Disturbances and successional dynamics shape the composition of tree communities, but data remain scarce for tropical forests of West Africa. We assessed the imprint of past disturbances on the composition of evergreen forests in an Ivorian National Park. We hypothesized that (i) Pioneer indices (PI) based on the relative proportion of pioneer and non-pioneer trees relate to changing floristic composition due to successional dynamics, (ii) local community richness peaks at an intermediate value of PI under the Intermediate Disturbance Hypothesis (IDH) and (iii) early successional communities have higher beta diversity due to erratic founder effects. We performed a Correspondence Analysis of tree composition of 38 plots and examined how the main components of floristic variation related to environmental factors and PI. In addition, we tested the relationship between PI, local richness and beta diversity. The variation of PI better explained the main components of floristic variation than abiotic environmental variation, supporting a primary role of successional dynamics in shaping tree communities. We found a peak of richness at intermediate values of PI, supporting the IDH, with a mixture and earlier and later-successional species and more even abundances. The communities were very diverse and included many endemics and rare species. The results underline that the composition of early successional forests greatly varies depending on chance colonization events, while more similar old-growth communities are eventually observed after several decades. The findings should guide management practices for forest restoration, and for conservation of endangered species depending on their successional status.

中文翻译：

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演替动态塑造了西非科特迪瓦常绿森林的树木多样性

干扰和演替动态塑造了树木群落的组成，但西非热带森林的数据仍然稀缺。我们评估了过去干扰对科特迪瓦国家公园常绿森林组成的影响。我们假设 (i) 基于先锋树和非先锋树相对比例的先锋指数 (PI) 与由于演替动态引起的植物区系组成变化有关，(ii) 在中间扰动下，局部群落丰富度在 PI 的中间值处达到峰值假设（IDH）和（iii）早期演替社区由于不稳定的创始人效应而具有更高的β多样性。我们对 38 个地块的树木组成进行了对应分析，并检查了植物区系变异的主要成分与环境因素和 PI 的关系。此外，我们测试了 PI、本地丰富度和 beta 多样性之间的关系。PI 的变化比非生物环境变化更好地解释了植物区系变化的主要成分，支持了演替动力学在塑造树木群落中的主要作用。我们在 PI 的中间值处发现了一个丰富度峰值，支持 IDH，具有混合和早期和晚期演替物种以及更均匀的丰度。社区非常多样化，包括许多特有物种和稀有物种。结果强调，早期演替森林的组成因偶然的殖民事件而有很大差异，而几十年后最终会观察到更相似的古老生长群落。调查结果应指导森林恢复的管理实践，