Improving the farmland biodiversity value of riparian buffer strips: conflicts and compromises
Th e intensity of management of lowland grassland fi elds in the United Kingdom, coupled with the fact that such grasslands dominate much of the lowland landscape, means that there are now few opportunities for many plants, invertebrates, birds, or mammals to survive. Th e Scottish Agricultural College (SAC) has investigated whether fencing off the margins of such fi elds next to watercourses to control diff use pollution has any positive impacts on biodiversity, based on assessments of vegetation composition and condition and structure of assemblages of invertebrates of importance as foodstuff s to farmland birds. Fencing watercourses increased the abundance of key groups of invertebrates. However, the invertebrate species diversity was not increased unless the margins were ≥5.4 m in width. Margins established in the study area to prevent access by livestock to watercourses or to enhance biodiversity are generally ≤2.6 m wide and are therefore unlikely to provide conditions for additional invertebrate species to use. Th e dense, tall swards within such margins are also unlikely to provide foraging opportunities for farmland birds. Management (such as low-intensity grazing by livestock in the margins) is essential to provide the conditions required for these groups, but this could confl ict with the diff use pollution mitigation aims. A compromise is proposed whereby limited autumn/winter grazing by livestock could be used to open the vegetation structure in the margins. Grazing by livestock at that time may be acceptable since it is not occurring in the period of main diff use pollution concern (i.e., the fecal contamination of watercourses and bathing waters in the spring and summer). It is also essential that a landscapescale approach is taken, driven by knowledge of the full needs of the species concerned, when deciding where best to target agrienvironmental actions aimed at farmland bird conservation.
Journal Title/Title of Proceedings
Journal of Environmental Quality