Community structure and insecticidal effect of different spider guilds in Orchid Island forest ecosystems. (NSC 89-2621-Z-029-006)

Abstract

Orchid Island is 92 kilometers 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 four types of habitats receiving different degree of aboriginal activities were compared. Habitat types examined in this study included the primary forest, forest receiving small degree of disturbances (disturbed forest), meadow generated from clear-cut of forests and the areas between the forests and meadows (forest edge). 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 2845 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 habitat types. Plots in the primary forest, disturbed forest and forest edge habitats exhibited significantly higher species richness and diversity than those in the meadow. Compared with plots in the disturbed forest habitats, those in the primary forest had lower species richness and diversity due to high relative abundance of dominant species. Result of a UPGMA analysis using pair-wise Euclidean distances showed 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. Plots in the primary forest, disturbed forest and forest edge habitats were dominated by space web builders and orb weavers, while those in meadows contained much higher proportion of wandering sheet weavers and ground runners. Results of this study suggest that while clear-cutting of the forest generates a distinct spider community, limited scale of disturbances generated by local people in the forests seem to increase the diversity of spiders by suppressing the dominant species.

Keywords

biodiversity, spider, Orchid Island, tropical forest, aboriginal

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Updated: Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).