Abstract: To understand the influence of land use change on earthworm communities, the quantitative distribution of earthworms and its relationships with environmental factors in the tropical secondary forest and rubber plantation in Xishuangbanna, Southwest China were studied in January 2006. The results showed that after the secondary forest converted into rubber plantation, soil nutrients and organic C input from plants reduced significantly, and earthworm communities altered. In rubber plantation, the density of tropical exotic earthworm (Pontoscolex corethrurus) (52.27 ind·m^-2) was significantly higher than that of native earthworm (Amynthas sp.) (0.53 ind·m^-2); while in secondary forest, no significant differences were observed in the density and biomass of the two earthworm species. The density (0.53 ind·m^-2) and biomass (0.32 g·m^-2) of Amynthas sp. in rubber plantation showed a decrease trend compared with those in secondary forest (6.93 ind·m^-2, 7.76 g·m^-2). An increasing population of P. corethrurus was accounted by the larger proportion of its juvenile’s density and biomass, while Amynthas sp. was mainly composed of adults. The fine-root biomass of rubber plantation was positively correlated with the density of P. corethrurus. It was suggested that the vegetation change and soil nutrient decrease due to the conversion of secondary forest into rubber plantation had promoted the reproduction of exotic earthworm, and the adaptive strategies of exotic and native earthworms could not be ignored.

Key words: Insect community, Diversity, Evenness, Dominance, Niche, Plum orchard