百山祖自然保护区植物群落beta多样性

本文采用植物群落学的典型样方法,研究了百山祖自然保护区森林植物群落beta多样性格局及其维持机制。通过对45个20m?20m标准样地的调查数据进行分析,运用Chao’s群落距离指数衡量该植物群落beta多样性格局,并通过Mantel检验、基于距离矩阵的偏RDA分析和方差分解等方法初步检验和衡量了各环境因子差异（包括群落郁闭度、海拔、坡度、坡向和坡位）和群落空间距离对该区域beta多样性格局的影响。结果显示,该区域内植物群落beta多样性随着群落间综合环境差异或群落空间距离的增加而增大, 但环境差异和群落空间距离只能解释36%左右的beta多样性格局。检验的5个环境因子中,只有群落郁闭度和海拔对百山祖自然保护区植物群落beta多样性有显著影响,并且群落郁闭度对beta多样性的解释度（20.0%）略高于海拔对beta多样性的解释度（18.0%）。群落空间距离对百山祖自然保护区beta多样性的解释度最小（9.0%）。本文展现了百山祖自然保护区内植物群落beta多样性格局及其与群落环境和空间距离的关系,所获得的结果支持生境异质性和扩散限制联合对植物群落beta多样性起作用的假说。     

浙江遂昌马尾松林物种和谱系β多样性驱动因子分析

生境过滤和扩散限制是影响森林群落间物种组成差异(β多样性)的主要生态过程。为了探究生境过滤和扩散限制对亚热带马尾松(Pinus massoniana)群落物种和谱系β多样性的相对贡献,该文以浙江省遂昌县37个马尾松林样地为研究对象,结合物种和谱系β多样性分析,探讨了影响群落间物种组成差异主要生态机制; 通过计算群落内物种β多样性指数(Bray-Curtis指数)和谱系β多样性指数(Dnn指数和Dpw指数),分析土壤、地形等生境因子和地理距离与物种和谱系β多样性之间的相关性,并通过方差分解分析生境因子和地理距离对物种和谱系β多样性的相对作用大小; 此外,还进行了不同径级和生长型的上述相关性分析和方差分解。结果表明:(1)Bray-Curtis指数与土壤、地形因子和地理距离均显著正相关,Dnn指数仅与地理距离显著正相关,Dpw指数与土壤因子和地理距离均显著正相关。(2)环境因子对Bray-Curtis指数和Dpw指数的解释度均高于地理距离的解释度。(3)从物种多样性角度来说,生境因子对不同生长阶段Bray-Curtis指数的解释度均高于地理距离的解释度; 从谱系多样性角度来说,地理距离对幼树阶段的Dnn指数和Dpw指数的解释度更高,生境因子则对成树阶段的Dpw指数的解释度更高。由此可以推论,生境过滤是驱动该地区马尾松林物种和谱系β多样性的主要生态机制,扩散限制仅在幼树阶段对马尾松林谱系β多样性起主导作用。     

