1. CFAES, Carbon Management and Sequestration Center, The Ohio State University, Columbus, OH 43210, USA
2. Department of Plant and Environmental Sciences, New Mexico State University, Las Cruces, NM, USA
3. Biological Station and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
4. Northern Institute of Applied Climate Science, Houghton, MI, USA
5. Institute of Biological and Environmental Sciences, University of Aberdeen, Aberdeen AB24 3UU, UK