Estrutura e dinâmica de uma floresta tropical seca em Pernambuco, Brasil

• Autor(a) principal: SILVA, Anderson Francisco da
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRPE
• Texto Completo: http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/7373
• topic: Floresta tropical seca; Fitossociologia; CIENCIAS AGRARIAS::RECURSOS FLORESTAIS E ENGENHARIA FLORESTAL

The forest’s dynamics allows the evaluation of growth, mortality, recruitment and variations in floristic composition, which are extremely important factors for the sustainable management and conservation of forest ecosystems. The objective of this work isto analyze the structure and dynamics of a Tropical Dry Forest, in the municipality of Floresta, Pernambuco. The forest inventory was carried out overfour years (2008, 2011, 2014 and 2017) to analyze the dynamics of shrub-tree vegetation in the intervals of 2008-2011; 2011-2014; 2014-2017; 2008-2014 and 2011-2017. For the survey of adult individuals, 40 permanent plots with dimensions of 20 x 20 m were used, and 40 subplots of 5 x 5 m were used for natural regeneration. The phytosociological parameters for the components of the horizontal structure and for the regenerants, diversity indexes, as well as the diametric distribution analysis were evaluated. In the surveys, the number of families oscillated between 7 to 9 and the number of species between 23 and 25. The period of 2008-2017 showed a reduction of 38.85% of the individuals. In all surveys, the Poincianellabracteosastood out in terms of individual density, frequency and dominance, but the Aspidospermapyrilifolium showed the highest average number of stems per individual. The species with the highest values of importance werePoincianellabracteosa, Mimosa ophthalmocentra, Myracrodruonurundeuva and Aspidospermapyrifolium. The Shannon index ranged from 1.73 to 1.92 nats.ind-1 and the Pielou index from 0.43 to 0.48. All species presented small gross and net growths, and in some cases, negative ones due to the high mortality rate caused by the long drought in the studied period. The diametrical distribution presents a tendency to be balanced with a form of an inverted J shape. The first two diametric classes had the highest losses of individuals in the analyzed periods. The number of regenerating individuals in the area also decreased over time, corroborating the problem of the permanence of young plants in the two initial diametric classes, also as a consequence of the long drought period. The floristic composition and diversity of shrub-tree species presented few modifications in the studied periods. In all periods, the species Poincianellabracteosa, Mimosa ophthalmocentra, Myracrodruonurundeuva, Aspidospermapyrifolium and Cnidoscolusquercifolius are predominant in terms of horizontal structure. In terms of natural regeneration,allperiodswere dominated by the species Bauhinia cheilanta, Poincianellabracteosa and Jatropha molissima, though low changes were made. Some species presented gross and net positive growth despite the severe drought in the area. The diametric distribution showed a decrease in individuals in the first classes due to a higher mortality rate than that of recruitment. The prolonged drought was the main factor of structural modifications of the vegetation.