RESUMO
Fire is an important ecological disturbance, but anthropogenic wildfires increasingly threaten native ecosystems and human lives. In fire-prone ecosystems, zero-fire policies have been replaced by active fire management to reduce the risk of wildfires and improve ecological outcomes. The environmental drivers of fire behavior are widely known, but climate change and deforestation are changing their roles, making fires less predictable. Thus, reassessing the main determinants of fire behavior is preeminent to allow for safe and adaptive uses of fire in protected areas (PA). We did this research in collaboration with PA managers during the initial implementation of a pilot Integrated Fire Management (IFM) program in the Brazilian savanna. The program mainly aimed to prevent large wildfires in the late-dry season and included prescribed burns during the rainy, early- and mid-dry seasons to create vegetation patch mosaics with different fire histories. We assessed fire behavior and its environmental drivers during prescribed fires in the mid-dry season (MF) and experimental late-dry season fires (LF) (emulating wildfires). We applied Linear Models to test for differences in fire intensity, heat released, combustion factor and flame height between fire seasons and to check the influence of meteorological and fuel conditions in these parameters. LF had a significantly higher fire intensity (3508 vs. 895 kW m-1), heat released (5537 vs. 3329 kW m-2), combustion factor (90 vs. 51%) and flame height (2.5 vs. 1.9 m) than MF. Relative humidity, air temperature, wind speed and fuel load were the best predictors of fire behavior, corroborating previous research. Air temperature and relative humidity pushed the seasonal differences in fire behavior while wind speed and fuel load showed similar effects across seasons. Our results emphasize the importance of considering primarily environmental variables during fire management planning, especially in the current climate changing world where extreme events and seasonal weather fluctuations are constantly defying our knowledge about fire behavior.
Assuntos
Ecossistema , Incêndios , Brasil , Pradaria , Humanos , Tempo (Meteorologia)RESUMO
Wildfires continue to cause damage to property, livelihoods and environments around the world. Acknowledging that dealing with wildfires has to go beyond fire-fighting, governments in countries with fire-prone ecosystems have begun to recognize the multiple perspectives of landscape burning and the need to engage with local communities and their practices. In this perspective, we outline the experiences of Brazil and Venezuela, two countries where fire management has been highly contested, but where there have been recent advances in fire management approaches. Success of these new initiatives have been measured by the reduction in wildfire extent through prescribed burning, and the opening of a dialogue on fire management between government agencies and local communities. Yet, it is clear that further developments in community participation need to take place in order to avoid the appropriation of local knowledge systems by institutions, and to better reflect more equitable fire governance.
Assuntos
Ecossistema , Pradaria , Brasil , Participação da Comunidade , HumanosRESUMO
The use of fire by cattle ranchers is a major source of conflict between conservationists and local communities in tropical savannas. We evaluate the role of traditional pastoral management in wildfire prevention in two protected areas within the Brazilian savanna. Fine-grain field data from transect walks and interviews were combined with geospatial data at landscape scale to compare fire regimes in community-managed areas with those in government-managed areas. Local pastoral management creates seasonal mosaic patterns of burnings performed for productive activities and for deliberate landscape management, i.e. to protect fire-sensitive vegetation and avoid wildfires. Whereas government-managed areas were affected by large biennial late dry season wildfires, community-managed areas with a regular fire regime suffered less damage. These systems are under threat and poorly understood by researchers and environmental managers. In order to improve fire management in tropical savannas, greater understanding of pastoral management practices and their spatiotemporal dimensions is required.