| Summary: | 博士 === 國立東華大學 === 自然資源與環境學系 === 104 === This research aims to explore the difference of invertebrates’ community structure between organic farming and conventional farming in paddy fields of eastern rural Taiwan. It is also expected to indentify agro-biodiversity indicator species which can be helpful in monitoring integrity of agricultural environment and promoting environmentally friendly farming. Organic fields were found to have a higher number of species of various functional groups. In paddy fields, the difference of similarity between organic and conventional farming was mainly form the contribution of 29 invertebrates among which the abundance of three predators including Micraspis discolor, Tetragnatha maxillosa, Tetragnatha javana was also significantly different under different farming methods. Results show that there is a positive linear relationship between the richness/abundances of invertebrates and the abundance of the three mentioned species which can be used in the future as indicator species to reflect artificial disturbance in paddy fields. The Similarity Analyse does not indicate that different farming methods caused significant community separation. Twenty-two variables concerning farming practices and habitat heterogeneity were investigated and then proceeded by principle component analysis (PCA) to show a main context. Three distinct gradients of axis were extracted and showed the significant linear relationships among the total abundance, richness and intensity of the particular functional assemblage composed of predators, parasitoids, pests, graminivores, scavengers, pollinators and visitors. The first principle axis strongly correlated with variables in terms of the status of field banks and the drainage/irrigation that could explain 27.4% of total environmental variance. The second principle axis had stronger correlations with the adjacent land-used that could explain 20.1% of total environmental variance. The third principle axis mostly correlated with the artificial inputs that could explain 14.3% of total environmental variance. The findings also showed that modern day forms of intensive farming could reduce habitat heterogeneity and cause negative effects on agro-biodiversity of rice paddy wetland environments.
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