Department of Ecology, College of Urban and Environmental Sciences and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China.
College of Life Sciences, Zhejiang University, Hangzhou, China.
Glob Chang Biol. 2024 Mar;30(3):e17217. doi: 10.1111/gcb.17217.
Although nitrogen (N) enrichment is known to threaten the temporal stability of aboveground net primary productivity, it remains unclear how it alters that of belowground microbial abundance and whether its impact can be regulated by grassland degradation. Using data from N enrichment experiments at temperate grasslands with no, moderate, severe, and extreme degradation degrees, we quantified the temporal stability of soil microbial abundance (hereafter 'microbial community stability') using the ratio of the mean quantitative PCR to its standard deviation over 4 years. Both bacterial and fungal community stability sharply decreased when N input exceeded 30 g N m year in non-degraded grasslands, whereas a reduction in this threshold occurred in degraded grasslands. Microbial species diversity, species asynchrony, and species associations jointly altered microbial community stability. Interestingly, the linkages between plant and microbial community stability were strengthened in degraded grasslands, suggesting that plants and soil microbes might depend on each other to keep stable communities in harsh environments. Our findings highlighted the importance of grassland degradation in regulating the responses of microbial community stability to N enrichment and provided experimental evidence for understanding the relationships between plant and microbial community stability.
尽管氮（N）富集已知会威胁到地上净初级生产力的时间稳定性，但它如何改变地下微生物丰度的时间稳定性，以及其影响是否可以通过草原退化来调节，这些问题仍不清楚。本研究使用无、中度、重度和极度退化温带草原 N 富集实验的数据，通过在 4 年内将定量 PCR 的平均值与其标准差的比值来量化土壤微生物丰度的时间稳定性（以下简称“微生物群落稳定性”）。在非退化草原中，当 N 输入超过 30 g N m 年时，细菌和真菌群落稳定性急剧下降，而在退化草原中，这个阈值降低了。微生物物种多样性、物种不同步和物种关联共同改变了微生物群落稳定性。有趣的是，在退化草原中，植物和微生物群落稳定性之间的联系得到了加强，这表明植物和土壤微生物可能相互依赖，以在恶劣环境中保持稳定的群落。本研究结果强调了草原退化在调节微生物群落稳定性对 N 富集响应方面的重要性，并为理解植物和微生物群落稳定性之间的关系提供了实验证据。
