Biogeography and diversity of wetland soils bacterial communities across temperature zones based on independent studies

Wetlands are vital ecosystems that perform essential functions such as climate regulation, environmental purification, material circulation and energy flow. They play an essential role in global biogeochemical cycles, driven primarily by microorganisms. Understanding the distribution of wetland microorganisms across different temperature zones is key to comprehending their ecological roles. A meta-analysis of 704 wetland soil samples on microbial communities was conducted, using statistical methods like analysis of variance, principal component analysis, non-metric nultidimensional scaling, and structural equation modeling to examine biogeography and diversity across temperature zones. Our findings revealed a clear latitudinal diversity gradient pattern, with the highest microbial abundance in the tropics and the lowest in the southern temperate zone, which differed significantly from other temperature zones. Proteobacteria (37.76 %-51.04 %), Acidobacteria (5.11 %-30.70 %) and Bacteroidetes (3.43 %-16.16 %) dominanted the bacterial communities. Notably, the southern temperate zone showed significant variations, with a higher prevalence of Acidobacteria (30.07 %). To investigate the causes of this variability, we screened 177 core microbiome and identified latitude as the core environmental factor influencing microbial community composition. Moreover, soil microorganisms exhibited strong nitrogen cycling potentials (particularly nirD and nirB) and carbon cycling potentials (especially accA), with gene abundances showing little variation across temperature zones. Wetland bacterial communities also demonstrated high stability, with average variation degree index values ranging from 0.1 to 0.3. Our results improve the understanding of the diversity and biogeographic mechanisms of wetland bacterial communities and hold significant implications for the management and conservation of wetlands.