Research

Collaborators on this project: Andrew Richardson, Lynne Zummo, Rachel Neurath

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. Presumably, 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. There are some indications that deep-soil carbon in eastern North American soils may be released during logging activities.

Collaborators on this project: Ross T. Jones, Thomas F. Gross, Stephen D. Blackmer

The Northern Forest is among the largest areas of relatively intact and undeveloped forest in the eastern United States. Increasing changes in landownership, wood extraction, nutrient cycling, air pollution and other human-caused impacts raise concern about long-term ecological and economic health of the forest. The division of the Northern Forest among several distinct groups of landowners makes the forest potentially vulnerable to large-scale fragmentation and development. We examined and characterized the current status of and potential threats to various aspects of the Northern Forest including land-use patterns, extent of forested area, species diversity, biological threats such as introduced species, pests and pathogens and air and water quality. Our findings reveal that total area of the Northern Forest and the sum total of tree growth minus tree removals is approximately stable, although there are variations within the region. Tree species diversity in recent decades is approximately equal. A number of viable woodland bird species show significant decreases both in the long-term and short-term while others are increasing in abundance. The water quality of most lakes, streams, and rivers, while generally improving, is still hampered by high levels of mercury, PCBs, and other contaminants in fish tissue. Land development and habitat fragmentation have remained a minor threat to the health of the Northern Forest in comparison to more highly disturbed forests (e.g., tropical forests). Continuation of this pattern will depend largely on whether or not trends in land purchases persist and if development--and resulting fragmentation--of the Northern Forest becomes economically viable.

Collaborators on this project: Tillman U. Gerngrossb and Richard B. Howarth

With increasing frequency, individuals deliberately choose specific actions which they hope will lessen environmental impact. Given the complexity of modern society, it is not always easy to know how to minimize environmental harm without sacrificing one's standard of living. Recycling of solid waste materials is a personal choice made by many people in the U.S.A. guided by the belief that recycling is not only good for the environment but that it constitutes a major contribution to improving environmental quality. By using energy usage as a proxy for overall environmental impact, we show that the overall impact reduction achieved through recycling varies for different materials. It is small but significant for some materials, such as aluminum, and minimal for other materials, such as plastic, when compared to other choices individuals make such as the type of vehicle they drive or the amount they drive. While the recycling of certain materials, such as aluminum, does result in measurable energy savings, the net benefit of recycling is orders of magnitude smaller than the gains that can be achieved from switching to more fuel-efficient vehicles. Despite this fact, environmental policy and public perception in the United States have focused on recycling rather than fuel efficiency and fuel economy.

Collaborators on this project: Jim Kaste, Stefan Sturup, Andrew Schroth, Ruth Yanai, Tom Siccama

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. In collaboration with Stefan Sturup and Jim Kaste, we sampled a 1 X 1 m plot that was sprayed with an enriched Pb-207 lead carbonate in 1983. Preliminary analyses have allowed a direct determination of lead migration in soil during the intervening 18 years. Migration rates appear to be similar to estimates by other methods. Early indications are that atmospheric lead will remain in soils for the immediate future.