Estudo da dispersão de sementes, banco de sementes e regeneração natural de três espécies arbóreas da caatinga.

Abstract

Studies on the pattern of seed dispersion, seed bank and natural regeneration are fundamental for the understanding of forest structure and species distribution of an area. Although the selected tree species considered in this study (Amburana cearensis, Myracrodruon urundeuva, and Handroanthus impetiginosus) are components of the caatinga forest that show high potential for wood production, their ecological behavior is not clearly determined. This study has the objective to evaluate the natural regeneration of these three tree species in a preserved caatinga forest, specifically their seed production and seed dispersion patterns, seed bank before and after seed dispersion, survival of plantules germinated during the raining season of two consecutive years and stratification. The study was divided in three phases. The first consisted of tree selection, point location, litter collection just after seed dispersion and greenhouse experiment. During the second phase, seed germination and plantule development were monitored. In the last one, counting and diameter and height measurements were performed. Seed dispersion showed to be stronger to the northern, western, and northern portion under the canopy of the A. cearencis, M. urundeuva and H. impetiginosus seed producer trees, respectively, probably due to the wind observed locally and at the period of seed dispersion. Germination begun promptly and more than 75% of the plantules germinated during a 4-week period under greenhouse condition. Under natural condition in the forest floor, seed germination begun after the first rains, although showing a delay to begin and lasting longer than under greenhouse conditions. Shorter and thinner individuals of the three tree species predominated over the higher and thicker ones. Amburana cearencis contributed with more individuals than Myracrodruon urundeuva and Handroanthus impetiginosus.