Is deforestation beneficial? The knee-jerk reaction by most people involved in green building would be "No way!", however a study from Dartmouth College is saying "Well, maybe."
The study raises questions about how strong of a role carbon sequestration and albedo should play in forest management decisions depending on geography. The study, whose findings were presented at the American Geophysical Union'sfall meeting last December and are published in Climatic Change Journal this month, asserts that more frequent logging or deforestation may be beneficial in high latitude areas where snowfall is common and timber productivity is low. In these areas, the study findings suggest that snowfall on the ground may provide greater climactic benefits than a standing forest, based on the surface reflection of solar energy off of the snow and the rotation periods of that forest. If this is true, could the future hold a cap-and-trade style program that pays land owners to maintain snow cover, rather than conserve forests in these regions?
The study argues that albedo should be valued in a manner similar to carbon so that it can be adequately factored into forest management in the context of climate regulation. One of the theories tested in the study is that the cooling effects of albedo (the reflection of solar radiation off of a surface) can be equal to or greater than the benefits of carbon sequestration from forest growth, depending on the lifespan of the forest and its geographic location. To test this, the researchers placed an economic value on albedo-related shortwave radiation using shadow prices, and examined the potential effect of this value on two forest types in the White Mountain National Forest (WMNF) in New Hampshire against the value of just considering timber and carbon sequestration. In the forest, they modeled the effects over hardwood and softwood forest rotations, with a rotation period defined as the time frame from when new trees are planted to when most of the trees are harvested, according to a release from the College.
According to a draft of the study released ahead of time, the research models seek to "discuss the influence of each ecosystem service on the optimal rotation period for each forest stand type, comment on the potential ecological impact of including albedo, examine how such results may vary in forests with different growth trajectories, and provide a scenario in which climate change abatement is more stringent."
Consider, for example, what is factored into determining an optimal rotation period for a forest. The Dartmouth study found that optimal rotation periods for hardwood and spruce-fir forest in the WMNF were 33 and 34 years, respectively. However, when carbon sequestration was valued into the equation, the optimal periods grew to 81 and 248 years, respectively. Then, when albedo was also calculated into the equation, the rotation periods dropped to 69 and 28 years, respectively. In the case of the spruce-fir forest, factoring in albedo lowered the optimal rotation period the most, which the researchers posit "is a result of the large benefits of albedo compared to the somewhat limited potential overall carbon storage benefits."
So how does this translate to a boost for deforestation? Based on this research, the study authors go on to say that if albedo was more frequently assessed in climate mitigation projects, "high-latitude low-productivity forests with minimal carbon sequestration potential and frequent snowfall are more likely to be harvested more frequently." While the study focused on New Hampshire, its co-author David Lutz, a post-doctoral research associate at Dartmouth, said "high-latitude forest" could refer to forests across the northern hemisphere where there is often substantial snow cover and the biggest activity, in this regard, would be farther North and likely in Canada.
However, Lutz and his co-author Richard Haworth, a professor and environmental economist at Dartmouth, note that the same deforestation seen as beneficial in the context above could also be harmful to forest biodiversity and "compromise the generation of other ecosystem service." And another caveat exists: If snowfall were to decrease in these areas due to climate change, it would decrease albedo values, which would affect the model.
The final conclusion? More research is needed on the relationships between snowfall, albedo, and forest structure, with critical recognition that "optimal forest management may vary quite drastically as the planet responds to climate change."
Photo courtesy Flickr user Iain Farrell under a Creative Commons license.