In the 1990s, ecological survey work was carried out in English landscapes containing semi-natural habitats that were perceived to be under threat, or which represented areas of concern ("key habitats"), complementing the national Countryside Survey of Great Britain. The landscapes were lowland heath, chalk and limestone grasslands, coasts and uplands. Standardised procedures were used to record ecological data from representative 1 km squares throughout England in 1992 and 1993.