage ditches with hoggin and heather bales appears to operate well. Clay plugs have the potential to erode, particularly on high energy streams. These are not evident at Penny Moor and the techniques appear to be operating well.

Lessons learned Compromise restoration schemes such as this at Penny Moor and at White Moor result in only partial restoration of wetland systems. At Penny Moor, the retained bund and drain along the southern side of Denny Bog will require continual maintenance to prevent drainage of the mire. However, this maintains artificially high water levels in Denny Bog and deters access to New Forest stock leading to under-grazing and the development of dense Molinia dominated mire of reduced nature conservation value. The restored meander channel on Penny Moor has re-vegetated well and supports a rich aquatic flora including the rare New Forest water crowfoot. Restoration of water courses in Penny Moor, to raise water to ground level, reconnects the drainage channel with its floodplain. Further monitoring of the effects of seasonal flooding on wet grassland composition and productivity is needed to assess the effects of restoration on habitat composition and function.

Summary The restoration of wetland habitats within Penny Moor has been compromised by requirements to preserve wet grassland vegetation for commonersâ&#x20AC;&#x2122; livestock. The resultant scheme has maintained or even increased water levels within Denny Bog and has partially restored Rowbarrow Pond and its rich flora. Elsewhere, the restoration of former stream meanders has improved habitat within areas of wet woodland and streamside lawn. This site has also demonstrated the need for good baseline botanical survey in River Restoration Centre/Jonathan Cox Associates

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identifying and subsequently modifying the restoration scheme to conserve rare plant locations. The resulting restoration scheme will require long-term maintenance to retain water levels in Denny Bog. The vegetation in Denny Bog is dominated by tussocky purple moor-grass mire (M25) indicating a lack of grazing pressure. Raised water levels and artificial water courses may be limiting access to the Bog by commonersâ&#x20AC;&#x2122; livestock.

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Summary & Conclusions The following section provides a summary of the key conclusions and proposed recommendations from the review of eight restoration sites.

Overview All of the sites assessed have shown sustained positive change over the period since their restoration both in terms of improving the quality of habitats and restoring the physical functioning of the mire/ river systems. Some of the restoration techniques used in the sites that were restored earlier sites have been changed or adapted since to inform and improve best practice. There are no examples where techniques which have been found to have failed or be inappropriate have continued to be applied without revision, adaptation or a new approach being adopted. Over the life of the programme so far, FC has reviewed progress with Natural England to discuss the methods used and learn from issues encountered. The New Forest restoration sites have been well used to discuss progress, issues, lessons and success, to learn from a range of expert input and to help amend both the design and implementation of works. However, as yet there has been no formal systematic review to evaluate change and learning across the Forest-wide restoration works and programme. With future changes in delivery teams, the less well documented project-by-project approach could result in significant loss of specific experience and understanding. A more strategic and well documented approach to selection, objective setting, appropriately targeted monitoring and evaluation would derive significant benefits and inform each future project.

Summary of Findings The following section provides a summary of the key findings in relation to the eight restoration sites that have been reviewed.

Holly Hatch The restoration works at Holly Hatch were undertaken in 2005 and are showing their 10 year age. The site is difficult as it is a headwater and has a relatively steep gradient (for a New Forest stream). Some of the techniques trialled on this site, for example the use of wooden boards, are no longer considered to be best practice, as the science and understanding of river restoration has developed. The FC are now using alternative techniques in the New Forest where there are steep gradients (such as the use of heather bale ramps and woody debris dams, where permitted) to retain bed gravels and add habitat complexity. The gradient has meant that the steady bed slope has become more stepped with the boards acting as weirs in places. A better understanding of the long section profile (energy gradient) is required for these steeper stream sections when planning what techniques to use and how to apply them.

White Moor The restoration works at White Moor were undertaken in 2006. . Their effect on habitats in the area has been varied. Where drains have been fully backfilled good wet woodland, mire and wet heath has developed. However, partial drain infilling has resulted in only partial habitat restoration and there is some evidence of continued erosion and drainage of wet heath habitat as a consequence. Growth of scrub and vegetation in partially filled drains and deposits of wood are unlikely to re-activate a dynamic stream flow and floodplain interaction. It is more likely that the drain will develop into a linear pond with flow through it. River Restoration Centre/Jonathan Cox Associates

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Soldiers Bog The restoration of Soldiers Bog was undertaken in 2013/2014. The vegetation and ecology is still in a state of some flux as a consequence of these recent changes. However, the works undertaken appear to have been very successful with good restoration of mire and stream hydro-morphology. Further monitoring will be needed to record the development of the mire vegetation and associated stream ecology as these habitats reach equilibrium with the restored conditions.

