1. Rubenstein School of Environment and Natural Resources University of Vermont Burlington VT05405 USA
2. Department of Biology Western Washington University Bellingham WA98225‐9160 USA
3. Centre for Forest Research Département des sciences biologiques Université du Québec à Montréal CP 8888, Succursale Centre‐ville Montréal QC Canada H3C 3P8
4. Center for Ecosystem Science and Society and Department of Biological Sciences Northern Arizona University Flagstaff AZ86011 USA