近日，美国加州大学伯克利分校Trevor F. Keenan团队揭示了全球旱地雨水引起的土壤碳排放普遍低估。相关论文于2025年7月31日发表在《自然—地球科学》杂志上。

旱地碳通量，特别是由生态系统呼吸作用驱动的碳通量，对水分供应和降雨脉冲高度敏感。然而，全球降雨引起的碳排放规模仍不清楚。

研究组量化了雨脉冲事件对全球旱地碳平衡的影响，并表征了其时空控制。利用对全球34个旱地站点的碳、水和能量通量的涡旋协方差观测，研究组编制了一份超过1800个人工确定的降雨引起的二氧化碳脉冲事件的清单。基于此清单，他们开发了一种机器学习算法来自动检测降雨引起的二氧化碳脉冲事件。研究结果表明，在雨脉冲事件期间，现有的划分方法低估了生态系统呼吸和光合作用高达30%，而这些因素每年贡献了16.9±2.8%的生态系统呼吸和9.6±2.2%的净生态系统生产力。

研究表明，碳损失强度与年生产力、干旱程度和土壤pH值相关性最强。最后，研究组确定了降雨引起的二氧化碳脉冲的普遍衰减率，并将其主题为偏差校正呼吸估计。该研究强调了降雨引起的碳排放对全球旱地碳平衡的重要性，并提出生态系统模型可能在很大程度上低估了雨脉冲对旱地碳循环的影响。

附：英文原文

Title: Widespread underestimation of rain-induced soil carbon emissions from global drylands

Author: Nguyen, Ngoc B., Migliavacca, Mirco, Bassiouni, Maoya, Baldocchi, Dennis D., Gherardi, Laureano A., Green, Julia K., Papale, Dario, Reichstein, Markus, Cohrs, Kai-Hendrik, Cescatti, Alessandro, Nguyen, Tuan Dung, Nguyen, Hoang H., Nguyen, Quang Minh, Keenan, Trevor F.

Issue&Volume: 2025-07-31

Abstract: Dryland carbon fluxes, particularly those driven by ecosystem respiration, are highly sensitive to water availability and rain pulses. However, the magnitude of rain-induced carbon emissions remains unclear globally. Here we quantify the impact of rain-pulse events on the carbon balance of global drylands and characterize their spatiotemporal controls. Using eddy-covariance observations of carbon, water and energy fluxes from 34 dryland sites worldwide, we produce an inventory of over 1,800 manually identified rain-induced CO2 pulse events. Based on this inventory, a machine learning algorithm is developed to automatically detect rain-induced CO2 pulse events. Our findings show that existing partitioning methods underestimate ecosystem respiration and photosynthesis by up to 30% during rain-pulse events, which annually contribute 16.9±2.8% of ecosystem respiration and 9.6±2.2% of net ecosystem productivity. We show that the carbon loss intensity correlates most strongly with annual productivity, aridity and soil pH. Finally, we identify a universal decay rate of rain-induced CO2 pulses and use it to bias-correct respiration estimates. Our research highlights the importance of rain-induced carbon emissions for the carbon balance of global drylands and suggests that ecosystem models may largely underrepresent the influence of rain pulses on the carbon cycle of drylands.

DOI: 10.1038/s41561-025-01754-9

Source: https://www.nature.com/articles/s41561-025-01754-9