Regional microbial biogeography linked to soil respiration

The relationships between α-diversity and ecosystem functioning (BEF) have been extensively examined. However, it remains unknown how spatial heterogeneity of microbial community, i.e., microbial β-diversity within a region, shapes ecosystem functioning. Here, we examined microbial community compositions and soil respiration (Rs) along an elevation gradient of 853–4420 m a.s.l. in the southeastern Tibetan Plateau, which is renowned as one of the world's biodiversity hotspots. There were significant distance-decay relationships for both bacterial and fungal communities. Stochastic processes played a dominant role in shaping bacterial and fungal community compositions, while soil temperature was the most important environmental factor that affected microbial communities. We evaluated BEF relationships based on α-diversity measured by species richness and β-diversity measured by community dispersions, revealing significantly positive correlations between microbial β-diversities and Rs. These correlations became stronger with increasing sample size, differing from those between microbial α-diversities and Rs. Using Structural Equation Modeling (SEM), we found that soil temperature, soil moisture, and total nitrogen were the most important edaphic properties in explaining Rs. Meanwhile, stochastic processes (e.g., homogenous dispersal and dispersal limitation) significantly mediated effects between microbial β-diversities and Rs. Microbial α-diversity poorly explained Rs, directly or indirectly. In a nutshell, we identified a previously unknown BEF relationship between microbial β-diversity and Rs. By complementing common practices to examine BEF with α-diversity, we demonstrate that a focus on β-diversity could be leveraged to explain Rs.