The extent of semi-natural grassland communities in lowland England and Wales: a review of conservation surveys 1978-96

The extent of semi-natural grassland has diminished considerably across low land landscapes of England and Wales during the second half of the twentiet h century. Locating, describing and evaluating the dwindling cover has been a major challenge for conservationists. A concentrated vegetation survey e ffort at grassland sites has been mounted within different parts of Britain since the late 1970s. Plant community recognition has benefited considerab ly from the development of the contemporary National Vegetation Classificat ion, and its widespread adoption permits national inventory of comparable v egetation data. Findings of a range of surveys (ninety-eight in total), undertaken between 1978 and 1996 in England and Wales covering different forms of unimproved l owland grassland, are collated and reviewed. Vegetation data were abstracte d from internally published survey reports. Calcicolous and neutral grassla nds have been covered more thoroughly than acidic and wet or marshy grassla nds. Cover data are summarized at community level. Overall estimates from s urvey results indicate that there are some 27500-40000 ha of calcicolous gr assland, 7500-15000 ha of unimproved neutral pasture and hay meadow, 8000-1 5000 ha of acidic grassland and 9000-17500 ha of wet grassland in lowland E ngland and Wales; these represent only 1-2% of the cover of permanent lowla nd grassland. Some communities have additional representation in heathlands , mires and upland environments. Although they require further refinement, the cover data for individual com munities provide a context for assessing priorities in site-based and agri- environment conservation programmes. It is concluded that, as well as arres ting further depletion, it will be necessary to restore and expand lowland grassland habitats to counteract the negative impacts of fragmentation and isolation of various community types, such as the Centaureo-Cynosuretum, wh ich is widely but thinly distributed. Habitat rehabilitation schemes also n eed to assimilate local patterns of community diversity characteristic of b oth wet and dry grasslands. It is suggested that reversal of the recent suc cessional trends that followed relaxation of grazing at certain sites might produce a more appropriate balance in the relative cover of coarse tall gr asslands and fine short turf. Vegetation surveys provide a source of spatia l data for identifying local aggregations of semi-natural grassland remnant s.