1. Department of Ecosystem Science and Management, University of Wyoming, Laramie WY, USA
2. Department of Evolution, Ecology and Organismal Biology, The Ohio State University, Columbus OH, USA
3. Department of Plant Sciences, Stable Isotope Facility, University of California, Davis, Davis CA, USA
4. Max Planck Institute for the Science of Human History, Kahlaische Str. 07745 Jena, Germany
5. Department of Evolution, Ecology and Organismal Biology, The Ohio State University at Mansfield, Mansfield OH, USA