2008-2011 The effects of differential thinning on species diversity and community structures of insects in Cryptomeria japonica plantations. (NSC 99-2621-M-029 -001)


Insects account for the majority of terrestrial fauna on the earth, and are important in mediating material and energy flow in food webs of ecosystems through their richness of trophic relationships and interactions with other organisms. Moreover, insects are numerous and very sensitive to the change of their habitats, and therefore are suitable ecological indicators to assess the effects of environmental impacts on biodiversity. Understanding the effects of forest structures on insect biodiversity plays a central role in long-term management and restoration of native forests in Taiwan. This study aims to assess the influences of various degree of forest thinning on insect diversity by comparing the species composition and community structure of terrestrial insects in Cryptomeria japonica plantations. We propose to sample, monitor, and quantify insect diversity using sampling plots and transects, and microhabitat parameters (e.g. temperature, humidity, coverage, intensity of light, & biomass of leaf litter) in three plantation types with 0%, 25% and 50% thinning treatments, and nearby primary forests. Once each three months we will systematically collect insects from the soil, ground, understory vegetation, and canopy of each habitat. Collected insect specimens will be sorted, identified into morpho-species and functional groups, and databased. Differences in insect diversity during the course of study and among habitat types will be estimated by calculating the species richness, index of dominance, index of diversity (e.g., Shannon-Wiener function), and index of similarity. Multivariate analyses will be used to examine the relationships between microhabitat structure, microclimates, and insect diversities. The findings will provide basic information useful for biodiversity databases and suggestions for long-term and sustaining forest management of mid to lowland forests in Taiwan.

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