澳门城市栖息地斑块中鸟类群落功能和谱系多样性

了解群落构建过程是生态学的核心和基本问题,这对于解释物种共存和物种多样性的维持,完善生物多样性保护政策至关重要。与传统的物种多样性相比,功能和谱系多样性能够提供更多的信息,特别是在群落构建过程方面提供深刻见解。2014年5月—2017年1月,采用样线法对澳门地区5个城市栖息地斑块中(生态一区、鹭鸟林、赛马场滩涂、关闸口岸滩涂和莲花桥侧红树林)的鸟类进行繁殖季和越冬季的调查,共调查14次。利用鸟类丰富度和多度来表征群落的物种多样性,其中多度以最大值保留法计;功能和谱系多样性分别采用功能丰富度(functional richness:FRic)和Faith'PD。同时,利用基于多度加权的平均成对功能距离(mean pairwise functional distance,MFD)和平均成对谱系距离(mean pairwise phylogenetic distance,MPD)来表征群落的功能和谱系结构。结果表明:共记录98种鸟类,隶属于14目32科,目、科、种中数量最多的依次为,雀形目鸟类最多为47种,鹭科物种数为11种,白鹭多度为849只;鸟类物种丰富度(68种)和PD在生态一区最高,多度在莲花桥侧红树林最高为2940只,MFD和FRic在赛马场滩涂最高,MPD在生态一区最高;斑块面积在鸟类丰富度、多度、FRic和PD中具有普遍重要性,植被面积和滩涂面积则分别强烈影响着MFD和MPD;关闸口岸滩涂和莲花桥侧红树林的鸟类群落SES.MFD显著低于随机值(P <0. 05),鹭鸟林和赛马场滩涂的鸟类群落SES. MPD显著低于随机值(P<0.05),表明关闸口岸滩涂和莲花桥侧红树林鸟类群落功能聚集(functional clustering),可能与生境过滤驱动群落构建有关。栖息地斑块的特征差异导致了鸟类群落构建机制的不同,这是仅仅考虑物种多样性难以提供的信息,说明了研究群落构建机制时考虑多维度多样性的必要性。     

澳门城市栖息地斑块中鸟类群落功能和谱系多样性

了解群落构建过程是生态学的核心和基本问题,这对于解释物种共存和物种多样性的维持,完善生物多样性保护政策至关重要。与传统的物种多样性相比,功能和谱系多样性能够提供更多的信息,特别是在群落构建过程方面提供深刻见解。2014年5月—2017年1月,采用样线法对澳门地区5个城市栖息地斑块中(生态一区、鹭鸟林、赛马场滩涂、关闸口岸滩涂和莲花桥侧红树林)的鸟类进行繁殖季和越冬季的调查,共调查14次。利用鸟类丰富度和多度来表征群落的物种多样性,其中多度以最大值保留法计;功能和谱系多样性分别采用功能丰富度(functional richness:FRic)和Faith'PD。同时,利用基于多度加权的平均成对功能距离(mean pairwise functional distance,MFD)和平均成对谱系距离(mean pairwise phylogenetic distance,MPD)来表征群落的功能和谱系结构。结果表明:共记录98种鸟类,隶属于14目32科,目、科、种中数量最多的依次为,雀形目鸟类最多为47种,鹭科物种数为11种,白鹭多度为849只;鸟类物种丰富度(68种)和PD在生态一区最高,多度在莲花桥侧红树林最高为2940只,MFD和FRic在赛马场滩涂最高,MPD在生态一区最高;斑块面积在鸟类丰富度、多度、FRic和PD中具有普遍重要性,植被面积和滩涂面积则分别强烈影响着MFD和MPD;关闸口岸滩涂和莲花桥侧红树林的鸟类群落SES.MFD显著低于随机值(P 0. 05),鹭鸟林和赛马场滩涂的鸟类群落SES. MPD显著低于随机值(P0.05),表明关闸口岸滩涂和莲花桥侧红树林鸟类群落功能聚集(functional clustering),可能与生境过滤驱动群落构建有关。栖息地斑块的特征差异导致了鸟类群落构建机制的不同,这是仅仅考虑物种多样性难以提供的信息,说明了研究群落构建机制时考虑多维度多样性的必要性。     

