1. Institute of Plant Sciences; University of Bern; Altenbergrain 21; CH-3013; Bern; Switzerland
2. Institute of Biochemistry and Biology; University of Potsdam; Maulbeerallee 1; D-14469; Potsdam; Germany
3. Institute of Landscape Ecology; University of Münster; Robert-Koch-Str. 28; D-48149; Münster; Germany