Assessment of Plant Species Diversity at Pasir Tengkorak Forest Reserve, Langkawi Island, Malaysia

Plant species diversity of a logged-over coastal forest within the Pasir Tengkorak Forest Reserve, Langkawi Island,Malaysia was assessed by establishing a 1-ha plot. All plants above 1.0 cm dbh (diameter of a tree at breast height), or4.5 feet above ground level, the accepted point of diameter measurement for most trees were enumerated. Speciesdiversity was defined as a combination of species richness and evenness. The jackknife estimate and species-area curvewere applied to estimate the species richness. It was estimated using Simpson’s index of diversity, Shannon-Weinerfunction and Brillouin index. Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’sindex of evenness were also used to estimate species evenness. A total of 3414 individual trees representing 120 species,81 genera and 31 families were recorded. Species with highest relative abundance were Swintonia sp1 (0.12), Garciniaeugnifolia (0.09) and Syzygium sp1 (0.05). The jackknife estimate of species richness was 132.9 and the regress ionequation to estimate species richness was Ln Sˆ = 2.53 + 0.24 ln (A) with r2 = 96.0 %. Species diversity was high withSimpson’s index of diversity with a value of 0.96, while Shannon-Weiner index was 5.42 and Brillouin’s Index was5.14. However, Simpson’s measure of evenness, Camargo’s index of evenness and Smith and Wilson’s index ofevenness were 0.264, 0.378, and 0.419, respectively. Results indicated that species richness and species diversity werehigh, but evenness was low in this logged-over coastal forest.