North Oakley The restoration of North Oakley was undertaken in 2005 has been very successful. The obvious paleochannel needed little additional work other than excavation of organic material and removal of isolated earth â&#x20AC;&#x2DC;plugsâ&#x20AC;&#x2122;. Monitoring of erosion is recommended in the lower 30m section, from the headcut and scour pool to the join with the old channelised course. It is recommended that the use of significant quantities of woody material (including whole trees), to reduce velocities in this scouring section and to accrete gravel should be considered. Thinning of the woodland canopy and restoration of the former Blackensford Lawn would also improve the value of the floodplain vegetation communities. These are likely to revert to species rich rush pasture (Annex 1 habitat type Eu-Molinion). The currently heavily shaded floodplain is generally species poor but shows clear patterning between flooded grassy areas and higher bracken dominated areas.

Dames Slough Inclosure The restoration of Dames Slough Inclosure was undertaken in 2005. The upper two thirds of the restored River Blackwater at North Oakley Inclosure are functioning better as a meandering floodplain stream than the lower third. Comparison of the 1996 River Corridor Survey shows the magnitude of structural change that has occurred. The increased length and diversity of structure in the Blackwater have significantly improved it as a habitat for aquatic macrophytes, invertebrates and fish. The high sinuosity and comparatively small depth and width both combine to allow the river to flow out onto the floodplain in periods of high rainfall. Whilst still visible (as there is an absence of mature trees), the old in-filled channel is vegetating well (except the clay plugs which remain visible and soft under foot).

Fletchers Thorns The river restoration at Fletchers Thorns was undertaken in 2011 and has naturalised and achieved significant nature conservation benefits in a very short period of time. The excavated meandering channel of the Blackwater through Fletchers Thorns has restored connection between the river and its floodplain. The flora and vegetation of the area is still responding to these changes but is likely to be substantially improved. The old channel is re-vegetating well and can only be recognised by the discerning eye.

Akercome Bottom The restoration of Akercome Bottom was undertaken in 2010/11. Akercome Bottom restoration scheme demonstrates a wide range of wetland restoration techniques ranging from mire restoration to stream restoration within woodland and across stream side lawn. The resultant system is now largely selfsustaining and operating in sympathy with adjacent habitats. Some minor adjustments may be required to River Restoration Centre/Jonathan Cox Associates

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stabilise local erosion features caused by changes in gradient and where clay plugs have been used, but in general the wetland restoration techniques used have succeeded in meeting their objectives. Further ecological monitoring will be required to assess further changes as habitats and species populations adjust to the restored conditions.

Penny Moor The restoration of the wetland habitats within Penny Moor were undertaken in 2012/2013. The effectiveness of the restoration has been compromised to some extent by the requirements to preserve wet grassland vegetation for commonersâ&#x20AC;&#x2122; livestock. The restoration of former stream meanders and blocking of side drains has improved habitat within areas of three Annex 1 SAC habitat types; wet woodland, streamside lawn and valley mire. The works have maintained or even increased water levels within Denny Bog and have acted to help maintain water levels in Rowbarrow Pond. The main drain through the centre of Penny Moor has been retained (for livestock management reasons) and as a consequence, continues to have adverse effects on wetland habitats through this section of the wetland system. This restoration scheme demonstrated the value of good baseline botanical survey in helping to identify and subsequently modify the proposed works to conserve rare plant locations.

The following table provides a summary of the key lessons learnt, SAC habitats that have been restored and any compromises that have been made to the restoration proposals that may have affected their overall success.

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Restoration Scheme Holly Hatch

White Moor

Lessons learned  Split restoration objectives (i.e. nature conservation and livestock management) lead to partial restoration.  Headwater streams are difficult to restore due to absence of bed material supply.  Wooden board structures have not worked effectively and should be replaced with longer term solution such as use of large woody material. A good example of this is the large fallen beech that has blocked the channel and is diffusing flow whilst holding back the gravel bed above far better than the wooden boards downstream.  Partial infilling of drains has had partial benefits. Where drains have been fully backfilled, good wet woodland, mire and wet heath has developed. Full restoration of wet heath, mire and wet woodland and the downstream transition from seepage flows to stream flow has not been achieved.  There is a need to better understand the effects of wetland and watercourse restoration on wet grassland lawns and forage quality for New Forest stock.

SAC Habitats restored Northern Atlantic wet heath

Compromises made Incompatibility between retained Inclosure edge drainage ditch and main stream channel restoration.

Partial restoration of Northern Atlantic Wet Heath and Depressions on peat substrates of the Rhynchosporion

This restoration scheme has been compromised as nature conservation objectives have been constrained by livestock management objectives.

