Land of the tree: Nasa maps America's forests for first time to reveal how canopy covers a THIRD of the U.S.


With a burgeoning global population exhausting the world's resources at an alarming rate, along with rapid urban sprawl and rash industrial development, forests are under threat like never before.



A new map, created by Nasa with the help of government conservationists, accurately documents for the first time the tree population in the U.S. - and all that there is to lose.



The map depicts the concentration of biomass - a measure of organic carbon - that is stored in the branches, trunks and leaves. The darkest green reveals where there are the leafiest forests and the tallest trees in America.



Tree topography: Nasa and the U.S. Forest Service have release a detailed map depicting the tree population of America

Almost a third of the U.S. is covered in forest. The darkest patches are along the east and west coasts of the U.S where forestry is the most dense. The region surrounding the Appalachian Mountains which runs down the east coast is one of the country's most heavily wooded. Since 1937, the Appalachian Trail has been in place - a 2,181-mile long public footpath that runs from Maine's Mount Katahdin to Georgia's Springer Mountain taking in some of the most breathtaking scenery.



On the opposite coast, a heavy area of green depicts the Rockies - stretch 3,000 miles from the tip of British Columbia, in Canada to New Mexico in the southwest.

The green shading over California accounts for the redwoods - the state's coast is lined with the trees which include the tallest on earth, stretching to 380 ft. It has been estimated that 95 per cent of the original species, at times more than a thousand years old, have been chopped down for timber.

Other notable 'green spots' include the Cuyahoga National Park in Ohio, the Grand Tetons in Wyoming and the Florida Everglades.

Spiritual setting: The breathtaking panorama from Catawba Mountain on the Appalachian Trail, Virginia. The area has some most dense forestry in North America

In the centre of the country there is little green - accounting for the Great Plains and the deserts including Mojave, the hottest U.S. desert in California and Arizona, and the largest - Chihuahuan Desert covering Texas and New Mexico.



Over six years, researchers at the Woods Hole Research Center (WHRC), the U.S. Forest Service and Geological Survey put together the national map from space-based radar, satellites, computer programs and lots of groundwork.

Forests in the U.S. were worked out at 30 square meters to every ten computer display pixels. The researchers estimated that their mapping database includes the measurements of around five million trees, according to Nasa's Earth Observatory.



The forest files: Coastal Redwood Trees at the Muir Woods National Monument, California (left) and Snake River in the Grand Tetons National Park, Wyoming



According to one researcher Josef Kellndorfer: 'Forests are a key element for human activity. We have to know how much we have, and where, in order to conduct sound management and harvesting.'

Around a third of the United States is forested, according to Nationalatlas.gov and this has changed little in the last century. However there have been significant regional shifts due to forest fires, large scale planting in the South, increased urbanisation and the construction of reservoirs.



The situation is worse for city dwellers. The non-profit organisation American Forests worked out that cities across America have lost 25 per cent of trees in the last 30 years. To provide adequate canopy cover for the largest cities, some 634 million trees would need to be planted.



Arid lands: The map, created by Nasa and the U.S Forest Service, shows little green across regions like Death Valley in California (left) and Bonneville Salt Flats in Utah