REVITALIZING THE MANGROVES
DESIGN STRATEGIES FOR COASTAL ECOSYSTEMS
BY: Poh Qiying, Anushree Agarwal, Chen Xu, Shuchi Jhalani, Nandini
MANGROVES & THEIR ECOSYSTEM SERVICES Mangroves consist of large and extensive salt tolerant trees living at the confluence of land and sea. Abundantly found in Asia, followed by Africa and South America. Total mangrove area is around 15000 km2.
Indonesia , Brazil, Australia and Nigeria alone account for 41 % of all mangroves .
Image: http://www.google.com.sg/ mangrove-imgres.htm
Image :http://www.plant-talk.org/studyinvestigates-global-mangrove-loss.htm
COASTAL ZONE
MIDDLE ZONE
INLAND ZONE
Mangroves are an essentially valuable ecological and economic resource and are an important eco system on our planet. According to DANIEL M. ALONGI, in his paper ‘Present state and future of the world’s mangrove forests’1, it is stated that mangroves provide various services as transition of zone between land and sea, anchoring the shoreline while buffering coastal ecosystems against hurricanes and tsunami, Sequester massive amounts of carbon to combat climate change . Adapt to rising sea level protecting coral reefs from sedimentation. They also provide Service nurseries and Vital food source for marine life.
Image :http://www.mangroveactionproject.org/cbemr/
Mangrove swamps have rich organic soil layer in the first 0.5 – 5 m soil depth with high levels of below ground Biomass. Mangroves also help to retain, concentrate and recycle nutrients and also trap sediments, debris through their natural filtering process and this then improves water quality of tidal rivers that drain through the mangroves.
Image :http://www.plant-talk.org/study-investigates-global-mangroveloss.htm
MANGROVES : GLOBAL CONCERNS According to Beth A. Polidoro, In his paper “The Loss of Species: Mangrove Extinction Risk and Geographic Areas of Global Concern“, he brings to notice the economic valuation of mangrove forests ie. they provide at least US $1.6 billion each year in ecosystem services and support coastal livelihoods worldwide. Globally, mangrove areas are declining rapidly as they are cleared for coastal development and aquaculture and logged for timber and fuel production.”
ALARMING FACTS :
Image : http://oneocean.org/download/db_files/201001WhyProtect Mangroves.pdf
Almost half (44%) of the world's population living within 150 km of a coastline , heavily populated coastal zones have increasingly spurred the widespread clearing of mangroves for the coastal development, aquaculture, and resource use. 1
Globally, mangrove area between 20% and 35% of has been lost since approximately 1980, and these areas are disappearing at the rate of approximately 1% per year, with estimates as high as 2–8% per year. 1
It is estimated that about 26% of mangrove forests worldwide are getting degraded due to over-exploitation for timber production and fuel wood. 1
clearing of mangroves for shrimp culture contributes ~38% of global mangrove loss, with other aquaculture accounting for another 14%. 1
The loss of individual mangrove species is also of great concern, especially as even pristine mangrove areas are species-poor compared with other tropical plant ecosystems. 1
Given their accelerating rate of loss, mangrove forests may at least functionally disappear in as little as 100 years.1
Image :http://oneocean.org/download/db_files/201001WhyProtectMangroves.pdf 1: http://oneocean.org/download/db_files/201001WhyProtectMangroves.pdf
THREATS TO MANGROVE ECOSYSTEM 1
Fragmentation of Mangroves due to human activities
SPECIFIC TO OUR SITE
WAVE ACTION
Natural state of mangrove along edge of island
Introduce gap in mangrove for access. Edge introduced
Gap widens because of spread of development. Increased edge o area ratio
Loss of small patches because of fragmentation and edge effects. Increased boat traffic
The artificial gaps created for access to buildings in the mangrove belt breaks the belt into small fragments which creates edges. As urbanization happens the number of these gaps increases and so does the edge to area ratio. The boats coming in trample the new shoots and aerial roots of the mangrove and create small artificial waves which disturbs the ecosystem. Eventually the small patches will not be able to withstand the disturbances and die. This will create wide openings in the mangrove belt exposing the vulnerable coastline to the harsh wave action and erosion. As a result the sea starts to creep in towards the developments and the eroded sediments decrease water quality and suffocate corals.
