Data from: Biogeographic history and habitat specialisation shape floristic and phylogenetic composition across Amazonian forests

A major challenge remains to understand the relative contributions of history, dispersal and environmental filtering to the assembly of hyperdiverse communities across spatial scales. Here, we examine the extent to which biogeographical history and habitat specialization have generated turnover among and within lineages of Amazonian trees across broad geographic and environmental gradients. We replicated standardised tree inventories in 102 0.1-ha plots located in two distant regions - the western Amazon and the eastern Guiana shield. Within each region, we used a nested design to replicate plots on contrasted habitats: white-sand, terra firme, and seasonally-flooded forests. Our plot network encompassed 26386 trees that together represented 2745 distinct taxa, which we standardized across all plots and regions. We combined taxonomic and phylogenetic data with detailed soil measurements and climatic data to: (i) test whether patterns of taxonomic and phylogenetic composition are consistent with recent or historical processes, (ii) disentangle the relative effects of habitat, environment and geographic distance on taxonomic and phylogenetic turnover among plots, and (iii) contrast the proportion of habitat specialists among species from each region. We found substantial species turnover between Peru and French Guiana, with only 8.8% of species shared across regions; genus composition remained differentiated across habitats and regions, whereas turnover at higher taxonomic levels (family, order) was much lower. Species turnover across plots was explained primarily by regions but also substantially by habitat differences and to a lesser extent by spatial distance within regions. Conversely, the composition of higher taxonomic levels was better explained by habitats (especially comparing white-sand forests to other habitats) than spatial distance. White-sand forests harboured most of the habitat specialists in both regions, with stronger habitat specialization in Peru than in French Guiana. Our results suggest that recent diversification events have resulted in extremely high turnover in species and genus composition with relatively little change in the composition of higher lineages. Our results also emphasise the contributions of rare habitats, such as white-sand forests, to the extraordinary diversity of the Amazon and underline their importance as conservation priorities.

阐明历史过程、扩散作用与环境过滤对不同空间尺度下超高多样性群落构建的相对贡献，仍是当前生态学研究的核心挑战之一。本研究聚焦亚马孙树木类群，在大范围地理与环境梯度下，明确生物地理历史与生境特化在多大程度上驱动了类群内部与类群之间的群落物种更替。我们在两个相距甚远的区域——亚马孙西部与圭亚那盾地东部——共设置102块0.1公顷的标准样地，并开展标准化林木调查。在每个区域内，我们采用嵌套样地设计，在三类差异化生境中设置重复样地：白沙林、永久旱林与季节性淹水林。本次样地调查共记录26386株林木，隶属于2745个独立分类单元，所有数据均在全部样地与区域间完成标准化处理。本研究整合分类学与系统发育学数据，结合高精度土壤与气候观测数据，开展三项分析：(1) 检验分类与系统发育组成格局是否符合近期或历史生态过程的预期；(2) 解析生境、环境因子与地理距离对样地间分类与系统发育物种更替的相对影响强度；(3) 对比两个区域内物种的生境特化物种占比。研究结果显示，秘鲁与法属圭亚那之间存在显著的物种更替，两区仅共享8.8%的物种；属级组成在不同生境与区域间仍存在显著分化，而科级、目级等高级分类单元的物种更替程度则相对较低。样地间的物种更替主要由区域差异解释，其次为生境差异，区域内的空间距离仅能解释较小部分的变异。与之相反，高级分类单元的组成更易受生境差异（尤其是白沙林与其他生境的对比）而非区域内空间距离的影响。在两个区域中，白沙林均承载了绝大多数的生境特化物种，且秘鲁区域的生境特化程度显著高于法属圭亚那。本研究结果表明，近期的物种分化事件导致了物种与属级组成的极高更替率，而高级分类类群的组成则未发生显著变化。本研究同时强调了白沙林等稀有生境对亚马孙超高生物多样性的重要贡献，并凸显其作为优先保护对象的关键地位。