Tree diversity and soil chemical properties drive the linkages between soil microbial community and ecosystem functioning

Abstract

Microbial respiration is critical for soil carbon balance and ecosystem functioning. Previous studies suggest that plant diversity influences soil microbial communities and their respiration. Yet, the linkages between tree diversity, microbial biomass, microbial diversity, and microbial functioning have rarely been explored. In this study, we measured two microbial functions (microbial physiological potential, and microbial respiration), together with microbial biomass, microbial taxonomic and functional profiles, and soil chemical properties in a tree diversity experiment in South China, to disentangle how tree diversity affects microbial respiration through the modifications of the microbial community. Our analyses show a significant positive effect of tree diversity on microbial biomass (+25% from monocultures to 24-species plots), bacterial diversity (+12%), and physiological potential (+12%). In addition, microbial biomass and physiological potential, but not microbial diversity, were identified as the key drivers of microbial respiration. Although soil chemical properties strongly modulated soil microbial community, tree diversity increased soil microbial respiration by increasing microbial biomass rather than changing microbial taxonomic or functional diversity. Overall, our findings suggest a prevalence of microbial biomass over diversity in controlling soil carbon dynamics.

Tree diversity effects on soil microbial biomass and respiration are context dependent across forest diversity experiments

“…Individual tree species can affect the structure of the litter layer by influencing microclimatic conditions that drive soil microbial functions (Gottschall et al., 2019). Therefore, improved data on litter and root traits, in addition to their influence on soil quality and microclimate, are needed to improve our mechanistic understanding of the effects of tree identity on soil functions (Beugnon et al., 2021; Laliberté, 2017). Using belowground traits, rather than aboveground traits, is essential to predict soil functions, because different mechanisms are likely to operate belowground.…”

Tree and shrub richness modify subtropical tree productivity by modulating the diversity and community composition of soil bacteria and archaea

“…In contrast with our first hypothesis that soil microbial alpha diversity increases with the increasing tree species diversity, we found that plant community richness had a negative effect on soil bacterial diversity under the canopy of focal trees, indicating that the most diverse bacterial communities in our study occurred in monocultures and that diversity decreased with increasing community-level tree richness. This is in contrast with earlier work in grassland [10] and on fungal communities in the BEF-China experiment [26]. Unlike these earlier studies, we have collected soil samples underneath individual trees rather than at the community-level, and it is therefore reasonable to suggest that the decline in soil bacterial diversity may point to a ‘dilution effect’ [23, 76].…”

“…In forests, fungi are known to form symbiotic relationships with plants in forest soils [22][23][24] and fungal community composition is closely linked to tree diversity [25][26][27][28].…”

Climate-Driven Legacies in Simulated Microbial Communities Alter Litter Decomposition Rates

“…The challenge of identifying underlying mechanisms may arise from interrelated conceptual and methodological issues in the fields of microbial ecology and biogeochemistry. First, many litter decomposition studies de-emphasize the role of microbial composition in controlling soil carbon dynamics (e.g., Beugnon et al, 2021). This approach reflects the influential conceptual framework of hierarchical control of litter decomposition (e.g., Lavelle et al, 1993;Aerts, 1997).…”