Fire effects on vegetation and environmental variables in grasslands of the eastern hills (Sierras del Este), Uruguay

Doctoral thesis abstract

Abstract

Disturbances are biomass removal events and have global relevance as they are capable of causing changes in the structure and functioning of ecosystems over time. Fire is employed in grasslands as a management tool to release space and improve the quality of forage for livestock. This thesis evaluated the effects of fire, and in some cases the interaction with grazing, at different levels of organization and at different spatial-temporal scales, on the plant structure of a grassland community dominated by Saccharum angustifolium in the Sierras del Este region from Uruguay. Through a field study, the succession process was described in patches with different time since fire through a spatial chrono-sequence. Through a laboratory study, the effects of heat shock and smoke, at different levels of light intensity, on the germination of six native species were evaluated. By means of a field experiment, along three growing stations, the effects of fire-grazing interaction on the structure of vegetation at different levels of organization were analyzed. Field burning carried out in a patchy and asynchronous manner seemed to be necessary to maintain heterogeneity at a landscape scale and the diversity of the community in the Sierras del Este grasslands.