冀北辽河源自然保护区土壤微生物碳代谢对阔叶林叶凋落物组成的响应

Responses of soil microbial carbon metabolism to the leaf litter composition in Liaohe River Nature Reserve of northern Hebei Province,China

利用凋落物袋法研究了冀北辽河源地区阔叶混交林内山杨、白桦、蒙古栎叶凋落物单一分解及混合分解对0-5、5-10和10-20 cm表层土壤微生物生物量碳、微生物呼吸和微生物代谢熵的影响.结果表明：0-20 cm土层对照、白桦、山杨和蒙古栎处理的土壤微生物生物量碳平均含量分别为124.84、325.29、349.79和319.02 mg·kg^-1;微生物呼吸平均速率分别为0.66、1.12、1.16和1.10μg·g^-1·h-1.0-20 cm土层单一凋落物处理、两种叶凋落物混合处理、3种叶凋落物混合处理的土壤微生物生物量碳平均含量分别为331.37、418.52和529.34mg·kg^-1;微生物呼吸平均速率分别为1.13、1.30和1.46μg·g^-1·h-1.土壤微生物代谢熵则呈现出与微生物生物量碳、微生物呼吸相反的变化趋势.说明凋落物质量不同,其土壤微生物碳代谢特征不同,表现为高质量凋落物土壤微生物生物量碳、微生物呼吸速率以及微生物对土壤中有机质的利用效率较高,低质量凋落物则与之相反.植物叶凋落物混合能够增强土壤微生物活性,增加土壤微生物对土壤碳的利用效率,促进土壤微生物代谢途径的多样化,有利于林地土壤质量的维护和提高.

Using litter bag method,we studied the effects of single and mixed litters from Betula platyphlla,Populus davidiana and Quercus mongolica on soil microbial biomass carbon（ MBC）,microbial respiration（ MR） and microbial metabolic quotient（ q CO2） in 0-5,5-10 and 10-20 cm soil layers. The results showed that the average contents of MBC in 0-20 cm soil layer were 124.84,325.29,349.79 and 319.02 mg·kg^-1in the leaf litter removal treatment,Betula platyphlla treatment,Populus davidiana treatment and Quercus mongolica treatment,and the corresponding average rates of MR were 0.66,1.12,1.16 and 1.10 μg·g^-1·h-1,respectively. Meanwhile,in 0-20 cm soil layer,the average contents of MBC in the treatments with single leaf litter,mixed litter of two plant species and mixed litter of three plant species were 331. 37,418. 52 and 529. 34mg·kg^-1,and the corresponding average rates of MR were 1.13,1.30 and 1.46 μg·g^-1·h-1,respectively. In contrast to the MBC and MR,q CO2 in soil showed a reverse pattern. Our study suggested that characteristics of microbial carbolic metabolism were influenced by litter quality. Namely,the treatment with high litter quality had higher MBC,MR and utilization efficiency of soil carbon,compared with the treatment with low litter quality. Moreover,mixture of different species of leaf litter improved soil microbial activities,increased utilization efficiency on soil carbon and promoted diversity of microbial metabolic pathways,which could then contribute to maintaining and enhancing soil quality of forestland.