Carbon allocation in vegetation, particularly to leaves and roots responsible for resource assimilation, plays a crucial role in regulating the global carbon cycle and is highly sensitive to environmental changes. However, due to the limited observational data, the response of carbon allocation—particularly between resource-acquiring organs—to rapid global environmental changes remains unclear for global vegetation. State-of-the-art ecosystem models provide valuable insights into the spatiotemporal patterns of carbon allocation across global vegetation. In this study, we developed a weighted model average (WMA) by optimally integrating ecosystem models based on their performance in simulating the spatiotemporal changes in root and leaf carbon. The WMA well captured the satellite-observed leaf carbon trend and the spatial variations in root carbon along climate gradients (R2 = 0.82). The WMA suggested global vegetation has increasingly allocated more carbon to roots than leaves (the trend of allometric scaling relations between leaf and root: 0.0014 ± 0.0013 g g-1 yr-1, p < 0.05) during 1982–2018. Elevated atmospheric CO2 concentration was the dominant driver of changes in root/leaf carbon allocation globally (0.0010 ± 0.0005 g g-1 yr-1, p < 0.05), particularly in tropical regions. Climate change influenced carbon allocation in vegetation differently across regions, contributing to increased root carbon allocation in the Northern Hemisphere and enhanced leaf carbon allocation in tropical areas. Land use change led to more carbon being allocated to leaves than roots (-0.0003 ± 0.0006 g g-1 yr-1, p < 0.05). Overall, we tentatively quantified the changes in the carbon allocation to the leaf and root across global terrestrial vegetation under the dramatic environmental change based on WMA, which helps further understanding of the changes in the functioning of the terrestrial ecosystem and reasonable projection of changes in the future global carbon cycle.

中文翻译：

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通过最佳整合生态系统模型模拟的全球植被叶片和根碳分配变化


植被中的碳分配，特别是负责资源同化的叶子和根的碳分配，在调节全球碳循环中起着至关重要的作用，并且对环境变化高度敏感。然而，由于观测数据有限，全球植被的碳分配（特别是在资源获取器官之间）对全球快速环境变化的响应仍不清楚。最先进的生态系统模型为了解全球植被碳分配的时空模式提供了有价值的见解。在这项研究中，我们通过根据生态系统模型在模拟根和叶碳的时空变化方面的表现对其进行优化整合，开发了加权模型平均值 （WMA）。WMA 很好地捕捉了卫星观测的叶碳趋势和根碳随气候梯度的空间变化 （R2 = 0.82）。WMA 表明，在 1982-2018 年期间，全球植被越来越多地分配给根而不是叶（叶和根之间的异速生长缩放关系趋势：0.0014 ± 0.0013 g g-1 yr-1，p < 0.05）。大气中 CO2 浓度升高是全球根/叶碳分配变化的主要驱动因素 （0.0010 ± 0.0005 g g-1 yr-1，p < 0.05），尤其是在热带地区。气候变化对不同地区植被碳分配的影响不同，导致北半球根系碳分配增加，热带地区叶片碳分配增加。土地利用变化导致分配给叶子的碳多于根（-0.0003 ± 0.0006 g g-1 yr-1，p < 0.05）。 总体而言，我们基于 WMA 初步量化了剧烈环境变化下全球陆地植被叶片和根的碳分配变化，有助于进一步了解陆地生态系统功能的变化，合理预测未来全球碳循环的变化。