1. Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham NH 03824, USA.
2. Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, PA USA.
3. Northern Research Station, USDA Forest Service, Durham NH USA.
4. Peatland Ecology Group, Department of Forest Sciences, University of Helsinki, Helsinki, Finland.
5. Department of Geography, McGill University, Montreal, QC, Canada.