Wildlife that has evolved over millions of years is steadily falling prey to modern farming practices and a relentless onslaught from road-builders and developers.
The most comprehensive scientific study of Britain's animals, plants and insects has revealed the extent of a decline that has impoverished the countryside and put countless species at risk.
On Wednesday, John Gummer, the environment secretary, will announce a 14 per cent fall in the diversity of woodland wildlife in little more than a decade. Meadows have 13 per cent fewer species. Even upland areas, far from any source of pollution, have suffered an 11 per cent loss.
The results of the Countryside Survey, carried out at more than 1,000 sites by the government-funded Institute of Terrestrial Ecology in 1978 and 1990, have alarmed conservationists. Dr Ian McLean, head of species conservation at English Nature, the statutory wildlife agency, said: "Thirty years ago, pastures were more flowery. Now they are all green and people think that is normal."
Government ministers are drawing up a plan to protect Britain's biological diversity under a treaty signed at last year's Earth summit. Tony Juniper, of Friends of the Earth, said: "Far from maintaining biodiversity, we are turning our countryside into a homogenous landscape populated by dandelions and starlings."
Almost half Britain's ancient woodlands have been destroyed since the second world war. In what remains, pollution and neglect have made the trees the unhealthiest in Western Europe. Birds in decline include owls, woodpeckers, nightingales and six species of tit.
Sir Edward Greenwell, chairman of the Country Landowners' Association environment committee, said the neglect of woodlands would worsen because of tax changes that removed incentives to manage them. Grants for new woodlands should be spent on the old ones instead because they contained more wildlife, he said.
More than a fifth of all hedgerows were lost during the 1980s, according to the institute. Pesticide use fell by a third during the survey period, but is still blamed for the disappearance of wild flowers and birds. Moors have fared better, partly thanks to a resurgence of birds of prey. Downland areas, however, have been hit by acid pollution.
Species that died out after the institute's 1978 study include the mouse-eared bat, the viper's bugloss moth, the red-backed shrike and the meadow wood ant.
When the survey is published Gummer is expected to emphasise recent improvements such as รบ20m annual grants to farmers protecting traditional landscapes in environmentally sensitive areas. Ministers believe reforms of the EC's common agricultural policy, which has encouraged intensive farming, will also help.
