Peng Jinlong, Tang Jiwang, Xie Shudi, Wang Yiheng, Liao Jiaqiang, Chen Chen, Sun Chuanlian, Mao Jinhua, Zhou Qingping, Niu Shuli
Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing, 100101, China.
College of Resources and Environment, University of Chinese Academy of Sciences, Beijing, 100049, China.
Nat Commun. 2024 Nov 12;15(1):9795. doi: 10.1038/s41467-024-54156-7.
Ecosystem gross primary productivity (GPP) is the largest carbon flux between the atmosphere and biosphere and is strongly influenced by soil moisture. However, the response and acclimation of GPP to soil moisture remain poorly understood, leading to large uncertainties in characterizing the impact of soil moisture on GPP in Earth system models. Here we analyze the GPP-soil moisture response curves at 143 sites from the global FLUXNET. We find that GPP at 108 sites exhibits hump-shaped response curves with increasing soil moisture, and an apparent optimum soil moisture ( , at which GPP reaches the maximum) exists widely with large variability among sites and biomes around the globe. Variation in is mostly explained by local water availability, with drier ecosystems having lower than wetter ecosystems, reflecting the water acclimation of . This acclimation is further supported by a field experiment that only manipulates water and keeps other factors constant, which shows a downward shift in after long-term water deficit, and thus a lower soil water requirement to maximize GPP. These results provide compelling evidence for the widespread and its acclimation, shedding new light on understanding and predicting carbon-climate feedbacks.
生态系统总初级生产力（GPP）是大气与生物圈之间最大的碳通量，并且受到土壤湿度的强烈影响。然而，GPP对土壤湿度的响应和适应仍知之甚少，这导致在地球系统模型中表征土壤湿度对GPP的影响时存在很大的不确定性。在此，我们分析了来自全球通量网（FLUXNET）143个站点的GPP-土壤湿度响应曲线。我们发现，108个站点的GPP随着土壤湿度增加呈现驼峰状响应曲线，并且明显存在一个最优土壤湿度（ ，此时GPP达到最大值），全球各地的站点和生物群落之间存在很大差异。 的变化主要由当地的水资源可利用性解释，较干旱的生态系统的 低于较湿润的生态系统，这反映了 的水分适应。一项仅控制水分并保持其他因素不变的田间实验进一步支持了这种适应，该实验表明长期水分亏缺后 向下移动，因此使GPP最大化所需的土壤水分更低。这些结果为广泛存在的 及其适应提供了有力证据，为理解和预测碳-气候反馈提供了新的思路。