芦芽山寒温性针叶林冠层下植被beta多样性格局及其成因

群落构建机制是生态学的中心议题之一。对山地植被beta多样性格局及其成因的探究有助于加深对此问题的认识。以芦芽山寒温性针叶林群落冠层下植被为研究对象,结合野外调查与室内实验获取的详细数据,运用Mantel检验、普通最小二乘回归和典范对应分析(CCA)等统计方法,探讨了林下植被的beta多样性格局及其成因,结果显示:(1)沿海拔梯度相邻群落间草本层物种周转率呈现递减格局,而灌木层变化规律不明显;(2)灌、草层beta多样性与海拔差异、地理距离呈显著正相关关系,而与局地环境异质性关系不显著。控制海拔作用后发现,灌、草层beta多样性与地理距离关系依然显著,而当消除地理距离的线性影响后,beta多样性与海拔关系也变得不显著(3)CCA模型中,环境因子共解释了物种组成变异的74.4%,其中,海拔、坡度、凋落物厚度、乔木密度与总干面积对林下灌、草植被物种组成具有显著影响,但土壤因子的作用未见显著。综上,生境筛滤与扩散限制共同主导了芦芽山寒温性针叶林冠层下群落构建过程,但扩散限制的影响强于生境筛滤作用。     

冰雪灾害前后的浙江古田山亚热带常绿阔叶林群落谱系结构变化

冰雪灾害是自然干扰的主要类型之一,为中高纬度地区森林群落更新的重要驱动因子.以往研究集中在冰雪灾害对群落动态的影响,鲜有分析冰雪灾害前后群落谱系结构的变化特点.本文以浙江省古田山国家级自然保护区内的亚热带常绿阔叶林作为研究对象,在2008年冰雪灾害前(2005年)和灾害后(2010年)分别进行了群落调查,并分别在3个粒度、4种地形生境和3个径级水平上分析了群落谱系结构在冰雪灾害前后的变化.研究发现,(ⅰ)在各个粒度、生境和径级水平上,灾后的群落净亲缘关系指数(net relatedness index, NRI)和净最近种间亲缘关系指数(net nearest taxa index, NTI)均明显高于灾前.(ⅱ)对灾前和灾后群落的植株存活进行随机模拟,并与其观测值进行比较发现,除3个径级以及2种生境的最近谱系距离(mean nearest taxon distance, MNTD)无明显差异外,其他情况下的MNTD以及所有情况下平均谱系距离(mean phylogenetic distance, MPD)的随机模拟期望值均显著大于观测值.以上结果表明,冰雪灾害后的群落谱系结构在各个空间粒度、森林垂直层次和生境中均变得更加聚集.本研究对于了解冰雪灾害干扰对于亚热带常绿阔叶林群落构建的影响,具有重要理论价值.     

海南尖峰岭热带山地雨林林冠层树种功能多样性特征

以海南尖峰岭热带山地雨林3块1 hm²样地为研究对象,利用11个林冠功能性状结合样地地形及林冠乔木树种样地清查数据,分别基于单维性状和多维性状比较物种多度加权对群落功能离散度指数——平均成对距离(MPD)和平均最近类群距离(MNTD)的影响;同时分析林冠层功能丰富度(FRic)与物种丰富度之间的关系,最后利用零模型探讨不同生境类型下标准化效应MPD和MNTD(经过物种多度加权且剔除群落物种丰富度差异影响)的变化,进而评价林冠层群落水平功能多样性格局及其对局域生境异质性的响应.结果表明: 功能性状维度和物种多度对MPD的影响强烈,不同维度功能性状多度加权前后MPD相关性较弱(R=0.359～0.628);但对MNTD的影响相对较弱,不同维度功能性状多度加权前后MNTD相关性较强(R=0.746～0.820);未经物种多度加权的MPD和MNTD均普遍高估了林冠层的功能离散度.林冠层功能丰富度与物种丰富度基本呈指数相关关系(F=128.20;R²=0.632;AIC=97.72;P＜0.001),且功能丰富度很有可能存在一定的物种丰富度阈值.基于不同维度功能性状的林冠层功能多样性格局及其生境响应存在一定的差异性.在生物竞争激烈的低沟生境中,林冠层功能多样性倾向于比预期零模型随机产生的功能多样性高,林冠树种功能性状表现出离散分布;而在其他生境类型中,林冠层功能多样性倾向于接近或低于随机产生的功能多样性,林冠树种功能性状随机或聚集分布.     

