■基于功能特征的方法被广泛应用于沿环境梯度控制社区组装的机制研究。这些方法经典地基于研究物种之间的平均值差异,但是越来越多的人认识到,应该考虑性状分布的替代指标来破译决定群落组装和物种共存的机制。在这个框架下,这项研究的主要目的是揭示环境条件作为地中海次生态区植物群落聚集驱动因素的影响。
■我们在西班牙中部地中海下森林的六个植物群落中设置了60个地块,并测量了属于19个物种的411个个体的主要地上和地下功能特征,以及非生物变量。我们计算了社区加权平均值(CWM),三个植物维度的偏度(CWS)和峰度(CWK),并使用最大似然技术来分析这些功能性群落性状的变异是如何由非生物因素驱动的。此外,我们估计了种内性状变异性和物种周转对CWM变异的相对贡献。
■主成分分析的前三个变化轴与三个主要植物生态维度有关:叶经济学谱,根经济学谱和植物水力建筑,分别。群落类型是决定群落功能结构差异的最重要因素,与非生物变量的作用相比。我们发现社区中CWM的巨大差异与其生物地理起源(欧洲西伯利亚vs地中海)一致,虽然CWS和CWK的差异表明社区之间功能结构的趋势不同,并且不同的功能策略并存,分别。此外,功能组成的变化主要是由于种内变异性。
■我们在森林中观察到了大量的策略,不同的群落沿着资源利用的获取-保守轴传播,部分匹配他们的欧洲西伯利亚-地中海性质,分别。种内性状变异性,而不是物种周转,在分析社区之间的功能变化和组装模式时,是最相关的因素。总之,我们的数据支持这样的观点,即过渡带是生态系统,相对较小的环境变化可能导致植物和功能组成的变化。
UNASSIGNED: Functional trait-based approaches are extensively applied to the study of mechanisms governing community assembly along environmental gradients. These approaches have been classically based on studying differences in mean values among species, but there is increasing recognition that alternative metrics of trait distributions should be considered to decipher the mechanisms determining community assembly and species coexistence. Under this framework, the main aim of this study is to unravel the effects of environmental conditions as drivers of plant community assembly in sub-Mediterranean ecotones.
UNASSIGNED: We set 60 plots in six plant communities of a sub-Mediterranean forest in Central Spain, and measured key above- and belowground functional traits in 411 individuals belonging to 19 species, along with abiotic variables. We calculated community-weighted mean (CWM), skewness (CWS) and kurtosis (CWK) of three plant dimensions, and used maximum likelihood techniques to analyze how variation in these functional community traits was driven by abiotic factors. Additionally, we estimated the relative contribution of intraspecific trait variability and species turnover to variation in CWM.
UNASSIGNED: The first three axes of variation of the principal component analyses were related to three main plant ecological dimensions: Leaf Economics Spectrum, Root Economics Spectrum and plant hydraulic architecture, respectively. Type of community was the most important factor determining differences in the functional structure among communities, as compared to the role of abiotic variables. We found strong differences among communities in their CWMs in line with their biogeographic origin (Eurosiberian vs Mediterranean), while differences in CWS and CWK indicate different trends in the functional structure among communities and the coexistence of different functional strategies, respectively. Moreover, changes in functional composition were primarily due to intraspecific variability.
UNASSIGNED: We observed a high number of strategies in the forest with the different communities spreading along the acquisitive-conservative axis of resource-use, partly matching their Eurosiberian-Mediterranean nature, respectively. Intraspecific trait variability, rather than species turnover, stood as the most relevant factor when analyzing functional changes and assembly patterns among communities. Altogether, our data support the notion that ecotones are ecosystems where relatively minor environmental shifts may result in changes in plant and functional composition.