喀斯特峰丛洼地不同森林土壤微生物量碳在团聚体中的分布

采用野外调查和室内分析相结合的方法,以喀斯特峰丛洼地森林土壤为研究对象,就土壤各粒径团聚体中有机碳和微生物量碳的分布特征进行了研究,以期反映森林类型对土壤团聚体及其养分循环的影响,为喀斯特地区植被恢复和生态重建的实施提供依据。结果表明:各森林土壤均以>2 mm大粒径团聚体为主,占总团聚体的60%-80%。原生林土壤各粒径团聚体平均有机碳含量较次生林、人工林分别高出48.11%和61.24%,次生林较人工林高出25.29%。各粒径团聚体微生物量碳含量原生林较次生林、人工林分别高出18.13%和42.60%,次生林较人工林高出29.89%。各粒径土壤团聚体微生物熵介于0.26%-1.00%,除桉树林外,土壤各粒径团聚体微生物熵随着森林发展阶段的递进而降低。减少人为干扰有利于喀斯特地区森林土壤碳的固定和积累。团聚体粒径对团聚体中有机碳和微生物量碳的含量影响不显著。侧柏林和枫香林土壤团聚体中有机碳和微生物量碳较其他3种森林土壤的丰富,且微生物熵较低,是喀斯特地区植被恢复和生态重建的适宜树种。

Carbon Distribution of Microbial Biomass of Soil Aggregation under Different Forest Types in Depressions Between Karst Hills

To reflect the influence of vegetation types and provide evidence for recovering and restoration patterns, variation characteristics of soil organic carbon and microbial biomass carbon in different forest soil aggregation with different scales were analyzed by field investigation and laboratory analysis in depressions between karst hills. The results showed that soil aggregation of particle diameter with >2 mm was main in all the forest types and accounted about 60%-80% for the whole soil aggregation. The average value of soil aggregation in primary forests was 48.11% higher than that of secondary forest, and that of manmade forest had 61.24% higher. At the same time, organic carbon in secondary forest was 25.29% higher than that of manmade forest. The average microbial biomass carbon of soil aggregation in primary forests were higher than secondary forest and manmade forest in 18.13% and 42.60% respectively, and microbial biomass carbon in secondary forest was 29.89% higher than that of manmade forest. The microbial quotient of soil aggregates in different scales ranged from 0.26% to 1.00%, and decreased with the forest succession except Eucalyptus robusta forest. Reducing human disturbance and strengthening the protection of forests, would be greatly helpful to improve sequestration and accumulation of soil organic carbon in karst region. The influence of particle diameter on soil organic carbon and microbial biomass carbon contents in soil aggregation was not significant. The contents of organic carbon and microbial biomass carbon of soil aggregates in Platycladus orientalis and Liquidambar formosana were more abundant than those other communities, and had low microbial quotient. Thus, Platycladus orientalis and Liquidambar formosana were more adapted than other three species to restore ecology in karst region.