Key Laboratory of Urban Environment and Health, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; University of Chinese Academy of Sciences, Beijing 100049, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China.
Key Laboratory of Urban Environment and Health, Ningbo Observation and Research Station, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China; Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control, CAS Haixi Industrial Technology Innovation Center in Beilun, Ningbo 315830, China.
Sci Total Environ. 2024 Nov 10;950:175274. doi: 10.1016/j.scitotenv.2024.175274. Epub 2024 Aug 6.
Rising instances of flash droughts are contributing to notable variability in soil moisture across terrestrial ecosystems. These phenomena challenge urban ecosystem services, yet the reaction of soil ecological functions (SEFs) to such events is poorly understood. This study investigates the responses of SEFs (about nutrient metabolism capacity and potential) and the microbiome under two specific scenarios: a flooding-drought sequence and a direct drought condition. Using quantitative microbial element cycling analysis, high-throughput sequencing, and enzyme activity measurements, we found that unlike in forests, the microbial composition in urban soils remained unchanged during flash drought conditions. However, SEFs were affected in both settings. Correlation analysis and Mantel test showed that forest soils exhibited more complex interactions among soil moisture, properties, and microbial communities. Positive linear correlation revealed that bacteria were the sole drivers of SEFs. Interestingly, while multi-threshold results suggested bacterial α diversity impeded the maximization of SEFs in urban soils, fungi and protists had a beneficial impact. Cross-domain network of urban soils had higher number of nodes and edges, but lower average degree and robustness than forest soils. Mantel test revealed that fungi and protist had significant correlations with bacterial composition in forest soils, but not in urban soils. In the urban network, the degree and eigenvector centrality of bacterial, fungal and protistan ASVs were significantly lower compared to those in the forest. These results suggest that the lower robustness of the microbial network in urban soils is attributed to limited interactions among fungi, consumer protists, and bacteria, contributing to the failure of microbial-driven ecological functions. Overall, our findings emphasize the critical role of fungi and protists in shielding urban soils from drought-induced disturbances and in enhancing the resistance of urban ecological functions amidst environmental changes.
日益增多的闪发性干旱事件导致陆地生态系统土壤湿度出现显著变化。这些现象给城市生态系统服务带来了挑战，但人们对土壤生态功能（SEFs）对这些事件的反应知之甚少。本研究调查了 SEFs（约营养代谢能力和潜力）和微生物组在两种特定情况下的反应：洪水-干旱序列和直接干旱条件。使用定量微生物元素循环分析、高通量测序和酶活性测量，我们发现与森林不同，在闪发性干旱条件下，城市土壤中的微生物组成保持不变。然而，SEFs 在这两种情况下都受到了影响。相关分析和 Mantel 检验表明，森林土壤中土壤水分、性质和微生物群落之间的相互作用更为复杂。正线性相关表明，细菌是 SEFs 的唯一驱动因素。有趣的是，虽然多阈值结果表明细菌 α 多样性阻碍了城市土壤中 SEFs 的最大化，但真菌和原生动物具有有益的影响。城市土壤的跨域网络具有更多的节点和边，但平均程度和稳健性低于森林土壤。Mantel 检验表明，真菌和原生动物与森林土壤中细菌组成有显著相关性，但与城市土壤中无相关性。在城市网络中，细菌、真菌和原生动物 ASVs 的度和特征向量中心度明显低于森林网络。这些结果表明，城市土壤中微生物网络的稳健性较低是由于真菌、消费者原生动物和细菌之间的相互作用有限，导致微生物驱动的生态功能失效。总的来说，我们的研究结果强调了真菌和原生动物在保护城市土壤免受干旱干扰以及增强城市生态功能对环境变化的抵抗力方面的关键作用。
