Positive relationship between seedlings and saplings with adult trees at small scale influenced by dispersal vectors in semiarid thornscrub

Abstract

Seed dispersal is a process that can drive the spatial distribution of the community and subsequent plant-to-plant interaction and the study of these processes provides information for biodiversity management. Seed dispersal has been scarcely studied for Tamaulipan thornscrub, but dispersal syndromes based on fruit and seed characteristics are helpful to predict sites of seed deposition. In the present work, we determine the spatial relationships between seedlings and saplings around adult trees with different dispersal syndromes and infer the interactions through the community with spatial point pattern analysis using univariate and bivariate pair correlation functions, as well as multivariate Spatially explicit Simpson index β(r) and Individual species-area relationship (ISAR). We found a clustered distribution pattern of animal-dispersed seedlings and saplings at 1 m around adult trees, regardless of the dispersal syndrome. We also observed a repulsion of these seedlings at 7-9 m from the stems. Non-animal dispersed adult trees, seedlings, and saplings exhibited a random distribution. Species with animal dispersal syndrome are clumped and have mainly interspecific interactions at a small scale. Using dispersal syndromes, our findings illustrate the influence that seed dispersion might have on the spatial organization and intra- and interspecific interactions of species of Tamaulipan thornscrub.

Keywords:
Acacia; dispersal syndrome; point pattern analysis; Prosopis; seedling; thornscrub