1. Teagasc; Johnstown Castle; Environmental Research Centre; Co. Wexford Ireland
2. School of Biology and Environmental Science; University College Dublin; Belfield Dublin 4 Ireland
3. Department of Biosystems and Technology; Swedish University of Agricultural Sciences; PO Box 103 SE 23053 Alnarp Sweden
4. Department of Plant Ecology; Justus-Liebig University Giessen; Heinrich-Buff-Ring 26 35392 Giessen Germany
5. Environmental Agency; South East Regional Office; Kings Meadow House; Kings Meadow Road Reading Berkshire RG1 8DQ UK