These woes make a long catalogue. In the 1920s drought and caterpillar plagues so ravaged oaks that it was predicted the oak had no future in Britain. Elm disease ravaged elms in the 1930s. Foresters in the 1950s thought it their duty to exterminate ancient woodland and replace it with planted trees. Farmers were encouraged to grub out woods and hedges. Elm disease struck again in the 1970s. Next came the great drought of 1975-76 and others in the 1980s, along with rumours of deterioration from acid rain. The great storms of 1987 and 1990 were followed by cleaning- up operations more destructive than the storms themselves.
Not all these are new - the Victorians grubbed out woods and were worried about air pollution and Dutch elm disease - but the 20th century has unquestionably been destructive.
Are matters worse in 1995? After one of the four great droughts of the century, the trees that are chiefly suffering are recently planted ones, which have not rebuilt their roots after being dug up; also beeches and sycamores, most of which are planted trees put in the wrong place. Among oaks, the great dieback of the 1920s was not repeated in the 1970s; although some oaks have fared badly in dry years since, 1995 looks like being a good year.
Many storm-damaged woods - where not subsequently ravaged by tidying- up - are full of horizontal trees which have now got used to the new direction of gravity and will be objects of wonder and delight for centuries to come. Trees whose tops were broken in 1987 have fared better in subsequent droughts than intact trees. Green walls of young elm again border elm- lined lanes; elm disease still smoulders on, but regrowth is usually gaining on it. Ancient woods, which 20 years ago I said were irretrievably wrecked by replanting, have come back to life as the original trees recover from felling and poisoning.
Acid rain has done many evils: nearly 400 years ago it was recognised as dissolving Old St Paul's Cathedral. But I doubt whether it has killed any trees in Britain since the decline of heavy oil as a domestic fuel 30 years ago. Nor is it doing hidden damage: if it were, foresters would be complaining that annual rings were getting narrower year by year, which is not happening. Trees in the last century withstood air pollution more severe than any that occurs now. Studies on lichens show that rain in polluted areas has been getting steadily less acid. Epping Forest is now less polluted than when Battersea and Bankside power stations breathed fire and brimstone and steam locomotives puffed into Liverpool Street Station.
Much of the trouble lies not in the trees themselves but in people's expectations of them. The myth has got about that the countryside is a mere artefact, decorated with posts with leaves that come from garden centres, are stuck into holes in the ground, and last for a definite length of time before they succumb to "old age". Trees are not allowed to be themselves, living things each with its own agenda in life. They are expected to conform to the destinies that people foist upon them, and to the standards of appearance which people invent for them.
Writers define in advance what they consider to be a healthy tree. They decide that the normal state of any tree (unlike people or cats) is perfect health. When trees fail to live up to this standard, they declaim that there is a problem, invent a cause and demand a remedy. The reality is that trees are mysterious beings that we can never fully understand. They are not immortal; they flourish from no known cause and often die unpredictably.
Many complaints about trees' condition concern trees that have been planted, rather than growing naturally. Every planted tree has been dug up and moved to a different site, a drastic operation from which it may never have recovered. Disproportionately many trees broken or uprooted in storms were the result of planting earlier this century - like the seven oaks of Sevenoaks, planted in 1902.
People who plant trees inevitably put many of them where nature did not intend that sort of tree to grow. When beeches wither on Cambridgeshire chalklands, Monterey pines topple in Cornwall, or Sitka spruce languishes in Lincolnshire limewoods, these are examples of nature getting her way.
I do not want to be complacent, but remind readers that trees are living things and often resist the assaults of nature and mankind. Human intervention can becounter-productive; trees often do not like having money spent on them. Tidiness is the enemy of young and old trees: the young are swept away under the name of "scrub", and the old are burnt as "unsightly" or suffering "disease".
We should not assume that by planting trees we shall recreate for the future the qualities we value in the trees of the present. Planted trees tend to be boringly identical and to lack the irregularities - mossy crooked boughs, corkscrew trunks, burrs, holes - which make up the personality of trees, their beauty and value as a habitat.
In the 1970s the European Union introduced a regulation that young trees sold commercially had to come from certified seed sources. Everyone buying an oak or ash has to have one that is expected to grow into what foresters then regarded as a good timber tree, irrespective of whether that is what the buyer wants. Much of the significance of oaks and ashes is that they are all different, and it is time this regulation was repealed.
Ancient trees have traditionally been preserved in English parks as objects of beauty, veneration and delight. And they are something more: the home of creatures ranging from owls to rare beetles to rare lichens to mistletoe. They are irreplaceable: 10,000 200-year-old oaks are not a substitute for a single 500-year-old oak. The tidy-minded Continentals have swept away nearly all their ancient trees, and we should continue to cherish ours and to resist our own periodic fits of tidy-mindedness. We also have a duty to cherish trees in late middle age, such as oaks 250 years old, which will be the ancient trees of the future. Parks and avenues should grow and develop, not be set back periodically to what they are thought to have looked like when new.
The writer is the author of 'The Illustrated History of the Countryside' (pounds 25, Weidenfeld), which won the Sir Peter Kent Conservation Award and the Natural World Conservation Book prize.