Responses of the soil microbial community structure to multiple interacting global change drivers in temperate forests

Background The microbial community structure in forest soils is expected to change in response to global environmental change, such as climate warming and nitrogen deposition. Community responses to these environmental changes may further interact with the site’s land-use history and understory light availability. Uncovering the relative importance of these global change drivers is crucial to understand and predict soil microbial communities’ changes. Methods A full-factorial in situ mesocosm experiment was conducted and the soil microbiota were analyzed by phospholipid fatty acid and neutral lipid fatty acid. The soils in the mesocosms were sampled from forests with different land-use history, and mesocosms contained typical forest understory plants. The mesocosms were exposed to experimental treatments of warming, nitrogen addition and subcanopy illumination. Results Among the treatments, past land-use had the strongest effect shaping the microbial community structure. We found a significantly higher abundance of arbuscular mycorrhizal fungi and Actinobacteria in ancient forests. The soil microbial and plant communities were co-structured in ancient forests, but not in past-agricultural forests. Warming and nitrogen fertilization did not affect the soil microbial community composition, yet illumination resulted in slight changes in soil microbial composition. Conclusions Our results underpin the role of land-use legacies in shaping soil microbial communities. The stronger plant-microbe linkages in ancient forest soils compared to post-agricultural secondary forest soils may contribute to a higher resilience against environmental changes. Our results advocate for more multifactor global change experiments that investigate the mechanisms underlying the potential effects of land-use legacies on plant-microbe relationships in forest.