Estrutura e dinâmica do componente arbustivo-arbóreo em uma área de Caatinga sob diferentes sistemas silviculturais, em Macau, RN

Abstract

Considering the importance of evaluating the compatibility between the exploitation system usually used in the Caatinga and the vegetation regeneration process, identifying the growth dynamics and investigating the loss of floristic diversity, this study aims to characterize the adult shrub-tree component, in four stands aged 9-, 12-, 16-, 20- and 26-years postexploitation, submitted to clear-cut (CR) and three types of selective cuts (CS1, CS2 and CS3). In permanent plots of 20 x 20 m, individuals with CAP ≥ 6 cm and total height greater than 1.0 m were measured. Data analysis was performed by estimating phytosociological parameters (absolute and relative), such as: frequency, density and dominance, as well as the importance value index, diversity index, basal area and volumetry. In all, 10 species were recognized, distributed in 4 families, among them, the following stand out: Pityrocarpa moniliformis, Cenostigma pyramidale and Commiphora leptophloeos for the CR, adding up to 70.6% of the importance value (VI); P. moniliformis, C. pyramidale and Croton blanchetianus for CS1, CS2 and CS3, with accumulated VI of 75.0%, 73.4% and 74.0%, respectively. Over the years of monitoring, the CR presented the lowest density, dominance and volume values, obtaining recovery in basal area and volume only at 16 and 20 years of regeneration, respectively. In this sense, the CS2 and CS3 silvicultural systems stood out in relation to the CR and CS1 regarding the recovery of the original stock of woody biomass, presenting values higher than those of 1995 and indicating that the initial data did not correspond to the maximum potential of woody biomass. The forest dynamics pointed to the insufficiency of the 15-year clearcut cycle, common in PMFS in Rio Grande do Norte, regarding the recovery of forest composition and structure in this region.