不同利用方式对豫西黄土丘陵区土壤微生物生物量及群落结构特征的影响

以豫西黄土丘陵区乔木地、灌木地、果园、弃耕地和耕地土壤为对象,应用磷脂脂肪酸(PLFA)方法,研究了不同土地利用方式对土壤微生物生物量及其群落结构特征的影响,结果表明,与耕地相比,乔木地和灌木地土壤微生物量碳(MBC)含量分别提高了225.38%和265.73%(P<0.05),微生物量氮(MBN)含量分别提高了206.19%和245.03%(P<0.05),MBC/TOC值显著提高了2.89和3.00(P<0.05),MBN/TN值显著提高了5.05和5.57(P<0.05);果园土壤微生物量碳、微生物量氮含量和MBN/TN值分别提高了107.80%,84.99%和1.23(P<0.05);弃耕3年地土壤微生物量碳、氮、磷与耕地无显著差异(P>0.05)。乔木地和灌木地土壤细菌的PLFA含量增加了17.87%和17.18%(P<0.05),真菌增加了24.27%和28.45%(P<0.05);果园土壤细菌PLFA含量增加了9.04%(P<0.05);弃耕3年地土壤细菌、真菌和放线菌的PLFA含量与耕地之间均无显著差异(P>0.05)。乔木地和灌木地土壤的Shannon多样性指数和Pielou均匀度指数显著提高(P<0.05),Simpson优势度指数显著降低(P<0.05)。不同利用方式地土壤细菌、真菌及放线菌的PLFA及总PLFA与土壤总有机碳、微生物量碳,全氮、速效氮、微生物量氮,容重显著正相关(P<0.05)。以上结果说明相对于耕地、弃耕地和果园土壤,乔木地和灌木地土壤微生物多样性均提高,不同微生物物种的个体数量分布均匀,群落结构相对稳定,因此这两种利用方式对土壤质量以及微生物群落结构多样性的改良效果更佳。不同土地利用方式引起营养元素的投入和土壤结构的变化是造成微生物群落结构变化的主要原因之一。

Effects of land use on soil microbial biomass and community structure in the loess hill region of west Henan

In order to uncover the effects of different land use systems on soil microbial biomass and community structure characteristics,we selected five land use types;woodland,shrub land,orchard,abandoned farmland and farmland.We analyzed soil phospholipid fatty acids (PLFAs).Compared with the farmland,woodland in-creased soil microbial biomass carbon (MBC)and microbial biomass nitrogen (MBN)content by 225.38% and 206.19% respectively (P <0.05)while the MBC/total organic carbon (TOC)and MBN/TN value increased by 2.89 and 5.05 respectively (P <0.05 ).Shrub land increased soil MBC and MBN content by 265.73% and 245.03% respectively (P <0.05),the MBC/TOC and MBN/TN value increased by 3.00 and 5.57 respectively (P <0.05 ).Orchard management increased soil MBC and MBN content and MBN/TN value by 107.80%, 84.99% and 1.23 respectively (P <0.05).There was no difference in MBC and MBN and microbial biomass phosphorus (MBP)between the abandoned farmland and farmland soil (P >0.05).Bacterial and fungal PLFA in woodland soil increased by 17.87% and 24.27% respectively compared to farmland (P <0.05 )while in shrub land these traits increased by 17.18% and 28.45% respectively (P <0.05).Orchard soil bacterial PLFA content was increased by 9.0% (P <0.05).Soil bacteria,fungi and actinomycetes PLFA in abandoned farm-land and farmland were similar (P >0.05).The Shannon diversity index and Pielou evenness index of wood-land and shrub land were significantly higher than other systems (P <0.05)while the Simpson dominance in-dex was significantly decreased (P <0.05).The PLFA content of soil bacteria,fungi,and actinomycetes was significantly,positively correlated with TOC,MBC,total nitrogen (TN),available nitrogen (AN),MBN and bulk density (BD)(P <0.05 or P <0.01).The results showed that compared with farmland,abandoned farm-land and orchard soil,soil microbial diversity of woodland and shrub land is enhanced;microbial species are u-niformly distributed and community structure is relatively stable.This indicates that woodland and shrub land are superior for improving soil quality and microbial community structure diversity.The input of nutrients and the change of soil structure caused by different land use patterns is one of the reasons for the change of microbi-al community structure.