Elucidation and Application of Ecosystem Recovery Mechanisms after Large-scale Fires
Toward the mitigation of global warming
In the Arctic region of North America, the scale of wildfires is increasing due to global warming. As a result, the way ecosystems recovery progresses after fires is changing, and it is urgent to elucidate the mechanism of ecosystem recovery from a new perspective. It is also necessary to develop various methods for ecosystem restoration after large-scale disturbance by applying the knowledge obtained in this study.
Content of research
The belts of taiga and tundra in Alaska is a fire-prone area associated with lightning strikes, and ecosystem recovery has thus been acclimatized to fire. In the past, the fires were mostly canopy fires with low fire intensity that did not lead to the complete burning of organic layers including peat. In particular, black spruce was dominant on north-facing slopes, and fast forest regeneration was achieved immediately after canopy fires due to dispersion of black spruce seeds.
However, with the development of climate changes, wildfires are increasing in both intensity and frequency. During the 2004 Alaska wildfires, the total area burned exceeded that of Shikoku (Japanese fourth mainland), and the organic layer was also burned away. As a result, ecosystem recovery after large wildfires greatly differs from that after forest canopy fires. In particular, the existence of an organic layer is essential for seed germination and growth, and the development of methods to promote the establishment of Sphagnum moss as a base material is essential for organic matter accumulation. In addition, we studied the impact of wildfires on the ecosystems in the tundra zone.
The landscape of a black spruce forest after a large fire in Alaska in 2004 (photo taken in 2005). With conventional fires, total destruction is rare, but with this fire, even the organic layer was burned away. As a result, the way how ecosystem recovery progresses has changed. It is necessary to elucidate the transition mechanism and develop conservation and restoration methods as soon as possible.
Changes in key ecosystem functions caused by wildfires. In the short term, CO2 is directly released during fires, and in the long term, CO2 absorption is reduced due to reduced photosynthesis and methane is released due to thawing of the permafrost. Thus, there are positive (exacerbating) feedback effects on global warming.
Potential for social implementation
- ・By specifying the intensity and scale of disturbance, it can be applied to the restoration of ecosystems in various large-scale disturbed sites.
- ・Formulation of appropriate ecosystem conservation and restoration plans, including greening and disaster mitigation
Appealing points to industry and local governments
The intensity, scale, and frequency of wildfires vary widely, and so do the e responses of plants to wildfires. Identification of the characteristics of fires will allow their application to the restoration of ecosystems after wildfires and other large-scale disturbances, taking greening and disaster mitigation and prevention into account. The photo shows a soot-covered face during the survey soon after the fire.