土地利用方式变化对白浆土微生物生物量碳及代谢特征的影响

以林地、耕地和草地为研究对象,采用氯仿熏蒸结合Biolog-Eco微平板的方法研究土地利用方式变化对白浆土微生物生物量碳和代谢特征的影响,以期为东北丘陵地区白浆土的可持续利用及生态环境重建提供科学依据和理论指导。结果表明:土壤微生物生物量碳和微生物商的变化均表现为草地林地耕地,且3种土地利用方式间均差异显著。Biolog-Eco微平板分析表明,草地土壤微生物的平均颜色变化率值(Average well color development, AWCD)最高,其次为林地,耕地最低,Shannon指数、Simpson指数和McIntosh指数的变化趋势与AWCD相同。3种土地利用方式土壤微生物对6类碳源的相对利用率以糖类、氨基酸类和羧酸类最高,分别为44.63%~53.61%、21.09%~25.45%和8.31%~15.16%。林地对聚合物类碳源的相对利用率在3种土地利用方式中最高,而与林地相比,耕地对糖类和氨基酸类的相对利用率提升明显,草地则增高了对羧酸类、酚酸类和胺类的相对利用率,说明土地利用方式变化改变了土壤微生物对碳源利用的偏好。主成分分析表明,土壤微生物群落代谢特征随土地利用方式变化发生改变,与草地相比,耕地与林地土壤微生物群落代谢特征较为相似。冗余分析发现土壤pH、总氮、有机质、速效磷和硝态氮是影响微生物群落代谢特征变化的关键因子。本研究结果说明土地利用方式变化改变了土壤理化性质,进而导致了土壤微生物生物量碳、活性和代谢特征的变化。

The response of microbial biomass carbon and metabolic characteristics of albic soil to land use change

In this study, we investigated the changes in microbial biomass carbon and the metabolic characteristics of forests, arable land, and meadows in northeast China. Soil samples were analyzed using the method of chloroform fumigation combined with Biolog-Eco microplate method. The results showed that the changes in microbial biomass carbon and microbial quotient were significantly different among the three land use types, following the order of meadow > forest > arable land. Biolog-ECO microplate analysis indicated that the average well color development (AWCD) for meadow was the highest, followed by forest. The lowest AWCD occurred for arable land. The Shannon index, Simpson index, and McIntosh index results showed the same trends as the AWCD. The relative utilization ratio of soil microorganisms to six types of carbon sources for the different land use types showed higher values for carbohydrates, amino acids, and carboxylic acids, ranging 44.63%~53.61%, 21.09%~25.45%, and 8.31%~15.16%, respectively. The conversion of land use significantly changed the preference of soil microorganisms for carbon source utilization. Arable land had the highest relative utilization ratio of carbohydrates and amino acids, and forest had the highest relative utilization of polymers. Meadow had the highest relative utilization of carboxylic acids, phenolic acids, and amines. Principle component analysis showed that the metabolic characteristics of soil microorganisms varied among the different land use types. Arable land and forest had similar metabolic characteristics of the soil microbial community. Redundancy analysis indicated that soil pH, total nitrogen, organic matter, available phosphorus, and nitrate nitrogen were the key factors affecting the metabolic characteristics of the soil microbial community. This research shows that land utilization change altere the soil physical and chemical properties, resulting in changes in microbial biomass carbon, activities, and metabolic characteristics.