Climate and plant trait strategies determine tree carbon allocation to leaves and mediate future forest productivity
Climate and plant trait strategies determine tree carbon allocation to leaves and mediate future forest productivity
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DOI：
10.1111/gcb.14680
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发表时间：
2019-06
影响因子：
11.6
通讯作者：
A. Trugman;L. Anderegg;B. Wolfe;Benjamin Birami;N. Ruehr;M. Detto;M. Bartlett;W. Anderegg
中科院分区：
文献类型：
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作者：
A. Trugman;L. Anderegg;B. Wolfe;Benjamin Birami;N. Ruehr;M. Detto;M. Bartlett;W. Anderegg
森林叶面积对碳循环具有巨大的影响，因为它调节了森林生产力和对极端气候的适应能力。尽管广泛的证据表明，树木能够通过改变叶片的碳分配来适应空间和时间上的环境变化，但许多植被模型使用独立于环境的固定碳分配方案，这给未来森林对大气CO2施肥和人为气候变化的响应的预测带来了很大的不确定性。在这里，我们开发了一个基于优化的模型，其中树木的碳分配给叶片是环境和植物水力性状的紧急属性。结合meta分析、观测数据集和模型预测，我们发现了强有力的证据，证明最佳的水力-碳耦合解释了在大环境和二氧化碳浓度梯度中观察到的叶片分配模式。此外，我们还测试了叶片分配策略对水力和经济谱生理性状多样性的敏感性，表明植物水力性状对森林叶面积的全球变化响应具有巨大影响。我们的研究结果为通过推进叶面积的模型预测来改善碳循环预测提供了严格的理论基础，并强调了在下一代植被模型中，树木水平的叶片碳分配应该使用机械植物水力过程从第一性原理推导出来。
Forest leaf area has enormous leverage on the carbon cycle because it mediates both forest productivity and resilience to climate extremes. Despite widespread evidence that trees are capable of adjusting to changes in environment across both space and time through modifying carbon allocation to leaves, many vegetation models use fixed carbon allocation schemes independent of environment, which introduces large uncertainties into predictions of future forest responses to atmospheric CO2 fertilization and anthropogenic climate change. Here, we develop an optimization‐based model, whereby tree carbon allocation to leaves is an emergent property of environment and plant hydraulic traits. Using a combination of meta‐analysis, observational datasets, and model predictions, we find strong evidence that optimal hydraulic–carbon coupling explains observed patterns in leaf allocation across large environmental and CO2 concentration gradients. Furthermore, testing the sensitivity of leaf allocation strategy to a diversity in hydraulic and economic spectrum physiological traits, we show that plant hydraulic traits in particular have an enormous impact on the global change response of forest leaf area. Our results provide a rigorous theoretical underpinning for improving carbon cycle predictions through advancing model predictions of leaf area, and underscore that tree‐level carbon allocation to leaves should be derived from first principles using mechanistic plant hydraulic processes in the next generation of vegetation models.