MEAN ANNUAL temperatures for the northeastern U.S. are projected to increase 3-5 °C by the year 2100, which could increase water and nutrient uptake and carbon storage by trees. However, the increase in temperature will lead to a smaller winter snowpack and increased frequency of soil freeze/thaw cycles, which may offset the positive effects of warming by damaging roots. The overall result could be reduced nutrient uptake and storage of carbon and further elevation of atmospheric CO2 concentrations. Understanding the mechanisms and controls underlying changes in nutrient uptake by trees is necessary for improving predictions of how ecosystems will respond as the climate changes. Whereas many studies have evaluated the impacts of climate change on forests within a single season, few have examined the impacts of climate change across seasons and how these impacts interact. These "across season" effects could be antagonistic or synergistic, which would not be apparent from examining one season alone.
The goals of this research are to determine the interactive effects of winter and growing season climate on water and nutrient uptake and carbon sequestration in northern hardwood forests. These goals are being accomplished with a new ecosystem warming experiment at Hubbard Brook.
We hypothesize that warmer soil temperatures will increase forest productivity, as well as rates of water, carbon, and nutrient uptake by trees and saplings. However, we expect that a reduced winter snowpack and increased soil freezing will offset these changes by damaging roots. Results from this study will help us understand the effects of climate change on rates of carbon sequestration and nutrient retention of these forests, as well as potential effects on water air and water quality.
Funding for the establishment of this experiment came from the Long Term Ecological Research Network and a National Science Foundation CAREER grant (DEB 1149929).