1. Department of Biology University of Oulu P.O. Box 3000 FI‐90014 Oulu Finland
2. Institute of Agriculture and Environment ‐ Ecology Massey University Private Bag 11‐222 Palmerston North New Zealand
3. Finnish Environment Institute Natural Environment Centre University of Oulu P.O. Box 413 FI‐90014 Oulu Finland
4. Thule Institute Oulanka Research Station Oulanka Finland
5. Horizons Regional Council Private Bag 11025 Palmerston North New Zealand