Caracterização Componente arbustivo-arbóreo em um fragmento de caatinga no Município de Caicó – RN.

Abstract

Floristic studies, phytosociological and natural regeneration are of utmost importance to subsidize the conservation, management and / or restoration of areas of the Caatinga biome, which have suffered from degradation by exploration model applied since its colonization. The aim of this study was to conduct a floristic, phytosociological and natural regeneration of existing in an area of Caatinga located in Bell Stone Ranch, municipality of Caicó – RN woody stratum survey. According to information on the ground, the area has undergone an intensive exploitation of firewood to meet the needs of the local potteries region, approximately 25 years ago and has been used only for cattle grazing during the rainy season, and removal of timber for various purposes. The fragment used for the study has 45.4 hectares and is confined between the geographical coordinates: 37 06 '01.6 "to 37º06'33,6' west longitude and 06º32'33,5 'the 06º 33' 06.9 "south latitude. For the qualitative and quantitative evaluation of 25 vegetation plots were plotted, with dimensions of 20 x 20 m (400m2), distributed in a systematic way. All living or dead still standing, whose circumference 1.30 m tall shrub and arboreal individuals had values above 6 cm were inventoried. For data collection of natural regeneration, 25 plots of dimensions of 5 x 5 m were plotted with an interval of 100 m between plots and between tracks. Plants with a circumference of 1.30m (CAP) <6.0 cm and height ≥0,5 m were considered individuals in regeneration. All sampled individuals were grouped into four size classes: Class 1 - 0.50 to 1.00 m, Class 2 -of 1.01 to 2.00 m; Class 3 - 2.01 to 3.00 m; and Class 4 - greater than 3.00 m. The floristic list of species was organized according to the classification system of APG III. Indices of Shannon-Weaver and evenness for adult and regenerating stratum were calculated. Already phytosociological parameters were calculated: Absolute and Relative Density, Frequency Absolute and Relative, Absolute and Relative Dominance, Value and Importance of cover absolute and relative to the canopy layer; Density and Absolute, Absolute Frequency, Natural Regeneration and Relative Importance Value Relative for the refined. The adult and regenerating strata had low diversity and dominance of species A. pyrifolium, P. pyramidalis and M. tenuiflora to adult, and A. pyrifolium, C. blanchetianus and P. pyramidalis for regenerating. Both species are typical of early and intermediate the process of ecological succession. These results indicate that the area has not yet recovered from the impacts of past exploitation of firewood and they are being intensified by the current use for cattle ranching.