Abstract: A field microcosm experiment was conducted to study the effects of soil fauna on the earlystage litter decomposition in an evergreen broadleaf forest and a Cunninghamia lanceolata plantation in Huitong of Hunan, South-central China. The taxonomic diversity and abundance of soil macrofauna in the litters and soils were obviously lower in 2 mm mesh nylon net than in 4 mm mesh nylon net. After the exclusion of soil macrofauna, the C, P, Ca, and Mg concentrations in the litters in evergreen broadleaf forest and the Mg concentration in the litters in C. lanceolata plantation increased significantly, while both the mass loss rate and the nutrient release rates of the litters decreased significantly. Soil macrofauna had different effects on the release rates of different nutrients in the litters, with larger effects on the release rates of the litter Ca and Mg in evergreen broadleaf forest and C. lanceolata plantation, lesser effects on the release rates of N and K in C. lanceolata plantation, and least effects on the release rate of P in evergreen broadleaf forest.

Key words: precipitation events, artificial sand-fixation region, hydrogen and oxygen stable isotopes, soil moisture, water sources.