Abstract: A simulation test was conducted to study the effects of the root system and litter of Chinese fir (Cunninghamia lancceolata) on soil microbial pro
perties. After the amendment with C. lancceolata root system, the soil microbial biomass C, basal respiration, total organic C, and microbial quotient increased significantly (P<0.05), while soil metabolic quotient (qCO₂) presented an opposite trend. In the treatment amended with C. lancceolata litter, the soil basal respiration and qCO₂ decreased significantly (P<0.05), whereas soil microbial biomass C, total organic C, and microbial quotient had less change. A significant interaction between C. lancceolata root system and litter was observed on soil basal respiration and qCO₂. The qCO₂ had significant positive correlations with soil total organic C (R²=0.209) and dissolved organic C (R²=0.325), suggesting that the C use efficiency of soil microbes decreased with increasing soil organic C content. Comparing with litter, the root system of C. lancceolata played more important roles in soil ecological processes.

Key words: Chinese fir, root system, litter, microbial biomass carbon, soil metabolic quotient, soil organic C, Cinnamomum camphora plantation, understory removal;, soil labile organic carbon, light fraction organic matter.