Naturally occurring Mangrove Prevents erosion; Naturally protected beach
No Mangrove Beach prone to erosion; Artificial protection required
THREATS TO MANGROVE ECOSYSTEM 2
SPECIFIC TO OUR SITE
DEPLETION OF CORAL REEFS
Current and projected threats to Coastal ecosystems : Rapid deteriorationLoss of 40% of coral reefs and mangroves over the past 40 years. Causes for deterioration-Coastal deforestation, coastal reclamation, declining water quality, pollution, sewage, destructive fishing and overexploitation of marine life. Result of elimination of coral reefs- Loss of at least 30 to 50% of species that need corals and the reefs they build for food, shelter and reproduction. Source: The coral triangle and climate change (2009), www.panda.org/coraltriangle
Map: source- http://www.esri.com/news/arcuser/0112/exploringthreats-to-coral-reefs.html
Coral breakage and damage from throwing anchors in the reef
Blast fishing substantially damages the reef which provides shelter for the fish and creates coral debris
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DEPLETION OF FISH POPULATION
By 2050- 50% reduction in abundance of commercial fish. It is estimated that almost 80% of global fish catches are directly or indirectly dependent on mangroves (Ellison et al., 2008; Sullivan, 2005). Thus, the food security for many indigenous coastal communities is closely linked to the health of mangrove ecosystems (Horwitz et al., 2012). Global loss of seafood species Source- The journal of ‘Science’ using FAO data
SITE : BUNAKEN ISLAND, NORTH SULAWESI, INDONESIA Location
BUNAKEN NATIONAL PARK SINGAPORE
BUNAKEN ISLAND
Source: MLA Studio 2015
Source: MLA Studio 2015
Bunaken Island Area of land- 704.33 Ha Area of reef - 531.4 Ha
Source: ROJAS. P (2010), Reef front heterogenity analysis and coral genera diversity pattern in the Bunaken National Park, Indonesia
Source: MLA Studio 2015
Aerial view of Bunaken Island
Source: MLA Studio 2015
Source: MLA Studio 2015
Coral Seagrass
Mangrove Beach
PROPOSAL 1: SAVEGUARDING THE MANGROVES FIVE KEYS TO ACHIEVE MANGROVE RESTORATION AUTECOLOGY
HYDROLOGY
DISTUBANCE
REHAB DESIGN
PLANTING
Reproduction Dispersal Growth
Depth Duration Frequency
Stress Option Measurement
Tidal Stream Tidal Prisms Rehabilitation
Recruitment Nursery Space and Soil
Study site conditions and ecology Mangrove species and its reproduction patterns Dispersal Patterns: various size of propagules will float differently, with some further away from its original location. Access and design suitable conditions
Study of neighbouring mangrove to understand the tide table and suitable elevation Take reading from other mangrove
Design the pond/water travel area
Places to put saplings Implementation and Monitoring
Collection of seeds Transfer to bigger plastic Establishment of a nursery to supply the needs
Reforesting in denuded areas
Alberti, Marina et al. 'Integrating Humans Into Ecology: Opportunities And Challenges For Studying Urban Ecosystems'. BioScience 53.12 (2003): 1169. http://mangroveactionproject.org/wp-content/uploads/2013/08/5-Step-EMR-Manual.pdf, 2015. Web. 17 Sept. 2015
PROPOSAL 1: SAVEGUARDING THE MANGROVES Application to site The gaps are caused by the resort’s usage to transport people and goods. The sheer number of the resorts mean that the openings are many, and these openings will only get worse by the entry of boats and the waves cause by it.
Source: MLA Studio 2015
Removal of the boats entering the mangrove. Protect the area from more damages and repeated usage. EROSION CONTROL Hard structures disturb the dynamic equilibrium between sedimentation and erosion: sediment import by the tide is blocked and erosion by waves is increased due to reflection.
The local community can be engaged and taught so that they may get an income from the project. The mangroves will be better cared for when they are more involved in the project.
Plant saplings to regenerate the mangrove areas, and close back the gap.
Permeable structures are used through mimicking of mangroves and sediment is trapped and wave action is damped.
Source : https://publicwiki.deltares.nl
Permeable structure design. MHW = Mean High Water. View from the side.
PROPOSAL 3: CORAL REEF RESTORATION
Intervention Area
Due to increase in tourism, and dynamite fishing, the corals are damaged and in need of conservation and restoration. When the reefs are damaged, the mangroves will be subjected to destruction as well. The fish population will then be affected greatly since these ecosystems are dwindling.