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Soldiers Bog

North Oakley

Dames Slough Inclosure

The restoration works have led to increased:  channel sinuosity;  flow and habitat diversity;  macrophyte cover;  marginal vegetation;  a more species rich bog. The infilling of the old drainage channel has blended well into the landscape and it is now difficult to spot where the channels once were.  Clay plugs, used to separate old and restored channels, have remained poorly vegetated, very soft when wet and the only obvious sign of the old course where in-filled.  Plugs could be better ‘disguised’ if set further back from the new channel edge.  Channel backfill could be achieved by using excavated channel material combined with imported material.  Achieving a comprehensive restoration of channel size (at the lower end of the site) and the connectivity with the floodplain, would require redesign of the road bridge to accommodate a wider floodplain flow path.  Clay plugs have a propensity to remain soft and vegetation establishment slow

River Restoration Centre/Jonathan Cox Associates

Valley mire (potentially with Rhynchosporion habitat)

None known

 Eu-Molinion Fen Meadow if tree cover is significantly reduced from former streamside lawns.

None known, although tree cover within the inclosure may have been retained in line with the approved Forest Design Plan.

None

Road infrastructure. Rare species present in standing water of old meanders.

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to develop. These could be protected from pressure of grazing animals (in particular hoof damage) by placing brushwood, felled trees, root balls, etc. on these areas. This would promote better vegetation growth and gradual settlement and compaction of the clay plug with time. Fletchers Thorns

 This process based restoration has been None very successful in restoring the old meandering course of the Black Water at Fletchers Thorns.  There are no visible signs of any negative impacts or techniques that have been inappropriate or not worked.  The restored river has greatly increased sinuosity, habitat diversity and lateral connectivity.  Re-excavating and reconnecting the old meandering course combined with placement of imported gravel has created a hydromorphologically diverse system providing a number of ecosystem services such as natural flood management, habitats for many species and a popular recreational area.  Bed level raising, both upstream and downstream of the concrete ford, has worked well.

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None known

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Akercombe Bottom

 Infilling of the old drainage channel has blended well into the landscape.  The clay plugs are less prominent and have not created the soft ground with limited vegetation growth as seen at North Oakley.  The drainage system has been restored in its entirety avoiding the creation of breaks in the hydro-morphology that create instability and consequent erosion (as seen at Holly Hatch).  The use of significant quantities of imported hoggin to raise bed levels has been shown to be much more effective than the use of the timber boards used at Holly Hatch.  The downstream end of the Akercome Bottom stream now meanders across streamside wet grassland lawns. Flood flows are able to expand and retreat across the floodplain.  This contrasts with the partially restored drains at White Moor where attempts were made to preserve streamside wet grassland from deteriorating through excessive inundation.  Further monitoring is required to assess the effects of restoration of stream bed levels on streamside lawn vegetation

River Restoration Centre/Jonathan Cox Associates

 Eu-Molinion Fen Meadow  Northern Atlantic wet heath  Depressions in peat substrate (Rhynchosporion)

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The pond was retained due to the conditions set by the CDA and Verderers following the stakeholder consultation.

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Penny Moor



composition and productivity. Compromise restoration schemes such as at Penny Moor result in only partial restoration of wetland systems. At Penny Moor, the retained bund and drain along the southern side of Denny Bog will require continual maintenance to prevent drainage of the mire. The restored meander channel on Penny Moor has re-vegetated well and supports a rich aquatic flora including the rare New Forest water crowfoot. Restoration of the water courses in Penny Moor, to raise water to ground level has reconnected the drainage channel with its floodplain. Further monitoring of the effects of seasonal flooding on wet grassland composition and productivity is needed to assess the effects of restoration on habitat composition and function.

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 Eu-Molinion Fen Meadow  Northern Atlantic wet heath  Bog woodland

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This restoration scheme has been compromised which nature conservation objectives have been constrained by livestock management objectives.

