Abstract: Tree species can shape soil fauna communities by modifying both soil environment and litter properties, but their independent influences remain poorly understood due to natural covariation. To disentangle the drivers of soil and litter properties, we conducted a litter reciprocal transplant experiment in a subtropical common garden established in 2012, selecting three tree species with distinct litter properties: Castanopsis (Castanopsis carlesii, evergreen broadleaf), fir (Cunninghamia lanceolata, evergreen coniferous) and sweetgum (Liquidambar formosana, deciduous broadleaf). Over a completely broadleaf litter decomposition period from March to October 2024, soil fauna communities were monitored across all plantation-litter combinations. We found that Entomobryidae dominated soil fauna community, and saprophages were the most abundant functional group (46.76%) regardless of plantation types and litter types. Tree-mediated soil environment rather than litter was the primary driver of total fauna abundance (57.10% variation explained), taxon number (78.60%), diversity (68.90%) and evenness (72.40%). Compared with other plantation types, the Castanopsis forest stand supported a higher soil fauna abundance. Litter properties exhibited another considerable explanatory power for soil fauna abundance (42.90%). Higher soil fauna abundance was detected in sweetgum than in fir litter, with marked differences at early/middle decomposition stages (29–63 days). Predators/saprophages were more sensitive to changes in habitat conditions than herbivores/omnivores. Key regulators of tree species on soil fauna during litter decomposition included soil moisture and nitrogen content in the soil environment, as well as mass remaining and carbon content in litter properties. These findings advance understanding of tree species effects on soil fauna, supporting subtropical forest biodiversity conservation and sustainable management.

Key words: biodiversity, functional groups, litter decomposition, reciprocal transplant experiment, litter properties, subtropical forest