LEAF MINER ASSEMBLIES - EFFECTS OF PLANT SUCCESSION AND GRAZING MANAGEMENT

1. Changes in leaf-miner assemblies during 4 years of secondary succession, under different controlled sheep-grazing treatments, are described and compared to the miner fauna of older grazed grassland nearby. 2. Multivariate analyses were used in conjunction with examination of individual common species to assess the independent effects of time, grazing treatment, plant species composition and architecture on the leaf-miner assemblies. 3. Leaf-miner species composition was strongly related to plant species composition, but was modified by plant structure under different grazing treatments. There was a strong successional trend in miner assemblies, even when the effects of changes in plant composition had been taken into account. Conversely, local variation in miner species composition generally reflected foodplant distribution alone. 4. Grazed treatments had fewer mines than controls, but there were also species specializing in grazed areas, despite the abundance of their foodplants elsewhere. There was a weak indication that miner species in grazed treatments were more likely to fluctuate in abundance than those in controls. 5. The results are discussed in relation to the assembly of grassland insect communities during succession, and the use of 'indicator groups' in management for nature conservation.