1. School of Applied Sciences Auckland University of Technology Private Bag 92006 Auckland 1010 New Zealand
2. School of Environment The University of Auckland Private Bag 92019 Auckland 1142 New Zealand
3. Landcare Research P.O. Box 69040 Lincoln 7640 New Zealand
4. Department of Biology University of York Heslington York YO10 5DDUK
5. Department of Geography University of California Berkeley 507 McCone Hall #4740 Berkeley CA 94720 USA