Tropical Forest Science Program, National Institute of Amazon Researches, Manaus, AM, Brazil.
School of Natural Resources and the Environment, University of Arizona, Tucson, AZ, USA.
J Exp Bot. 2022 Jan 27;73(3):939-952. doi: 10.1093/jxb/erab432.
Addressing the intraspecific variability of functional traits helps understand how climate change might influence the distribution of organismal traits across environments, but this is notably understudied in the Amazon, especially for plant hydraulic traits commonly used to project drought responses. We quantified the intraspecific trait variability of leaf mass per area, wood density, and xylem embolism resistance for two dominant central Amazonian tree species, along gradients of water and light availability, while accounting for tree age and height. Intraspecific variability in hydraulic traits was high, with within-species variability comparable to the whole-community variation. Hydraulic trait variation was modulated mostly by the hydrological environment, with higher embolism resistance of trees growing on deep-water-table plateaus compared with shallow-water-table valleys. Intraspecific variability of leaf mass per area and wood density was mostly modulated by intrinsic factors and light. The different environmental and intrinsic drivers of variation among and within individuals lead to an uncoupled coordination among carbon acquisition/conservation and water-use traits. Our findings suggest multivariate ecological strategies driving tropical tree distributions even within species, and reflect differential within-population sensitivities along environmental gradients. Therefore, intraspecific trait variability must be considered for accurate predictions of the responses of tropical forests to climate change.
解决功能性状的种内变异性有助于了解气候变化如何影响生物性状在环境中的分布，但这在亚马逊地区，特别是在常用作预测干旱响应的植物水力性状方面，研究得并不多。我们量化了两种主要的亚马逊中部地区树种的叶片质量面积、木材密度和木质部栓塞抗性的种内性状变异性，同时考虑了树龄和高度。水力性状的种内变异性很高，种内变异性与整个群落的变异性相当。水力性状的变化主要受水文环境的调节，与生长在浅地下水位谷的树木相比，生长在深地下水位高原上的树木具有更高的栓塞抗性。叶片质量面积和木材密度的种内变异性主要受内在因素和光的调节。个体之间和个体内部的变异的不同环境和内在驱动因素导致碳获取/保护和水分利用性状之间的解耦协调。我们的研究结果表明，即使在同一物种内，多种生态策略也会驱动热带树木的分布，并反映出沿环境梯度的种群内差异敏感性。因此，为了准确预测热带森林对气候变化的响应，必须考虑种内性状变异性。
