[1] Univ Firenze, Dept Agr Food Environm & Forestry DAGRI, Piazzale delle Cascine 28, I-50144 Florence, Italy
[2] Croatian Forest Res Inst, Div Forest Ecol, Cvjetno naselje 41, Jastrebarsko 10450, Croatia
[3] Norwegian Inst Bioecon Res NIBIO, Dept Fungal Plant Pathol, Div Biotechnol & Plant Hlth, Hogskoleveien 8, N-1431 As, Norway
[4] Swiss Inst Forest, Snow Landscape Res WSL, Zurcherstr 111, CH-8903 Zurich, Switzerland