Empirical evidence for microbial regulation of soil respiration in alpine forests

Abstract

A growing body of literature emphasizes important roles of microbial community in driving a variety of soil processes including soil respiration (Rs). However, empirical evidence for microbial regulation of Rs is still lacking in field observations. Here, we used an in situ approach to explore microbial mechanisms for the variability in Rs across elevational gradients in an alpine forest of northwestern China. Our results revealed significant differences in abundance, diversity, and composition of both bacterial and fungal community, and the variability in microbial communities was mainly explained by climatic (mean annual precipitation) and soil (C:N ratios, available phosphorus, and nitrate nitrogen) variables. Elevation also had a significant effect on Rs, and the inclusion of microbial community composition rather than microbial abundance or diversity greatly improved the prediction of Rs dynamics along elevational gradients. Other soil properties such as C:N ratios and pH were also significantly correlated to Rs, however, they were not able to account for the variability in Rs explained by microbial community composition. Our study further identified Alphaproteobacteria and Acidobacteria as the major microbial taxa driving changes in Rs along elevational gradients, with important implications for the use of these taxa to predict soil C feedbacks under climate change scenarios in alpine forest ecosystems. Overall, our findings provided important empirical evidence for microbial regulation of Rs in field observations.