Liu Yang, Tan Xiangping, Fu Shenglei, Shen Weijun
Ecological Conservation and Restoration Laboratory of Qinghai-Tibetan Plateau, Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, China.
Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Front Microbiol. 2022 Jun 10;13:888121. doi: 10.3389/fmicb.2022.888121. eCollection 2022.
Atmospheric nitrogen (N) deposition is known to alter soil microbial communities, but how canopy and understory N addition affects soil bacterial and fungal communities in different soil layers remains poorly understood. Conducting a 6-year canopy and understory N addition experiment in a temperate forest, we showed that soil bacterial and fungal communities in the organic layer exhibited different responses to N addition. The main effect of N addition decreased soil bacterial diversity and altered bacterial community composition in the organic layer, but not changed fungal diversity and community composition in all layers. Soil pH was the main factor that regulated the responses of soil bacterial diversity and community composition to N addition, whereas soil fungal diversity and community composition were mainly controlled by soil moisture and nutrient availability. In addition, compared with canopy N addition, the understory N addition had stronger effects on soil bacterial Shannon diversity and community composition but had a weaker effect on soil bacteria richness in the organic soil layer. Our study demonstrates that the bacterial communities in the organic soil layer were more sensitive than the fungal communities to canopy and understory N addition, and the conventional method of understory N addition might have skewed the effects of natural atmospheric N deposition on soil bacterial communities. This further emphasizes the importance of considering canopy processes in future N addition studies and simultaneously evaluating soil bacterial and fungal communities in response to global environmental changes.
大气氮（N）沉降会改变土壤微生物群落，这一点已为人所知，但林冠层和林下添加氮如何影响不同土壤层中的土壤细菌和真菌群落，目前仍知之甚少。我们在温带森林中进行了一项为期6年的林冠层和林下添加氮实验，结果表明，有机层中的土壤细菌和真菌群落对添加氮的反应不同。添加氮的主要影响是降低了有机层中土壤细菌的多样性并改变了细菌群落组成，但并未改变所有层中真菌的多样性和群落组成。土壤pH是调节土壤细菌多样性和群落组成对添加氮反应的主要因素，而土壤真菌的多样性和群落组成主要受土壤湿度和养分有效性控制。此外，与林冠层添加氮相比，林下添加氮对有机土壤层中土壤细菌的香农多样性和群落组成影响更强，但对土壤细菌丰富度的影响较弱。我们的研究表明，有机土壤层中的细菌群落比真菌群落对林冠层和林下添加氮更敏感，传统的林下添加氮方法可能会歪曲自然大气氮沉降对土壤细菌群落的影响。这进一步强调了在未来的添加氮研究中考虑林冠层过程以及同时评估土壤细菌和真菌群落对全球环境变化反应的重要性。
