1. School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Dr., Houghton, MI 49931, USA.
2. USDA Forest Service, Northern Research Station, Center for Research on Ecosystem Change, 1831 Hwy 169 East, Grand Rapids, MN 55744, USA.
3. Natural Resource Sciences, Thompson Rivers University, 900 McGill Road, Kamloops, BC V2C 0C8, Canada.