SAND DUNE VEGETATION- SUCCESSION: CASE STUDY OF PANAMA VILLAGE IN EASTERN SRI LANKA

Abstract

Coastal sand dunes harbour special successional plant communities and are of immenseecological value. Henry Cowels, one of the pioneers to study ecological succession in thelate 19th century was inspired by the sand dunes of the shores of Lake Michigan.

In Sri Lanka coastal sand dunes occur along the dry zone coast. The stretch extendingnorthward from Hambantota has a well-developed dune system in Panama in the AmparaDistrict. The objective of the present study was to investigate the composition, structureand zonation of vegetation in the sand dune system of Panama between Kumbukkan Oyaestuary and Arugam Bay. It was carried out in April 2002 by random plot sampling.

The dunes supporting the vegetation are more or less parallel to the shore and occur within300m from the shoreline (berm). They rise in four successive levels up to about 8m fromthe berm level. The first three dunes are within SOm from the berm, while the fourth one isbetween 150 and 300m from the berm.

The vegetation shows a zonation in conformity with the successive dunes. The first zone(O-7m from berm) has creeping vegetation consisting of Spinifex Iittoreus etc. The secondzone (7-14m) has low herbs (e.g. Scaeovola sericea, Sesamum prostratum) in addition tocreeping forms. These two zones together have 16 plant species. The third zone is a morestabilized terrain with 17 plant species exceeding 15cm of height (Scaeovola, Crinum sp.and Calotropis gigantean etc.). The fourth zone is wider and more stabilized. It has aboutten stunted tree species such as Crateva adansoni, Strychnos potatorum and Grewiacarpinifolia.

The taller plants are swept in a southwest-northeast direction indicating the dominant winddirection.