The relative importance of dispersal limitation and habitat preference in shaping spatial distribution of saplings in a tropical moist forest: a case study along a combination of hydromorphic and canopy disturbance gradients

Introduction Various processes contribute to shaping the local assemblage of species in hyperdiverse tropical forest. The relative contribution of environmental factors and dispersal limitation in determining the spatial distribution of saplings at local scale is unclear. & Methods We examined two types of environmental factors: (a) soil type reflecting drainage regime and (b) past logging damages reflecting light regime in a neotropical moist forest site. We used a logistic model to predict presence or absence of a given species in a network of elementary small plots. & Results The effect of mapped environmental factors and a spatial correlation term were jointly estimated providing a direct measure of the relative role of habitat specialisation and dispersal limitation. At community level, dispersal limitation was the most important determinant of species absence at local scale. The two environmental factors examined played a balanced role. Different species however showed different degrees of dispersal limitation and habitat specialisation. The distribution of a large proportion of species-the majority of the most abundant species-was significantly affected by at least one environmental factor. We provide a ranking of 49 species sensitive to canopy disturbance (from shade specialist to pioneer) and 41 species affected by seasonal flooding (either positively or negatively). (Résumé d'auteur