Components of the system
Therefore, to sustain or re-grow the damaged coral reef areas, we can make use of the Biorock method. It causes minerals to crystallize from seawater onto rebar structures. Bits of Corals are transplanted attached onto the structures.
and
Break tip of coral
Attachment of corals
Overtime, these bits will grow in size and quantity. Energy consumption is at a minimal, even less than beach lights Innovative Methods of Marine Ecosystem Restoration Edited by Thomas J . Goreau and Robert Kent Trench CRC Press 2012, Chapter 5 ,6 and 7. PowerShow,. 'BIOROCK TECHNOLOGY The Most Cost Effective Solution For: Coral Reef Restoration Fisheries Restoratio'. N.p., 2015. Web. 18 Sept. 2015. Langenheim, Johnny. 'Biorock Giving New Life To Coral Reefs | Johnny Langenheim'. the Guardian. N.p., 2012. Web. 18 Sept. 2015.
PROPOSAL 4 – RECOVER ABANDONED FISH PONDS Ratio of 4:1 of mangrove: pond is necessary for environmental; and economic benefit. STRATEGIES
POND
MANGROVE AS BUFFER
Identify places with water-logged issue, and alter the elevation Identify suitable place for a nursery, out planting (outer abandoned pond, and inner abandoned pond) based on: Hydrology patterns Wave action Drainage Presence of shade
Ideally should have 50-100m of buffer zone
Planting of saplings Outer abandoned pond has bigger wave action, so plant at intervals of 0.5-1m Inner abandoned pond has smaller wave action, so plant at intervals of 1.5-2m Primavera, J. (2014). Manual on Mangrove Reversion of Abandoned and Illegal Brackishwater Fishponds. Retrieved September 17, 2015, from https://www.zsl.org/sites/default/files/media/201405/Manual on Mangrove Reversion of Abandoned and Ilegal Brackishwater Fishponds.pdf
PROPOSAL 5 –CONSERVING THE SOIL SRATA Introducing minimal Excavation Foundations: A construction technique that helps to minimizes disturbance of the natural soil profile in the footprint of the structure. Incorporating Elevated stilt pilings commonly used in areas that are prone to flooding BENEFITS:
Image:http://www.google.com.sg/imgres?imgurl=http://thi sfacade.com/wp-content/uploads/2011/01/house-onstilts4s.jpg
Helps to minimize soil compaction and site disturbance resulting from heavy equipment and machinery. Helps in preserving rainwater infiltration and subsoil water flows Helps to allow rainwater to flow more naturally at shallow soil subsurface level Image:http://www.co.jefferson.wa.us/commdevelopment/PD FS/SquareONE/LID_minimal_excavation_foundations_Sq1.pd
PRIMER ON LANDSCAPE CONNECTIVITY AND FRAGMENTATION
ABSTRACT The earth tissue is facing many disruptions. An urgent need emerges for developing tools and techniques to understand how to sustain without losing the nature . Working with larger patterns, understanding how they interact and designing in harmony with the natural systems , all strive to be the solution at the landscape scale. This primer/handbook is for designers with minimum knowledge of understanding landscape ecology, giving them exact ingredients and steps explaining principles, and guidelines for landscape connectivity and fragmentation through neat sketches and texts. It will also help designers knit together varied matrix of patches and corridor networks. The principles are extracted from the book “ Landscape ecology in landscape architecture and land use planning “ by Wenche E. Dramstad, James D. olson, and Rihard .T.T Foman. These principles are relatively broad scale nudging designers into long term planning and decision making.
CONTENTS 1. UNDERSTANDING LANDSCAPE AND ITS COMPONENTS...........3 2. CONNECTIVITY AND FRAGMENTATION………………..…..….…4 3. ROLE OF MATRIX IN CONNECTIVITY……………………..….……5 4. ROLE OF PATCH IN CONNECTIVITY……………………..……......6 5. ROLE OF CORRIDOR IN CONNECTIVITY………………..……......8 6. CASE STUDY IN BRIEF……………………………………...……....10 BIBLIOGRAPHY …………………………………………....................11
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UNDERSTANDING LANDSCAPE AND ITS COMPONENTS “Landscape is a heterogeneous land area composed of a cluster of interacting ecosystems that is repeated in similar form throughout". (Forman and Godron1986). Farina (2000) defines landscape as “heterogeneous land area, consisting of interaction sets between ecosystems”. The landscape structure consists of the three elements – Matrix, patch, & corridors These elements are the handle for landscape architecture and planning .
These landscape elements should be taken into consideration during the design process in order to achieve the desired objectives. The nearby patches and matrix influence the effectiveness and performance of the corridors by their structure, location , and management.
THE ISSUE The isolation and loss of habitat is a seemingly unstoppable process occurring throughout the modern urbanized world, mainly caused by various dynamic processes such as fragmentation, dissection, attrition, perforation & shrinkage. Architects, planners and ecologists must contend with this continuing process if further reductions in biodiversity are to be slowed or halted. 3
LANDSCAPE CONNECTIVITY
Landscape connectivity can be understood as both ‘structural’ and ‘functional’. Structural connectivity is the physical relationship between landscape elements whereas Functional Connectivity is referred to as the degree of a landscape that facilitates the exchange of organisms, energy, material, and information among habitats & various landscape elements.
