The Changing Face of Alaska
The Changing Face of Alaska
Jennifer Barnes wants to be able to predict the future. She does not look into a crystal ball, nor does she read tea leaves. She does, however, measure various indices of wildfire burn severity, and compares those with forest regeneration following the fire. The idea is to be able to use those indices predict the future of forest succession, on a landscape scale, after a forest fire. There is no magic involved, but there are a lot of measurements and data.
Wildfire is a natural part of interior Alaska’s boreal forests, but in the face of a warming climate, it could be one of the fastest drivers of change in Alaska’s landscape. Black Spruce forests commonly exist over permafrost – that is, permanently frozen ground insulated from the hot interior sun by a thin layer of organic soil and a thick coat of spongy moss. The shallow depth of the soils limits the ability of trees to put down roots, and so the landscape is often dominated by small, tightly-spaced black spruce. Thunder and lightning is a common summertime event in Alaska’s interior, and when the lightning ignites a fire, the tightly-packed black spruce burn like crazy.
Alaska has one of the fastest-warming climates on the planet, and the future of permafrost is in question. Wildfire is a big part of this equation: when a black spruce forest burns, what will grow back?
NPS scientists Jennifer Barnes and Carl Roland (with the help of their colleagues) are looking into exactly this. One thing they’re interested in is what they call “burn severity,” and how this interacts with forest regeneration.
Based on early observations, it appears that in low-severity burns – where the thick moss layer remains unburned – black spruce can regenerate, preserving the ground frozen below (at least for now). However, in high-severity burns, where the fire burns down to mineral soil, exposing the frozen soils to interior Alaska’s hot summer sun, the permafrost can rapidly thaw and a whole different kind of forest will take its place. This process has the potential to rapidly transform the landscape of interior Alaska, and this research may yield a view into the crystal ball, allowing the prediction of the future of Alaska's landscape.
These photos were taken in cooperation with the National Park Service.