1. Central Great Plains Research Station USDA-ARS; Akron CO 80720
2. School of Environ. and Natural Resources Ohio State Univ.; Wooster OH 44691
3. Dep. of Environmental Systems Science; Swiss Federal Institute of Technology; Zurich
4. Plant Science Research USDA-ARS; Raleigh NC 27695
5. Soil and Crop Sciences Colorado State Univ.; Fort Collins CO 80523
6. Santa Rosa Junior College; Santa Rosa CA 95401
7. Dep. of Natural Resources and the Environ.; Univ. of New Hampshire; Durham NH 03824
8. Center for Climate Systems Research; Columbia Univ.; New York NY 10027