The Lepidoptera fauna associated with Calluna vulgaris: effects of plant architecture on abundance and diversity

1. The effects of plant architecture on the Lepidoptera assemblage associated with heather Calluna vulgaris were studied at four locations in northern England and southern Scotland in 1992 and 1993. The study areas were Calluna vulgaris-Vaccinium myrtillus heaths, where management by rotational burning had created a mosaic of stands of different-aged Calluna. Lepidoptera were sampled in the larval stage. 2. Larval abundance was considered in relation to Calluna age, height, cover, green shoot density, and flower density. For most study areas and species, multiple regression selected Calluna height as the variable that explained most variation in larval density, although the explanatory variables were intercorrelated. 3. After compensating for the effects of different study locations, the slope of the regression between the logarithm of larval density and the logarithm of Calluna height was common to the macrolepidoptera, microlepidoptera, geometrid, and noctuid larval groups. 4. There was a significant progressive increase in larval diversity with increase in Calluna height, due to the presence of uncommon moth species in the samples from taller Calluna, and a change in the contribution of common species to the community in different height zones. 5. The significance of these results is discussed in relation to other heathland invertebrate studies and management practices.