Shifts in taxonomic and functional composition of trees along rainfall and phosphorus gradients in central Panama
Shifts in taxonomic and functional composition of trees along rainfall and phosphorus gradients in central Panama
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DOI：
10.1111/1365-2745.13442
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发表时间：
2020-07
影响因子：
5.5
通讯作者：
M. Umaña;R. Condit;R. Condit;Rolando Pẽrez;Benjamin L Turner;S. Wright;L. Comita;L. Comita
中科院分区：
文献类型：
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作者：
M. Umaña;R. Condit;R. Condit;Rolando Pẽrez;Benjamin L Turner;S. Wright;L. Comita;L. Comita
环境梯度作为物种分布的有效过滤器，推动了群落间的组成变化。组成的变化可能反映了对有限资源的生理耐受性的差异，导致耐受性物种的广泛分布和不耐受性物种的限制分布（即嵌套模式）。另外，资源利用的权衡或相互冲突的物种对多种资源的反应可能导致物种沿梯度的完全更替。在巴拿马中部不同土壤磷(P)和降雨梯度的72个地点，对550种树种的特征（叶面积、叶质量、木材密度和最大高度）和分布数据进行了分类和功能组成分析。我们确定了群落的功能和分类组成是巢式的还是完全翻转的，以及群落平均性状和物种组成是受P还是湿度的驱动更强。乔木群落功能组成以周转为特征。叶片性状对两种梯度均有响应，在较干燥、肥沃的土壤中，物种的叶片比在较潮湿、肥沃程度较低的土壤中大而薄。这些叶片性状-水分关系与基于干旱反应的预测相矛盾，表明光照有效性差异比水分差异的作用更大。木材密度和最大高度的变化弱于叶片性状，较高的物种主导湿地，低木材密度的物种主导富磷地。周转量是乔木群落分类组成的特征。地理距离对群落分类学组成变异的解释比对功能组成变异的解释更大，群落平均性状受磷的影响比对水分的影响更大。合成。我们的研究结果为巴拿马中部树木群落的耐受性假设提供了微弱的支持。相反，我们观察到功能和分类转换反映了权衡和冲突物种对多种非生物因素的反应，包括湿度，土壤磷和潜在的其他相关变量（如光）。
Environmental gradients act as potent filters on species distributions driving compositional shifts across communities. Compositional shifts may reflect differences in physiological tolerances to a limiting resource that result in broad distributions for tolerant species and restricted distributions for intolerant species (i.e. a nested pattern). Alternatively, trade‐offs in resource use or conflicting species' responses to multiple resources can result in complete turnover of species along gradients. We combined trait (leaf area, leaf mass per area, wood density and maximum height) and distribution data for 550 tree species to examine taxonomic and functional composition at 72 sites across strong gradients of soil phosphorus (P) and rainfall in central Panama. We determined whether functional and taxonomic composition was nested or turned over completely and whether community mean traits and species composition were more strongly driven by P or moisture. Turnover characterized the functional composition of tree communities. Leaf traits responded to both gradients, with species having larger and thinner leaves in drier and more fertile sites than in wetter and less fertile sites. These leaf trait–moisture relationships contradict predictions based on drought responses and suggest a greater role for differences in light availability than in moisture. Shifts in wood density and maximum height were weaker than for leaf traits with taller species dominating wet sites and low wood density species dominating P‐rich sites. Turnover characterized the taxonomic composition of tree communities. Geographic distances explained a larger fraction of variation for taxonomic composition than for functional composition, and community mean traits were more strongly driven by P than moisture. Synthesis. Our results offer weak support for the tolerance hypothesis for tree communities in central Panama. Instead, we observe functional and taxonomic turnover reflecting trade‐offs and conflicting species' responses to multiple abiotic factors including moisture, soil phosphorus and potentially other correlated variables (e.g. light).