1. B. H. Braswell and B. Moore III, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, USA.
2. D. S. Schimel, Ecosystem Dynamics and the Atmosphere, National Center for Atmospheric Research, Post Office Box 3000, Boulder, CO 80303, USA, and Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO 80523, USA.
3. E. Linder, Department of Mathematics, University of New Hampshire, Durham, NH 03824, USA.