Formigas como bioindicadores do sucesso de diferentes técnicas para a restauração da fauna savânica em uma Unidade de Conservação do Cerrado

Abstract

The creation of protected areas is one of the most common methods of biodiversity conservation in the world. Despite being an effective measure for biodiversity protection, some of the Conservation Units (UCs) in Brazil are affected by disturbances, requiring human interventions for removal of the disturbances and restoration of the biodiversity. The Brazilian Cerrado is a global biodiversity hotspot, but activities such as forestry and fire protection can cause a decrease in the biodiversity of species endemic to this biome. Management in protected areas generates intense debate, especially when related to fire management. Demonstrating the effectiveness of human interventions for restoration in protected areas is essential for conservation. Thus, to evaluate the effectiveness of intervention actions using ants as bioindicators, I analyzed taxonomic and functional data from ant communities collected at the Santa Bárbara Ecological Station, where fire management and habitat restoration experiments are taking place. First, I evaluated the long-term effects of different fire treatments on the species richness and composition of the ant community in savanna areas. I found that fire did not alter the total species richness; however, it caused a significant increase, independent of the fire regime, in the number of species typical of open savanna. Changes in species composition were due to the gradual increase in open savanna species replacing generalist or forest-associated species in the burned plots. These results indicate that the effects of fire on ant communities are indirect and continuous, that is, through constant changes in the structure of the vegetation. Second, I assessed whether the taxonomic and functional diversity of morphological traits of the ant community was affected by fire and whether this effect was dependent on vegetation type. Ant communities in the different vegetation types were affected differently by fire, and these effects were mediated by changes in the structure of vegetation. In the dry forest, despite the increase in taxonomic diversity and changes in taxonomic composition due to the entry of savanna species, the functional structure of the community was maintained. The Community Weighted Mean (CWM) for pilosity, eye length and eye position were the only morphological traits affected by fire regardless of the vegetation type. In both open and dense savanna, and only there, the CWM for body size, as well as for the relative size of the femur, mandible, and scape length, increased after fire. Finally, I evaluated the success of two savanna restoration techniques in areas previously used in the cultivation of Pinus elliotii, comparing the response of ants and plants. Results indicate that the ant community has a faster recovery when compared to the plant community, since the magnitude of differences between open savanna areas and areas under restoration were much greater for the plant community than for the ant community. However, for both taxonomic groups, the Pinus plantations had fewer species compared to areas under restoration and reference areas of open savanna. The results found here highlight the importance of management, whether of fire regime or the restoration of areas of non-native vegetation, for conservation of typical savanna species. Fire appears to be effective in maintaining these species only when constantly present in the system.