[1] Univ Guelph, Dept Integrat Biol, Guelph, ON N1G 2W1, Canada
[2] McMaster Univ, Sch Geog & Earth Sci, Hamilton, ON L8S 4K1, Canada
[3] Canadian Forest Serv, Great Lakes Forestry Ctr, Sault Ste Marie, ON P6A 2E5, Canada
[4] Univ Alberta, Dept Renewable Resources, Edmonton, AB T6G 2H1, Canada