Abstract: An investigation was made on the composition and structure of arthropod community on cultivated lucerne grassland in Qingyang City, Gansu Province. A total of 81 species belonging to 38 families and 15 orders were collected. According to the trophic level and feeding mode, three nutritional classes and fourteen functional groups were established, and the temporal dynamics of the diversities in species, functional group, and nutritional class were analyzed. The results indicated that during the growth season of lucerne, the species of arthropod community had the highest diversity, followed by functional group, and nutritional class. Both species diversity and nutritional class diversity had significant correlations with functional group diversity (P<0.01). Functional group biodiversity had a similar temporal variation trend with species biodiversity, while functional group diversity had less fluctuation. In studying the composition and structure of arthropod communities, species study could be replaced by functional group study to simplify the complicated network relationships among the species in the community, while functional group diversity could be used in evaluating the community similarity and stability.

Key words: Ecological evaluation, Assessing index, Analytical hierarchy process