Grassland conservation headlands: Their impact on invertebrate assemblages in intensively managed grassland

Grassland conservation headlands were established on intensively managed grassland fields on four farms in Scotland. Vegetation composition and structure, invertebrate activity density (as measured by pitfall trapping), ground beetle assemblage structure and bird utilisation in these grassland conservation headlands were compared with conventional headlands (i.e. areas of headland managed as per the rest of each field). Increased activity densities of Arionidae slugs, heteropteran bugs and homopteran bugs were recorded in the grassland conservation headlands when compared to the conventional headlands. Despite an increase in potential prey, very few birds were observed in the study fields, and the grassland conservation headlands were no richer in birds than the conventional headlands. The vegetation of the grassland conservation headlands was longer and denser than the conventional headland. Hence, while the activity density of potential prey was greater in the conservation headlands, accessibility to prey and foraging conditions for birds may have been poorer. While there was evidence that the ground beetle Nebria brevicollis utilised the grassland conservation headland as a summer aestivating site, the activity density of ground beetles in general was found to be lower in the conservation headlands than the conventional headlands. For grassland conservation headlands to reach their full potential, it is suggested that additional measures are taken to open the vegetation structure of such headlands.