PDF(Pubmed)
Abstract：
Assessing within-species variation in response to drought is crucial for predicting species\' responses to climate change and informing restoration and conservation efforts, yet experimental data are lacking for the vast majority of tropical tree species. We assessed intraspecific variation in response to water availability across a strong rainfall gradient for 16 tropical tree species using reciprocal transplant and common garden field experiments, along with measurements of gene flow and key functional traits linked to drought resistance. Although drought resistance varies widely among species in these forests, we found little evidence for within-species variation in drought resistance. For the majority of functional traits measured, we detected no significant intraspecific variation. The few traits that did vary significantly between drier and wetter origins of the same species all showed relationships opposite to expectations based on drought stress. Furthermore, seedlings of the same species originating from drier and wetter sites performed equally well under drought conditions in the common garden experiment and at the driest transplant site. However, contrary to expectation, wetter-origin seedlings survived better than drier-origin seedlings under wetter conditions in both the reciprocal transplant and common garden experiment, potentially due to lower insect herbivory. Our study provides the most comprehensive picture to date of intraspecific variation in tropical tree species\' responses to water availability. Our findings suggest that while drought plays an important role in shaping species composition across moist tropical forests, its influence on within-species variation is limited.
摘要：
评估物种内部变化对干旱的反应对于预测物种对气候变化的反应以及为恢复和保护工作提供信息至关重要。然而，绝大多数热带树种缺乏实验数据。我们使用相互移植和普通花园田间试验，评估了16种热带树种在强降雨梯度下对水可用性的种内变化，以及与抗旱相关的基因流和关键功能性状的测量。尽管这些森林中的物种之间的抗旱性差异很大，我们几乎没有发现抗旱性物种内变化的证据。对于测量的大多数功能性状，我们没有检测到显著的种内变异。在同一物种的较干和较湿起源之间确实存在显着差异的少数特征都显示出与基于干旱胁迫的预期相反的关系。此外，在共同的花园实验和最干燥的移植地点，在干旱条件下，来自较干燥和较湿润地点的相同物种的幼苗表现同样良好。然而,与预期相反，在相互移植和普通花园实验中，在较湿润的条件下，较湿润的幼苗比较干燥的幼苗存活得更好。可能是由于较低的昆虫食草动物。我们的研究提供了迄今为止热带树种对水可利用性的种内变异的最全面的描述。我们的发现表明，尽管干旱在塑造整个潮湿的热带森林的物种组成中起着重要作用，它对物种内变异的影响是有限的。
