Tuesday, August 4, 2009
Exhibit Hall NE & SE, Albuquerque Convention Center
Background/Question/Methods
In Canaima National Park (CNP), a protected area inhabited by Pemón Amerindians, social, demographic and cultural changes, have led to an unsustainable practice of fire use, resulting in forest reduction and habitat loss. Fire, mostly originated in savannas, is considered a threat because of its impacts upon ecosystems, triggering a process of forest substitution by treeless savannas. Also, Pemón people depend for their livelihood on the use of fire for shifting agriculture and hunting in forested areas. Fire exclusion has been the main fire management strategy adopted by government agencies at CNP. However, this has not been effectively achieved, because Pemón people do not agree with this approach, considering that it excludes the utilitarian and cultural significance of their burning practices. A long-term study of fire behavior and fire effects on biodiversity and biomass production in savanna ecosystems of the CNP shows that other management strategies could be possible. We simulated Pemón traditional methods of fire management by burning a series of 31 savanna plots of 50 x 100 m in different periods of the dry season over a seven-year period.
Results/Conclusions
We demonstrate that: a) fires can occur under a wide range of weather conditions and fuel characteristics, which in turn lead to a high variability in fire intensities, temperatures and spread rates, flame lengths, burn efficiencies and ash production; b) wind speed and fine fuel load constitute the principal drivers of fire behavior; and, c) opposite to what was longer believed, fires never reach an annual frequency but occur every 2, 3 or 4 years, due to the low recovery rates of the vegetation. Because fire could lead to a variety of scenarios depending on the amount of biomass (176 - 1,271 g.m-2), live/dead ratios (0.36 – 3.60) and biodiversity (species abundance and composition), we believe that patch mosaic burning can be used as a management tool for biodiversity conservation and to reduce the risk of hazardous wildfires by creating a patchwork mosaic with different fire histories to generate heterogeneity across space and time. This practice would not only help preserve different ecosystems but also the sustainable use of natural resources by the Pemón people in the park.
In Canaima National Park (CNP), a protected area inhabited by Pemón Amerindians, social, demographic and cultural changes, have led to an unsustainable practice of fire use, resulting in forest reduction and habitat loss. Fire, mostly originated in savannas, is considered a threat because of its impacts upon ecosystems, triggering a process of forest substitution by treeless savannas. Also, Pemón people depend for their livelihood on the use of fire for shifting agriculture and hunting in forested areas. Fire exclusion has been the main fire management strategy adopted by government agencies at CNP. However, this has not been effectively achieved, because Pemón people do not agree with this approach, considering that it excludes the utilitarian and cultural significance of their burning practices. A long-term study of fire behavior and fire effects on biodiversity and biomass production in savanna ecosystems of the CNP shows that other management strategies could be possible. We simulated Pemón traditional methods of fire management by burning a series of 31 savanna plots of 50 x 100 m in different periods of the dry season over a seven-year period.
Results/Conclusions
We demonstrate that: a) fires can occur under a wide range of weather conditions and fuel characteristics, which in turn lead to a high variability in fire intensities, temperatures and spread rates, flame lengths, burn efficiencies and ash production; b) wind speed and fine fuel load constitute the principal drivers of fire behavior; and, c) opposite to what was longer believed, fires never reach an annual frequency but occur every 2, 3 or 4 years, due to the low recovery rates of the vegetation. Because fire could lead to a variety of scenarios depending on the amount of biomass (176 - 1,271 g.m-2), live/dead ratios (0.36 – 3.60) and biodiversity (species abundance and composition), we believe that patch mosaic burning can be used as a management tool for biodiversity conservation and to reduce the risk of hazardous wildfires by creating a patchwork mosaic with different fire histories to generate heterogeneity across space and time. This practice would not only help preserve different ecosystems but also the sustainable use of natural resources by the Pemón people in the park.
