Efeitos do fogo na fenologia reprodutiva de angiospermas em vegetações campestres na Chapada Diamantina, Brasil

Abstract

The passage of fire in vegetation causing ecosystem changes and their recovery depends on characteristics of the various levels of organization: communities, functional groups, populations or other and the environment conditions. Given the importance of phenology and knowing that fire affects reproductive plants patterns, plus the small amount of studies in this perspective, this study aimed to evaluate the effects fire in reproductive phenology of a plant community in grassland and populations herbaceous of rosette plants. The studies were performed in the “Área de Proteção Ambiental” Marimbus-Iraquara in the Chapada Diamantina, Bahia, Brazil. The rosette plants, four species of Eriocaulaceae and one of Bromeliacae, were recorded in an area burned in november 2008, near the BR 242, in Lençóis (12 ° 27'50, 9 "S and 41 º 26'02, 6 "W, 795-841 m altitude). The observations were monthly and lasted 21 months, 22 months to Dyckia dissitiflora, and considered the presence/absence of flowering and fruiting. These species show differences in reproductive phenology related to the action of fire, since mass flowering after fire until the absence of sexual reproduction. The fire stimulated the production of flowers and fruits in D. dissitiflora, Cottendorfia florida and Actinocephalus ramosus, and did not alter the patterns of frequency and duration of phenological phases in relation to control of A. ramosus. Although these species had similar morphological characteristics (protection of buds in leaves arranged in rosettes), the action of fire caused different phenological responses. However, the presence of different answers does not mean necessarily that these characteristics evolved from pressures imposed by the fires. The study at the community level has been developed in an ecotone between grassland and “campo rupestre”, on the property of the Orquidário do Pai Inácio, Palmeiras (12 ° 31'44''S and 41 ° 33'32''W, 900 m altitude). For this, four 10x10m plots were selected, two of them being burned (AQ) in march 2009 and the other used as control (AC). Were subdivided into 100 plots of 1x1m, we randomly selected 10 for monthly monitoring of all species. The observations began at six months post-fire and lasted 14 months, considering the presence/absence of phenophases and quantification of reproductive structures. The community in both treatments presented with flowers and fruits throughout the study, with greater concentration in the rainy season. The fire did not alter the reproductive phenology of the community and life forms, possibly because of the degree of adjustment of vegetation to disturbance by fire in the levels studied or the characteristics of fire.