Soil bacterial and fungal richness and network exhibit different responses to long-term throughfall reduction in a warm-temperate oak forest

Abstract

Prolonged drought results in serious ecological consequences in forest ecosystems, particularly for soil microbial communities. However, much is unknown about soil microbial communities in their response to long-term consecutive droughts in warm-temperate forests. Here, we conducted a 7-year manipulated throughfall reduction experiment (TFR) to examine the responses of bacterial and fungal communities in terms of richness and networks. Our results show that long-term TFR reduced bacterial, but not fungal, richness, with rare bacterial taxa being more sensitive to TFR than dominant taxa. The bacterial network under the TFR treatment featured a simpler network structure and fewer competitive links compared to the control, implying weakened interactions among bacterial species. Bacterial genes involved in xenobiotic biodegradation and metabolism, and lignin-degrading enzymes were enhanced under TFR treatment, which may be attributed to TFR-induced increases in fine root biomass and turnover. Our results indicate that soil bacterial communities are more responsive than fungi to long-term TFR in a warm-temperate oak forest, leading to potential consequences such as the degradation of recalcitrant organics in soil.