Data from: Leaf traits of African woody savanna species across climate and soil fertility gradients: evidence for conservative vs. acquisitive resource use strategies

1. Establishing trade-offs among traits and the degree to which they co-vary along environmental gradients has become a key focal point in the effort to develop community ecology into a predictive science. While there is evidence for these relationships across global datasets, they are often too broad in scale, and do not consider the particularities of local to regional species pools. This decreases their usefulness for developing predictive models at scales relevant for conservation and management.
2. We tested for trade-offs between traits and relationships with environmental gradients in trees and shrubs sampled across southern African savannas and explored evidence for acquisitive vs. conservative resource use strategies using a phylogenetically explicit approach.
3. We found a distinct trade-off between two major poles of specialization indicative of acquisitive (high leaf nitrogen concentration (LNC), leaf phosphorus concentration (LPC), leaf N:P, specific leaf area (SLA) and average leaf area (ALA)) and conservative resource use strategies (high leaf carbon to nitrogen ratios (C:N), tensile strength (TS) and leaf dry matter content (LDMC)). Although we found that trait variance and species occurrence were constrained by phylogeny, phylogenetically informed analyses did not contradict non-phylogenetic analyses, strengthening relationships in most cases.
4. The high intra-site trait variability and weak relationships with soils and climate may in part be explained by the high levels of deciduousness and disturbance (i.e. fire and herbivory) inherent in African savannas.
5. Synthesis: The relationships between traits and between traits and environmental gradients were far weaker than, and often contradictory to, broad scale studies that compare these relationships across biomes and growth forms, cautioning against making generalizations about relationships at specific sites based on broad scale analyses.

1. 在将群落生态学（community ecology）发展为预测性科学的研究中，明确各性状间的权衡（trade-off）关系及其沿环境梯度（environmental gradient）的协同变化程度，已成为核心焦点。尽管全球数据集已为这类关联提供了证据，但此类研究往往尺度过大，未考虑局域至区域尺度物种库（species pool）的特殊性。这降低了其在保护与管理相关尺度上构建预测模型的实用性。
2. 本研究对南非稀树草原（southern African savannas）内采样的乔木与灌木开展分析，检验了性状间的权衡关系及其与环境梯度的关联，并通过系统发育明确性方法（phylogenetically explicit approach）探究了物种采取获取型资源利用策略（acquisitive resource use strategy）与保守型资源利用策略（conservative resource use strategy）的证据。
3. 本研究发现，两大特化极端间存在显著的性状权衡：一端对应获取型资源利用策略，表现为高叶片氮浓度（leaf nitrogen concentration, LNC）、高叶片磷浓度（leaf phosphorus concentration, LPC）、高叶氮磷比（leaf N:P）、高比叶面积（specific leaf area, SLA）与高平均叶面积（average leaf area, ALA）；另一端则对应保守型资源利用策略，表现为高叶碳氮比（leaf carbon to nitrogen ratios, C:N）、高抗张强度（tensile strength, TS）与高叶片干物质含量（leaf dry matter content, LDMC）。尽管研究发现性状变异与物种分布受系统发育（phylogeny）约束，但纳入系统发育的分析并未与非系统发育分析产生矛盾，且在多数情况下强化了性状间的关联。
4. 样点内极高的性状变异，以及性状与土壤、气候间较弱的关联，部分可归因于非洲稀树草原固有的高落叶性与干扰（即火与草食作用）。
5. 综合结论：性状间、性状与环境梯度间的关联远弱于跨生物群区（biome）与生长型（growth form）比较的大尺度研究，且往往与这些研究结果相悖，这警示我们不应基于大尺度分析对特定样点的关联做出泛化推断。