Agricultural Landscapes

SUMMARY Most agricultural landscapes are a mosaic of farmers' fields, semi-natural habitats, human infrastructures (e.g., roads) and occasional natural habitats. Within such landscapes, linear semi-natural habitats often define the edges of agricultural fields. This paper reviews the role and interactions within and between the flora and fauna of these elements. In temperate, intensive agriculture, such field margin habitats, which historically had true agricultural functions, now are important refugia for biodiversity. As man-made habitats, field margins may also have important cultural roles as part of landscape heritage, e.g., hedges in Britain. Although field margins are not usually specific or characteristic habitat types, they contain a variety of plant communities in a variety of structures. These may range from aquatic elements, to ruderal and woodland communities, with combinations of them over small spatial scales. Studies demonstrate a variety of interactions between fields and their margins. Some margin flora may spread into crops, becoming field weeds. Margins also have a range of associated fauna, some of which may be pest species, while many are beneficial, either as crop pollinators or as pest predators. Agricultural operations, such as fertilizer and pesticide application, can have adverse effects on the margins. The biodiversity of the margin may be of particular importance for the maintenance of species at higher trophic levels, notably farmland birds, at the landscape scale. Margins can also contribute to the sustainability of production, by enhancing beneficial species within crops and reducing pesticide use, though further research on the predictability of these effects is needed. In northwestern Europe, a variety of methods to enhance diversity at field edges have been introduced, including sown grass and flower strips. While minor conflicts exist, notably for the conservation of rare arable weed species and the spread of some pests and weeds, the impacts of well-managed field margins on weed flora and arthropods indicate mostly beneficial effects. Thus field margin strips offer a practical means of providing on-farm biodiversity and enhancing more environmental and sustainable production.