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Universidade Federal Rural de Pernambuco (2009)

Caracterização da serrapilheira em caatinga preservada e mudanças no carbono do solo após o desmatamento sem queima

AMORIM, Laerte Bezerra de

Titre : Caracterização da serrapilheira em caatinga preservada e mudanças no carbono do solo após o desmatamento sem queima.

Auteur : AMORIM, Laerte Bezerra de

Université de soutenance : Universidade Federal Rural de Pernambuco

Grade : Mestre 2009

Résumé
The Caatinga, a semi-arid ecoregion, is one of the most endangered Brazilian biome and transformed by human action. Despite its significant socioeconomic and environmental importance, few studies are directed to the sustainable management of this ecosystem. Accordingly, research related to the litter storage on the soil surface, total organic carbon (TOC) and light particulate organic matter (POML) in deforested areas without using fire is unknown or absent in the Brazilian semi-arid. This study was carried out at Embrapa Semi-Arid, Petrolina-PE, to evaluate the influence of deforested area in the dynamics of litter, TOC and POML in the mineral soil of a preserved environment of caatinga vegetation, and quantify the effects after seven months of deforestation on these variables. The experimental design was in non-ramdomized complete blocks (n = 3) with five treatments, consisting of the growing distance cleared around each experimental plot. The area of plots (10 x 40 m) and girth of 0, 15, 25, 35 or 45 m wide around them were the clear cuts. Plots in samples were collected from litter and soil. For each block as a control plot (forest) that were sampled. Sampling of litter and soil were carried out at the end of the dry period (December/2007) and after the rainy period (June/2008). We collected 162 samples of litter in the dry season in all plots before the cutting of vegetation and 27 samples after the rainy season, only in control plots, located in the area not deforested. The collected material was fractionated in non-woody (leaves, flowers and miscellaneous) and wood (bark and twigs), evaluated on the content of dry matter (DM) and chemical composition (N, P, K, Ca, Mg). A total of 54 soil samples were taken from each layer (0-10, 10-20 and 20-30 cm) in both periods, and analyzed for TOC, DM of POML, particle size, pH, extractable P and exchangeable bases. Litter storages at the end of the dry period presented modal range between 3 to 5 Mg ha-1, consistent with data already published. The litter had a wide C/N ratio (37), and its decomposition was 89 and 21% for the non-woody and woody fractions, respectively, determined by the DM before and after the rainy season. The gradient of nutrients concentration was Ca> N> K> Mg> P for all fractions studied. Concentrations and storages of TOC and POML showed seasonal variation with the highest values observed at the end of the dry season. There was a significant relationship between the amounts of POML and TOC, suggesting that part of the C in the POML is incorporated into the humified C fraction.

Assunto(s) : Semi-árido, Folheto, Carbono orgânico total, Matéria orgânica particulada leve, , Desmatamento, Semi-arid, Leaf litter, Total organic carbon, Light particulate organic matter

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Page publiée le 24 mars 2011, mise à jour le 21 février 2019