Reconstituição da composição, estrutura e biomassa arbustiva-arbórea a partir de cepas em caatinga sob manejo florestal

Abstract

The knowledge of the regrowth of woody species Caatinga, as a mechanism of survival after disturbance, allows to infer the capacity of natural regeneration of vegetation. Strains left in the field after cutting besides functioning as a nutritional reserve favoring regrowth can be used as a facilitator of supervision, once suppressed the vegetation of an area, it is difficult to estimate the biomass removed so that you can prosecuting those responsible. The objective of this study was to evaluate the reconstruction of the composition, structure and shrub-tree biomass from strains in an area of Caatinga under for Sustainable Forest Management Plan (SFMP). The research was conducted in the municipality of Floresta, Pernambuco, from analysis in SFMP and survey of 18 permanent plots distributed systematically in 2015, after two years of the prescribed cut. For comparisons between SFMP and the survey, phytosociological analyzes were performed using estimated parameters of the horizontal structure, as well as diversity index Shannon, evenness of Pielou, dominance of Simpson and Jentsch Mix Ratio. The study of regrowth was carried out by quantifying the regrowth and mortality strains shrub-tree per species identified in the survey of 2015. There were measured and identified all strains, the remaining individuals and regrowth. The sampled individuals were separated in classes of circumference at base height (CAB) strains and height of tillers. For reconstruction of biomass, initially was adjusted diameter at breast height (DBH) models depending on diameter of the strains (DS). To select the best equation it was used statistics: adjusted coefficient of determination, standard error of the estimate, coefficient of variation and Furnival index. Subsequently, with the estimation of individual DBHs from the DS it was applied the equation adjusted by Silva and Sampaio (2008) to estimate biomass prior to cutting in the study area. The floristic composition of the area was represented by seven families and 16 species, the most representative families Fabaceae and Euphorbiaceae. The resisted species in the area after intervention and prevailed in regrowth were Poincianella bracteosa (Tul.) L.P. Queiroz, Aspidosperma pyrifolium Mart. and Cnidoscolus quercifolius Pohl. The Mimosa ophtalmocentra Mart. ex Benth and Mimosa tenuiflora (Willd.) were the species with the highest mortality rate. There was a decrease of the floristic diversity when the community was subjected to clearcutting. There was a correlation between the variables, circumference of the strains (CS) and number of tillers and the Poincianella bracteosa and Aspidosperma pyrifolium when the strain showed CS above 30 cm, greater were the amount of tillers. The reconstruction of the floristic composition and structure was possible through floristic and phytosociological parameters obtained for the vegetation before the cut and two years after. The biomass was rebuilt by estimating the DBH by DS and the equation adjusted to Caatinga. Thus, the equation becomes an effective tool for environmental agencies to control illegal devastation.