Threats to large trees

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Threats to large trees

Oak Quercus in open farmland © A Willstrop

Large old trees are among the biggest organisms on the planet. They are the central structures in forests, woodlands, savannahs, agricultural landscapes and urban areas.

These trees provide vast nesting and sheltering areas for birds and animals, create rich areas for other species, provide abundant fruit, foliage and flowers, recycle soil nutrients, and influence the flow of water within landscapes and the local climate as well as storing large amounts of carbon.

A study of the, Rapid Worldwide Declines of Large Old Trees, by David B. Lindenmayer, William F. Laurance and Jerry F. Franklin published in December 2012 in the journal Science found that there was an alarming increase in death rates among trees 100 to 300 years old across a range of global landscapes.

The study outlines the unique ecological roles large old trees play, roles that younger and smaller trees cannot fulfil.

“The alarming decline in old trees in so many types of forest appears to be driven by a combination of forces, including land clearing, agricultural practices, man-made changes in fire regimes, logging and timber gathering, insect attack and rapid climatic changes,” said Professor Jerry Franklin of the University of Washington, USA.

“It’s a worldwide problem and appears to be happening in most types of forest”, said lead author Professor David Lindenmayer of the Australian National University.

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Europe’s last primeval forest under threat

Oak in Bialowieza © Zubron at English Wikipedia

Poland’s ancient Bialowieza Forest occupies nearly 580 square miles of woodland, which straddles Belarus and Poland, is under threat from bark beetle that is eating its spruce trees.

Both the foresters and the Polish government believe the only remedy is to cut down more trees in order to save the forest itself, so they recently began work to remove infested trees along routes used by tourists.

But environmentalists believe that this is destroying natural habitats. Others have commented that the forest has already survived past infestations and any intervention will be the end of the forest’s natural character.

Bialowieza Forest is the last significant remaining stretch of the primeval temperate forest that once covered most of lowland Europe and is home to wild European bison (a population of about 800). In 1979, part of the site was declared a World Heritage Site by UNESCO, which is sending a delegation to check on the situation.

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References: Rapid Worldwide Declines of Large Old Trees, David B. Lindenmayer, William F. Laurance and Jerry F. Franklin, Science; Nature magazine; Polish National Forest Holding; UNESCO.