Diversidade de fungos micorrízicos arbusculares e de bactérias fixadoras de nitrogênio simbióticas em áreas de mineração de bauxita com diferentes idades de revegetação

Abstract

To the adequate management and use of different resources of a certain ecosystem, knowledge of the ecological processes is of fundamental importance. In this context, biodiversity, nutrients cycling and energy flux are shown to have important regulatory roles. Recent data showed that there is a relationship between the plants diversity and biomass productivity and that in addition to soil fertility, temperature, latitude, precipitation and herbivory, the interaction among species from the different functional groups and the microbial diversity participates in the determination of vegetal diversity. Currently, natural ecosystems are known to have interconnected components located above and below-ground and regulatory effects are known to be established between the populations of each component. The aims of this study was to improve protocols of DNA extraction and to evaluate the diversity of arbuscular mycorrhizal fungi and nitrogen-fixation bacteria in areas with different ages of revegetation after bauxite mining, as well as to relate the diversity of these microorganisms with the plant diversity. It was observed that addition of the PVP, PVPP and activated charcoal improved both quality and yield of DNA extracts. Also, high rhizobial diversity was observed in the different areas, and this was highest in the degraded areas that were revegetated longer ago. Glomus macrocarpum was the most abundant arbuscular mycorrhizal fungi species among the 13 species found. The results showed that the revegetation strategies adopted in these areas are enabling the establishment of a community of arbuscular mycorrhizal fungi in the soil. However, the richness level and the spore numbers continue to be low, mainly in the degraded areas revegetated after the year 2000. No correlation was observed with respect to the richness values and Shannon-Wiener index between plants community and arbuscular mycorrhizal fungi. The relationship between above and below-ground diversity was dependent of plant community composition.