O papel das beiras de estradas na conservação da diversidade vegetal do cerrado

Abstract

There is evidence that roadside vegetation can conserve local native flora. However, the studies providing this evidence were conducted primarily in grasslands. Not much is known of the potential conservation of roadside vegetation in more complex physiognomies, such as tropical savannas. We compared the structure of cerrado vegetation (sensu stricto) along roadsides areas with that in preserved areas. On average there were, on the superior layer, 2.7 times more individuals and 1.4 times more species in the reserves than in the roadside. In the intermediate layer we found 1.7 times more individuals and 25% more species in reserves than in roadside. In addition, in the roadside there was a lower prevalence of tree species with thin bark, forest species and species pollinated by specialist agents. Similarly, in the intermediate layer, we found a lower proportion of forest species and scattered by animals in the roadside. These differences occur, possibly because during the construction of the roads, the vegetation of their banks is cleared and part of the land is taken to landfill the road. Later, they suffer from a higher fire frequency and high coverage (80% average) of exotic grasses. Moreover, it is likely that the absence of some pollinators and dispersers on roadsides may affect the recruitment of new individuals. Despite these differences, the roadsides are able to maintain at least 70% of tree species and 72% of shrub species found in reserves. These results suggest that roadside vegetation can contribute to the conservation of the flora of Cerrado, especially considering that over 60% of the original area of this ecosystem has been destroyed and that less than 4% is protected.