1. School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK
2. Centre for Crop Systems Analysis, Wageningen University, 6700 AK, Wageningen, The Netherlands
3. Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
4. Institute of Biological, Environmental & Rural Sciences, Aberystwyth University, Gogerddan, Aberystwyth SY23 3EE, UK
5. Lancaster Environment Centre, Lancaster University, Lancaster, UK