Wildfire dynamics and impacts on a tropical Andean oak forest

Wildfires have increasingly damaged Andean tropical forests. However, both a poor understanding of wildfire dynamics and ecosystem response limits awareness about the magnitude of the problem and design management strategies. We estimate the impacts and significant drivers of wildfires by dating and mapping recent wildfires in an Andean tropical forest area, the Iguaque mountains. A large part of Iguaque hosts a population of the only Quercus species in South America, Quercus humboldtii. We used remote-sensing, official reports and social mapping to reconstruct the recent history of wildfires and change in oak forest patches in Iguaque. Between 1990 and 2017, 25 wildfires were recorded, with fire intervals between 4 and 21 years. These events burned 28.4% of the Iguaque mountains and showed a significant increasing trend in extent. Wildfires mostly occurred in the south, during the driest months, and their number and extent showed substantial interannual variations related to El Niño-Southern Oscillation cycles. Wildfires contributed to a 45% reduction in oak forests along with the fragmentation of existing populations. Our study presents evidence of the extent and impact of wildfires in Iguaque and provides new insights on fire dynamics in Andean tropical forests.