The Impacts of Prescribed Fires on the Physical and Chemical Properties of Soils

Although wildfires result in tremendous financial and sometimes human losses, they also provide essential ecosystem services to forests or other wildland areas. Lightening naturally ignites wildfires, which clean out underbrush and minimize fuel load. However, over one hundred years of fire suppression has left forests accumulating fuel and susceptible to large-scale destructive fires. As the ever-increasing population of California drives people closer to these wildland areas, the chance for human ignited fires increases. As a result the growing fuel loads and increasing risk to populations, forest managers now actively manage many forested regions to reduce fuel load and minimize the likelihood of catastrophic wildfires. This study investigated the impacts of two fire management strategies (localized pile intense burning and regional mild broadcast burning) in two forest types (old growth and secondary growth) on the soil environment.Soil tests of biogeochemical properties were performed pre-, one year post-, and two year post- fire to observe initial impacts and subsequent recovery of fundamental properties including hydrophobicity, infiltration rate, and grain size distribution. Results indicate that management strategies and forest types result in differing magnitude of initial changes soils, as well as differing rate of longer-term recovery.Future work will incorporate carbon and nitrogen analyses and mineralogical analysis (results pending) to determine nutrient availability, ecosystem recovery, and sediment weathering. This project is an integral piece of ongoing research that will contribute new insights into how best to manage forests to minimize fire risk and maximize natural ecosystem functions