1. Western University, 1151 Richmond St., London, ON N6A 5B7, Canada.
2. INSTAAR, 1560 30th St., Boulder, CO 80309, USA.
3. US Geological Survey, 6000 J St., Sacramento, CA 95819, USA.
4. Plymouth State University and Northern Research Station, US Department of Agriculture Forest Service, Plymouth, NH 03264, USA.
5. US Geological Survey, 3215 Marine St., Boulder, CO 80303, USA.
6. US Geological Survey, 425 Jordan Rd., Troy, NY 12180-8349, USA.
7. Cary Institute of Ecosystem Studies, P.O. Box AB, 2801 Sharon Turnpike, Millbrook, NY 12545, USA.
8. US Geological Survey, P.O. Box 628, Montpelier, VT 05601, USA.
9. US Geological Survey, 1770 Corporate Drive, Norcross, GA 30093, USA.
10. US Geological Survey, Denver Federal Center, Denver, CO 80225, USA.
11. Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden, 090-7868584.
12. Division of Earth and Ocean Sciences, Nicholas School of the Environment, Duke University, 109 Old Chemistry, P.O. Box 90227, Durham, NC 27708-0227, USA.
13. Department of Forest Resources and Environmental Conservation and Virginia Water Resources Research Center, Virginia Tech, 210 Cheatham Hall, Blacksburg, VA 24061, USA.
14. US Geological Survey, MS 413 National Center, Reston, VA 20192, USA.