Avaliação do método de pousio na recuperação de caatinga desertificada

Abstract

The degradation of arid, semi-arid and sub-humid regions, characterized by the loss of physical, chemical and biological properties of the soil and the vegetable coverage, is caused by an association of anthropic action and climate change. Ceará has 92% of its territory under semi-arid climate and presents regions in state of advanced desertification. Several measures of desertification prevention and mitigation are studied. Considering the ecological and socioeconomical importance of the Caatinga biome, the comprehension of desertification’s dynamics it’s indispensable for enhancing the efforts to stop its progress. This study analyses regions of Caatinga in Irauçuba-CE in a conservation gradient (natural, fallow for 18 year and desertified) focusing in some edaphic variables (soil humidity, soil pH and soil organic matter) and assessing microbial community’s structure by denaturing gradient gel electrophoresis (DGGE), with the goal of comprehending how desertification affects the studied variables and how effective fallow is in restoring desertified Caatinga. The results show that the more conserved soils, in the natural and fallow areas, presented a higher richness of operational taxonomic unities (OTUs), as well as the presence of exclusive taxa. The analysis of the edaphic variables shows mixed responses, with exception of soil pH that held stable. The fallow soil presented soil organic matter compatible with the natural Caatinga’s soil, while its humidity was similar to the desertified soil. Comparing the diversity analysis to the change in the edaphic variables, the disparity between what is known of the importance of soil composition to the microbiome and what was observed, led us to consider that the community analysis method does not have enough sensibility to assess the changes in a sufficiently precise manner. Thus, in conclusion, we believe that in order to fully comprehend the effects of desertification in the soil microbiome, more refined techniques, such as next generation sequencing, are necessary.