The distribution of insects near a low hedgerow
Journal of Applied Ecology, 6, 443 - 452
Small, flying insects accumulate in the sheltered zones near to artificial windbreaks, especially to leeward. The height and permeability of the windbreaks, and the angle and speed of incident wind, largely determine the patterns of distribution in the air (Lewis 1966a; Lewis & Stephenson 1966) which are reflected on the vegetation beneath (Lewis 1965b, 1966b). Windbreaks of cane, heather, straw, coir or plastic netting are widely used to shelter small acreages of valuable crops but in agricultural districts in Great Britain shelter is more often provided by living hedges or belts of trees than by artificial wind- breaks. A living hedge is both a windbreak and a habitat, so patterns of insect distribution caused by the 'windbreak' effect are complicated by the addition of insects that spread from hibernating, breeding and feeding sites in the hedge itself. This paper shows (i) that the same factors affecting patterns of insect distribution near artificial windbreaks are also important near hedges, though their effect is modified by the position of the source of insects in relation to the hedge, and (ii) that insects accumulate near hedges more in windy than in calm weather. The accumulations occur there partly because the immediate local populations spread from the sheltering vegetation, but largely because the hedge acts as a windbreak and concentrates insects from passing airborne populations.
Author(s): Lewis, T
Journal: Journal of Applied Ecology, 6, 443 - 452