Soil Acidification Destabilizes Terrestrial Ecosystems via Decoupling Soil Microbiome

Soil microbiome is essential for terrestrial ecosystem preservation. β-diversity information on the former, although dynamic due to its sensitivity to environmental conditions driven by climate change, is limited. Our knowledge becomes poorer for microbiomes subjected to environmental gradients, especially for those across multiple ecosystems-information important for biological conservation management. In this study, using next generation sequencing and machine learning at samples from 207 locations among 4300 km of transects that spanned among six typical terrestrial ecosystems of China, we established the divergent distance-decay relationships between bacterial and eukaryotic communities in response to soil pH (pH as proxy of climate and edaphic conditions). The findings, pH-decrease results in lower β-diversity (convergent tendency) among the bacterial communities opposite to the eukaryotic ones (low pH-high β-diversity (divergent tendency)). Meanwhile, competition between bacteria and eukaryotes intensifies at lower pH while the predominant genera and communities are re-structured. Under these circumstances, potential soil acidification due to climate change or other factors could alter soil bacteria and eukaryotes into decoupling directions influencing ecosystems' stability. Thus, soil pH is a pivotal environmental variable that not only describes, but also controls, soil microbiome dynamics at a large scale under ongoing global changes; hence, a cornerstone variable for the biodiversity conservation of China's nature protected areas and not only.