Rapid biodiversity assessment of spiders in nature reserves of Singapore.

Abstract

As a continuation of an ongoing spider biodiversity monitoring project, a rapid spider biodiversity assessment was conducted at Bukit Timah Nature Reserve, Nee Soon swamp forest and four sites near the Eco-Link. Active searching, beating and leaf litter sifting were used to collect spiders within two 2m x 2m quadrats at each survey site. The Shannon-Wiener diversity index (H'), species richness (S) and Pielou's evenness index (E) were used to assess spider diversity at all six survey sites. The spiders were also grouped to ground wanderers, plant wanderers and web builders and analyzed accordingly. Furthest Neighbor Cluster Analysis with interval of Euclidean distances was used to determine site similarity. Chao1 was used to estimate total spider richness and sampling completeness at all sites. During these 11 weeks, 1647 specimens from 194 species (including morphospecies) were collected, with three new family records for Singapore. Active searching is likely to be a universally efficient collection method. Disturbance may affect spider abundance more than richness. The results also suggest no significant differences in spider species assemblages across the Bukit Timah Expressway. The collected data will serve as baselines for comparisons with future surveys to determine the ecosystem health patterns of Singapore's forests.