Abstract: To explore the effects of soil fauna on litter mass loss and the release of elements during decomposition, litters of two typical evergreen tree species, Cyclobalanopsis glauca (CG) and Kmeria septentrionalis(KS), were selected to conduct a field decomposition experiment with three different mesh sizes (5, 2 and 0.03 mm) of litterbags for one year in the virgin forest of Maolan karst area. The relationships between litter mass loss, changes of element contents and soil fauna communities were analyzed. The results showed that the contribution of soil fauna to litter mass loss of those two species ranged from 42.0% to 45.9%. Soil macrofauna had the maximum contribution to the mass loss of the mixed litter (CG+KS, with a ratio of 1:1), while meso and microfauna had the minimum contribution to the mass loss of KS litter. Soil fauna promoted or inhibited N release from the KS litter, and promoted N release from the mixed litter. Soil fauna promoted Ca release from the KS litter. The effects of soil fauna on P and K release were relatively complicated and depended on litter types. There was no effect of soil fauna on the release of C and Mg. In conclusion, the effects of soil fauna on mass loss and nutrient release were more significant in the high quality (with low C/N ratio) litter, such as that of KS. Our results provide a reference for understanding the mechanism of litter decomposition in Maolan karst forest.

Key words: annual average precipitation, spatial interpolation method, geo-statistic analyst, Loess Plateau.