Fenologia e variações sazonais no status hídrico e na termotolerância em espécies lenhosas em um fragmento de mata semidecídua em Belo Horizonte, MG

Abstract

Physiological characteristics of species established on tropical natural environment are influenced by climate seasonality that is common in the region, mainly due to dry and rainy periods well defined. With the aim of evaluate the physiological performance of native species on these situations, a seasonal monitoring of water relations was taken, as phenology and leaf total chlorophyll content monthly recorded in seven woody species (four Melastomataceae and three Leguminosae). The plants were found in a semideciduous forest fragment, at Estação Ecológica UFMG, in Belo Horizonte, Minas Gerais. The focus on the behavior within each botanical family was done according each evaluated parameter, as well interactions between these parameter and physical environment characteristics. The prediction that a similarity on the water status seasonal variation would be found within each family was supported mainly by Leguminosae, which presented a pattern, with hard water deficit on dry season.. Among the Melastomataceae, the water status variation was different for each species. Also was observed greater similarity on Leguminosae phenology. These species presented a seasonal phonological pattern as the leaf flushing, which increased on the end of dry season and onset of the rainy, and leaf abscission, intense during dry season. Variation on leaf total chlorophyll content follow the pattern of the phenophases sequence, and, in general, it was lower during leaf flushing periods. The results provide evidence that the climate characteristics have greater influence on the water status than the phylogenetic relationship, but that both are crucial on the species phenology.