A Look at Amazon Basin Seasonal Dynamics with the Biophysical ...

Fire behavior in savannas of Parupa, North Gran Sabana, VenezuelaBibiana Bilbao 1 , Carlos Méndez, Alejandra Leal & Maria Dolores Delgado. 4Departamento de Estudios Ambientales, Universidad Simón Bolívar, Apartado 89000,Caracas, Venezuela.1. bbilbao@usb.ve, 2. carlosmendez@etheron.net 3. 4. mdelgado@cesma.usb.veThe objective of this study was to estimate the fuel properties and meteorological variablescontribution in fire behavior in savannas of Parupa, North Gran Sabana, Venezuela. Firebehavior were studied in experimental burns done in fifteen 0.5 ha plots under differenttreatments: at the beginning, middle and the end of dry season in year 2000, 2001 and 2002with 3, 4 and 5 years of fire exclusion, respectively. Before and after burning, a total ofnine samplings per plot were carried out to estimate frequency, density and cover of plantspecies, humidity content and fuel accumulation. Meteorological variables were recordedduring the experimental burns, and air and flame temperature, fire propagation speed;combustion efficiency, and characteristic of ashes were also determined. Dailymeteorological variations had a major effect on fire behavior than seasonal variations in thedry period. Meteorological variables, as wind speed and % relative humidity, had a majorcontribution on fire behavior than those of fuel material (800-1200 g m -2 ). However, a lowfuel accumulation in plots burned in year 2000, did not allow a new burning for twoconsecutive years. The combustion efficiencies were lower respect to those reached inOrinoco Llanos (Central Plains), in part due to a high fuel humidity (22 to 54%), irregulardistribution of vegetation and specially to the presence of big superficial rhizomes thatmaintain live tissues during the dry season.