哀牢山亚热带中山湿性常绿阔叶林树种beta多样性格局形成的驱动力

Beta多样性通常指群落在时间和空间上物种组成的差异, 包括物种周转组分和物种丰富度差异组分。驱动beta多样性格局形成的生态过程决定了群落的时空动态, 然而关于beta多样性及其两个组分格局形成的驱动力还存在较多争议。以往研究表明, beta多样性的格局存在取样尺度的依赖性, 驱动其形成的生态过程在不同取样尺度下的相对重要性也随之改变。本研究以哀牢山亚热带中山湿性常绿阔叶林20 ha动态监测样地为研究对象, 在不同取样尺度上, 将样方间的Bray-Curtis指数分解为物种周转组分和物种丰富度差异组分, 通过典范冗余分析和方差分解的方法揭示环境过滤和扩散限制对于beta多样性及其两个组分格局形成的相对重要性及其尺度依赖性。结果表明: (1) beta多样性、物种周转组分和物种丰富度差异组分均随取样尺度的增大而减小。在不同取样尺度下, 物种周转组分对于beta多样性的贡献始终占主导地位。(2)随着取样尺度的增大, 环境过滤驱动beta多样性格局形成的相对重要性逐渐增加, 而扩散限制的相对重要性逐渐降低。本研究进一步证实了取样尺度在beta多样性格局形成及其驱动力定量评价中的重要性, 今后的研究需要进一步解析上述尺度效应的形成机制。     

海南岛3个林区热带云雾林植物多样性变化

以分布在海南岛西部(霸王岭国家级自然保护区, 21个样方)、西南部(尖峰岭国家级自然保护区, 12个样方)和中部(黎母山省级自然保护区, 15个样方)的热带云雾林为研究对象, 研究α及β物种多样性、功能多样性、谱系多样性的变化, 为植物多样性的保护提供科学依据。结果表明: 尖峰岭群落树木个体多度、物种丰富度最大, 黎母山群落树木个体多度、物种丰富度最小; 黎母山群落间物种组成差异最大, 霸王岭群落间物种组成差异最小, 海南岛霸王岭(西部)、尖峰岭(西南部)和黎母山(中部) 3个林区热带云雾林物种多样性差异可能与空气温度和相对湿度有关。尖峰岭群落内功能丰富度、Rao’s二次熵最低, 功能均匀度最高, 群落间平均成对性状距离最小, 反映群落构建主要受环境筛影响; 霸王岭群落Rao’s二次熵最高, 功能均匀度最低, 群落间平均成对性状距离最大, 反映群落构建主要受限制相似性影响; 黎母山群落内功能丰富度最高, 群落间平均最近性状距离最大, 表明限制相似性在黎母山热带云雾林群落构建中的作用更重要。霸王岭群落内谱系多样性、物种间平均最近相邻谱系距离均较大, 反映物种间谱系关系趋于发散; 黎母山群落内谱系多样性、物种间平均成对谱系距离及群落间平均成对谱系距离均最小, 反映物种间谱系关系趋于聚集; 而尖峰岭群落内物种间平均成对谱系距离、群落间平均成对谱系距离最大, 但物种间平均最近相邻谱系距离最小, 反映物种间谱系关系既具有发散又具有聚集的共存格局。因此, 海南岛热带云雾林群落植物多样性变化格局与环境及物种间相互作用有关。     

