Distance-decay differs among vertical strata in a tropical rainforest

1. Assemblage similarity decays with geographic distance—a pattern known as the distance-decay relationship. While this pattern has been investigated for a wide range of organisms, ecosystems, and geographical gradients, whether these changes vary more cryptically across different forest strata (from ground to canopy) remains elusive. 2. Here, we investigated the influence of ground vs arboreal assemblages to the general distance-decay relationship observed in forests. We seek to explain differences in distance-decay relationships between strata in the context of the vertical stratification of assemblage composition, richness, and abundance. 3. We surveyed for a climate sensitive model organism, amphibians, across vertical rainforest strata in Madagascar. For each tree, we defined assemblages of ground-dwelling, understory, or canopy species. We calculated horizontal distance-decay in similarity across all trees, and across assemblages of species found in different forest strata (ground...

1. 集合群落（assemblage）相似性随地理距离增加而衰减，这一规律被称为距离衰减关系（distance-decay relationship）。尽管该规律已在诸多类群、生态系统及地理梯度中得到研究，但不同森林层位（从地表到冠层）间的变化是否更为隐晦，目前仍不明确。
2. 本研究针对森林中普遍观测到的距离衰减关系，探究了地表群落与树栖集合群落对其的影响。我们旨在从集合群落组成、物种丰富度及个体多度的垂直分层视角，阐释不同层位间距离衰减关系的差异。
3. 我们以对气候敏感的模式生物两栖动物为研究对象，在马达加斯加的热带雨林中开展了垂直层位调查。针对每一株树木，我们分别划定了地表栖居、林下或冠层的物种种群集合。我们计算了所有树木间相似性的水平距离衰减效应，以及不同森林层位（地表……）中集合群落的相似性水平距离衰减。