Patterns of forest insect distribution within a large city: microlepidoptera in St Peterburg, Russia
Short-scale distribution patterns of eight species and one species-group of forest moths with low migratory abilities were studied within the city of St Peterburg, Russia. For species of native fauna which have either completely ( Micropterix calthella L.) or partly (Eriocrania spp., Stigmella spp.) vanished, at least in downtown, the city is considered as a lacuna within the primary distribution range. The opposite pattern (city as an island outside the primary area) was recorded for two invaders, Caloptilia syringella F. and Coleophora sibiricella Flkv. The distribution of Parornix scoticella Stt. was not altered by the city. Habitat fragmentation affected survival of populations of small moths by decreasing colonization rate more than by decreasing patch size. For eurytopic species limited mostly by host plant range (like Eriocrania ), lacunae can disappear if host plants are planted over the city; extinction of stenotopic species (like Micropterix) or species with very limited dispersal (like Stigmella ) is practically irreversible. Changes in moth distribution in the city have a strong historical background; they can be both reconstructed and predicted.