Restoration techniques for cerrado grasslands and ecological factors involved

The extension of areas occupied by grasslands in the Cerrado have been dramatically reduced by different factors which include land conversion for agricultural production, biological invasions and even the increase in woody biomass resulting from fire suppression. Actions to ensure the conservation of these ecosystems must include stopping land conversion, enabling sustainable management practices and developing restoration techniques for grassland physiognomies. Aiming at to contribute to the challenges of restoration, in this study we assessed the success of different ecological restoration techniques to be applied to dry and wet Cerrado grasslands, as well as the resilience of natural ecosystems that were used as propagule sources. The study was conducted at Santa Bárbara Ecological Station, where material was collected from intact ecosystems to be used in the restoration of areas where the native vegetation has been totally suppressed by the invasive tree Pinus elliottii. After eradication of the invasive species, no potential for natural regeneration was observed. To restore the dry grassland we compared five restoration treatments: 1 - removing the needles remaining from of invasion; 2 - direct seeding; 3 - transfer of topsoil; 4 - topsoil transfer + direct seeding, 5 - transplant of plant material, and control plots. To restore the wet grassland, we used the treatments 1, 2 and 5, and control plots. To assess the resilience of the areas used as source of propagules in both physiognomies, the material (plants and top soil) was removed in plots of three different sizes. Among the restoration techniques tested for dry grassland, transfer of topsoil and transplant of plant material were the best treatments. For wet grassland restoration, all treatments were effective, and simply removing the needles layer was enough to allow the establishment of a plant community structurally similar to the reference ecosystem. Transplantation was the best treatment in terms of recovery of endemic species, density and vegetation cover for both physiognomies. Areas that were source of propagules showed high resilience after disturbance by removing the material (plants and topsoil), overtaking the richness of pre-disturbance community in less than one year. We concluded that it is possible to restore dry and wet grasslands using natural areas as source of propagules without degrading them (AU)