Floristic Survey of Meethirigala Forest Reserve in Gampaha District

Abstract

Meethirigala forest reserve consists of approximately 384 ha. It is the largest forest reserve in Gampaha District managed by the Forest Department. It has different topographic positions such as ridges, midslopes and valley areas close to the Kelani River. The present study was conducted to enumerate plant species found in all three topographic positions of the reserve. Plots were demarcated purposively to sample woody perennials equal or greater than 5 cm dbh (diameter at breast height) in 18 plots (5×100 m, rectangular shape). Seedlings greater than 1 m tall were sampled in 18 plots (5×5 m). Shannon diversity indices were calculated to compare dominance of particular species in different topographic positions. A total of 360 individuals of woody perennials belonging to 73 species in ridge, 368 individuals of woody perennials belonging to 100 species in midslope and 272 individuals of woody perennials belonging to 69 species in valley were recorded. And 132, 123 and 100 individuals of seedlings were enumerated in ridge, midslope and valley respectively. In ridge 58 generas, 28 families, in midslope 83 generas, 35 families and, in valley 68 generas, 29 families were observed. 28 species were found in all three different altitudes of the reserve. Forest species in study sites gave a total of 138 plant species belonging to 113 tree species, 11 climber species, 14 shrub species, 109 generas and 46 families. Of this total 138 species, 34 (25%) species are endemic to Sri Lanka. Highest endemism was recorded in the ridge (41.6%). Stratification of the ridge showed a very similar pattern to a Dipterocarp forest type. Highest diversity was recorded in midslope (1.7290) and lowest recorded in ridge (1.5626) of the forest. 18 threatened species were observed (3-Endangered and 15-vulnerable species). As a conclusion, Meethirigala forest reserve can be considered as an important refuge for wet zone forest species.