青藏高原高寒草甸不同海拔梯度下土壤微生物群落碳代谢多样性

土壤微生物群落功能多样性对维持生态系统功能和稳定性具有非常重要的意义。为探究青藏高原高寒草甸不同海拔梯度下土壤微生物碳源利用差异以及影响机制,运用Biolog微平板技术,研究了西藏当雄县草原站4300—5100 m的6个不同海拔梯度下土壤微生物群落碳源代谢多样性。研究结果表明:(1)不同海拔下高寒草甸土壤微生物碳源的利用程度均随培养时间的延长而升高;微生物代谢活性和群落多样性指数均随海拔升高呈现先上升后下降的单峰变化趋势,整体表现4800 m4950 m4400 m4650 m5100 m4300 m;(2)主成分分析表明不同海拔显著影响了土壤微生物群落碳源代谢多样性,其中碳水化合物类、氨基酸类和胺类碳源是各海拔土壤微生物的偏好碳源;碳水化合物类、羧酸类、氨基酸类和胺类碳源的利用强度受海拔影响较大;(3)分类变异分析表明,土壤、植物和气候因素是影响不同海拔碳源利用变异的主要影响因子,可解释不同海拔的碳源利用差异的79.0%;排除环境因子之间的多重及交互作用,偏曼特尔检验表明土壤含水量、植被丰富度和年均降水量是影响不同海拔微生物碳源利用多样性的最重要的环境因子。综上,研究表明青藏高寒草甸不同海拔土壤微生物碳源代谢多样性呈现显著的海拔差异趋势,其海拔差异主要受到土壤含水量、植被丰富度和年均降水量的影响。

Soil microbial functional diversity patterns and drivers along an elevation gradient on Qinghai-Tibet, China

Microbial diversity plays critical roles in regulating multiple ecosystem functions and enhancing ecosystem stability. In this study, we investigated the functional diversity of the microbial community and its driving factors at six different elevations in Tibet by using Biolog microplate analysis. The results showed that:(1) The carbon utilization of the soil microbial community at different elevations of the alpine meadow increased gradually with culturing time. As elevation increased, microbial metabolic activity and the community diversity index all exhibited unimodal trends in the order of 4800 m > 4950 m > 4400 m > 4650 m > 5100 m > 5300 m. (2) The principal component analysis showed that the elevation gradient significantly influenced the metabolism diversity of microbial community. Polymer, carboxylic acids, and amino acids were the preferred carbon sources for the soil microorganisms. The utilization of carbohydrates, carboxylic acids, and amino acids was more sensitive than that of other carbon sources to changes in elevation. (3) The variation partitioning analysis showed that the soil, plant, and climate were the most important factors for explaining the carbon metabolism of the microbial community diversity and explained 79% of the variation. The partial mental test showed that the soil moisture, vegetation richness, and average annual precipitation were the most important environmental factors that influenced the variations in the utilization of microbial carbon sources at different elevations. In conclusion, our study showed that the metabolic diversity of soil microbial carbon sources was clearly varied with elevation, and soil water content, vegetation richness, and mean annual precipitation were the main factors underlying this variation.