Sustainable Biomass Use in the Northern Forest

Collaborators on this project: Chelsea Petrenko, Serita Frey

There are reasons to question whether increased reliance on biomass in the northern forest will actually contribute to stabilizing or reducing atmospheric carbon dioxide concentrations. Many researchers have concluded that older forests in the Northern Forest are in a near-steady state (i.e., respiratory losses are equal to photosynthetic uptake) and are no longer actively sequestering carbon. If this is true, then burning wood to displace fossil fuel, and converting older forests to younger, faster growing forests should utilize modern carbon rather than fossil carbon and replace a carbon-neutral forest with a carbon accumulating forest. Under this scenario, the carbon released by burning wood from a mature forest would be sequestered more rapidly by young forests than old forests and would result in a net reduction in atmospheric carbon concentrations. However, if during the removal of biomass, sequestered carbon stored deep in soil is mobilized and released to the atmosphere, the active harvesting of woody biomass may not actually be carbon neutral. Our recent work, and that of others, has led to the suggestion that deep-soil carbon in eastern North American soils may be released during logging activities.


Trace Metal Accumulation and Loss

Collaborators on this project: Justin Richardson, Jim Kaste, Brian Jackson

Atmospheric lead deposition has decreased significantly in the last two decades. However, there are large quantities of lead bound in the organic horizon of forest soils. Earlier work identified that this lead was slowly moving downwards, and could possibly enter streams and aquifers in 50-100 years. In the summer of 2001, we resampled forested sites sampled in 1980 and 1990 to gain an understanding of lead losses and indirectly calculate lead leaching rates. We sampled a 1 X 1 m plot that was sprayed with an enriched Pb-207 lead carbonate in 1983 allowing a direct determination of lead migration in soil during the intervening 18 years. It is likely that atmospheric lead will remain in soils for the immediate future. We have reported on the results of a resampling of our sites in 2011 and have expanded our analyses to include mercury (Hg).