Abstract: Litter is one of the most critical components in forest ecosystem, and plays a key role in ecosystem functioning. Investigating the influences of litter on soil will not only help understand the forest ecosystem functional traits, but also facilitate to provide theoretical basis for scientific management measurements. In this study, three types of litter including Pinus massoniana needles, Quercus chenii leaves and Imperata cylindrica stalks and leaves were used in a laboratory microcosm experiment. Ten treatments were designed, through incorporation of different proportions of the three kinds of litter at an overall loading level of 1% (relative to soil weight). After 180 days of incubation, soil physicochemical and biological properties were measured. Results showed that soil pH values were significantly increased after litter addition regardless of litter treatments. Moreover, soil pH in the mixed litter treatments was consistently higher than that in the single litter treatments. Cumulative CO₂ emissions and C mineralization rate of the threespecies mixed (1∶1∶1) treatment increased by 30.48% (P<0.01) and 29.69% (P<0.01) compared to the weighted average of the three single litter treatments, respectively. BIOLOG analysis showed that the average well color development (AWCD) of the P. massoniana needles + Q. chenii leaves (1∶1) treatment was the highest among all treatments. The significant alteration and carbon utilization potential pattern implicated the modifications of microbial community structure due to the amendment of different litter. The responses of soil process to different types of litter combination may be vital to the maintenance of forest soil quality, mitigation of global change, and appropriate mixture and matching of plant species.

Key words: tree-ring stable carbon isotope, tree-ring width, water use efficiency, stomatal conductance