School of Life Sciences/Hebei Basic Science Center for Biotic Interaction, Institute of Life Science and Green Development, Hebei University, Baoding, Hebei, 071002, China.
Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, State Key Laboratory of Estuarine and Coastal Research, School of Ecological and Environmental Sciences, East China Normal University, Shanghai, 200241, China.
New Phytol. 2024 Dec;244(5):1775-1787. doi: 10.1111/nph.20144. Epub 2024 Sep 20.
Redistribution of precipitation across seasons is a widespread phenomenon affecting dryland ecosystems globally. However, the impacts of shifting seasonal precipitation patterns on carbon (C) cycling and sequestration in dryland ecosystems remain poorly understood. In this study, we conducted a 10-yr (2013-2022) field manipulative experiment that altered the timing of growing-season precipitation peaks in a semi-arid grassland. We found that the delayed precipitation peak suppressed plant growth and thus reduced gross ecosystem productivity, ecosystem respiration, and net ecosystem productivity due to middle growing-season water stress. Surprisingly, shifting more precipitation to the early growing season can advance plant development, increase the dominance of drought-tolerant forbs, and thus compensate for the negative impacts of middle growing-season water stress on ecosystem C cycling, leading to a neutral change in grassland C sink. Our findings indicate that greater precipitation and plant development in spring could act as a crucial mechanism, maintaining plant growth and stabilizing ecosystem C sink. This underscores the urgent need to incorporate precipitation seasonality into Earth system models, which is crucial for improving projections of terrestrial C cycling and sequestration under future climate change scenarios.
降水在季节间的再分配是一种广泛存在的现象，影响着全球干旱生态系统。然而，季节降水模式变化对干旱生态系统碳（C）循环和固存的影响仍知之甚少。在这项研究中，我们进行了一项为期 10 年（2013-2022 年）的野外控制实验，改变了半干旱草原生长季降水峰值的时间。我们发现，推迟的降水峰值由于中期生长季水分胁迫抑制了植物生长，从而降低了总生态系统生产力、生态系统呼吸和净生态系统生产力。令人惊讶的是，将更多的降水转移到生长季早期可以促进植物发育，增加耐旱草本植物的优势，从而弥补中期生长季水分胁迫对生态系统 C 循环的负面影响，导致草原 C 汇的中性变化。我们的研究结果表明，春季更多的降水和植物发育可能是维持植物生长和稳定生态系统 C 汇的关键机制。这凸显了将降水季节性纳入地球系统模型的紧迫性，这对于改善未来气候变化情景下陆地 C 循环和固存的预测至关重要。
