The impact of herbicides on weed abundance and biodiversity PN0940 IACR - Long Ashton Research Station & Marshall Agroecology Ltd Dr Jon Marshall Marshall Agroecology Limited, 2 Nut Tree Cottages, Barton Winscombe, North Somerset, BS25 1DU. Email:
[email protected] CAER, University of Reading Professor Valerie Brown Centre for Agri-Environmental Research (CAER), Department of Agriculture, University of Reading, Earley Gate, P.O. Box 236, Reading, RG6 6AT. Email:
[email protected] CSL, York Dr Nigel Boatman Central Science Laboratory, Sand Hutton, York, YO41 1LZ. Email:
[email protected] IACR – Rothamsted Dr Peter Lutman IACR- Rothamsted, Harpenden, Hertfordshire, AL52JQ. Email:
[email protected] Scottish Crops Research Institute Dr Geoff Squire Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA. Email:
[email protected] The impact of herbicides on weed abundance and biodiversity PN0940 Contents Page Acknowledgements EXECUTIVE SUMMARY AND CONCLUSIONS 1. INTRODUCTION 1 1.1. Policy Rationale 1 1.2. Scope of the Desk Study 1 1.3. Objectives 1 1.4. Target and Non-Target Plant (Weed) Species 2 2. ECOLOGY OF REPRESENTATIVE WEED SPECIES 7 3. UPDATING PN0923 - NON-TARGET EFFECTS OF HERBICIDES 13 3.1. Is Biodiversity Important? 13 3.2. Change in Weed Communities 13 3.3. Impacts of Farming 14 3.4. Interactions Between Weed Diversity and Biodiversity 15 3.5. Non-Target Effects Within the Crop 15 3.6. Non-Target Effects Beyond the Crop 15 3.7. Genetically Modified Herbicide Tolerant (GMHT) Crops 16 3.8. Spatial Distribution, Remote Sensing and Mapping of Weeds 16 3.9.