Trees are the natural state of things - or at least of the earth's land surface. Before agriculture got under way, when our ancestors only hunted and gathered, trees covered some 60 per cent of all the continents (excluding ice-covered Antarctica and Greenland), according to a new analysis by the Cambridge-based World Conservation Monitoring Centre.
In these mild, low and damp islands off western Europe, the tree cover was proportionately even higher once the last Ice Age ended some 10,000 years ago. Back then, ours was an unimaginably different land of billions of trees, of almost continuous forest, Scots Pine in the north, broadleaf trees such as oak, lime and elm in the south.
You could walk for weeks without seeing a horizon. There was the only occasional bald patch, on the highest mountain ridges and plateaux, in valleys where rivers were changing their course and the ground was too soft and marshy, and along the coasts.
But a thousand years or more before the Romans came people had begun to eradicate those forests to grow crops, graze their animals and aid their hunting. By the time William the Conqueror conquered as much as four fifths had been lost, and the felling carried on relentlessly thereafter - to provide farmland, fuel and timber for ships and buildings. What woodlands remained were, for the most part, intensively but sustainably exploited, which is often the reason they survived.
Typically they would be coppiced, with the tree cut across right at the base of the trunk. This causes new shoots to grow up rapidly from the stump or `stool'. After a few years, when these shoots had become surprisingly tall, woody and thick they would be cut off at the base to provide poles and firewood, and the cycle of growth would restart. Coppice trees can be a thousand years old or more, and there are still huge numbers of them in Britain.
By the end of the First World War only one twentieth of Britain's land area was still tree covered. The war effort and the demand for pit props in coal mines had made heavy inroads into what little remained. When we condemn rainforest destruction in tropical countries, we should remember that we went through the same process here, for similar reasons. (And while we lost more than 90 per cent of our woodlands, the world as a whole has lost about two thirds of the original total, says the World Conservation Monitoring Centre).
Having reached this sorry state of affairs, the Government accepted that Britain had become dangerously dependent on timber imports. It created the Forestry Commission in 1919 to finance and organise a grand replanting effort. Tree planting by private landowners was subsidised, while the state put in huge tracts itself. Since then we have doubled the area under trees but with 10.6 per cent tree cover the United Kingdom is still one of the least forested nations of Europe. Only the Republic of Ireland is significantly more denuded with five per cent.
Until just a few years ago, the great bulk of the nation's tree growing efforts went into planting conifers on the country's cheapest land - high hills, mountains and bleak grazing moors, areas of poor soil and peat bogs. The species chosen were usually fast-growing imports such as the Sitka spruce. And they were usually planted in an unimaginative, highly regimented fashion; big, square-shaped blocks with sharp corners and trees all of the same age crowded closely together.
So far from bringing back a more natural state of things, Britain's efforts to increase its tree cover started to blight some of our most spectacular and prized upland scenery. As well as Government grants to put in these conifer plantations, there was also a way in which wealthy individuals could use them as a useful tax shelter for their high incomes.
Meanwhile, in the lowlands, the more natural broadleaf woodlands - some of them remnants of woods hundreds or even thousands of years old, and still providing a habitat for classic woodland plant and animal species - continued to decline. Piecemeal development of roads and towns, and conversion to conifer plantations and fields, was nibbling away at them. Woods which had survived for centuries under management because they were useful to people were abruptly abandoned. As a result, some of today's woods are choked with undergrowth and full of elderly, decrepit trees.
Fortunately, things have begun to change. There is now far more emphasis, by the Forestry Commission and other parts of Government, on planting native, broadleaf species in lowland areas of Britain which have the lowest tree cover. The tax loophole which brought forestry into disrepute has been outlawed. There is a real recognition that we need more trees and woods for reasons aside from just producing timber and reducing our dependence on imports, and grants have been changed to reflect this.
Two years ago the last Government set a target for doubling England's woodland cover by 2050, from 7.5 per cent to 15 per cent. Subsequently Wales - current woodland cover 12 per cent - got its own target for a 50 per cent increase by the midpoint of the next century. There are no such vaulting ambitions for Scotland, already the most wooded of the three mainland British nations with 15 per cent cover.
Britain's woodlands are gradually spreading but at far to slow a rate - at least, for now - to enable those targets to be hit. The current Government incentives seem nowhere near high enough to lure enough landowners into devoting their land to trees rather than crops or livestock. Nor do these tree planting grants seem very likely to be increased.
But the times are changing. As Europe's taxpayers and food consumers become increasingly reluctant to over-subsidise farming through the bloated Common Agriculutral Policy, forestry may become more attractive, farming less so.
National Lottery money is now going into planting projects while more and more charities and voluntary bodies are backing woods. The century which is just ending was when we hit rock bottom in caring for our trees. The one about to begin is a time of hope.