A BRIEF SURVEY OF THE BOTANY AT SHINGLE STREET, SUFFOLK SEBASTIAN E .
HEATH
In 1979 I was involved in an ecological survey at Shingle Street, Suffolk (Barnes and Heath. 1980). Our paper summarises zoological. geomorphological and historical developments. Here I shall put most emphasis on plant communities and relate them to the role man has come to plav at Shingle Street. Shingle Street (TM 2752) is a hamlet about half way between Felixstowe and Aldeburgh at the mouth of the river Ore. Its history can be traced back to the 12th Century and is centred around the tremendous effects which storms have had on its coastline. There have been occasions when overnight widths of up to 300 m of beach have been eroded to the sea or washed up. Today this strip of coast, some 3 km long, represents the third largest pure shingle deposition in Britain. An 8 km long spit lies in apposition to the coast. The natural conditions under which plants grow on shingle beaches are quite inhospitable. Their main antagonists are storms, the mobility of the substrate and its inability to retain water and nutrients. In various studies describing shingle plant communities (Randall, 1977; Scott, 1965; Tansley, 1953) the succession of Vegetation appears to be the result of two main factors. These are the length of time for which the shingle has been left undisturbed by storms and waves, etc., and the extent to which fine material has accumulated between the individual pebbles. Today a third factor must be added, the influence of man. Those plants which have successfully colonised this habitat show a high degree of specialisation. Many of the plants which occur there are nationally scarce, e.g. the sea pea (Lathyrus japonica), yellow vetch (Vicia lutea), sea kale (Crambe maritima) and sea holly (Eryngium maritimum). Others might be nationally abundant, but their appearance at Shingle Street is quite exceptional. A typical survey of plants in a shingle environment would be 60 total, 20 very rare and 16 rare (Tansley, 1953, on Chesil Bank, Dorset). At Shingle Street these tigures may be divided by a factor of three. Just how vulnerable the habitat is, can be observed on the sea side of the village, where a sea wall is bulldozed three or four times a year to prevent excessive erosion. Here not a Single plant grows! Where plants do grow the Vegetation is typically patchy, as in most harsh environments. The main colonists are grasses such as oat grass (Arrhenatherum elatius), mosses, L. japonicus, and in the early summer there are bright yellow patches of wall pepper (Sedum acre). It is quite surprising to find L. japonicus as one of the main colonisers. This plant has a scarce national distribution. and little is known of its regional and historical origins. At Shingle Street it grows abundantly enough to allow for an extensive study of the factors contributing to its colonisation and growth habits. Fortunately, the picking of plants is prohibited at Shingle Street, but neverTrans. Suffolk Nat. Soc. 18 pari 3.
250
Suffolk Natural History, Vol. 18, Part 3
theless collecting of certain plants has led to their extinction here. Reliable records prove the existence of climax Vegetation such as sea bindweed (Calystegia soldanella) and E.maritimum until about ten years ago (F. Bingley, pers. comm.). These are now absent locally. The attempts of locals to transplant growing specimens back to Shingle Street have unfortunately not resulted in successful recolonisation. Another plant which seems to suffer from human violation is C. maritima. Last year only a few bushes could still be found. Despite these small numbers I have seen how several of these spectacular plants had been vandalised to such an extent that they would not recover. It is not surprising that the main colony now grows offshore on the spit, where it is forbidden to set foot. Fig. 1 is an example from the belt transect survey which was used to determine the serial succession of plants at Shingle Street inward from the coast (Fig. 2). The first site of colonisation is on the storm-shelf, a ridge left by the last major storm, but which is not affected by tidal movements. Here drift material accumulates and often provides the initial medium for the settling of sea beet (Beta maritima). Later, with a small degree of stability, L. japonicus will settle, sending down long tap roots. These can reach up to one metre in length and autonomise the nutrient supply of the plant from the harsh surface conditions. These two plants grow perennially, building up a reservoir of deciduous leaves, providing more fine fraction (particles smaller than 2mm in diameter) and organic material for other plants to settle. These will be Gramineae, such as A. elatius and sea couch-grass (Agropyron pungens), which spread vegetatively by runners. These four plants initiate a massive process of reproduction, recycling nutrients and accumulating consumable material and fine fraction. This lays the foundations for all subsequent developments. When the environment has become stable enough, annual plants and lichens begin to colonise. Lichens encrust the shingle and so decrease its mobility. This adds to the list of beneficial factors which allow Chenopodiaceae, short lived Compositae, curly dock (Rumex crispus), annual meadow grass (Poa annua) and sea campion (Silene maritima), intermingled with Shingle Street's most common plant, A. elatius, to replace the pioneer species. Further stabilisation induces a fifth stage of the succession, characterised by S. acre, red fescue (Festuca rubra), sticky groundsel (Senecio viscosus) and mosses. These two stages are the most common at Shingle Street. They represent areas which have been left undisturbed for some 20-70 years. This coincides with new shingle masses being deposited on the shore, providing further protection from the sea. These two stages also increase the humus content of the substrate. When a sufficient level has been reached, the shingle takes on characteristics of calcareous waste ground. Great thistle (Cirsium vulgare), nettle (Urtica dioica) and sea pink (Armeria maritima) can then be found. The natural succession from here into climax Vegetation is disturbed at Shingle Street and remains incomplete. Presumably the development would continue into heathland, as Scott (1965) describes at Chesil Bank, Dorset. It will be noticed that this study has been confined to unusually few species Trans. Suffolk Nat. Soc. 18 part 3.
