Fire has been historically rare in the Arctic tundra, but is projected to increase in severity and frequency in a future warmer world. The rarity of fires in this biome has made it challenging to measure, understand, and predict the consequences of fire on important ecosystem services such as species diversity and ecosystem carbon cycling. Furthermore, the impacts of fire last a long time-- years to decades-- by altering critical biogeochemical cycles that are important for long term ecosystem recovery. Since fire severity can dramatically reduce soil nutrient availability, it is hypothesized that ecosystem recovery is dependent on both burn severity and post-fire soil resources. This project continues a ten-year project studying the effects of fire on terrestrial carbon cycling in Alaskan tundra ecosystems. The research combines long-term ecological observations, a nutrient addition experiment, and improvement of an ecosystem model. Training and workforce relevant skills for both undergraduate students and graduate students are being provided. A children’s book will be published to reach the general public, as well as a YouTube video. A large amount of data about ecosystem processes is being contributed to public databases. This research will acquire and synthesize a multi-decadal record (2008-2026) of ecosystem function from the unprecedented 2007 Anaktuvuk River fire on the North Slope of Alaska. Eddy covariance fluxes and biomass harvests will measure temporal changes in ecosystem carbon fluxes and stocks across a burn severity gradient (Severe-, Moderate-, and Un-burned tundra), while nutrient fertilization experiments at the Severe- and Un-burned tundra sites will determine the role of nutrient availability on the rate of ecosystem recovery. These records will inform a coupled biogeochemical model (i.e. the Multiple Element Limitation [MEL] model) to improve predictions of the long term impacts of fire on Arctic ecosystem carbon cycling. The development of the MEL model will provide a powerful tool for scientists, land managers, and policy makers to quantify the future impacts of fire in this rapidly-changing region.

This project will continue a Long Term Research in Environmental Biology (LTREB) to investigate how soil nutrient availability affects long-term Arctic tundra ecosystem recovery following wildfire disturbance. Fire has been historically rare in Arctic tundra, but with climate warming, fire frequency and severity are expected to increase. The team seeks to understand how burn severity and nutrient availability influence post-fire recovery trajectories, particularly with respect to ecosystem carbon cycling, species composition, and biogeochemical feedbacks. The study builds on more than a decade of data collected since the 2007 Anaktuvuk River Fire. The project will inform how climate-driven changes in fire regimes impact ecosystem services over decadal timescales. Field access is primarily supported through Toolik Field Station infrastructure, and helicopter support to access remote tundra plots which include boardwalk maintained by Battelle ARO. Fieldwork is conducted annually from mid-May to early September 2022 through 2026. From 2022 through 2024, researchers visited three field sites via helicopter representing a burn severity gradient (Severe, Moderate, and Unburned tundra). Fieldwork included greenhouse gas flux measurements, biomass harvests, and ecological monitoring. Nutrient addition plots were maintained at the Severe and Unburned sites to assess the role of nitrogen and phosphorus in ecosystem recovery. In 2023, an expanded team of eleven participants conducted a large-scale biomass harvest ("pluck") collecting tundra vegetation and separating samples into components for drying, weighing, and analysis. This provided information for ecosystem carbon modeling. In 2025, a team of five researchers will deploy to Toolik Field Station to continue burn site measurements of soil nutrients and additional parameters used as model inputs. Remote site day trip access will continue via Toolik-based helicopter support and established boardwalk infrastructure. This is the final year of fieldwork for the project. Battelle ARO will demobilize boardwalk in 2026.

Battelle ARO will provide user days at Toolik Field Station, satellite phone, medical kits, helicopter support and inert bear spray. The University of Alaska, Fairbanks (UAF) Institute of Arctic Biology (IAB) will provide access to services and infrastructure at Toolik Field Station. All other logistics, including land use permits, will be arranged and paid for by the PI from the research grant.