A área foliar específica (SLA) tem sido relacionada a distúrbios ambientais, apresentando uma correlação positiva entre a intensidade de perturbação e a SLA da comunidade vegetal. Estes estudos, no entanto, avaliaram as respostas da comunidade vegetal como um todo, negligenciando os atributos por espécies, tais como a posição vertical no estrato florestal. Considerando a importância da SLA para entender os processos ecológicos das florestas, este estudo teve como objetivo determinar a influência do regime de perturbação na SLA de espécies de sub-bosque, cuja hipótese é que, ao contrário de comunidades como um todo, um aumento na intensidade de perturbação implica na diminuição da SLA de espécies de sub-bosque. Este estudo foi realizado em nove sub-bosque de florestas estacionais no Brasil. As espécies mais abundantes foram selecionados e suas SLA foram avaliadas. A variabilidade de SLA entre as populações em diferentes florestas foi analisada pelo teste t de Student. O SLA dos sub-bosque (SLAu) também foi comparado por uma adaptação do índice de média ponderada da comunidade. A comparação de SLA das espécies mostraram diferenças significativas entre as populações de sub-bosque sob um regime de distúrbios diferentes, mostrando um decréscimo na SLA com um aumento na intensidade de perturbação. Resultados semelhantes foram encontrados para o SLA dos sub-bosque (SLAu), corroborando nossa hipótese. A correlação entre a redução no SLA espécies e SLA do sub-bosque com um aumento na intensidade de perturbação contradiz a tendência observada na literatura para a comunidade como um todo. Este estudo destaca a importância da avaliação de SLA em sub-bosque, como um indicador do estágio sucessional das comunidades.

The specific leaf area (SLA) has been related to environmental disturbances, showing a positive correlation between the disturbances intensities and SLA in a plant community. These studies, however, assessed the responses of plant community as a whole, neglecting species attributes, such as the position in the vertical stratum of forests. Considering the importance of SLA to understand forest ecological processes, this study aimed to determine the influence of the disturbance regime on the SLA of understory species, considering that, unlike for communities as a whole, an increase in the disturbance intensity implies a decrease in SLA of understory species. This study was conducted in nine understories of seasonal forests in Brazil. The most abundant species were selected and their SLA were evaluated. The variability of SLA among populations in different forests was analyzed by Student’s t-tests. The SLA of the understories (SLAU) was also compared by an adaptation of the Community-weighted mean index. The comparison of species SLA showed significant differences among the populations of understories under different disturbance regime, showing a decrease in SLA with an increase in the disturbance intensity. Similar results were found for the SLA of understories communities (SLAU), corroborating our hypothesis. The correlation between a reduction in species SLA and in SLA of understory with an increase in disturbance intensity, contradicted the trend observed in the literature for the community as a whole. This study highlights the importance of the evaluation of SLA in understories, as an indicator of the successional stage of communities.

BACKGROUND: Plants in a seasonal environment that become close to the artificial lake after dams construction may have enhanced growth or die due to the new conditions. Changes in mortality or growth rates lead to changes in community diversity, and we do not know if the community functions will change; our main hypothesis was that a few years after impoundment, species richness and diversity will increase because the increased supply of water would favor the establishment of water-associated species. Therefore, we evaluated the consequences of proximity of three dry seasonal forests to the water table after damming, with a dynamic evaluation of the species studied to understand changes in diversity in these areas. We sampled 60 plots of 20x10 m in each forest and measured all trees with a diameter equal to or greater than 4.77 cm before damming and 2 and 4 years after damming. We calculated dynamic rates and compared species changes during these periods. We also compared diversity and richness using Shannon index and rarefaction curves. RESULTS: Many species had high dynamic rates and many trees of specialists of dry forests died; conversely, others had high growth rates. Some typical species of riparian forests were found only after damming, also enhancing forest richness in deciduous forests. In general, the deciduous forest communities seemed to change to a typical riparian forest, but many seasonal specialist species still had high recruitment and growth rate, maintaining the seasonal traits, such as dispersion by wind and deciduousness in the forests, where an entire transformation did not occur. CONCLUSIONS: We conclude that even with the increment in basal area and recruitment of many new species, the impacts of damming and consequent changes will never lead to the same functions as in a riparian forest.