1. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences (SLU), SE–901 83, Umeå, Sweden;,
2. Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, Tennessee 37996;
3. Rocky Mountain Biological Lab, Crested Butte, Colorado 81224
4. Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, DK-2100 Copenhagen, Denmark