Trait velocities reveal that mortality has driven widespread coordinated shifts in forest hydraulic trait composition
Trait velocities reveal that mortality has driven widespread coordinated shifts in forest hydraulic trait composition
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DOI：
10.1073/pnas.1917521117
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发表时间：
2020-03
期刊：
影响因子：
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通讯作者：
A. Trugman;L. Anderegg;J. Shaw;W. Anderegg
中科院分区：
文献类型：
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作者：
A. Trugman;L. Anderegg;J. Shaw;W. Anderegg
树木的水力特性决定了植物的水分利用和树木对干旱胁迫的脆弱性，从而影响森林生产力和地表与大气之间的水分流动。在这里，我们利用一个广泛的性状数据库和一个长期的大陆森林地块网络来绘制美国各地树木群落水力性状的变化。我们发现了树木死亡率导致的向具有更耐旱特征的社区转变的证据。这种特征组成的变化可能会缓冲森林生产力和水通量在短期内从气候变化的影响。了解植被水力性状和群落性状多样性现有模式背后的驱动机制对于推进陆地碳循环的预测至关重要，因为水力性状影响生态系统和地球系统对水资源变化的响应。在这里，我们利用一个广泛的性状数据库和一个长期的大陆森林地块网络来绘制社区性状分布的变化，并量化“性状速度”（社区加权性状的变化率）为不同地区和不同的森林类型在美国从2000年到现在。我们发现，在水力特性和光合特性的多样性更相关的局部水的可用性比整体物种多样性。最后，我们发现了树木死亡率驱动的向具有更耐旱特征的社区协调转变的证据，但响应的程度因森林类型而异。水力性状分布图提供了一个公开可用的平台，从根本上提高对气候变化和机械植被模型预测能力的社区性状变化的理解。
Significance Tree hydraulic traits determine plant water use and tree vulnerability to drought stress thereby affecting forest productivity and the movement of water between the land surface and the atmosphere. Here, we leverage an extensive trait database and a long-term continental forest plot network to map changes in the hydraulic traits of tree communities across the United States. We find evidence for shifts toward communities with more drought-tolerant traits driven by tree mortality. This trait compositional change may buffer forest productivity and water fluxes in the near term from the effects of climate change. Understanding the driving mechanisms behind existing patterns of vegetation hydraulic traits and community trait diversity is critical for advancing predictions of the terrestrial carbon cycle because hydraulic traits affect both ecosystem and Earth system responses to changing water availability. Here, we leverage an extensive trait database and a long-term continental forest plot network to map changes in community trait distributions and quantify “trait velocities” (the rate of change in community-weighted traits) for different regions and different forest types across the United States from 2000 to the present. We show that diversity in hydraulic traits and photosynthetic characteristics is more related to local water availability than overall species diversity. Finally, we find evidence for coordinated shifts toward communities with more drought-tolerant traits driven by tree mortality, but the magnitude of responses differs depending on forest type. The hydraulic trait distribution maps provide a publicly available platform to fundamentally advance understanding of community trait change in response to climate change and predictive abilities of mechanistic vegetation models.