How do different agricultural management strategies affect bird communities inhabiting a savanna-forest mosaic? A qualitative reasoning approach

Abstract

Most of the world's biodiversity is threatened by agricultural intensification. Agricultural intensification also is considered as major human thread to one of the world's most threatened ecosystems, the Cerrado in Brazil. The Cerrado can be characterized as a natural mosaic of grasslands, woodlands, dry savannas and forests forming a naturally heterogeneous landscape representing the home for an enormous amount of endangered bird species. In this paper, we present a qualitative reasoning model to compare impacts of Intensive farming and traditional management on bird communities inhabiting a mosaic of savanna-forest landscape in the Brazilian Cerrado ecoregion, by using non-numerical knowledge and explicit representation of causal relations. Three groups of bird species were represented, based on their distinct use of the forest-savanna mosaic: forest specialists, forest generalists and non-forest inhabitants. The qualitative model was built in Garp3, a qualitative simulation engine. The qualitative model was successful in representing the impacts of both agricultural systems on the bird groups, addressing advantages and disadvantages of this method. The model shows that intensive agriculture leads to non-forest and forest specialists decline, whereas forest generalists are kept stable. On the other hand, traditional management may lead to either a decline or maintenance of the non-forest and maintenance of both forest groups. Replacement of traditional management by intensive agriculture may negatively affect birds. Heterogeneity is a key process to maintain diversity in agricultural landscapes.