Securing Biodiversity in Breckland - European Commission

Recommendations: Review the success and apparent value of current ESA field margin agreements and wherethese appear to have provided benefits make every effort to secure transition to ES. In viewof uncertainty over the response of invertebrates to habitats, the presumption should be thatany open vegetation with a diversity of annual plants is beneficial. ES advisers should recognise the benefits of cultivated margin prescriptions that should beseen as the key mechanism for biodiversity delivery in Breckland farmland. Juxtaposition of cultivated margins alongside grass strips, either already in place inpermanent grassland, hedge-banks, along pine lines and track-ways, or created through ESoptions, could bring enhanced benefits.A crucial feature of ESA implementation in Breckland has been to have static non-rotationalcultivated margins, whilst in ES these cultivated margins may be either fixed or rotational. Nonrotationalmargins seem preferable for scarce invertebrates – that lack a seedbank and thereforerequire suitable conditions every year. Although it is possible that some more dispersive species (e.g.Harpalus froelichii) may be able to readily colonise new areas from healthy source populations, someother species may be much less mobile. It seems sensible therefore to take a precautionary approachand to persist with non-rotational treatments.Recommendation: Implement ES cultivated margin agreements as predominately non- rotational.Cultivated Margins Compared to Unsprayed Cereal MarginsThe potential role or otherwise of the cereal crop in the dynamics of these assemblages, and therelative value of cultivated (uncropped) margins versus unsprayed cereal margins (conservationheadlands) is unclear. Work conducted by Robert Marrs on Ropers Heath, an area of cerealagriculture restored to heathland adjacent to Cavenham Heath in the Breckland, suggested thatcereal cropping was not effective in reducing nutrient status of soils (Marrs, 1985). Prescriptionsinvolving an unsprayed and essentially weed rich cereal margin are generally not attractive tofarmers, as the harvested grain cannot be included with the rest of the cereal crop and subsequentcrops in the rotation may be affected by the build up of weeds. In contrast, simple cultivation is anoperation that can be applied either together with cultivation of the rest of the field at the same timeas normal crop management, or in a single operation on the cultivated margin. Thus for many farmermanagers, cultivated margins are preferable.Evidence accumulating to date, is that both thinly-sown cultivated margins and uncropped(cultivated) margins were equally effective for scarce plants of arable and cereal habitats. In contrast,thickly sown margins (i.e. suitable for subsequent harvesting of a crop) could be detrimental as thecrop might grow too densely shading out the conservation priority species. Further evidence thatuncropped (cultivated) field margins are more beneficial for arable plants than field-scale unsprayedcereal is confounded by both the fact that vascular weed seed densities are much greater at fieldmargins and that unsprayed cereal treatments may nevertheless receive fertiliser inputs (C.Shellswell pers. comm.).166