Abstract:

Litter decomposition, as one of the important processes in the forest ecosystem, is mainly controlled by climate, forest type, litter quality, and soil organisms. In order to investigate the mass loss rates in for the different mesh sizes of litterbags and analyze the contributions of soil fauna and soil microbe to the litter decomposition, a field experiment using litterbags was conducted in Picea aspoerata pure and mixed plantations of western Sichuan. First, our results showed that the total amount of soil fauna was decreasing during the whole litter decomposition stages, which suggested that soil fauna was the dominant factor of the litter decomposition at the early stage. We also found that the phytophagous soil macrofaunal species during the whole litter decomposition stages appeared earliest, followed by the predatory and saprozoic species. Correlation analysis showed that the correlation coefficient of nematode amount and litter decomposition rate was the highest, followed by that of macrofauna amount. Secondly, quantity of soil microbe was increasing during the whole litter decomposition stages, which meant that the microbe prevailed as the regulator of the litter decomposition at the later stage. Correlation analysis showed that the correlation coefficient of litter decomposition rate with fungus quantity and was higher than those with bacteria and actinomycete. Thirdly, we found that the rates of litter mass loss in P. asperata pure plantation were lower than that of the mixed plantation. The decomposition rates of small mesh litterbags in pure plantation were 65.51%, 95.73%, 98.91%, 94.8% of that in the mixed plantation and the decomposition rates of big mesh litterbags in pure plantation were 89.83%, 92.95%, 98.13%, 97.13% of that in the mixed plantation at 3,15,21,24 months respectively. The difference of the rate of litter mass loss between two forest types was more significant at the early stage than at the later stage and more significant in small mesh litterbags than in big mesh litterbags. Our results inferred that the rates of litter mass loss were influenced not only by the quality of litter, but also by the soil organisms which involved in the litter decomposition, especially nematode, macrofauna and fungus.