Contribution of soil fauna to litter decomposition in Songnen sandy lands in northeastern China

Soil fauna are considered to be an important determinant of the litter decomposition in terrestrial ecosystems. However, the contributions of soil macrofauna and mesofauna to litter decomposition in semi-arid environments are not well-recognized. In this paper, litterbags with different mesh sizes (4.7 mm, 2 mm and 0.01 mm) were employed to examine the intraspecific differences in the decomposition of Stipa baicalensis, Achnatherum avinoides, Lespedeza davurica and Agropyron cristatum. In addition, the effects of soil macrofauna and mesofauna on litter decomposition were determined in Songnen sandy land. The results of this study showed that Prostigmata, Psocidae and Oribatida were dominant fauna in the litterbags. Significant intraspecific differences were found in litter decomposition rates, and the process of litter decomposition can be separated into two apparent stages. Ac. avinoides exhibited the highest contribution rate to litter decomposition, followed by Ag. cristatum, L. davurica and S. baicalensis. Contribution rates of macrofauna and mesofauna to litter decomposition were different. The rate of litter decomposition was positively correlated with the group density of fauna. Our results suggested that both macrofauna and mesofauna could accelerate litter decomposition and, consequently, nutrient cycling in semi-arid ecosystems, although their functional roles were different in litter decomposition.

► Mites and Psocidae were the dominant soil fauna in litterbags during the process of decomposition.
► There were remarkable intraspecific differences among litterbags after one year decomposition.
► The process of litter decomposition can be separated into two stages apparently.
► There was a significant difference in the contribution rate between macrofauna and mesofauna.
► Results showed there was a close relationship between group density and litter decomposition.