Differentiation Strategies for Microbial Community Assembly and Their Associations with Soil Functions in Lemon Farmland

In addition to providing food, agricultural ecosystems also have crucial ecological roles as a buffer zones and species reservoirs. Understanding the biogeographic patterns, assembly mechanisms, and potential environmental responses of microbial communities is crucial for maintaining ecosystem functions. However, differences in ecological strategies among different microorganisms and their association with ecosystem functions remain unclear for agricultural ecosystems. Using multiple statistical methods based on data obtained by high-throughput sequencing, the biogeographic patterns of soil bacteria, fungi, and protists in lemon farmland at a local scale were investigated and compared to explore the relationships between their biodiversity and ecosystem functions. The community similarity of bacteria was mainly contributed by species replacement whereas richness difference governed that of fungi and protists. Determinism and stochasticity dominated the community assembly of bacteria and fungi, respectively, with weakest homogenizing for fungi and weakest differentiating for protists. Environmental breadth showed stronger environmental adaptation of bacterial communities at the taxonomic level; in contrast, fungi showed stronger phylogenetic signals and broader habitat niche breadth. Finally, we found that bacterial communities maintained ecosystem functions through their diversity, composition, and assembly ecological processes. In contrast, fungi and protists only contributed ecosystem functions via their diversity and composition, respectively. Our results revealed the differentiation strategies that shape biogeographic patterns among soil microbiomes of lemon farmland and might support the sustainability of lemon farmland under further global climate change.