Mobilization of Carbon and Organic Matter after the Rim Fire, Yosemite National Park

Erosion is a significant driver of soil carbon (C) cycling in fire-affected forest uplands, such as the Sierra Nevada. The Rim Fire burned over 250,000 acres of forest in Yosemite National Park and Stanislaus National Forest between August and October of 2013. Enhanced post-fire erosion rates have already been well documented in other ecosystems, however these enhanced erosion rates need to be quantified and impacts on soil organic matter (SOM) quality need further investigation. Sediment fences were established along a singular hillslope in three separate combinations of fire severity (high or moderate) and hillslope steepness (high or moderate). Sediment was collected from these fences after each major precipitation event from after the fire through the spring of 2014. The initial storm events (one during February and one during March) transported an order of magnitude more sediment than the later events (sampled in April and May), however the initial events had more sand size class than the April and May events. This may be indicative of changes in the quality of organic matter and the quantity of C transported during the months following the Rim Fire. We will also present initial bulk C and nitrogen transported in sediment within this hillslope, with estimates of C mobilization throughout the fire area.