Colette Brown

The Arctic is warming four times more than the global average, and this warming is causing an increase in total area burned. In my dissertation I investigate how high-severity wildfires in the Arctic cause shifts in the vegetation composition and abundance. My preliminary results suggest a move toward a more shrub, rather than graminoid-dominated ecosystems.

Wildfires in the Arctic are increasing in area, duration, and severity, with uncertain impacts on Arctic ecosystems and their carbon dynamics. Vegetation recovery plays a significant role in both, but large spatial heterogeneity and the remote nature of fire scars make it challenging to predict post-fire vegetation succession trajectories. Robust quantification of vegetation recovery after fire is lacking and a fresh approach is needed. In my work, we have taken the largest recorded tundra fire – the 2007 Anaktuvuk River Fire and adjacent unburned tundra in northern Alaska – as a case study, we use satellite imagery and a random forest model to generate annual maps of plant functional types (PFTs) at a 30 m resolution pre-fire and for 13 years afterwards (2005-2020). Early results indicate high model accuracy and precision for evergreen and deciduous sub-shrub classes, which are hypothesized to have the greatest long-term impacts on the Arctic carbon budget. The documented increases in vegetation cover and changes in vegetation composition post-fire have implications on ecosystem function and carbon budgets with increasing wildfire in the Arctic.