The spread of coarse grasses and changes in numbers of lepidoptera in a woodland nature reserve

in the last 15-20 years, coarse grasses have spread to dominate much of the ground vegetation of open areas in Monks Wood, a woodland nature reserve in eastern England. Possible causes of these vegetational changes are discussed briefly. Since the 1970s, butterflies and maths have been monitored in the wood as part of national monitoring schemes. Three butterfly species with larvae that feed on coarse grasses have become much more abundant in the wood while most other butterfly species have declined in numbers relative to other sites in eastern England. Moths with grass-feeding larvae, as a group, have increased in abundance significantly more than other moths. There is evidence for butterflies that the trends recorded in Monks Wood have occurred elsewhere in eastern England, although less strongly than in the wood. (C) 1998 Elsevier Science Ltd. All rights reserved.