Search

Forest fragmentation is one of the main causes of biodiversity loss, directly affecting the ecological processes. This study aimed to evaluate tree diversity, structure, and composition parameters in three sectors of a forest fragment with distinct disturbance records. The arboreal vegetation was evaluated in twenty-four 10 × 10 m plots, sampling a total of 1,228 living individuals. We calculated Shanon’s diversity index, Pielou’s equability, and jackknife estimators of first and second orders. The sampled individuals were distributed in diameter classes and the importance value (VI) was calculated for each species. It was made a Detrended Correspondence Analysis (DCA) to verify whether there were significant distinctions between the sectors. It was noticed that the sector where there was clear cutting and vegetation burning in a recent past had higher abundance and richness but also the worst equability. That corresponds to the effects of perturbation as confirmed by the tree diameters and the presence of species of greater importance value. The sector that had no record of disturbance, situated in a location with greater variety of microenvironments, presented diversity, structure, and composition consistent with a no disturbance scenario. The other sector, which did not have clear cutting, was subjected to cattle trampling presented ecological parameters consistent with the absence of major disturbances. On the other hand, this third sector had the smallest environmental diversity, which puts this last sector in an intermediate situation.

ABSTRACT This study aimed to characterize the dynamics, structural changes and floristics of a Northern Minas Gerais Seasonally Deciduous Forest tree community, in a 5 year interval. In 2005, 10 (20 x 20m) plots were allocated. All trees (CBH ≥ 10 cm) were tagged and measured. A second census was carried out in 2010 in order to measure surviving, new recruits and dead trees. In 2005, 46 species were recorded, moving to 45 in 2010. No significant differences were found for Shannon - diversity (H’ = 2.62 nats ind-1 in 2005; H’ = 2.60 nats ind-1 in 2010) and Pielou eveness (J = 0.683 in 2005; J = 0.682 in 2010) in the interval. A total of 57 dead records (rate of 1.64% year-1) were found whereas 18 trees were recruited (rate of 0.53% year-1). Despite the higher mortality as compared to recruitment, the results suggest that the community remained stable in both structural and diversity terms in the interval considered.

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.