Influência do extrativismo da casca do caule sobre o sucesso reprodutivo pré-emergente de Himatanthus drasticus [Mart.] Plumel (Apocynaceae) e Stryphnodendron rotundifolium Mart. (Fabaceae, Abaceae, Mimosoidae)

Abstract

Although the collection of non-timber forest products (NTFPs) is considered less harmful to ecosystems than timber extraction, there is evidence that these resources are exploited unsustainably, because they affect the dynamics of populations that are targeted in this activity. The latex and the stem bark of some plant species are NTFPs of medicinal and economic value, spread widely throughout the world. In areas of Cerrado and Moist Forests in Northeastern Brazil, local human populations extract the stem bark of Himatanthus drasticus [Mart.] Plumel (to collect the latex) and Stryphnodendron rotundifolium Mart. for medicinal use. The removal of the bark of these species in the region is a very common activity locally, however there are no known consequences of this activity to the biology and ecology of these. The present study aims to verify the consequences of the extraction of stem bark of H. drasticus e S. rotundifolium on reproductive performance of these species. Our hypothesis is that such activity interferes negatively in their reproductive capacity. We selected 30 individuals without extraction of each species, with similar height and diameter, and half was subjected to the extraction of the bark. The dimensions of the extracted area were similar to those performed by extraction of the region in the study area. The dimensions of the extracted area were similar to those performed by extraction of the region in the study area. Compared between the two groups of individuals (extracted-treatment; non-extracted control) the number of inflorescences, buds, flowers, pollen, ovules, fruits and seeds, as well as characteristics of fruit and seed size and reproductive success preemergent. All reproductive parameters of H. drasticus were negatively affected by the extraction of the bark, except for the production of pollen and ovules. By contrast, the only reproductive parameters in S. rotundifolium negatively affected by the extraction of the bark were producing pollen and ovules. The extraction of the bark of the species undertakes its reproduction and hence the generation of new individuals, suggesting that this activity may not be sustainable extractive.