Forest fires and water erosion effects on soil organic matter in the Serrano River basin (Chilean Patagonia)

Abstract

Forest fires have become a major threat to some soils in the Chilean Patagonia. More than 36,000 ha of predominantly native forest have been burned in the last four decades in the Serrano River basin, most of them in the Torres del Paine National Park, a world biosphere reserve. A study was conducted to evaluate the effects of forest fires and water erosion on the SOM in the Serrano River basin. A total of 17 sites were sampled, three major soil types were found (Dystric Cambisols, Lithosols, and Luvic Phaeozems), and three main forest fires were identified. Soils were sampled at two depths and analyzed to determine their texture, organic matter content, cation exchange capacity, total N, P, and K, and aggregates stability. Soil erosion rates were estimated using the Water Erosion Prediction Project (WEPP) model with actual soil, vegetation, and weather data. The burned and unburned sites were not found to be significantly difference different in their SOM contents or other soil properties, with the exception of P availability. As a result of the bareness of their soil, the burned sites had the highest water erosion rates (9.25 t ha-1 yr-1) and SOM losses (0.93 t ha-1 yr-1).