"Forests on both the eastern and western slopes of the Cascade Range will lose carbon stored in live biomass because area burned across the state is expected to increase," Raymond said. "Even small increases in area burned can have large consequences for carbon stored in living and dead biomass."
The researchers looked at live biomass, which includes living trees and vegetation, as well as nonliving biomass in the form of coarse woody debris, which includes dead standing trees and downed logs. Both contribute to the carbon cycle, but in different waysliving biomass removes carbon from the atmosphere as vegetation grows, and coarse woody debris releases carbon over time as the material decomposes.
Raymond and McKenzie projected forests of the Western Cascades to be most sensitive to climate-driven increases in fire, losing anywhere from 24 to 37 percent of their live biomass and from 15 to 25 percent of their coarse woody debris biomass by 2040. These forests store significant carbon and typically burn with high severity, killing many trees and consuming coarse woody debris.
On the other side of the mountains, the researchers also projected a decrease in live biomass by 2040of anywhere between 17 and 26 percent in the Eastern Cascades and in the Okanogan Highlandsbut no change in coarse woody debris biomass, or possibly even an increase, because coarse woody debris biomass increases as trees are killed by fire and subsequent low-severity fires burn only a small portion of it.
"Changes in fire regimes in a warming climate can limit our potential to use forests in the Pacific Northwest to store a
|Contact: Yasmeen Sands|
USDA Forest Service - Pacific Northwest Research Station