Abstract: A comparative study was conducted on the differences in the community structure and diversity of soil fauna beneath and outside the canopy of shrub Pittosporum tobira, aimed to understand the effects of single trees on the soil fauna community through changing microenvironment. Higher taxonomic richness and abundance of soil macrofauna were observed beneath the tree canopy than outside the tree canopy. There were no significant differences in the abundance of soil meso and microfauna in the two habitats, but the rare taxa of the soil meso and micro fauna beneath the tree canopy were more, indicating a more complex community. The abundance of soil nematode outside the tree canopy and the abundance of Acarina beneath the tree canopy were higher, but the abundance of other taxa had no significant difference between the two habitats. Further analysis showed that the soil moisture content outside the tree canopy was relatively high, which benefited aquatic groups to live, but the rare taxa were less, due to the stronger human disturbance. Oppositely, the soil moisture content beneath the tree canopy was lower, which fitted for xeric groups to survive, and the human disturbance was weak, leading to more rare taxa. This study indicated that tree canopy had remarkable effects on the community composition and distribution of soil fauna via affecting soil environment.

Key words: flue-cured tobacco, variety, rhizosphere microorganism, functional diversity.