Functional traits and community composition: a comparison among community-weighted means, weighted correlations, and multilevel models

1. Of the several approaches that are used to analyze functional trait-environment relationships, the most popular is community-weighted mean regressions (CWMr) in which species trait values are averaged at the site level and then regressed against environmental variables. Other approaches include model-based methods and weighted correlations of different metrics of trait-environment associations, the best known of which is the fourth-corner correlation method.
2. We investigated these three general statistical approaches for trait-environment associations: CWMr, five weighted correlation metrics (Peres-Neto et al. 2017), and two multilevel models (MLM) using four different methods for computing p-values. We first compared the methods applied to a plant community dataset. To determine the validity of the statistical conclusions, we then performed a simulation study.
3. CWMr gave highly significant associations for both traits, while the other methods gave a mix of support. CWMr had i...

1. 在解析功能性状与环境关联的各类分析方法中，应用最为普遍的是群落加权平均回归（community-weighted mean regressions, CWMr）：该方法首先在样地水平上对物种性状值求均值，随后将其与环境变量进行回归分析。其他方法涵盖基于模型的分析手段，以及针对不同性状-环境关联度量指标的加权相关分析，其中最广为人知的当属第四角相关法（fourth-corner correlation method）。
2. 本研究系统考察了三类用于性状-环境关联分析的通用统计方法：一是CWMr，二是5种加权相关度量指标（Peres-Neto等，2017），三是采用4种不同p值计算方法的2种多层模型（multilevel models, MLM）。我们首先将这些方法应用于植物群落数据集开展对比分析；为验证统计结论的可靠性，随后又进行了模拟研究。
3. CWMr对两类性状均得到了极显著的关联结果，而其余方法的支持度则参差不齐。CWMr具备……