Several active fire signals in Venezuela and Columbia are recorded by NOAA/OSEI with the NOAA AVHRR Sensor on 3 April 2000.
Fig.1. NOAA image of the vegetation fires in Venezuela and Columbia 3 April 2000
The fires are currently burning in a subregion of Venezuela between the Rio Orinoco and the Cordillera de Mérida. The main vegetation type affected by the fires in this region is a mosaic of grassland and fragmented forest cover. The satellite image shows further a second main fire area in the northern part of Columbia. Fires take place in agricultural mosaic-cultivated land with degraded formations. Some of these fires may be controlled burns.
Most of the fires in South America must been seen in the context of intensive land development. Fire is used as a tool in forest conversion. This is done by small farmers as well as large agro-industrial companies. The careless use of fire often allow the “prescribed” burnings to escape and become forest fires in the adjacent forests. These wildfires are of global importance because they threaten global biodiversity as well as the livelihood and cultural identity of the indigenous people in South America.
Almost all fires in the Venezuela and Columbia are human-caused, natural fires play a minor role in the tropical rain forest of South America. In the seasonally dry forests and bush formations (cerrado) lightning fires are observed occasionally.
Under normal weather conditions the primary forest in the humid tropics does not catch fire. The hydrological cycle in the closed forests produces a very humid microclimate where unfavourable conditions for forest fire exist. But in forests where selective logging already took place the former closed canopy is disturbed. This allows more light to penetrate through the canopy and thereby changing the energy balance within the forest – the forest becomes more susceptible to drought and consequently to fire.