Site: Bonanza Creek LTER

A recent shift in the Alaska fire regime has increased the frequency and size of high-severity fires that combust deep organic layers, exposing mineral soil and favoring the invasion of hardwoods. Within the BNZ LTER Regional Site Network, many sites that were dominated by black spruce prior to burning in 2004 have now converted to dense birch stands with very different vegetation and ecosystem characteristics (BD1 site).
Credit: Roger Ruess

 

Severe late summer fires consume the soil organic layer, allowing deciduous tree species, such as aspen and birch, to establish at high densities. The fast decomposing litter and rapid evapotranspiration of deciduous trees maintain a thinner, drier organic layer that does not sustain spruce forests or insulate permafrost. This ecosystem state change alters an iconic Alaskan ecosystem by modifying productivity and carbon storage, climate regulation, and other ecosystem services to society.