元江流域干热河谷灌草丛土壤种子库与地上植物群落的物种组成比较

土壤种子库与地上植被之间的关系和相似性是长期争议的群落生态学问题之一。本研究旨在通过比较元江流域干热河谷典型灌草丛群落与其土壤种子库的物种组成, 探讨土壤种子库与地上植物群落存在怎样的相似性关系。在元江干热河谷上、中、下游选取典型灌草丛群落, 采用典型样地调查法进行植物群落调查, 同时在样方内采集0-5 cm、5-10 cm、10-15 cm三层土壤样品, 采用萌发实验研究土壤种子库的种子数量和物种组成, 并与地上植物群落进行比较。结果表明: (1)全部调查样方的地上植被中共包含种子植物76种, 隶属于25科64属, 主要集中在豆科、禾本科、菊科、大戟科, 群落物种组成以多年生草本为主、灌木为辅; (2)土壤种子库中共发现33种植物, 隶属于14科32属, 以旱生型禾本科、豆科、菊科物种为主; (3)土壤种子库中的植物种子密度在表层土壤中最高, 随着土层的加深而递减; (4)各样方的土壤种子库与地上群落共有物种数较少, 相似性较低; 土壤种子库密度与地上群落的种群密度没有显著的相关性。总体而言, 本研究发现元江流域干热河谷典型灌草丛群落其土壤种子库与地上群落之间没有显著的相关性, 并且地上群落和土壤种子库都有外来入侵种类。     

The hypothesis of sympatric speciation as the dominant generator of endemism in a global hotspot of biodiversity

Allopatric or sympatric speciation influence the degree to which closely related species coexist in different manners, altering the patterns of phylogenetic structure and turnover among and between communities. The objective of this study was to examine whether phylogenetic community structure and turnover in the Brazilian Atlantic Forest permit conclusions about the dominant process for the formation of extant angiosperm richness of tree species. Therefore, we analyzed phylogenetic community structure (MPD, MNTD) as well as taxonomic (Jaccard similarity) and phylogenetic turnover (betaMPD, betaMNTD) among and between 49 tree communities distributed among three different habitat types. Mean annual precipitation and mean annual temperature in each survey area were estimated. Phylogenetic community structure does not differ between habitat types, although MPD reduces with mean annual temperature. Jaccard similarity decreases and betaMNTD increases with spatial distance and environmental differences between study sites. Spatial distance explains the largest portions of variance in the data, indicating dispersal limitation and the spatial aggregation of recently formed taxa, as betaMNTD is related to more recent evolutionary events. betaMPD, that is related to deep evolutionary splits, shows no spatial or environmental pattern, indicating that older clades are equally distributed across the Brazilian Atlantic Forest. While similarity pattern indicates dispersal limitations, the spatial turnover of betaMNTD is consistent with a high degree of sympatric speciation generating extant diversity and endemism in the Brazilian Atlantic Forest. More comprehensive approaches are necessary to reduce spatial sampling bias, uncertainties regarding angiosperm diversification patterns and confirm sympatric speciation as the dominant generator for the formation of extant species diversity in the Brazilian Atlantic Forest.     

The influence of biogeographic history on the functional and phylogenetic diversity of passerine birds in savannas and forests of the Brazilian Amazon

Passeriformes is the largest and most diverse avian order in the world and comprises the Passeri and Tyranni suborders. These suborders constitute a monophyletic group, but differ in their ecology and history of occupation of South America. We investigated the influence of biogeographic history on functional and phylogenetic diversities of Passeri and Tyranni in forest and savanna habitats in the Brazilian Amazon. We compiled species composition data for 34 Passeriformes assemblages, 12 in savannas and 22 in forests. We calculated the functional (Rao's quadratic entropy, FD_Q) and phylogenetic diversities (mean pairwise distance, MPD, and mean nearest taxon distance, MNTD), and the functional beta diversity to investigate the potential role of biogeographic history in shaping ecological traits and species lineages of both suborders. The functional diversity of Passeri was higher than for Tyranni in both habitats. The MPD for Tyranni was higher than for Passeri in forests; however, there was no difference between the suborders in savannas. In savannas, Passeri presented higher MNTD than Tyranni, while in forest areas, Tyranni assemblages showed higher MNTD than Passeri. We found a high functional turnover (~75%) between Passeri and Tyranni in both habitats. The high functional diversity of Passeri in both habitats is due to the high diversity of ecological traits exhibited by species of this group, which enables the exploitation of a wide variety of resources and foraging strategies. The higher Tyranni MPD and MNTD in forests is likely due to Tyranni being older settlers in this habitat, resulting in the emergence and persistence of more lineages. The higher Passeri MNTD in savannas can be explained by the existence of a larger number of different Passeri lineages adapted to this severe habitat. The high functional turnover between the suborders in both habitats suggests an ecological strategy to avoid niche overlap.     

