Descripción del régimen de incendios del bosque seco tropical de la cuenca alta del Río Magdalena y su relación con la variación climática

Abstract

Fire is a disturbance that has modeled the dynamics and diversity of many ecosystems over time. In ecosystems such as the Tropical Dry Forest (BS-T) of Alto Magdalena, a large number of forest fires have been reported, but their occurrence and dynamics are unknown over time. The objective of this work was to describe the fire regime of the BS-T, based on the annual and multiannual climatic variation of precipitation, temperature, relative humidity and extreme events such as the El Niño phenomenon. First, the occurrence of fires in the dry forest cover was obtained between 2000 and 2017. This was done through the classification of annual forest maps with the use of Landsat 7 and 8 satellite images and overlapping with the thermal anomalies of the MODIS sensor for the same period. Second, the climatic variables precipitation, relative humidity and maximum temperature obtained from local stations were spatialized. These climatic variables were correlated with the number of fires and their temporal distribution. 424 fires were found, as well as two fire hotspots in the municipalities of Ortega and Coello, in the department of Tolima, with a frequency of up to 5 fires in 18 years. In terms of the relation of fires and climatic variables, the severity of the dry season measured as the accumulated rainfall was correlated with a high probability of occurrence of fires. Likewise, a relationship was found between the occurrence of fires and the El Niño phenomenon. From these results, the presence of fires in the BS-T and its strong relationship with the severity of the dry season and its distribution in the upper Basin are recognized in recent years, allowing detailed information on the threat and areas to prioritize in departmental and municipal risk management plans, as well as early warnings and fire risk management.