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The UK Farm Scale Evaluations (FSE) compared the effects on biodiversity of management of genetically modified herbicide-tolerant (GMHT) crops and conventional crops over the shorter term. We simulated population changes over seven 4-year rotations (28 years) for weeds in crop rotations that included cereals and spring-sown GMHT and conventional oilseed rape and beet, using FSE data and assuming the continuation of the weed management systems practised in the FSE. The weed density dependence that was modelled integrated change caused by population dynamics and farmers’ responses to changes in weed density. Predicted weed seed populations decreased under conventional management and at a greater rate under GMHT. Total seed densities were lower for GMHT cropping by a factor of 0.7–0.8. The predicted distributions of weeds had more fields with lower weed densities under GMHT cropping. Such changes could affect animal populations on farmland, depending on the scale of uptake of GMHT crop cultivars. [ABSTRACT FROM AUTHOR]

Abstract: Miscanthus is a newly introduced crop grown primarily to produce biomass for energy production and the area grown in the UK is anticipated to increase. Major differences in crop management from conventional arable crops have led to speculation that miscanthus may also have effects on farmland biodiversity. Six miscanthus fields were paired with six of a conventional crop, winter wheat, and bird diversity and abundance were compared in winter and during the breeding season along with potential food sources. Miscanthus fields had a greater abundance and diversity of birds than did wheat in winter and summer. In winter, the greater numbers of birds in miscanthus fields were probably attracted by the shelter provided by the crop and by the abundance of non-crop plants. During the breeding season, the abundance of non-crop plants in miscanthus fields, and greater numbers of insects associated with these plants, provided food resources. However, the miscanthus crop plants provided less insect food than wheat crop plants. Changes in crop structure during the breeding season influenced the breeding birds. The results from this study suggested that an increase in the area of miscanthus grown in the UK may have temporary benefits for farmland bird populations during establishment. These benefits are likely to diminish with age of crop and as crop management improves with experience. Management for wildlife will be required to maintain the diversity of features attractive to birds because many of these will be lost if miscanthus is managed solely to maximise crop yields. [Copyright &y& Elsevier]