IMAGE : Transition of patches (lower connectivity) to corridors (higher connectivity)
LANDSCAPE FRAGMENTATION Fragmentation is a common landscape pattern, which is often associated with habitat loss and isolation. Dramstad, W., Olson, J. and Forman, R. (1996). define fragmentation as “Breaking up of a ecosystem or a land use type , a habitat, into smaller parcels”. It causes land transformation (important process in landscape as urbanisation begins), mainly resulting from disturbances caused by human activities or natural processes , such as fires and herbivores.
IMAGE : FRAGMENTATION LEADING TO REDUCTION IN HABITAT OF A PARTICULAR TYPE, PRIMARILY INTERIOR HABITAT
IMAGE : FRAGMENTATION LEADING TO FRACTAL PATCHES AS A NATURAL REACTION TO TRANSITION
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ROLE OF MATRIX IN CONNECTIVITY “The role of matrix and patches needs to be considered while designing corridors in order to enhance biodiversity. In human dominated landscape areas, the matrix comprises of mostly developed lands (e.g., urban, agriculture) while patches comprise of remnants which have different plant and animal community than the surrounding area”. (Dramstad, W., Olson, J. and Forman, R.1996).
KEY MATRIX GUIDELINES 1. Minimizing introduction and the spread of non-native species.
2. Minimizing disturbance of the natural vegetation.
3. Considering the matrix at multiple spatial and temporal scales.
4. Managing the disruption (i.e. earth -moving, haying) in order to reduce the negative impacts.
IMAGE 4 : INCREASE IN VALUE OF A CORRIDOR IN A LESS SUITABLE MATRIX
IMAGE 5 : DECREASE IN VALUE OF A CORRIDOR IN A MORE SUITABLE MATRIX
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ROLE OF PATCHES IN CONNECTIVITY Patches must be differentiated and analyzed in terms of (a)location, (b)number, (c) size. Size of the patch may vary from a single tree to a national forest. They may be numerous in a landscape , such as rock slides on a mountainside or avalanches or be scarce such as an oases in a desert. Large patches allow higher diversity and abundance in species by means of typically conserving a greater variety and quality of habitats
KEY PATCH GUIDELINES
1.
Breaking up large patches into smaller ones helps to create additional edge habitat but eradicates interior habitat
3.
A large patch will evidently have more habitats and greater number of species.
2.
Reducing local extinction probability by creating larger patches
4. Smaller patches or low quality habitats may lead to species becoming locally extinct. 6
“The larger the size of the patch, the higher the percentage of interior habitat that it will contain. This benefits the interior species which are often the most vulnerable to habitat loss and fragmentation. Large patches typically conserve a greater variety and quality of habitats, resulting in higher species diversity and abundance�. (Dramstad, W., Olson, J. and Forman, R.1996).
KEY PATCH GUIDELINES
FIRE
5.
FIRE
Dividing large patch into smaller ones creates barrier in spreading some disturbance.
7. Avoiding removal of a patch that slows down the recolonisation process, and leads to reduction in stability of meta population
6.
Maximizing number of closely knit smaller patches to act as stepping stones for species movement.
8. Grouped patches as habitats can, in the absence of large patches, help generalist species to survive. 7
ROLE OF CORRIDORS IN CONNECTIVITY “Connecting patches with corridors can benefit biodiversity by providing access to other areas of habitat, increasing gene flow and population viability, enabling recolonization of patches, and providing habitat. Connectivity can be undesirable or unsuccessful in some cases. Corridors can be dominated by edge effects, can increase risk of parasitism and disease, and can facilitate dispersal of invasive species. Corridors can be unsuccessful if they do meet the movement or habitat requirements for the target species�. (Dramstad, W., Olson, J. and Forman, R.1996).
IMAGE : Historic view of a matrix consisting of woodland, grass land, & wet land
IMAGE :A small patch of grassland between the developed matrix, connected via corridor
KEY CORRIDOR GUIDELINES
1.
Corridor gap effectiveness w.r.t movement of species depends on length of gap and contrast between corridor and the gap.
2.
Effectivness of distance between successive stones can be determined by the ability of organism to see each steeping stone.