元江干热河谷主要环境因子(气温和降水)变化规律及蕨类植物的分布响应

为了解蕨类植物多样性及种群分布对环境因子的响应,建立元江干热河谷不同海拔气温和降水的分布模式,对蕨类植物在元江干热河谷内的自然分布进行了研究。结果表明,元江干热河谷从低海拔到高海拔,气温逐渐下降,但降水量却逐渐增加;河谷内蕨类植物多样性及种群分布呈现差异化;干热河谷内蕨类分布受气温影响不大,但与生境水分条件密切相关。元江干热河谷水热条件分布不均,生态环境破碎,气温和降水分布不均,差异化显著,促进了小生境发育。蕨类植物可以指示生态环境的完整性和连续性,某些种群可以指示和监测环境因子尤其是水因子的变化。     

Climate and geographic distance are more influential than rivers on the beta diversity of passerine birds in Amazonia

Variation in the spatial structure of communities in terms of species composition (beta diversity) is affected by different ecological processes, such as environmental filtering and dispersal limitation. Large rivers are known as barriers for species dispersal (riverine hypothesis) in tropical regions. However, when organisms are not dispersal limited by geographic barriers, other factors, such as climatic conditions and geographic distance per se, may affect species distribution. In order to investigate the relative contribution of major rivers, climate and geographic distance on Passeriformes beta diversity, we divided Amazonia into 549 grid cells (1° of latitude and longitude) and obtained data of species occurrence, climate and geographic position for each cell. Beta diversity was measured using taxonomic, phylogenetic and functional metrics of composition. The influence of climatic variables, geographic distance and rivers on these metrics was tested using regression analyses. Passerine beta diversity is characterized mainly by the change in species taxonomic identity and in phylogenetic lineages across climatic gradients and over geographic distance. However, species with similar traits are found throughout the entire Amazonia. The size of rivers was proportional to their effect on species composition. However, climate and geographic distance are relatively more important than rivers for Amazonian taxonomic and phylogenetic species composition.     

Phylogenetic alpha and beta diversity in tropical tree assemblages along regional-scale environmental gradients in northwest South America

Aims Environmental gradients are drivers of species diversity; however, we know relatively little about the evolutionary processes underlying these relationships. A potentially powerful approach to studying diversity gradients is to quantify the phylogenetic structure within and between assemblages arrayed along broad spatial and environmental gradients. Here, we evaluate the phylogenetic structure of plant assemblages along an environmental gradient with the expectation that the habitat specialization of entire lineages is an important evolutionary pattern influencing the structure of tree communities along environmental gradients.Methods We evaluated the effect of several environmental variables on the phylogenetic structure of plant assemblages in 145 plots distributed in northwestern South America that cover a broad environmental gradient. The phylogenetic alpha diversity was quantified for each plot and the phylogenetic beta diversity between each pair of plots was also quantified. Both the alpha and beta diversity measures were then related to spatial and environmental gradients in the study system.Important findings We found that gradients in temperature and potential evapotranspiration have a strong relationship with the phylogenetic alpha diversity in our study system, with phylogenetic overdispersion in low temperatures and phylogenetic clustering at higher temperatures. Further, the phylogenetic beta diversity between two plots increases with an increasing difference in temperature, whereas annual precipitation was not a significant predictor of community phylogenetic turnover. We also found that the phylogenetic structure of the plots in our study system was related to the degree of seasonal flooding and seasonality in precipitation. In particular, more stressful environments such as dry forests and flooded forests showed phylogenetic clustering. Finally, in contrast with previous studies, we find that phylogenetic beta diversity was not strongly related to the spatial distance separating two forest plots, which may be the result of the importance of the three independent mountain ranges in our study system, which generate a high degree of environmental variation over very short distances. In conclusion, we found that environmental gradients are important drivers of both phylogenetic alpha and phylogenetic beta diversities in these forests over spatial distance.     

