College of Geography and Environmental Science, Henan University, Kaifeng 475004, Henan, China.
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences/CAS Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai 264003, Shandong, China.
Ying Yong Sheng Tai Xue Bao. 2024 Sep 18;35(9):2445-2454. doi: 10.13287/j.1001-9332.202409.014.
Soil respiration, the main pathway for transferring terrestrial carbon pool to atmospheric carbon pool, is profoundly affected by the intensification in global precipitation variability in the context of climate change. Nowadays, variable controlling methods and field manipulation experiments are two main methods widely used to investigate the effects of simulated precipitation changes on soil respiration. Yet, due to the heterogeneity of soil properties, vegetation types, and the magnitude of precipitation change, there is substantial inconsistency in the conclusions of simulated precipitation change effects on soil respiration. Here, we analyzed data from domestic and foreign literature, and examined the effects of simulated precipitation change on soil respiration. Firstly, we described the response pattern of soil respiration to soil moisture fluctuation and pointed out that the magnitude and direction of the response of soil respiration to simulated precipitation change depended on whether soil moisture was optimally conditioned at different precipitation treatments. Second, we summarized the response patterns of soil respiration to symmetric increase and decrease in precipitation, which mainly included symmetric and asymmetric responses (positive and negative asymmetric). Meanwhile, the adaptation of plants and soil microorganisms to drought stress and soil oxygen limitation, as well as the reduction of organic substrates, were the main mechanisms accounting for the shifts of soil respiration response patterns to simulated precipitation change from symmetric to asymmetric responses. Third, we identified a significant effect of ambient climate on soil respiration in response to precipitation treatments as increasing duration of the experimental treatments. In addition, cumulative or buffering effects of ambient climatic conditions on precipitation treatment could affect the sensitivity of soil respiration along precipitation gradient by altering hydrothermal conditions. Finally, to accurately assess the implications of precipitation changes on soil carbon balance processes, we proposed three aspects of future precipitation effects on soil respiration for attention: 1) focusing on the phenomenon of "threshold effects" in the asymmetric response of soil respiration along precipitation gradients; 2) distinguishing the intrinsic mechanisms of autotrophic and heterotrophic components in soil respiration in response to precipitation changes; and 3) focusing on the impacts of intensified precipitation variability on soil respiration in the context of future climate extremes. In conclusion, with the intensified variability in global precipitation patterns, clarifying the response mechanism of soil respiration to precipitation changes is of great significance for accurately predicting and evaluating the alterations of soil carbon cycle processes and carbon balance in the context of global changes.
土壤呼吸是将陆地碳库转移到大气碳库的主要途径，在气候变化背景下，强烈受到全球降水变率增强的影响。如今，可变控制方法和野外操作实验是广泛用于研究模拟降水变化对土壤呼吸影响的两种主要方法。然而，由于土壤性质、植被类型和降水变化幅度的异质性，模拟降水变化对土壤呼吸影响的结论存在很大的不一致性。在这里，我们分析了国内外文献的数据，并研究了模拟降水变化对土壤呼吸的影响。首先，我们描述了土壤呼吸对土壤水分波动的响应模式，并指出土壤呼吸对模拟降水变化的响应幅度和方向取决于不同降水处理下土壤水分是否得到最佳调节。其次，我们总结了土壤呼吸对降水对称增加和减少的响应模式，主要包括对称和非对称响应（正和负非对称）。同时，植物和土壤微生物对干旱胁迫和土壤氧气限制的适应，以及有机底物的减少，是导致土壤呼吸对模拟降水变化的响应模式从对称转变为非对称响应的主要机制。第三，我们发现环境气候对土壤呼吸对降水处理的响应有显著影响，随着实验处理持续时间的增加而增加。此外，环境气候条件对降水处理的累积或缓冲效应可以通过改变水热条件来影响土壤呼吸沿降水梯度的敏感性。最后，为了准确评估降水变化对土壤碳平衡过程的影响，我们提出了未来降水对土壤呼吸的三个方面需要注意：1）关注土壤呼吸沿降水梯度非对称响应中的“阈值效应”现象；2）区分土壤呼吸对降水变化响应中自养和异养成分的内在机制；3）关注未来气候极端条件下降水变率增强对土壤呼吸的影响。总之，随着全球降水模式变率的加剧，阐明土壤呼吸对降水变化的响应机制对于准确预测和评估全球变化背景下土壤碳循环过程和碳平衡的变化具有重要意义。
