Metacommunity dynamics is marked by a gradient ranging from pure ecological determinism to pure stochasticity. This gradient encompasses compositional turnover that is governed by ecological drift, selection and dispersal. Here we estimate the influences of selection, dispersal limitation acting in concert with drift, drift acting alone and homogenizing dispersal on the structure of tropical restinga heath vegetation growing under stressful conditions in north‐eastern South America. We hypothesize that if abiotic heterogeneity is strong enough, it could select distinct sets of colonizing species from neighbor ecosystems, with stress sensitive species occupying refuges created by abiotic heterogeneity and stress tolerators dominating the more exposed areas. In this case selection would occur at both biogeographical and local scales. Under its prevalence, we expect selection to have a major signature in the woody plant community structure in a phylogenetic null model. Alternatively, if abiotic heterogeneity is not strong enough to impose significant selection, the environment would be homogeneously stressful for the majority of species, and would be dominated species selected at biogeographical scale only. Under its prevalence, we expect drift to have a major signature in the phylogenetic null model. We used an analytical framework based on phylogenetic and community structure null models to assess the relative importance of ecological processes. We also aimed to characterize the ecosystem features that impose selection and dispersal limitation. We found that 95.1% of turnover in composition is attributable to drift, 2.4% to homogenizing dispersal, 2.1% to selection, and just 0.40% to dispersal limitation, thus confirming our Neutrality hypothesis. As expected, both soil and topographic variables influenced metacommunity structure. However, contrary to our prediction, light availability and vegetation structure were also important. The predominance of coarse spatial patterns correlated to topographic and soil properties suggests that coarse differences in wind exposure and associated vegetation and soil factors represent the main selective forces acting on the studied vegetation. The dominance of drift in the assembly of restinga heath vegetation is likely to result from homogeneously stressful environmental conditions and also from the ongoing colonization process that is taking place in the restinga by immigrants from species‐rich neighboring ecosystems.

RESUMO:A erosão hídrica tem se tornando um dos maiores problemas para a preservação dos recursos naturais. PALAVRAS-CHAVES:Erosão hídrica, modelagem da erosão, produção agrícola sustentável USE OF WEPP AND RUSLE MODELS IN THE SIMULATION OF SOIL LOSS AT A HILLSLOPE AREA SUMMARY:The water erosion has become one of the major problems for the natural resources preservation. In this context, the aim of this work was to perform a comparative analysis between the prediction of soil loss using the WEPP and RUSLE models. The work was developed in a hillslope área in a microbasin of the Piracicaba river, MG, with a length of 225 m and an average slope of 31%. The input data of the models referring to topography, soil type and current land use were obtained from remote sensing information. The region's climate information was