1. Forest and Rangeland Stewardship Department and Colorado Forest Restoration Institute, Colorado State University, 1472 Campus Delivery, Fort Collins, CO 80523, USA
2. School of Environmental and Forest Sciences, University of Washington, Box 352100, Seattle, WA 98195-2100, USA
3. Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, 5320-122nd St. NW, Edmonton, AB T6H 3S5, Canada
4. School of the Environment, Washington State University, Pullman, WA 99164, USA