Edge effects on insect abundance in the forests of Central European Russia

Forest edges are ecotones on the boundary of closed (forest) and open (meadow, field) ecosystems. These are peculiar habitats for a variety of insects which can traverse these boundaries and influence the functioning of adjacent ecosystems. They have become more prevalent in recent years due to anthropogenic fragmentation. Using beer traps, we investigated the number of insects in three locations. Each location represented an open natural ecosystem (a large glade in a forest, a meadow) or an artificially created ecosystem (agroecosystem) and a nearby deciduous forest. The traps were placed on trees at two levels (1.5 and 7.5 m above the soil) at the edges and in the forest interior (300–350 m from the edge). A total of 46116 specimens were collected from ten orders. At the edges in all locations, the total abundance of all orders of insects is higher than inside the forest areas. Dermaptera, Mecoptera and Trichoptera dominated at the edge. The number of Hemiptera in the traps was small, with predominance in the lower traps. Blattodea in all locations dominated at the bottom (the total abundance in the lower traps was 12.5 times higher than in the upper traps). At the edges, the abundance of Blattodea was 3.3 times higher than in the forest interior. The total abundance of Coleoptera at the edges was lower (with the exception of one location). The number of Hymenoptera at the edges and in the forest interior, as well as in the lower and upper traps, did not differ. The number of Diptera in all locations was higher at the edges and always in the lower layer. At the level of 7.5 m, the number of Neuroptera was higher both at the edges and in the forest interior.