Efeito de clareiras na dinâmica populacional de espécies arbóreas em floresta manejada no município de Moju-Pará.

Abstract

The analyzes of the behavior of the species according to the size of the gap, the center and the border and the cardinal directions within the range of the gap allow to infer the most suitable place within the forest where the tree species presents acceptable development. This context led to the following scientific question: does the amount of solar radiation influence the selfdevelopment of tree species? Thus, the hypotheses will be tested: size, cardinal direction and the different distances of the center of the gap allow differences in the development of populations. The following species were selected: Sterculia pruriens (Aubl.) K. Schum, Tachigali paniculata Aubl. e Eschweilera ovata (Cambess.) Miers. The overall objective of the study was to evaluate the dynamics of the populations of three tree species during 12 years in a managed forest that will be approached in the form of two articles within this research: the first one is about the population dynamics of tree species under the Effect of gaps and the second on the Dynamics of diameter growth of tree species after the forest exploitation. The study area is located in the experimental field of Embrapa Amazônia Oriental, in the municipality of Moju. In this area, selective exploration was carried out and nine gaps were used in the research. In each gap were installed plots of 10 m x 50 m. With data collected between 1998 and 2010, mortality, recruitment, natural regeneration and diametric growth were calculated. These parameters were related to the sizes of the gaps, the cardinal directions and the distance from the center of the gap. The Tukey test results show that the tree species presented better behavior in the medium gaps. Regarding the cardinal directions, only S. pruriens benefited from the greater amount of radiation available in the eastern direction. T. paniculata presented better initial behavior in the north direction, but, at the end of the monitoring in that direction, the microclimatic conditions were not beneficial. E. ovata did not depend on the incident light in different cardinal directions for its development. The distances from the center of the gap did not affect the dynamics of T. paniculata and E. ovata. The distance of 40 meters was adequate for germination and development of S. pruriens. In addition, the size, direction and distance of the gaps caused significant changes in the diametric growth of T. paniculata. The growth in diameter of S. pruriens is higher in medium gaps and at a median distance from the center of the gap. The difference between the sizes, directions and the distances of the gaps did not imply dynamics in the diametric growth of T. paniculata. All species are affected by canopy closure over the years. Thus, the dynamics of diametric growth of T. paniculata was more affected by the forest exploitation in the area than the population dynamics. The species S. pruriens presented better development and diametric growth in places in the gap where the light intensity was medium. The population dynamics and the diametric growth of E. ovata do not depend on the opening of gaps in the area.