Spatio-temporal effects of human drivers on fire danger in Mediterranean Chile

Abstract

The aim of this study was to analyze how human factors, specifically land use and cover change (LUCC), influence wildfire danger in a mediterranean region of central Chile. Main drivers of LUCC were associated with changes in socio-economic conditions, which had strong effects on the structure of the landscape and on the danger of wildfires. Ignition and flammability were evaluated as key components of fire danger. Ignition probability was modeled for 1999 and 2009 using an autologistic regression, based on fire records from Corporación Nacional Forestal (CONAF) and geographic, biophysical, and socioeconomic databases. Flammability was assessed by combining the National Vegetation Cadastre of 1999 and its update of 2009, and the fuel model developed by Julio (1995). Spatiotemporal analysis of flammability was performed and related with primary LUCC processes, namely, plantation expansion, forest regrowth, and agricultural abandonment. We combined the ignition probability and flammability analysis to produce wildfire danger maps. Results show that fire danger is a dynamic indicator that depends largely on human factors. By 1999, the area under high fire danger comprised 31,399 ha, whereas by 2009 this area had increased by 54,705 ha. For both periods, wildfire danger had a similar spatial distribution, concentrating near main roads, cities, and larger towns (26.3 % of the high fire danger area). Also high fire danger areas concentrated over zones covered by exotic forest plantations (33.2 %). These results provide a basis for a more effective design of fire control strategies.