Precipitation varies significantly in the southwest China karst regions, with a significant increase in the number of years with abnormally low precipitation during the rainy season and longer dry periods. Soil moisture and nitrogen chemical patterns are the main limiting factors for plant growth in this region. However, there are fewer studies on the impact of extreme precipitation on soil nitrogen cycling in abandoned farmland in karst ecosystems. In this study, we investigated the effects of changes in precipitation frequency and single precipitation amount on the nitrogen-cycle related microbial community in karst abandoned farmland through a two-year precipitation manipulation experiment. Our results showed that more frequent, smaller precipitation events increased soil water content, alleviating water limitation in karst abandoned farmland and resulting in higher abundance of functional genes (, , , and ), which accelerated soil nitrogen turnover compared to natural precipitation (Control). The changes in the gene abundance were associated with shifts in the dominant microbial taxa, such as Proteobacteria and Actinobacteria. In addition, nitrogen-cycling microbial communities exhibited resistance and resilience to extreme precipitation conditions. These findings shed light on the influence of precipitation regimes changes on soil nitrogen cycling in karst abandoned farmland, offering valuable insights for predicting the ecosystem's response to future precipitation changes.

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极端降水改变喀斯特废弃农田土壤氮循环相关微生物群落

西南喀斯特地区降水变化明显，雨季降水异常偏少年数显着增多，旱期较长。土壤湿度和氮化学模式是该地区植物生长的主要限制因素。然而，关于极端降水对喀斯特生态系统废弃农田土壤氮循环影响的研究较少。本研究通过为期两年的降水操纵实验，研究了降水频率和单次降水量的变化对喀斯特废弃农田氮循环相关微生物群落的影响。我们的结果表明，更频繁、更小的降水事件增加了土壤含水量，缓解了喀斯特废弃农田的水分限制，并导致功能基因（、、、和）丰度更高，与自然降水（对照）相比，这加速了土壤氮周转。基因丰度的变化与优势微生物类群的变化有关，例如变形菌门和放线菌门。此外，氮循环微生物群落表现出对极端降水条件的抵抗力和恢复力。这些发现揭示了降水状况变化对喀斯特废弃农田土壤氮循环的影响，为预测生态系统对未来降水变化的响应提供了宝贵的见解。