J Renee Brooks, U.S. Environmental Protection Agency Corvallis, Western Ecology Division, Ecological Effects Branch, Corvallis, OR, United States, John S Roden, Southern Oregon Univ, Ashland, OR, United States, Rolf T Siegwolf, WSL Swiss Federal Institute for Forest, Snow and Landscape Research, Birmensdorf, Switzerland and Mattias Saurer, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland