Soil microbial biomass and community composition along a latitudinal gradient in the arid valleys of southwest China

•Latitudinal patterns and drivers of soil microbial biomass were elucidated.•Soil microbial biomass was closely related to plant inputs and soil nutrients.•Fungi/bacteria ratio was mainly related to mean annual precipitation and soil pH.•Fungal biomass and bacterial biomass (only in the subsoil) increased with latitude.•Our findings facilitate predicting microbial response to global climate change.