Abstract:
Meethirigala Forest Reserve is situated in Dompe DS division. This 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. Within this reserve there is a Buddhist monastery that has been there
since 1968. The present study was conducted to enumerate the plant species found in all
topographic positions of the reserve. Field investigations carried out during the period of June to
December, 2017. Plants equal or greater than 5 cm dbh (diameter at breast height) were sampled
in 18 plots (5×100 m). Seedlings greater than 1 m tall were sampled in 18 plots (5×5 m).
Diversity indices and important value index were calculated to compare the dominance of
particular species in different topographic positions. A total of 360 individuals of woody
perennials belonging to 73 species were also recorded in the ridge. 368 individuals of woody
perennials belonging to 100 species were recorded in them midslope. In the valley 272
individuals of woody perennials belonging to 69 species were recorded. 132, 123 and 100
individuals of seedlings were enumerated in ridge, midslope and valley respectively. In the ridge
58 generas, 28 families and, in the midslope 83 generas, 35 families and, in the 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. The 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. From identified species 18 threatened species were observed (3 Endangered and 15
vulnerable species). According to the IVI values most dominant family in the ridge was
Dipterocarpaceae and species was Dipterocarpus zeylanicus. Most dominant family in midslope
was Apocynaceae and species was Alstonia scolaris. The dominant family in valley was
Euphorbiaceae and species was Adenanthera pavonina. This study found that natural population
of Zeuxine regia which is an endemic, endangered species belongs to family Orchidaceae first
time in Gampaha district. Alstonia macrophylla shows invasive characteristics inside the forest.
