Understanding the elevational pattern of soil microbial diversity is crucial for microbial biogeography, yet, the elevational patterns of diversity across different climatic zones, trophic levels and taxonomic levels remain unclear.

In this study, we investigated the elevational patterns of species richness, evenness and the relationship between species richness and evenness (RRE) in the forest soil bacterial and fungal communities and individual phyla across three climatic zones (tropical, subtropical and cold temperate).

Our results revealed that soil bacterial richness (alpha diversity) decreased with elevation, while fungi richness exhibited a hump-shaped pattern in tropical and cold temperate forests. Elevational patterns of evenness in bacterial and fungal communities showed hump-shaped patterns across climatic zones, except bacterial evenness in the tropical forest. Both bacterial and fungal richness and evenness were positively correlated in the subtropical and cold temperate forests, while negatively correlated for bacteria in the tropical forest. The richness and evenness of soil microorganisms across different regions were controlled by climatic and edaphic factors. Soil pH was the most important factor associated with the variations in bacterial richness and evenness, while mean annual temperature explained the major variations in fungal richness. Our results addressed the varieties of elevational patterns of microbial diversity in climate zones and taxonomic levels, further indicating that richness and evenness may respond differently to environmental gradients.