2026/04/25 by Stewart G. Wilson, John F. Brune, Yamina Pressler · 1 voice
Environmental Science · #Fire effects on ecosystems
paper · doi:10.1016/j.geoderma.2026.117815
openalex created_date 2025/10/10 · openalex publication_date 2026/04/25 · openalex updated_date 2026/07/15
Wildfire activity in the Western United States has increased with widespread consequences for soil biogeochemistry and forest ecosystem resilience. As wildfires become more severe and frequent, the reoccurrence of high-severity wildfires on decadal timescales is expected to increase. However, studies that examine the impacts of repeated wildfires on forest soil properties were limited. This study investigates the effects of sequential high-severity wildfires in temperate conifer forests on soil carbon and nitrogen dynamics, soil nutrients, and pH. We studied two locations in California that experienced sequential, overlapping high-severity fires within an 11-year period: Sierra Nevada (2014, 2020) and Coast Range (2009, 2020). Soil samples were collected in combinations of soil burn severity classes for each fire (high-high, high-unburned, unburned-high, and unburned-unburned) to assess the effects of single vs. repeated high-severity wildfire on soil properties. Repeated high-severity wildfires significantly impacted the carbon, nitrogen and phosphorus cycles. For example, repeated high-severity wildfires reduced total soil organic carbon, total nitrogen, and mineralizable carbon at both sites. Permanganate-oxidizable carbon was lower after repeated high-severity wildfire in the Coast Range, but not the Sierra Nevada. Available phosphorus decreased with single and repeated wildfire at both sites. While patterns generally agree between the two sites, soils in the Coast Range were more responsive overall and some idiosyncratic differences between sites, fire combinations and soil properties were observed. These findings suggest that repeated high-severity wildfires may exacerbate negative impacts to soils from single wildfires in some contexts and could hinder long-term soil recovery and forest soil resilience.