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“Corridors often interconnect with one another to form networks, enclosing other landcape elements. Networks in turn exhibit connectivity, circuitry, and mesh size. Networks also exhibit connectivity and circuitry�. (Dramstad, W., Olson, J. and Forman, R.1996). They emphasize on the functioning of landscapes and can therefore be used by designers and planners to facilitate or inhibit movements and flows across land mosaics.
KEY CORRIDOR GUIDELINES
3.
5.
Avoiding loss of stepping stones, forming a part of the corridor to facilitate the movement of species between larger patches
4.
Maximizing clustering of stepping stones to provide alternate or redundant routes for movement of species .
Increasing network connectivity and circuitry can provide an overall index of effectivness of linkages for species movement
6.
Maximizing loops and alternative routes in a network can reduce adverse effects of gaps, disturbances, predators and hunters within 9 corridors.
CASE STUDY IN BRIEF 1
The Terai Arc Landscape, Nepal CONNECTIVITY THROUGH NETWORKS The Terai is a belt of land along the foothills of the Himalayas about 35 kilometres wide that stretches across southern Nepal and into India, Bhutan and Bangladesh. It has a remarkable landscape and harbours a rich diversity of flora and fauna. The dominant forms of vegetation are dense tropical monsoon Sal forests and exceptionally tall grasslands. Many mammal species are endangered, including the Indian rhinoceros, the Asian elephant and the royal Bengal tiger1. Creating corridors between critical protected areas.
THREATS & IMPACTS :
A VISION FOR SUSTAINABILITY
1. Degradation of vegetation due to deforestation and wood collection. 2. Pollution of surface water due to release of untreated waste water . 3. Degradation of ecological integrity of the river basins threatened by upcoming hydroelectric projects. 4. Extinction of rhinoceros, tiger and elephant as a result of extensive poaching .
Terai arc landscape Programme aims at achieving goal of sustainable development and biodiversity conservation. The programme is frame worked to achieve the follwing :
1. https://portals.iucn.org/library/efiles/documents/2004-002.pdf
1. Strengthening the existing protected areas. 2. Conserving remaining forests. 3. Restoring the degraded forests. 4. Establishing community forests. 5. Introducing management practices in buffer zones. 6. Creating effective corridors between critical and protected areas.
BIBLIOGRAPHY Andersson, E. and O. Bodin. 2009. Practical tool for landscape planning? An empirical investigation of network based models of habitat fragmentation. Ecography 32: 123-132. Bentrup, G. 2008. Conservation buffers: design guidelines for buffers, corridors, and greenways. Gen. Tech. Rep. SRS-109. Asheville, NC: Department of Agriculture, Forest Service, Southern Research Station. 110 p. Dramstad, W., Olson, J. and Forman, R. (1996). Landscape ecology principles in landscape architecture and land-use planning. [Cambridge? Mass.]: Harvard University Graduate School of Design. Forman, R.T.T. and M. Godron. 1986. Landscape Ecology. John Wiley and Sons, New York, N.Y. 619p. Forman , R.T.T. 1990. “Ecologically sustainable landscapes: the role od spatial configuration.” In zonneveld, I.S and R.T.T Forman, eds, Changing Landscapes: An ecological Perspective. Springer-Verlag, New York, pp. 261-278 Graham Bennett. (2004). Integrating Biodiversity Conservation and Sustainable Use: Lessons Learned From Ecological Networks. IUCN, Gland, Switzerland, and Cambridge, UK. vi + 55 pp. Hilty, J., W.Z. Lidicker Jr. and A.M. Merenlender. 2006. Corridor Ecology. Island Press, Washington D.C. Luken, J.O.; Hinton, A.C.; Baker, D.G. 1991. Forest edges associated with power-line corridors and implications for corridor siting. Landscape and Urban Planning. 20: 315-324. McDonald, R.I.; Urban, D.L. 2006. Edge effects on species composition and exotic species abundance in the North Carolina Piedmont. Biological Invasions. 8: 10491060. Merriam, G.,1991. “ Corridors and connectivity: animal populations in heterogeneous environments.” In Saunders, D.A. and R.J.Hobbs, eds.Nature Conservation 2: The Role of Corridors. Survey Beatty, Chipping Norton, Australia, p.p, 133-142. Saunders, D.A and C.P. Rebeira. 1991,”Values of corridors to avain population in a fragmented landscape.” In saunders, D.A. and R.J. Hobbs, eds. Nature Conservation 2: The Role of Corridors. Survey Beatty, Chipping Norton, Australia, p.p, 221-240 Verkaar, H.J. 1990.:” Corridors as a tool for Plant Species conservation?” In bunce, R.G.H and D.C. Howard, eds. Species dispersal in Agricultural Habitats, Belhaven Press, London, p.p,82-97. 11