Soil variables shape the functional potential of forest soil microbial communities through their differential regulation of β-diversity in abundant taxa and α-diversity in rare taxa

Rare and abundant microbial taxa in forest soils display striking contrasts in diversity, biogeographic patterns, environmental responsiveness, and ecological roles. However, despite sustained scientific interest, their spatial ecological differentiation and contributions to ecosystem functional potential remain poorly understood. Here, we investigated soil bacterial communities across 66 representative forest sites spanning diverse climate zones in China using high-throughput 16S rRNA gene sequencing. By integrating comprehensive soil physicochemical properties and climatic data, we assessed the spatial distribution, environmental drivers, and potential functional implications of rare and abundant taxa. Our results revealed that abundant taxa exhibited lower α-diversity but higher spatial concordance and community stability compared to rare taxa. The α-diversity of abundant taxa was significantly influenced by spatial heterogeneity in soil properties, whereas rare taxa were less affected. In contrast, β-diversity of abundant taxa was primarily shaped by soil organic carbon and mean annual precipitation, while rare taxa were mainly driven by SUVA 254 characters (a proxy for the aromaticity of dissolved organic matter) and MAP. Our structural equation modeling results demonstrate that environmental variables regulate microbial functional potential through distinct diversity dimensions: β-diversity of abundant taxa is primarily associated with shifts in energy and carbohydrate metabolism potential, whereas α-diversity of rare taxa exerts significant influence on functional variation, particularly in energy metabolism. Our findings highlight the distinct contributions of rare and abundant microbes to forest soil ecosystem functioning, revealing distinct diversity-mediated pathways by which abundant and rare taxa contribute to ecosystem functional potential under environmental change. • Soil variables differentially regulate microbial communities • Environmental factors shape microbial functional potential by regulating β-diversity in abundant taxa and α-diversity in rare taxa. • Community similarity declines with increasing geographic distance. • Rare contribute significantly to community diversity and functional potential, while abundant taxa ensure community stability.