u c c CO <U£»p w i>O 2
•o
1/5
-
-c
d-tf)
OI o
tu E o QL J B w u < tu OS D CO
o o OO O —I o
o o o O —I —I CN
•c •c« o 2<u S<3pc ÖD 3 «•> n "" > £ <L> ga'o 7t U oi-3 U ^ I u ,, u 3 JU > CO « U uS 1> ü1/5 « oa uac -So1"a = i>,üc/1 E a U u "< uO tu —"u •jt aso o 't 8-5 •u CoO u uco s .2 u u t/3 SSI J= B3F— »i > o •j V.
C
f > oo
3
» I
4»
J3
O
O <u . ü o x: c • o cCO 1CO1 D £>
6 IT)
CJ C <U S 8 =o o n. cä ra ST) 3 = w -3 «31 ^ o e • » E §"3 5 5 •c~S <ur 3?c5oc>a c co s S : J=O .
Q. y X! u •o H u c u/i </UaOi— t je u C3 3* " < >E o8-2 - 0 •si C O C Co C O co Q. ä 1)CO •
X
CS
T3
-a c CO c« <u
X
<u
ES •J CJ 2 V '•6 cd c Q Q. s 1. O a - s 5 SS c <u E b 5 £ o . U U QS a, co O 00 v • E CS <D
X ea E aj M) M t/> £o c <4=
<U C ±: o co
A BRIEF REVIEW O F T H E BOTANY OF SHINGI.E STREET. SUFFOLK
253
of plants. The belt transect of Fig. 1 was taken about one mile south of Shingle Street village, in probably the most remote part of the area. The shingle depositions there date back to the 1890's and suffered their last major disturbance during the last war. when Shingle Street was used for bombing practice. The average coverage is still only 1.3 on the Braun-Blanquet scale (Braun-Blanquet, 1951). This scale describes vegetational coverage on a 0 to 5 density, 0 meaning present but with insignificant coverage and the figures 1 to 5 representing an increase in coverage in steps of 20%. This gives some idea of how long it takes for the shingle to be able to support plant life. It also means that the Vegetation at Shingle Street is still in a dynamic State, i.e. still developing a fĂźll succession of plants. Hence, interference with its natural progress will not only have temporary effects, but also long term consequences. An additional problem is already being caused by nature itself. As indicated above, the succession of plants develops parallel to the increasing physical stability of the foreshore. Until the late 1960's this had been made possible by constant large supplies of new shingle material from offshore. At the present time the rate of supply seems to be diminishing, and at places erosion to the sea is the predominating movement of the coastline. References Barnes, R. S. K. and Heath, S. E. (1980). The shingle foreshore/lagoon system of Shingle Street, Suffolk: a preliminary survey. Trans. Suffolk. Nat. Hist. 18, 168. Braun-Blanquet, J. (1951). Pflanzensoziologie. (2ndedn.) Vienna. Randall, R. (1977). Shingle Street and the sea. Geogr. Mag. 49, 569. Scott, A. G. M. (1965). Shingle succession at Dungeness. J. Ecol. 53. 21. Tansley, A. G. (1953). The British Isles and their Vegetation. Cambridge.
S. E. Heath Wolfson College Cambridge CB39BB
Trans. Suffolk Nat. Soc. 18 part 3.