We elucidated the changes of soil microbial biomass and community structure in soil profiles under four typical land use types (farmland, grassland, Betula platyphylla secondary forest and Larix principis-rupprechtii plantation)and across five soil layers (0-10, 10-20, 20-30, 30-40, 40-50 cm) in the northern mountainous region of Hebei Province. We measured soil microbial biomass by phospholipid fatty acid (PLFA) method, and investigated the effects of land use and soil depth on soil microbial biomass and community structure by variance analysis, correlation analysis and redundancy analysis. The results showed that soil water content, bulk density, and organic carbon content of farmland differed significantly from other land use types. The content of PLFA in farmland was significantly lower than that in other land use types. The Gram-positive bacteria/Gram-negative bacteria (G+/G-) in farmland were higher, and the nutrient stress was greater. With the increase of soil depth, soil water content, organic carbon, total nitrogen, total phosphorus and microbial biomass of the four land use types showed a decreasing trend. In grassland, secondary forest and plantation, G+/G- was larger in deep soil than top soil. Except for grassland, the bacteria/fungi was smaller in deep soil than top soil. Correlation analysis and redundancy analysis showed that soil bulk density, natural water content and organic carbon were the main environmental factors affecting microbial communities in the four land use types. Our results would provide theoretical basis for the optimization of land use structure in the northern mountainous region of Hebei Province.
为阐明不同土地利用方式下土壤微生物生物量及群落结构在土壤剖面上的变化规律,以冀北山地农田、草地、白桦次生林和华北落叶松人工林4种典型土地利用方式0～10、10～20、20～30、30～40、40～50 cm土层为研究对象,运用磷脂脂肪酸法(PLFA)测定土壤微生物生物量,使用方差分析、相关性分析和冗余分析探究土地利用方式及土层深度对土壤微生物生物量和群落结构的影响。结果表明: 农田土壤自然含水率、容重及有机碳含量与其余各土地利用方式普遍存在显著性差异。农田磷脂脂肪酸含量均显著低于草地、白桦次生林和华北落叶松人工林;农田的革兰氏阳性菌/革兰氏阴性菌(G+/G-)较高,受到的养分胁迫较大。随土层深度增加,4种土地利用方式的土壤自然含水率、有机碳、全氮、全磷及微生物生物量均呈现减少趋势;草地、次生林和人工林G+/G-表现为深层土壤大于表层土壤;除草地外,其余土地利用方式细菌/真菌表现为深层土壤小于表层土壤。相关性分析和冗余分析表明,土壤容重、有机碳、自然含水率是影响不同土地利用方式微生物群落的主要环境因子。本研究揭示了冀北山地4种土地利用方式土壤磷脂脂肪酸含量的分布及其影响因子,可为该地区土地利用结构优化提供理论依据。.
Keywords: PLFA; land use type; soil depth; soil microbial community structure.