微生物多样性对土壤碳代谢特征的影响

土壤微生物群落在生态系统过程中发挥着重要的作用,而关于土壤微生物多样性对生态系统功能的影响无一致结论.为了研究微生物多样性对土壤碳代谢特征的影响,将稀释10~(-1)、10~(-3)和10~(-5)倍(D1、D3和D5)的庞泉沟阔叶混交林土壤悬浮液接种在灭菌的土样中.通过碱式滴定法和Biolog Eco板等实验方法测定了不同多样性梯度下土壤碳矿化速率和碳代谢利用模式的变化.结果表明培养6周后,D1处理的碳矿化速率、累积碳矿化量、平均孔颜色变化率(AWCD)和多样性指数(Shannon、Mc Intosh和丰富度指数)均显著高于D5处理.且相关分析表明,累积碳矿化量和AWCD与丰富度呈显著负相关.对碳源吸光度做主成分分析(PCA)和单因素方差分析发现微生物多样性梯度的土壤碳源利用模式也存在差异.因此,微生物多样性下降影响土壤的碳矿化速率和碳源利用模式,导致陆地生态系统的功能发生改变,在森林土壤管理中,应重视土壤微生物物种多样性变化对生态系统功能的影响.

Effects of Microbial Diversity on Soil Carbon Mineralization

Soil microbial community plays an important role in ecosystem functions; however, little is known about the importance of microbial diversity to the ecosystems. In this study, serial dilution of soil suspension (10^-1, 10^-3, and 10^-5) was performed and inoculated into the sterilized soils that form the broadleaf mixed forests in Pangquangou. The change in the carbon mineralization rate and the pattern of the carbon source utilization were studied by titration, Biolog Eco, and other experimental methods. The results show that after being incubated for six weeks, carbon mineralization rate, the cumulative amount of carbon mineralization, average well color development (AWCD), and diversity index (Shannon, McIntosh, and richness index) of D1 were significantly higher than those of the D5 treatment. The cumulative amount of carbon mineralization and AWCD was strongly and inversely correlated with richness. Principal component analysis and one-way ANOVA also indicated that the patterns of carbon source utilization of microbially diverse soil were different. Therefore, the loss of microbial diversity affects the carbon mineralization rate and the pattern of carbon source utilization, leading to functional changes in terrestrial ecosystems. In the management of forest soils, the effects of soil microbial diversity on ecosystem functions should be considered.