放牧对冷蒿根际土壤微生物群落结构多样性的影响

摘要

为了明确冷蒿(Artemisia frigida)对放牧干扰下土壤微生物群落结构的影响特征,以内蒙古草原控制放牧为平台,运用磷脂脂肪酸标记法(PLFAs)研究不同放牧强度(CK、LG、HG)对冷蒿根际土壤(ARS)和非根际土壤(NRS)微生物群落结构多样性的影响.PLFAs结果分析显示:冷蒿根际土壤微生物群落PLFAs种类、含量丰富,共检测到24种PLFA生物标记,并且各处理土壤的优势PLFA类型是i16∶0,18∶18t,18∶1ω7c和18∶2ω6,9.3种特征微生物相对生物量在不同放牧处理土壤中分布相似,均以细菌分布量最多,真菌次之,放线菌最少.冷蒿根际土壤微生物总PLFAs量及各菌群PLFAs量均显著高于非根际土壤,且均以LG-ARS和HG-ARS最高,CK-NRS和HG-NRS最低.重度放牧后冷蒿根际土壤真菌/细菌PLFAs比值显著高于非根际,而CYC(cy/pre)值显著低于非根际,表明冷蒿根际土壤生态系统稳定性强,受放牧干扰较小.主成分分析表明,放牧和冷蒿对土壤微生物群落结构产生影响,而冷蒿的影响程度高于放牧处理.相关分析显示,土壤有机质、全氮和全磷与土壤微生物PLFAs总量及细菌、真菌、放线菌PLFAs均呈正相关,是影响土壤微生物种类和数量的主要养分.%In order to explore the effect of grazing intensities on Artemisia frigida rhizosphere soil microbial community diversity in the Inner Mongolia steppe of China, we selected different grazing intensities, i.e.no grazing (CK) plot, light grazing (LG) plot, heavy grazing (HG) plot, and different soil types, i.e.rhizosphere soil of A.frigida (ARS) and non-rhizosphere soil (NRS), to investigate soil microbial biomass and community structures using phospholipid fatty acids (PLFAs) method.The results showed that the kinds and content of microbes PLFAs in the rhizosphere soil of A.frigidahadmore were rich, and a total of 24 kinds of PLFA biomarkers were detected, and the advantage of soil PLFA types were i16∶0,18∶18t, 18∶1ω7c 和 18∶2ω6,9.The relative biomass of three typical microbes under different grazing soil distribution was similar.The quantity of bacteria was the most, fungi followed, and actinomycetes was the least.The total PLFAs quantity and the PLFAs quantity of all kinds of microorganisms in rhizosphere soil of A.frigida were significantly higher than that in non-rhizosphere soil, and the highest in LG-ARS and HG-ARS and the lowest in CK-NRS and HG-NRS.After heavy grazing, the fungi/bacterial PLFAs ratio in rhizosphere soil of A.frigida was significantly higher than that in the non-rhizosphere soil, and CYC(cy/pre) values was significantly lower than that in the non-rhizosphere, which indicated that the ecological system stability in the rhizosphere soil of A.frigida was strong, and less influenced by grazing.Principal component analysis showed that grazing and A.frigida had effect on soil microbial community structure, and the effect of A.frigida was higher than that of grazing.Correlation analysis showed that soil organic matter, total nitrogen and total phosphorus were positively correlated with total soil microbial PLFAs, bacteria, fungi and actinomycetes PLFAs, which were the main nutrients that affected the species and quantity of soil microbial.