Assessing trait-based scaling theory in tropical forests spanning a broad temperature gradient
Assessing trait-based scaling theory in tropical forests spanning a broad temperature gradient
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DOI：
10.1111/geb.12645
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发表时间：
2017-12-01
影响因子：
6.4
通讯作者：
Malhi, Yadvinder
中科院分区：
文献类型：
--
作者：
Enquist, Brian J.;Bentley, Lisa Patrick;Malhi, Yadvinder
目的：热带海拔梯度是评估气候变化如何影响热带森林的天然实验室。然而，需要从特征到生态系统的理论和综合数据收集。我们评估了一种新的基于性状的尺度理论的预测，包括观察到的森林性状在广泛的热带温度梯度上的变化是否与当地的表型最优和对温度的适应性补偿一致。位置：海拔梯度跨越3300米，由数千个热带树木性状指标组成，这些指标来自秘鲁南部16个1公顷的热带森林地块，在那里测量了总初级生产力和净初级生产力(GPP和NPP)。时间：2013年4月至11月。主要研究种类：植物；热带树木。方法：我们发展了从性状到群落和生态系统的尺度理论，并检验了几种预测。我们评估了气候、性状、生物量与GPP和NPP之间的协变性。我们测量了与树木生长变异有关的多个性状，并评估了它们在海拔梯度内和跨海拔梯度的频率分布。结果：与理论一致，森林净初级生产力和总初级生产力的变化主要随森林生物量的变化而变化，但温度对生产力的次要影响远小于预期。这种弱的温度依赖性似乎反映了几个平均群落性状的方向性变化，这些性状是树木生长的基础，随着现场温度的下降。主要结论：在更寒冷的环境中占主导地位的树木的性状的观察到的变化与温度对叶片光合作用和树木生长的动态影响的适应/驯化补偿是一致的。梯度上的森林性状分布显示出过高的峰值和偏斜的分布，这与当地过滤最佳生长性状的重要性以及气候变化导致的物种组成和优势地位最近的变化是一致的。基于特征的尺度理论为预测气候变化已经并将如何影响热带森林的特征组成和生态系统功能提供了基础。
Aim: Tropical elevation gradients are natural laboratories to assess how changing climate can influence tropical forests. However, there is a need for theory and integrated data collection to scale from traits to ecosystems. We assess predictions of a novel trait-based scaling theory, including whether observed shifts in forest traits across a broad tropical temperature gradient are consistent with local phenotypic optima and adaptive compensation for temperature.Location: An elevation gradient spanning 3,300 m and consisting of thousands of tropical tree trait measures taken from 16 1-ha tropical forest plots in southern Peru, where gross and net primary productivity (GPP and NPP) were measured.Time period: April to November 2013.Major taxa studied: Plants; tropical trees.Methods: We developed theory to scale from traits to communities and ecosystems and tested several predictions. We assessed the covariation between climate, traits, biomass and GPP and NPP. We measured multiple traits linked to variation in tree growth and assessed their frequency distributions within and across the elevation gradient. We paired these trait measures across individuals within 16 forests with simultaneous measures of ecosystem net and gross primary productivity.Results: Consistent with theory, variation in forest NPP and GPP primarily scaled with forest biomass, but the secondary effect of temperature on productivity was much less than expected. This weak temperature dependence appears to reflect directional shifts in several mean community traits that underlie tree growth with decreases in site temperature.Main conclusions: The observed shift in traits of trees that dominate in more cold environments is consistent with an 'adaptive/acclimatory' compensation for the kinetic effects of temperature on leaf photosynthesis and tree growth. Forest trait distributions across the gradient showed overly peaked and skewed distributions, consistent with the importance of local filtering of optimal growth traits and recent shifts in species composition and dominance attributable to warming from climate change. Trait-based scaling theory provides a basis to predict how shifts in climate have and will influence the trait composition and ecosystem functioning of tropical forests.