Data from: Edaphic factors, successional status, and functional traits drive habitat associations of trees in naturally regenerating tropical dry forests

1. Many studies have examined individual environmental drivers of tropical tree species distributions, but edaphic and successional gradients have not been considered simultaneously. Furthermore, determining how functional traits influence species distributions along these gradients may help to elucidate mechanisms behind community assembly. 2. To assess the influence of environmental filtering on tropical dry forest (TDF) tree species distributions we used forest inventory data from sites with large edaphic and successional gradients in NW Costa Rica. Our goals were to determine (1) whether edaphic or successional factors are more important determinants of the abundance of individual tree species in regenerating TDF, (2) how species-level functional traits are related to edaphic and/or successional niche associations of tree species, and (3) correlations between species-level edaphic and successional niche associations. 3. The distributions of 82 focal tree species were strongly driven by both edaphic and successional gradients. Overall, 94% of species responded to soil chemistry, 89% to soil texture, and 94% to stand age gradients. Some functional traits were correlated with the edaphic and successional niche associations of TDF tree species. Species that specialized on soils with high total nutrient concentrations had higher foliar nutrient concentrations (nitrogen and phosphorus) and lower leaf dry matter content (LDMC). Species with wider stand age niches had lower LDMC and wood density. There were no correlations between edaphic and successional niche optima of TDF tree species. 4. Our results indicate that successional and edaphic gradients concurrently drive community assembly in regenerating TDF. Moreover, our work underscores the importance of considering how the functional characteristics of TDF trees dictates species distributions across environmental gradients.1. 已有诸多研究探讨了热带树木物种分布的单一环境驱动因子，但尚未有研究同时考量土壤因子与演替梯度的协同效应。此外，解析功能性状如何沿此类梯度影响物种分布，或有助于阐明群落构建背后的核心机制。 2. 为评估环境过滤对热带干旱林（tropical dry forest, TDF）树木物种分布的影响，本研究使用了哥斯达黎加西北部兼具显著土壤与演替梯度的样地森林清查数据。本研究的核心目标为：（1）明确在恢复中的热带干旱林内，土壤因子与演替因子何者对单个树木物种的多度具有更强的调控作用；（2）解析物种水平的功能性状与树木物种的土壤及/或演替生态位关联之间的关系；（3）探究物种水平的土壤与演替生态位关联之间的相关性。 3. 本研究涉及的82个目标树种的分布，同时受到土壤与演替梯度的强烈调控。总体而言，94%的物种对土壤化学性质产生响应，89%的物种响应土壤质地，另有94%的物种响应林龄梯度。部分功能性状与热带干旱林树木物种的土壤及演替生态位关联存在显著相关性：偏好高总养分含量土壤的物种，其叶片养分浓度（氮与磷）更高，而叶片干物质含量（leaf dry matter content, LDMC）更低；林龄生态位更宽的物种，其LDMC与木材密度均更低。此外，热带干旱林树木物种的土壤与演替生态位最适值之间未发现显著相关性。 4. 本研究结果表明，演替与土壤梯度共同驱动了恢复中热带干旱林的群落构建过程。此外，本研究进一步强调，需考量热带干旱林树木的功能性状如何调控物种沿环境梯度的分布格局。