Flooding and soil composition determine beta-diversity of lowland forests in Northern South America

Beta diversity may be determined by dispersal limitation, environment and phylogeographic history. Our objective was to advance the understanding of plant species turnover in rainforests in Northern South America and determine which factors are affecting species beta-diversity. We evaluated the relative effect of environmental variables (i.e. soil, climate, fragmentation and flooding frequency) and dispersal limitation (i.e. geographical distance and resistance distance due mountain barriers) on tree beta diversity in 32 1-ha lowland forest plots. We found that tree species turnover was better explained by environmental distance than by geographic distance. Although, soil conditions and flooding regime were good predictors of tree species composition, almost half of the variance remained unexplained. In our study system, the Eastern Andean ridge had no significant effect on plant beta diversity, probably because of its young age in relation to the phylogeny. Our results provide support ...

β多样性（Beta diversity）的成因可归结为扩散限制（dispersal limitation）、环境条件与系统地理历史（phylogeographic history）。本研究旨在深化对南美洲北部热带雨林内植物物种更替的认知，并明确影响物种β多样性的核心驱动因子。我们针对32块1公顷低地森林样地中的树木β多样性，评估了环境变量（即土壤、气候、生境破碎化与淹水频率）及扩散限制（即地理距离与山地屏障引发的阻力距离）的相对影响程度。研究发现，相较于地理距离，环境距离更能解释树木物种更替现象。尽管土壤条件与淹水状况可较好预测树木物种组成，但仍有近一半的变异未得到阐释。在本研究的样地系统中，安第斯山脉东脊对植物β多样性无显著影响，这可能是由于相较于物种系统发育进程而言，该山脊的形成年代较晚。本研究结果为……提供了支撑。