黄土区侵蚀坡面土壤微生物群落功能多样性研究

为研究不同有机碳水平下坡面土壤侵蚀对微生物群落功能多样性的影响，以黄土区典型侵蚀坡面为对象，通过Biolog-Eco方法测定了高、低2个有机碳水平坡面沉积区、侵蚀区和对照区3个不同部位的土壤微生物活性、碳源利用能力和微生物群落功能多样性.结果表明：1）高碳水平下3个部位的微生物活性和碳源利用能力均显著高于低碳水平；2）在不同侵蚀部位上，沉积区微生物活性高于侵蚀区，在低碳水平下，沉积区微生物碳源利用能力显著大于侵蚀区（P<0.05），但在高碳水平下沉积区与侵蚀区无显著差异；3）在6类碳源中，微生物对氨基酸类、酯类的利用率最高，对醇类、胺类的利用率较低，从31种碳源中提取的主成分1和主成分2分别可解释变量方差的53.8%和11.9%，对主成分1起分异作用的主要是氨基酸类和酯类碳源；对主成分2起分异作用的主要为糖类和酸类碳源.4）高碳水平下3个部位微生物群落的Shannon指数、丰富度指数和McIntosh指数均显著大于低碳水平（P<0.05），但不同部位间的土壤微生物群落多样性指数并无明显差异.侵蚀对微生物群落功能多样性的影响主要表现在有机碳水平决定的微生物活性差别上，不同部位微生物的碳源利用能力在有机碳水平较低时差异显著，有机碳水平较高时则没有明显差别.

Functional diversity of soil microbial community on eroded slope in the Loess Plateau Region

Soil microbial activity and community functional diversity at the sedimentary area, erosion area and control area on the slopes with two organic carbon levels were determined by the Biolog-Eco method in the Loess Plateau region so as to explore the effects of erosion and organic carbon levels on the functional diversity of microbial communities. The results showed: 1) The microbial activity and carbon-use ability in the three areas of the slopes under the high carbon level were significantly higher than that under the low carbon level. 2) The microbial activity in the sedimentary area was higher than erosion area under the same carbon levels. However, the carbon-use capacity of microbes in the sedimentary aera was significantly higher than that in the erosion area (P<0.05)at low carbon level. No significant difference was found in the carbon-use capacity of microbes between sedimentary and erosion areas at high carbon level. 3) The microbes had the highest utilization on amino acids and esters but lowest utilization on alcohol and amines among the six types of carbon sources. The principal components 1and 2 extracted from 31 carbon sources could explain 53.8% and 11.9% of variance variables, respectively. Amino acids and ester carbon sources were the main carbon sources that differentiate the PC1, and carbohydrates and acids were the main carbon sources that differentiate the PC2. 4) The Shannon index, richness index and McIntosh index of microbial communities under high carbon levels were significantly greater than that under low carbon levels at the same area on the slopes (P<0.05), However, the diversity of microbial communities in different areas of the slopes was no obvious difference under the same carbon level. The impact of erosion on the functional diversity of microbial communities was mainly caused by the difference of microbial activity, which related to the organic carbon level. The carbon-use ability of microbes in different areas was significantly different under a low organic carbon level, but no obvious difference was found under the higher organic carbon level.