元江干热河谷植被数量分类及其多样性分析

基于43个代表性样地调查资料,用系统聚类方法中的离差平方和法将元江干热河谷的主要植被分为7个群落类型, 并采用Gleason物种丰富度指数、Simpson多样性指数和 Shannon Weiner多样性指数以及Pielou均匀度指数比较了各群落的物种多样性特征。结果表明:不同群落之间的物种多样性存在着明显的差异,这些差异与群落的分布地点、小生境有密切关系。     

Phylogenetic diversity and community assembly in a naturally fragmented system

We sought to assess effects of fragmentation and quantify the contribution of ecological processes to community assembly by measuring species richness, phylogenetic, and phenotypic diversity of species found in local and regional plant communities. Specifically, our fragmented system is Craters of the Moon National Monument and Preserve, Idaho, USA. CRMO is characterized by vegetated islands, kipukas, that are isolated in a matrix of lava. We used floristic surveys of vascular plants in 19 kipukas to create a local species list to compare traditional dispersion metrics, mean pairwise distance, and mean nearest taxon distance (MPD and MNTD), to a regional species list with phenotypic and phylogenetic data. We combined phylogenetic and functional trait data in a novel machine‐learning model selection approach, Community Assembly Model Inference (CAMI), to infer probability associated with different models of community assembly given the data. Finally, we used linear regression to explore whether the geography of kipukas explained estimated support for community assembly models. Using traditional metrics of MPD and MNTD neutral processes received the most support when comparing kipuka species to regional species. Individually no kipukas showed significant support for overdispersion. Rather, five kipukas showed significant support for phylogenetic clustering using MPD and two kipukas using MNTD. Using CAMI, we inferred neutral and filtering models structured the kipuka plant community for our trait of interest. Finally, we found as species richness in kipukas increases, model support for competition decreases and lower elevation kipukas show more support for habitat filtering models. While traditional phylogenetic community approaches suggest neutral assembly dynamics, recently developed approaches utilizing machine learning and model choice revealed joint influences of assembly processes to form the kipuka plant communities. Understanding ecological processes at play in naturally fragmented systems will aid in guiding our understanding of how fragmentation impacts future changes in landscapes.     

Phylogenetic community structure and phylogenetic turnover across space and edaphic gradients in western Amazonian tree communities

Ecological and evolutionary processes influence community assembly at both local and regional scales. Adding a phylogenetic dimension to studies of species turnover allows tests of the extent to which environmental gradients, geographic distance and the historical biogeography of lineages have influenced speciation and dispersal of species throughout a region. We compare measures of beta diversity, phylogenetic community structure and phylobetadiversity (phylogenetic distance among communities) in 34 plots of Amazonian trees across white‐sand and clay terra firme forests in a 60 000 square kilometer area in Loreto, Peru. Dominant taxa in white‐sand forests were phylogenetically clustered, consistent with environmental filtering of conserved traits. Phylobetadiversity measures found significant phylogenetic clustering between terra firme communities separated by geographic distances of <200–300 km, consistent within recent local speciation at the watershed scale in the Miocene‐aged clay‐soil forests near the foothills of the Andes. Although both distance and habitat type yielded statistically significant effects on both species and phylogenetic turnover, the patterns we observed were more consistent with an effect of habitat specialization than dispersal limitation. Our results suggest a role for both broad‐scale biogeographic and evolutionary processes, as well as habitat specialization, influencing community structure in Amazonian forests.