Zhang Zhihao, Tang Gangliang, Chai Xutian, Liu Bo, Gao Xiaopeng, Zeng Fanjiang, Wang Yun, Zhang Bo
Xinjiang Key Laboratory of Desert Plant Roots Ecology and Vegetation Restoration, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
State Key Laboratory of Desert and Oasis Ecology, Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi 830011, China.
Microorganisms. 2023 Oct 1;11(10):2471. doi: 10.3390/microorganisms11102471.
The effects of increased nitrogen (N) deposition on desert ecosystems have been extensively studied from a plant community perspective. However, the response of soil microbial communities, which play a crucial role in nutrient cycling, to N inputs and plant community types remains poorly understood. In this study, we conducted a two-year N-addition experiment with five gradients (0, 10, 30, 60, and 120 kg N ha year) to evaluate the effect of increased N deposition on soil bacterial and fungal communities in three plant community types, namely, Shap., (Pall.) Less. monocultures and their mixed community in a desert steppe located on the southern edge of the Taklimakan Desert, Northwest China. Our results indicate that N deposition and plant community types exerted an independent and significant influence on the soil microbial community. Bacterial α-diversity and community dissimilarity showed a unimodal pattern with peaks at 30 and 60 kg N ha year respectively. By contrast, fungal α-diversity and community dissimilarity did not vary significantly with increased N inputs. Furthermore, plant community type significantly altered microbial community dissimilarity. The Mantel test and redundancy analysis indicated that soil pH and total and inorganic N (NH and NO) levels were the most critical factors regulating soil microbial communities. Similar to the patterns observed in taxonomic composition, fungi exhibit stronger resistance to N addition compared to bacteria in terms of their functionality. Overall, our findings suggest that the response of soil microbial communities to N deposition is domain-specific and independent of desert plant community diversity, and the bacterial community has a critical threshold under N enrichment in arid deserts.
从植物群落角度，人们对氮（N）沉降增加对沙漠生态系统的影响进行了广泛研究。然而，在养分循环中起关键作用的土壤微生物群落对氮输入和植物群落类型的响应仍知之甚少。在本研究中，我们进行了为期两年的氮添加实验，设置了五个梯度（0、10、30、60和120千克氮/公顷·年），以评估氮沉降增加对中国西北塔克拉玛干沙漠南缘一个沙漠草原中三种植物群落类型（即梭梭（Shap.）、花花柴（Karelinia caspica (Pall.) Less.）单种群落及其混合群落）土壤细菌和真菌群落的影响。我们的结果表明，氮沉降和植物群落类型对土壤微生物群落产生了独立且显著的影响。细菌α多样性和群落差异呈现单峰模式，分别在30和60千克氮/公顷·年时达到峰值。相比之下，真菌α多样性和群落差异并未随氮输入增加而显著变化。此外，植物群落类型显著改变了微生物群落差异。Mantel检验和冗余分析表明，土壤pH值以及总氮和无机氮（NH₄⁺和NO₃⁻）水平是调节土壤微生物群落的最关键因素。与分类组成中观察到的模式相似，就功能而言，真菌对氮添加的抗性比细菌更强。总体而言，我们的研究结果表明，土壤微生物群落对氮沉降的响应具有领域特异性，且独立于沙漠植物群落多样性，并且在干旱沙漠中，细菌群落在氮富集下存在一个临界阈值。
