1. Centre for Integrative Ecology; School of Biological Sciences; University of Canterbury; Private Bag 4800 Christchurch 8140 New Zealand
2. Department of Life Sciences; Imperial College London; Silwood Park Campus Buckhurst Road Ascot Berkshire SL5 7PY UK
3. Bio-protection Research Centre; School of Biological Sciences; University of Canterbury; Private Bag 4800 Christchurch 8140 New Zealand
4. Landcare Research; PO Box 69040 Lincoln 7640 New Zealand
5. Department of Soil Quality; Wageningen University; P.O. Box 47 Wageningen 6700 AA The Netherlands