ABSTRACT Fragmentation is one of the main causes of biodiversity loss in tropical forests through consequences on their different components. Beta diversity patterns across fragments have been studied across multiple spatial scales, but comparisons with intact landscapes and in a variety of vegetation types are scarce. In order to address this issue of anthropogenic landscape disturbance, we tested two hypotheses relating to fragmentation and beta diversity: 1. Floristic homogenization at patch-level scale and 2. Floristic differentiation at landscape-level scale. The study was conducted in the Espinhaço Range biosphere reserve, Brazil. Three landscapes encompassing a broad range of vegetation types were sampled in 115 plots. Two landscapes were fragmented due to mining activities (Sabará and Brumadinho) and one is protected (Parque Estadual Serra do Rola-Moça). Results showed high overall beta diversity both between landscapes (conserved and fragmented) and vegetation types (forest, Brazilian savanna “campos rupestres”, ecotone and ironstone “canga”) with high turnover and species losses, even in highly disturbed vegetation types. The conserved landscape was most diverse in terms of richness. Thus, fragmentation effects differed from the expected with a main role of differentiation processes, and we argue that high beta diversity is not always a good predictor of ecosystem health.

ABSTRACT The objective of this work was to evaluate if the soil heterogeneity expressed by the different soil classes would condition tree communities with different dynamic behaviors. The data were collected from 25 plots sized 20 × 20 (400 m²), 10 of them with Inceptisols, 9 with Ultisols, 5 with Entisols B and 1 with Entisols A. All individuals with DBH ≥ 5.0 cm in the plots were sampled in 2000, 2005, 2009 and 2015. Rates of mortality, recruitment, gain, loss and turnover dynamics in number of individuals and basal area were estimated for each soil class. The tree communities present in the soil classes showed no differences in the dynamic behavior to the point of expressing edaphic fragment heterogeneity. The differences are associated with stochastic fluctuations in rates caused by small disturbances, suggesting little influence of the soils on the dynamics of small-scale communities.

RESUMO: Os objetivos deste estudo foram conhecer a composição florística de três fragmentos de floresta ciliar do Rio Cedro, Montes Claros - MG e selecionar espécies para serem utilizadas na recomposição. Realizou-se o levantamento florístico, análise de similaridade e a classificação sucessional. Foram amostrados 356 indivíduos em três fragmentos, sendo: 99 no 1º, 117 no 2º e 140 no 3º com um total de 53 espécies, duas não identificadas, 46 gêneros e 22 famílias. O 1º Fragmento apresentou a maior riqueza florística: 28 espécies, seguida pelo 2º com 26 e o 3º com 25. As famílias com maior número de indivíduos foram Fabaceae (111), Malvaceae (50), Arecaceae (45) e Anacardiaceae (32). A Fabaceae foi a família com maior número de espécies representas. Das análises, obteve-se um índice de similaridade de Sørensen para os Fragmentos: 1 e 2, 52,8%, 2 e 3, 40% e 1 e 3 33,3%. Os valores maiores de riquezas de espécies pioneiras e secundárias iniciais caracterizam uma fase de transição da floresta pioneira, típica de estágio sucessional médio. Os fragmentos apresentam características da floresta estacional decidual, encontrando-se perturbados. Para a recomposição da floresta ciliar propôs-se a seleção de espécies de diferentes grupos ecológicos.

ABSTRACT The objectives of this study were to know the floristic composition of three fragments of riparian forest from Rio Cedro, Montes Claros, Minas Gerais state and select species to be used in its recomposition. It was done a floristic survey, similarity analysis and sucessional classification of species. We sampled 356 individuals in three fragments, and: 99 at the 1st one, 117 at the 2nd one and 140 at the 3rd one with a total of 53 species, 2 unidentified, 46 genera and 22 families. The majority floristic wealth was found at the 1st fragment: 28 species, then at the 2rd one with 26 last at the 3nd with 25. The families with the highest number of individuals were Fabaceae (111), Malvaceae (50), Arecaceae (45), Anacardiaceae (32). The Fabaceae family showed the greatest number of species represented. By the tests, Sorensen's similarity rate was obtained for the fragments: 1 and 2, 52.8%, 2 and 3, 40% and 1 and 3 33.3%. The greatest wealth of pioneering species and secondary ones characterize an initial phase of transition from forest pioneering, typical of sucessional medium probation and show characteristics of seasonal decidual forest. The fragments studied are disrupted. In order to the recomposition of the riparian forest, a selection of species to be used in its recomposition and the combination of different ecological groups are proposed.

Os planos de manejo em execução na atualidade são, em sua maioria, uma exploração florestal realizada com o título de plano de manejo. Para subsidiar a diferenciação dessas duas modalidades de exploração, foi realizado o presente trabalho, que teve como objetivo verificar a sustentabilidade do plano de manejo de cerrado executado na fazenda Santa Cecília, no município de João Pinheiro, estado de Minas Gerais, por meio da análise estrutural da vegetação, identificando alguns de seus impactos, em relação a uma área de cerrado não explorada. A avaliação foi realizada por meio de parcelas, que foram lançadas na área explorada em 1994/95 e na área ainda não-explorada. Os resultados da análise da estrutura horizontal demonstraram que houve diferença significativa na Densidade Absoluta e Volume Total e na Dominância Absoluta entre as áreas estudadas. Os resultados da estrutura diamétrica demonstraram diferença significativa para a distribuição da densidade e entre a distribuição da área basal e do volume total. Esses resultados indicaram que a exploração foi realizada além dos limites que permitissem a recuperação da vegetação para um novo corte, ao final do ciclo de corte.

The management plans presently being carried out are, in the majority, a forest exploitation done with as if it were a management plan. This work was carried out in order to help differentiate these two types of exploitations. It was aimed at verifying the sustainability of the Cerrado management plan carried out on Santa Cecília farm, in the municipality of João Pinheiro, in the State of Minas Gerais, Brazil, through the structural analysis of the vegetation, identifying some of its impacts in relation to a non exploited cerrado area. The evaluation was made by plots that were established in the explored area in 1994/95 and in the non explored area. The results of the horizontal structure analysis showed that there were significant differences in the absolute density and the total volume and absolute dominance between the areas studied. The results of diametric structure showed a significant difference for the density distribution and between the basal area and total volume. These results indicate that the exploration was done beyond the limits that could allow the recovery of the vegetation for a new harvest at the end of rotation cycle.