Abstract

PENA, Miguel A.; CARDENAS, Dairon  and  DUQUE, Álvaro. SPECIES DISTRIBUTIONS AND THEIR RELATIONSHIP TO ENVIRONMENTAL AND SPATIAL VARIATION AT A LOCAL SCALE IN A TERRA FIRME FOREST IN THE COLOMBIAN AMAZONIA. Actu Biol [online]. 2010, vol.32, n.92, pp.41-51. ISSN 0304-3584.

In this study, we analyzed the extent to which environmental variation and the spatial template influenced the distribution of individual canopy species (DBH ≥ 10 cm) at a local scale in terra firme forest in the Colombian Amazonia. The survey was carried out in a 5-ha plot, divided into 125 quadrants of 20 m x 20 m, located in the Amacayacu National Park. To run the analyses we selected all species with presence in ten or more quadrants. In order to quantify the effect of the environment and geographical space, we used a logistic regression model, which was based on species presence-absence data for the selected species. Species distributions showed a higher correlation with the spatial variables than with the environmental ones, with an average of 50.7 ± 23.8% of unexplained variation remaining. Environmental variables were significant in 33 out of 45 models, ranging in relative importance between 0.21 and 23.71%. All explanatory models of species distributions included spatial variables, which reached a relative importance of up to 97.3%. We found differences in the factors determining the distribution of individual species within the same family and even within the same genera, which helped to understand the key factors structuring alpha diversity. In this way, our results support the idea that environmental filtering and spatially structured processes, such us dispersal limitation, are complementary rather than exclusive mechanisms promoting species coexistence. The results obtained in this study showed a relatively lower importance of soils and topography on species distribution, at a local spatial scale, than reported before. In this case study, we found a high random component related to the unexplained variation; however, it was also necessary to emphasize the effect of species undersampling on the unexplained variation, due to the high local diversity recorded in this forest.

Keywords : Amacayacu Natural National Park; Colombia; conservation; dispersal limitation; environmental filtering; logistic regression.

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