Study of ecological filters involved in the colonization of riparian forests undergoing restoration by tree species from the regional pool

Abstract

The self-sustainability of tropical forests undergoing restoration depends, among other factors, on their colonization by species from the regional species pool, which is represented by fragments of the preexisting vegetation. Colonization is the result of dispersal of propagules combined to the establishment of seedlings, which are key processes driving the future composition of the restored ecosystems. However, recent studies have shown that not all species from the regional pool can colonize areas under restoration if they have not been planted. The proposed research aims to identify the factors that hinder or facilitate colonization, based upon the functional attributes of tree species that are related to the processes of dispersal and establishment. For this analysis we will use data from previous surveys conducted in 26 forests undergoing restoration and nine fragments of natural forests in the region of Semideciduous Atlantic Forest (SP, PR and MS ) in a radius of approximately 350 km. We will comparatively analyze the frequency of occurrence of attributes in three sets of species: 1) set of all species in the regional pool (from which we will obtain the expected frequency for each attribute if there are no filters - null hypothesis), 2) number of species able to colonize areas being restored, and 3) set of species unable to colonize the areas undergoing restoration. For those species colonizing only part of the areas being restored, we will investigate the thresholds for dispersal or establishment (e.g. distance and size of the closest seed source, seed mass and time since restoration). The study has the potential to elucidate scientific issues relevant to Restoration Ecology of tropical forests. At the same time, we hope to contribute to the improvement of restoration actions, if a functional pattern can be identified for those species that will never naturally colonize the communities being restored or for those thresholds must be surpassed and, therefore, depend on planting.