Estudo de populações de Schizolobium parahyba (Vell.) S.F. Blake (Leguminosae: Caesalpinoidae) para avaliação do seu potencial invasor

Abstract

Schizolobium parahyba (Vell.) S.F. Blake is a pioneer heliophyte species, with irregular and discontinuous dispersion. It is native and exclusive of Atlantic Rainforest, however, due to its high growth rate and to the shape of its crown, S. parahyba is recommended for forest restoration in areas of Tropical Semideciduous Forest. Currently, it has been questioned the use of this species in forest restoration. Considering that tree species that have 1) phenotypic plasticity and / or tolerance and 2) formation of persistent seed bank, are capable to keep stable populations in different environments, the hypothesis of this research is that S. parahyba can become invasive in Semideciduous Forest fragments. To test this hypothesis, we analyzed the morphology and growth form of the species in the Atlantic Rainforest and Semideciduous Forest, as well as ontogenetic and spatial structures present in both physiognomies. This dissertation is divided into four chapters. Firstly, I contextualize and justify this research. Then, I make a brief description of physiognomies studied, as well as a characterization of sampling sites. In Chapter 3, I compare the allometric relationships and architectural models for the different populations. Finally, in Chapter 4, I compare the ontogenetic and spatial structures for the species between different sampling sites in order to detect whether the species is able to establish stable populations in Semideciduous Forest. After evaluation of morphological characters, populations were divided into four ontogenetic stages: a) seedling, b) juvenile c) subadult, and d) adult. The evaluation of the architectural model of S. parahyba showed no difference in the morphology of the crown of individuals between biomes. The allometry analysis showed that there were differences between the growth patterns of S. parahyba between biomes for seedlings and for the pooled data; however, allometric relationships had no difference between adults. The total individuals abundance in Semideciduous Forest was lower than in the Rainforest. We found no single pattern of ontogenetic structure for the studied populations. There were found individuals of intermediate ontogenetic stages in Semideciduous Forest fragments. In all populations, S. parahyba was distributed in aggregates; however, it was also found scattered individuals within the fragment. The results indicate that S. parahyba shows tolerance and plasticity in response to environmental differences, which are important characteristics when assessing the status of an alien species. Finally, from the results obtained, it can be assumed that S. parahyba may become invasive in fragments of Semideciduous Forest.