To evaluate to what extent effects of environmental heterogeneity and geographic distance determine beta-diversity of woody communities within and among vegetation types at a basin spatial scale. The importance of two components of beta-diversity (nestedness and replacement) were also assessed. Location: Cuitzeo basin, central Mexico. The Cuitzeo basin (ca. 4000 km²) encompasses different vegetation types, among which tropical shrubland, oak forest, and oak–coniferous forest are the most important. We sampled 49 sites (0.1 ha each) across these three vegetation types. All shrubs and trees with diameter at breast height (dbh) ≥ 2.5 cm were recorded and taxonomically identified. Evidence of distance decay model (DDM) was assessed through exponential regressions of Bray–Curtis (measured with basal area) and Sørensen (measured with presence–absence) similarities as function of geographic and environmental distances among sites. Mantel analyses were performed in order to evaluate the influence of distances on similarity values. Exponential decay models of nestedness and replacement as function of distances were evaluated. Evidence supporting DDM was found, but the statistical strength depended on the vegetation type, the variable used to quantify distance, and the way similarity (BC) was measured. Overall, the effect of environmental distance variables was relatively stronger than geographic distance, suggesting that niche-related processes might be more important across the Cuitzeo basin. There is evidence that environmental heterogeneity has a greater importance on beta-diversity of woody communities within the studied basin than geographic distance. We discuss that niche scale processes are causing this result.

为了评估环境异质性和地理距离的影响程度在多大程度上决定了盆地空间尺度上植被类型内部和之中的木质群落的β多样性。还评估了β多样性的两个组成部分（嵌套和替代）的重要性。地点：墨西哥中部Cuitzeo盆地。Cuitzeo盆地（约4000 km ²）涵盖了不同的植被类型，其中最重要的是热带灌木林，橡树林和橡针叶林。我们在这三种植被类型中采样了49个地点（每个地点0.1公顷）。记录所有灌木和树木，它们的胸径（dbh）≥2.5厘米，直径并分类。距离衰减模型（DDM）的证据是通过Bray–Curtis（以基础面积衡量）和Sørensen（以存在或不存在衡量）相似性随站点之间地理和环境距离的函数进行指数回归而评估的。为了评估距离对相似度值的影响，进行了壁炉架分析。嵌套和替换的指数衰减模型作为距离的函数进行了评估。找到支持DDM的证据，测量BC。总体而言，环境距离变量的影响相对强于地理距离，这表明在整个Cuitzeo盆地，与生态位有关的过程可能更为重要。有证据表明，环境异质性对研究盆地内木本群落的β多样性比地理距离具有更大的重要性。我们讨论了利基规模过程导致此结果。