Spider diversity on Orchid Island, Taiwan: A comparison between sites receiving different aboriginal activities.
Tropical forests exhibit very high spider diversity, but most related studies examined a particular functional group or layer of the habitat and few assessed the impacts of disturbance on tropical Araneae diversity. Orchid Island is 40 sea miles off the southeast coast of Taiwan and her forests are the northern most tropical forests in East Asia. In this study, the spider diversity of Orchid Island was studied and those from three types of habitats generated by various kinds of aboriginal activities were compared. Habitat types examined in this study included the forest, the meadow and the forest edge. All habitat types had four replicates each containing four 5 m × 5 m sampling plots. In addition, we also set up additional 8 plots in the relatively undisturbed primary forest in Tienchi for comparison. Spiders from the ground, understory shrubs and canopy were collected to have a comprehensive representation of diversity from all microhabitats in the sampling plots. From the adult specimens obtained, a total of 150 species from 19 families were identified. The composition and structure of spider communities were significantly different between different habitats. Plots in the forest habitats exhibited significantly higher species richness and diversity than those in the meadow. Compared with plots in the forest habitats, those in the Tienchi primary forest had lower species richness and diversity due to overrepresentation of dominant species. Result of a UPGMA analysis using pair-wise Euclidean distance demonstrated that most of the sampling plots could be clustered into two major groups, Forests and Meadows. Plots of forest edge habitats exhibiting less canopy cover were grouped with the meadow plots and those with more canopy cover were grouped with the forest plots. Foraging guild composition also differed significantly among types and layers of the habitats. Results of this study suggest that while clear-cutting of the forest generated a distinct spider community, limited scale of logging by local people seemed to increase the diversity of spiders by suppressing the dominant species.
Updated: Mar-10-2014 01:22:51 (Taiwan, GMT+08:00).