Resumo

The sugarcane is nowadays the most important crop in Brazil, mainly requested to feed the sugar and ethanol growing market. Considering the expansion of agricultural barriers and shifts in field management, such cultivation is under a rearrangement process, aiming a higher productivity and sustainability. In this context, the role of microbial communities present in soils can be essential, supporting the plant development. Therefore, understanding how clusters of species are distribute in nature is the major challenge, to give the necessary knowledge to manage the soil and achieve improved productivity results. The species abundance distributions (SADs) are considered an informative and synthetic describe the biological diversity, and reveal one of the most well-established patterns of ecology that are not frequently accessed, which is the predominant rare species in biological communities. Conventionally, two most important models explain the diversity, structure and composition of communities. The first one is the niche-based in the deterministic processes, and the other, is the neutral, which highlights the stochastic processes. Using molecular techniques, we surveyed the fungi community, by T-RFLP analyses. 119 samples were collected in areas with distinct soil managements spread in State of São Paulo and distributed along 11 different producer regions to test these both SAD models. Within this dataset, it was used the Tetame 2.1 resulting in the factors “Ө” (theta), that governs the appearance of new species in the regional species pool, and "m" that governs immigration into local communities of individuals, that composed the neutral model. The niche-models was obtained by R, and the comparison of all models was release by Akaike information criterion (AIC), measure of the relative quality of a statistical model. The results revealed that the fungi community in soils of sugarcane cultivation have a neutral species abundance distribution indicating that changes in fungi community composition will be relate to distance between samples, indicating the effects of dispersal limitation. It could suggest that in this environmental systems there are a greater uniformity of fungi community over space and there are less niches, hence the difference of the community would be an occasion by limit of dispersion, or distance.