Regeneração natural, relações ambientais e invasão biológica em duas veredas do Triângulo Mineiro

Abstract

Veredas are heterogeneous ecosystems when it comes to environmental conditions and floristic composition. Although regarded as Permanent Protection Areas – according to Brazilian environmental law, they are highly sensitive to indirect environmental impacts which might affect the plant community composition. In this sense, our research aimed to analyze the woody regeneration and the representativeness of plant groups on soil coverage at two vereda areas under similar environmental pressures in presence (vereda 1) and absence (vereda 2) of native vegetation adjacent to the edge. For this purpose we sampled 15 woody regenerating individuals throughout transects perpendicular to the drain line in which vereda area. We measured the soil coverage using the Line - Intercept method in the plots. We found 369 woody regenerating individuals in vereda 1 and 1.053 individuals in vereda 2. In despite of the significant difference in density, the woody regeneratings diversity was similar in both areas (30 species in vereda 1 and 35 species in vereda 2). The most representative families were as follow: Melastomataceae, Asteraceae and Myrtaceae in vereda 1 and Melastomataceae, Myrtaceae and Fabaceae in vereda 2. Besides the low observed diversity, a reduced number of species were dominant in woody regeneration at both vereda sites, being Leandra erostrata the species bearing the highest density value. We found species related to forest formations in the regenerating floristic composition, especially in vereda 2. We observed the alien species Pinus caribaea in both vereda areas, the vereda 1 showed the highest natural regeneration índex though. We also observed typical zonation tendencies on soil coverage and woody regeneration composition, although we recorded a “trembleyal zone” on the left edge. Regarding the presence of species more sensitive to environmental disturbances such as Miconia theizans and more resistant ones such as T. parviflora, the veredas seem to foster distinct degradation conditions. In despite of the presence of native regeneration adjacent to vereda 2, this are shows signs of impact on vegetation, linked to water table lowering whilst vereda 1 shows signs of higher disturbances in the edge, besides a remarkable biological invasion by Pinus caribaea.