[1] Univ Hamburg, Bioctr Klein Flottbek Vegetat & Populat Ecol, D-22609 Hamburg, Germany
[2] Schleswig Holstein State Agcy Nat & Environm, D-24220 Flintbel, Germany
[3] Colorado State Univ, USDA, Rocky Mtn Res Stn, Nat Resources Res Ctr, Ft Collins, CO 80526 USA
[4] Colorado State Univ, Nat Resource Ecol Lab, Natl Resources Res Ctr, Ft Collins, CO 80526 USA
[5] Univ Stuttgart, Inst Landscape Planning & Ecol, D-70172 Stuttgart, Germany