An Assessment of the Status of Biodiversity in the Muthurajawela ...

3. Flora of Muthurajawela
Vegetation types, floristic composition and abundance of species.
The Muthurajawela wetland sanctuary consists of a mosaic of seven major vegetation types:
marsh, lentic flora, shrubland, reed swamp, grassland, stream bank and mangrove forest (Table
3). Edaphic factors such as physiography, land form, soils, salinity, hydrological conditions
etc., appear to be the primary factors which govern the organisation of different vegetation
types within the Muthurajawela wetland. Climatic factors play a secondary role in determining
the plant life at Muthurajawela. In addition to edaphic and climatic factors, human disturbances
and the spread of invasive alien species have also determined the structure and composition of
vegetation types at a local level.
A total of 194 species belonging to 66 families were recorded from the study area, and these
included one endemic species, three nationally threatened species and 11 invasive alien species
(Appendix 1). Phoenix zeylanica (Family Palmae) is the sole endemic species recorded. Of the
total number of species documented, 30 were woody plant species. Among the different
vegetation types, the shrubland harbored the highest number of species (115), while the
Table 3
Vegetation types and dominant plant species in the Muthurajawela Wetland Sanctuary
Vegetation Types Description Dominant Species 1 and Families
Marsh Aquatic and semi-aquatic herbs Eleocharis dulcis (Cyperaceae)
and some woody plants
Acrostichum aureum (Pteridaceae)
Lentic flora Aquatic vegetation associated Pistia stratiotes (Araceae)
with static or slow-flowing
Nymphaea stellata (Nymphaeaceae)
aquatic habitats
Eleocharis dulcis (Cyperaceae)
Eichhornia crassipes (Pontederiaceae)
Salvinia molesta (Salviniaceae)
Reed swamp Aquatic or semi-aquatic tall Phragmites karka (Poaceae)
reeds rooted in soil.
Typha angustifolia (Typhaceae)
Short grassland Herbaceous grasses Ischaemum rugosum (Poaceae)
Eragrostis spp. (Poaceae)
Shrubland Broad-leaved shrub Annona glabra (Annonaceae)
Lygodium microphyllum (Schizaeaceae)
Stream bank/Riparian Broad-leaved flora bordering Annona glabra (Annonaceae)
streams and canals
Pandanus tectorius (Pandanaceae)
Cerbera manghas (Apocynaceae)
Syzygium caryophyllatum (Myrtaceae)
Mangrove Forest
1
Based on % cover (Braun-Blanquet method)
Broad-leaved trees and shrubs which are Rhizophora mucronata (Rhizophoraceae)
adapted to grow under saline and Avicennia marina (Verbenaceae)
anaerobic conditions, along or near sea
shores and estuaries
9