The Biogeography of Soil Bacteria in Australia Exhibits Greater Resistance to Climate Change Than Fungi.

Soil microorganisms are crucial to ecosystem health, and their composition and distribution are shaped by a range of environmental factors. However, the effects of accelerating climate change on soil microbiomes remain under-explored. This study examines the continental-scale factors controlling soil microbiomes and evaluates their responses to climate change. We applied machine learning algorithms to analyze the distribution patterns of bacteria and fungi in 1300 Australian topsoil samples. Our results indicate that bacterial distributions align closely with the soil class map, highlighting the dominant impact of soil properties. In contrast, fungal distributions are more strongly associated with temperature gradients, emphasizing the critical role of climate. Climate projections for 2040 suggest a notable southward shift in both bacterial and fungal patterns, particularly around latitude 25° S. Moreover, our findings suggest that fungal biogeography is likely to undergo more pronounced changes, with approximately 24% of Australian topsoils expected to experience significant shifts in fungal community structure, compared to about 19% for bacteria, which appear more resistant. This study emphasizes the diverse vulnerabilities of soil microbial communities and stresses the need to account for microbial dynamics in future land use and management practices.