Wildfires risk and spatio-temporal dynamic in the Chiquitania region (Bolivia)

Wildfires risk in the Amazonian forest will probably increases in the future as a consequence of the predicted increased frequency of droughts combined with the growing rate of deforestation. The main cause of fire ignition in the Amazon tropical rainforest is anthropogenic (human-made). Indeed, burning is the easiest and cheaper way to clear the land, especially in the absence of transport or roads. This practice, known as slash-and-burn, consist on cutting trees and low vegetation/agricultural residuals and finally burning the biomass. The purpose is to make way for agriculture, livestock, logging, or simply to clear the agricultural land for new cultivations. In Bolivia this centuries-old practice of burning portions of tropical forest to prepare fields for the next year’s crop is called chaqueo. This practice can get out of control and initiate large fires, burning hectares and hectares of forest. Moreover, in September 2019 a controversial national decree, allowed the use of chaqueo in forestry areas to promote the expansion of the agricultural frontier, triggered an unprecedented situation. Although it is evident that fires in Bolivia, mainly cause by the practice of chaqueo, and land use and land cover change (LULCC), mainly the deforestation, are related, the spatio-temporal association among these two elements has not been deeply investigated jet.

The present study aims at investigating the spatio-temporal evolution of wildfires in the Chiquitania region, Bolivia, and its relationship with LULCC, particularly with regards to the deforestation, in the last three decades. The investigated region is located in the Department of Santa Cruz and is part of the Chiquitano dry forest ecoregion - spreading over Bolivia, Brazil and Paraguay - connecting the Gran Chaco shrublands to the south with the Amazon rainforests to the north. The characteristic tropical forest biome combined with the the near future drier and more seasonally extreme climatic conditions will increase the risk of wildfires in the Chiquitania region. Changes are also driven by the actual policies supporting the settlement of new farming communities and the expansion of the agricultural frontier and the road network in the region.

The investigation methods are based on a geospatial statistical approaches allowing to: 1) explore LULCC within the entire the study period and elaborate the map of changes showing the transitions among different classes; 2) quantify gained and lost areas for the classes forest, urban and croplands; 3) investigate the evolution in space and in time of fires and map local over-densities; 4) asses the main drivers for fire risk in the region.