Mudança no uso da terra e efeito na composição e atividade microbiana de solos arenosos no semiárido brasileiro

Abstract

Natural ecosystems have suffered great human interventions and one of them is the conversion of forests into agricultural land, and the TDF (FTS) one of the most affected in the world. Changes in land use can be reflected by biological, biochemical, chemical and physical parameters, the first two being the fastest and most sensitive to changes in soil quality. This study evaluated how the conversion of FTS in pasture with different levels of conservation acts on the community and microbial activity in Neossolos Regolíticos. The characterization of the microbial community and enzymatic activities of sandy soils of the semiarid region of Pernambuco in areas of drought and forest disturbed. In the first chapter, the study was conducted in the city of Saint John and the selected areas were: FTS = dry tropical forest, PP = preserved and PD = degraded pasture pasture. In the second chapter were selected five cities of Pernambuco semiarid region, which were collected two composite soil samples, one in FTS and another in area with human intervention. For Chapter 1 were determined analysis of the microbial biomass carbon (MBC), total organic carbon (TOC), the fatty acid profiles of the microbial community (FAMEs) and absolute and specific enzymatic activities. In chapter 2 were determined profiles of fatty acids and enzymes absolute. FTS conversion to pasture with different levels of conservation affected the microbial community and enzymatic activities of Entisol. And the type of vegetation is shown as one of the main factors responsible for the variation of the microbial community. Quantification of FAMEs in different areas analyzed demonstrated that populations of fungi are sensitive to changes in land use that bacterial populations, because these showed a faster metabolism, ie, unable to adapt to disturbances in the ecosystem. The evaluation of specific enzymes showed how these are influenced by the TOC and MBC, where enzymes by CBM unit expressed higher values.