不同土地利用方式下喀斯特峰丛洼地土壤微生物群落特征

Characteristics of soil microbial populations in depressions between karst hills under different land use patterns

基于对喀斯特峰丛洼地6种土地利用类型(坡耕地、草丛、灌丛、人工林、次生林、原生林)的土壤微生物、养分、矿物质和植被4组变量35个指标的调查分析,研究了不同土地利用方式下土壤微生物种群数量、微生物生物量C、N、P及其分形特征,以及土壤微生物与植被、土壤养分、矿物质的关系.结果表明:不同土地利用方式下喀斯特峰丛洼地的土壤微生物种群数量及组成不同.微生物种群数量均以原生林和坡耕地最高,人工林最低;3种森林土壤的细菌比率较大,坡耕地、草丛、灌丛的放线菌比率较大,真菌的比率均很小;土壤微生物生物量C、N、P的含量均很高,其中原生林最高;土壤微生物生物量碳与土壤微生物种群数量具有良好的分形关系,而土壤微生物生物量氮、磷与种群数量不存在分形关系;土壤微生物与植被、土壤养分、土壤矿物质显著相关,其中土壤微生物生物量碳与乔木层的Shannon指数、土壤速效氮、Fe2O3、CaO含量显著相关.

Based on the investigation and analysis of six soil microbial radices, eight SOlJ. conven- tional nutrient indices, six soil mineral nutrient indices, and 15 vegetation indices in the farmland, grassland, scrub, forest plantation, secondary forest, and primary forest in the depressions between karst hills, this paper analyzed the main soil microbial populations, soil microbial biomass carbon （MBC）, nitrogen （MBN）, and phosphorus （MBP） and their fractal characteristics, and the rela- tionships of the soil microbes with vegetation, soil nutrients, and soil mineral components under dif- ferent land use patterns. The soil microbial populations differed in their quantity and composition under different land use patterns. Primary forest and farmland had the highest quantity of soil micro- bial populations, while forest plantation had the lowest one. The three forests had a higher propor- tion of soil bacteria, the farmland, grassland, and scrub had a higher proportion of actinomycetes, and all the six land use patterns had a low proportion of soil fungi. Under the six land use patterns,the soil MBC, MBN, and MBP were all high, with the maximum in primary forest. There was a good fractal relationship between the soil MBC and microbial populations, but no fractal relation- ships between the soil MBN and MBP and the microbial populations. Significant relationships were observed between the soil microbes and the vegetation, soil nutrients, and soil mineral components, and the soil MBC had the closest relationships with the Shannon index of tree layer and the soil total nitrogen, Fe203, and CaO contents.