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Monitoring Biological monitoring It is recommended that baseline biological surveys should be undertaken prior to wetland restoration schemes being carried out and that systematic post-restoration monitoring of the effects of wetland restoration on habitats and species populations of importance would be advisable. The surveys undertaken to accompany the Penny Moor scheme provide a good example of the value of such surveys. It is understood that a monitoring programme is now being developed by the Forestry Commission. This initiative should be integrated into a programme of targeted monitoring of a sample of wetland restoration schemes. Those considered in this report could provide a good initial sample. Monitoring should be targeted at the habitats and species populations for which the New Forest has been designated as SSSI, SAC and Ramsar site. It is recommended that the existing monitoring programme be reviewed to ensure all of the following are included:  Fixed point quadrats (either stratified random quadrats or transects) and photography to record vegetation composition and structure including aquatic macrophytes and associated wetland vegetation.  Distribution of rare or indicator plant species.  Distribution and extent of vegetation types.  Fish abundance and diversity.  Aquatic invertebrate abundance and diversity.  Distribution and abundance of rare or indicator invertebrate species e.g. southern damselfly.  Bird monitoring – particularly species such as snipe, lapwing, curlew, redshank and kingfisher. The conflict between wetland restoration and grazing productivity needs to be better understood. This study has found that schemes that have been adopted to preserve grazing for commoners stock will require continued management to maintain them and may be causing continued damage to wetland habitats. It is recommended that properly targeted monitoring of the effects of wetland restoration on grazing productivity and vegetation composition should be undertaken to inform future wetland restoration schemes. This should cover a number of habitat types including wet grassland (lawns), heathland, mire and woodland. Morphological monitoring The end of LIFE 3 report (Sear et al)12 stated the need for the monitoring of restoration works to allow improvement to the overall programme of works. This project has shown that there have been significant improvements to the techniques used to undertake wetland restoration works within the New Forest over the past 10 years. It is recommended that this process of evaluation and refinement should be formalised with systematic surveys undertaken at 5 year and 10 year intervals (as recommended in the Life 3 report). 12

German, S.E., Sear, D.A. and Jeffries, R.J. (2003) Geomorphological baseline assessment of the Highland Water and Blackwater catchments in the New Forest. In, Final Report to LIFE 3 Project. Bristol, UK, Environment Agency.

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There were some difficulties encountered in undertaking this study accessing the site specific methodologies for the proposed works and fixed point photographs. This has not compromised the robustness of these study findings. It is however recommended that the Forestry Commission should create an archive of material that is being generated by the wetland restoration programme, to improve the process of evaluation and monitoring in the future. The River Restoration Centre has published a widely used reference guide to monitoring river restoration, including the techniques that should be used in the adjacent wetland and mire systems. It is important that the linkages between physical and biological processes are implicitly stated and combined to properly evaluate success, adapt management to reflect failings and refine techniques for future use. In 2015, the addition of a monitoring planner to this guidance now helps to frame and set out an appropriate monitoring and evaluation plan for projects. http://www.therrc.co.uk/monitoring-guidance. This is being adopted by the Environment Agency, Natural England and SEPA in planning their large restoration programmes.

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References GeoData Institute/ School of Geography University of Southampton (2005) Ober Water Geomorphological Dynamics Assessment. Report to the Forestry Commission German, S.E., Sear, D.A. and Jeffries, R.J. (2003) Geomorphological baseline assessment of the Highland Water and Blackwater catchments in the New Forest. In, Final Report to LIFE 3 Project. Bristol, UK, Environment Agency. Holzer, T. (1996) Strategic River Corridor Survey of the New Forest Catchment Report Two Volume 6 Tributaries of the Lymington - the Blackwater and Oberwater. Report to the Environment Agency, Bugle Ecological Services JBA report – http://publications.naturalengland.org.uk/file/6101543870791680 LIFE 3. Sustainable Wetland Restoration in the New Forest (2006) Technical Final Report. Hampshire County Council Rodwell, J.S. Ed (1991). British Plant Communities, Volume 2: Mires and Heaths. CUP. Sanderson, N.A. (2013) Rare Plant Survey of Penny Moor, New Forest, July 2012. Report to The Forestry Commission Sear, D. E. (2012). New Forest Hydrogeomorphology, University of Southampton. Smith, Jane. (2006) New Forest Wetland Management Plan 2006 – 2016 LIFE02/NAT/UK8544 April 2006. Forestry Commission, The Queen’s House, Lyndhurst, Hampshire, SO43 7NH Sustainable Wetland Restoration in the New Forest (LIFE 3) (2006). Technical Final Report (Annex 9.1 – 9.25). Tuckfield, C G (1976) A Geomorphological Appraisal of Some Recent Drainage Work Carried out in the New Forest by The Forestry Commission. Report to the Nature Conservancy Council Wright, R.N. & Westerhoff, D.V. (2001). New Forest SAC Management Plan. English Nature, Lyndhurst

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Acknowledgements We are very grateful to the Forestry Commission for providing us with information on the many wetland restoration schemes we have considered. In particular we would like to thank Nick Wardlaw, Marianne Bergin and Sonia Lorenzo MartĂn. We are also grateful to Sarah Young at Land Use Consultants for her assistance and guidance.

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