Recovery of arctic tundra carbon and energy fluxes from fire
Arctic ecosystems are experiencing large ecological and environmental changes as a result of increased temperatures. Cold temperatures have allowed arctic soils to accumulate carbon, and as a whole, arctic soils contain nearly twice the amount of carbon that is currently in the atmosphere. The impact of increased temperature on arctic carbon cycling will result in both direct and indirect impacts that could feedback into future climate change. One of these feedbacks could be a change to the arctic fire regime that results from increased growing season length, soil temperature, permafrost thaw, vegetation cover, and species composition as a response to increased temperatures.
Fires release carbon into the atmosphere, decrease surface albedo, and remove vegetation and soil organic carbon from the surface; all of which have a warming effect on the atmosphere. Vegetation returns to the surface after fire in a process known as secondary succession. Secondary succession is poorly understood in the arctic, but may follow different trajectories that will influence the long-term impact on climate and ecosystem function. Post-fire recovery in tundra ecosystems could be; non-existent to slow, which would degrade the systems ability to sequester carbon in the future; fast, which would indicate that fire impacts on carbon cycling are brief; or result in a change in dominant species, which would be a long term and permanent impact on species function. It is currently unknown, which one of these post-fire succession trajectories is the most common.
In this project, we are measuring carbon cycling processes in different aged fires scars to parameterize a model of post-fire secondary succession in arctic systems. Carbon cycling processes are measured with several roving eddy covariance towers and biomass harvests in different areas and over a single growing season for the next two years. These data will be used to parameterize an ecosystem process model of carbon and nutrient cycling (i.e. MEL: Multiple Element Limitation) and will be scaled up to the region with remote sensing data from MODIS. We will determine how long these systems take to recover from fire and how potential future changes to the arctic fire regime will influence regional carbon cycling in Alaska.