Adaptive strategies in burned subtropical grassland in southern Brazil

Extensive parts of subtropical South America are covered by grassland vegetation, despite climatic conditions that allow for forest development, and fire may have been an important factor in the evolutionary history of these grasslands. In a regularly burned grassland area, situated in a forest-grassland-mosaic near Porto Alegre, RS, Brazil, life form spectrum and plant species' reaction to fire were examined, allowing for (1) a physiognomic description of the grassland, and (2) a functional classification of grassland species in relation to fire. Grassland sites with different time since the last fire occurred were compared between each other as well as to sites at the forest-grassland border. South Brazilian grassland is dominated by hemicryptophytic caespitose graminoids that resist fires, but contains a large number of geophytic or hemicryptophytic forbs, in general sprouting after fire. Shrubs, mostly sprouting species of the grassland community, were present with high cover values even in recently burned areas. In contrast to Central Brazilian Cerrado, trees were of little importance: most species found were forest pioneer species without the capacity to survive fires unless growing on sites protected from fire or at the forest border where burns stop. Non-sprouting species were of little importance in the community, and only two species found were therophytes. Lack of therophytes in South Brazilian grassland vegetation deserves further attention.