Comportamento fenológico de espécies lenhosas em um cerrado sentido restrito de Brasília, DF

Abstract

In this study we followed the phenology of 19 woody species of a cerrado sensu stricto in the IBGE Ecological Reserve (15o55'06-15o57'57 S and 47o51'22-47o54'07 W), in Brasilia, Federal District, Brazil. Phenological observations were made every fortnight between August 2000 and October 2003. The vegetation studied is a seasonal semi-deciduous wood savanna, where a hot wet season (from October through to April) is followed by a cool dry season (from May through to September). Vegetation canopy is reduced during the dry season and foliage cover reaches a minimum of 50% at the end of the dry season. Even though new leaves and flowers appear along the year, their production is intensified during the transition between the dry and wet seasons. According to the vegetative phenology, four groups were identified: four evergreen species with continuous growth, five evergreen species with seasonal growth, eight brevideciduous species and two deciduous species. The evergreen species with continuous growth produced leaves along the wet season, while the remaining groups produced leaves more intensely at the end of the dry season. Fruit maturation of autochoric and anemochoric species occurred within the dry season; zoochoric species dispersed seeds mainly during the wet season. Soil water availability seemed not to have restricted leaf production and reproduction of most species since the peak of flushing and blooming was at the end of the dry season. However, endogenous factors such as leaf longevity and internal water balance, as well as exogenous factors such as evaporative demand and irradiation seem to influence the phenological patterns observed in this vegetation.