Climate and microbial composition rather than species richness promote multiple ecosystem services across elevational gradients

Mountains are biodiversity hotspots and provide a wide range of ecosystem services. Yet, it remains unclear how ecosystem services change with elevation and if they are predominately regulated by climate or biodiversity. Here, we investigated the elevational distributions of five key ecosystem services (net plant productivity, soil organic carbon, organic matter decomposition, macronutrients, micronutrients) and the diversity of plants and microbes on three mountains of the Hengduan Mountains region, southern China. We found that elevational patterns of plant and bacterial richness and ecosystem services were significant on the three subtropical mountains, with most of patterns changing progressively from unimodal to monotonic with changes in the base elevation. Unexpectedly, plant and bacterial richness were negatively correlated with multiple ecosystem services. Instead, climate and soil pH were the key predictor of most ecosystem services which were additionally triggered by changes of the microbial species composition. This study is the first to observe correlative elevational patterns of biodiversity and ecosystem services with comparable montane gradients. Our results suggest that climate and microbial composition rather than species richness promote multiple ecosystem services across elevational gradients. These novel findings have important implications for understanding mountain biogeography and biodiversity-ecosystem services relationship under global change scenarios.