Yu Yang, Liu Lu, Zhao Jianing, Wang Shuchen, Zhou Yijun, Xiao Chunwang
Key Laboratory of Ecology and Environment in Minority Areas, Minzu University of China, National Ethnic Affairs Commission, Beijing, China.
College of Life and Environmental Sciences, Minzu University of China, Beijing, China.
Front Microbiol. 2022 Jun 14;13:906818. doi: 10.3389/fmicb.2022.906818. eCollection 2022.
The response of soil microorganisms to altered nitrogen (N) and rainfall patterns plays an important role in understanding ecosystem carbon and nitrogen cycling processes under global change. Previous studies have separately focused on the effects of N addition and rainfall on soil microbial diversity and community composition. However, the combined and interactive impact of N addition and rainfall on soil microbial diversity and function mediated by plant and soil processes have been poorly investigated for grassland ecosystems. Here, we conducted a field experiment with simulated N addition (N addition: 10 g N myr) and altered rainfall pattern [control, rainfall reduction (compared to control -50%); rainfall addition (compared to control + 50%)] to study their interactive effects on soil microbial diversity and function in a temperate steppe of Inner Mongolia. Our results showed that N addition and rainfall addition significantly increased soil bacterial diversity, and the bacterial diversity was positively correlated with soil microbial biomass nitrogen, inorganic nitrogen, and root exudate C:N ratio, root exudate C and N, and root exudate C:N ratio. N addition and rainfall reduction significantly reduced fungal diversity, which correlated closely with soil microbial biomass carbon and the C:N ratio of root exudates. Bacteria were mainly eutrophic r-strategists, and the responses of bacterial function guilds to the interaction between N addition and rainfall pattern were not significant. However, the arbuscular mycorrhizal fungi (AMF), in the functional classification of fungi, were significantly reduced under the condition of N addition and rainfall reduction, and the absolute abundance of the phylum Glomeromycota increased under rainfall addition, suggesting that AMFs are sensitive to altered N and rainfall patterns over short timescales (1 year). Collectively, our results have important implications for understanding the plant-soil-microbe system of grasslands under climate change.
土壤微生物对氮（N）和降雨模式变化的响应在理解全球变化下的生态系统碳氮循环过程中起着重要作用。以往的研究分别聚焦于施氮和降雨对土壤微生物多样性及群落组成的影响。然而，对于草地生态系统，施氮和降雨对由植物和土壤过程介导的土壤微生物多样性及功能的综合交互影响却鲜有研究。在此，我们开展了一项田间试验，设置模拟施氮（施氮量：10 g N myr）和改变降雨模式[对照、降雨减少（相较于对照 -50%）；降雨增加（相较于对照 +50%）]，以研究它们对内蒙古温带草原土壤微生物多样性及功能的交互影响。我们的结果表明，施氮和降雨增加显著提高了土壤细菌多样性，且细菌多样性与土壤微生物生物量氮、无机氮、根系分泌物碳氮比、根系分泌物碳和氮以及根系分泌物碳氮比呈正相关。施氮和降雨减少显著降低了真菌多样性，这与土壤微生物生物量碳以及根系分泌物碳氮比密切相关。细菌主要是富营养型r策略者，细菌功能类群对施氮和降雨模式交互作用的响应并不显著。然而，在真菌的功能分类中，丛枝菌根真菌（AMF）在施氮和降雨减少的条件下显著减少，而在降雨增加时球囊菌门的绝对丰度增加，这表明AMF在短时间尺度（1年）内对氮和降雨模式的变化敏感。总体而言，我们的结果对于理解气候变化下草地的植物 - 土壤 - 微生物系统具有重要意义。
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