Background information and definitions
Hedges are used to separate fields but are also extremely important habitats on many farms, providing heterogeneity in the landscape and resources not found elsewhere. In much of Europe, hedges are being removed as field sizes are increased, potentially reducing the biodiversity value of farmland. Planting new hedges may mitigate this change, but may be both costly and unattractive to farmers, as they can reduce the efficiency of farming.
Supporting evidence from individual studies
A small 1967 before-and-after study on a 1,214 ha farm in Maryland, USA (Burger & Linduska 1967), found that after the introduction in 1957 of a number of management interventions, including planting 11.4 miles of new hedges, the number of coveys of northern bobwhites Colinus virginianus increased from five coveys identified in the winter of 1956/1957 to 38 in the winter of 1964/1965. Although this study does not isolate the effect of the individual interventions made, it is noted that 14 of 33 new coveys were located in multi-flora hedges planted during the eight years of management interventions. Interventions included planting shrub lespedeza Lespedeza thunbergii and sericea lespedeza Lespedeza cuneata strips, seeding 20 ha of grassland, and limiting livestock grazing. Sightings of coveys were reported by farm employees and hunting parties during each winter from 1956 to 1965.Study and other actions tested