December 7, 2012
Researchers Say Large Old Trees Are Dying Off Around The Planet
Brett Smith for redOrbit.com - Your Universe Online
According to a new study by a trio of Australian and American researchers, large, old trees, which provide shelter for a multitude of animals, are declining in record numbers around the world.“It´s a worldwide problem and appears to be happening in most types of forest,” said lead author David Lindenmayer, an environmentalist with the Australian National University.
“It is a very, very disturbing trend. We are talking about the loss of the biggest living organisms on the planet, of the largest flowering plants on the planet, of organisms that play a key role in regulating and enriching our world,” added co-author William Laurance of School of Marine and Tropical Biology at Australia´s James Cook University.
Swedish forestry records stretching back to the 1860s first tipped off the environmentalists to the growing problem. Those records contained a 30-year study of the Mountain Ash forest in Australia that confirmed that the big old trees were dying off not only because of annual forest fires, but also during non-fire years due to drought, logging and other causes.
After widening their scope, the researchers found further evidence of the big trees dying off in all climate zones, including tropical climes, the temperate forests of Europe and the boreal forests of the northern polar region.
According to co-author Jerry Franklin from the University of Washington, human activity is one explanation for the losses.
“For example, populations of large old pines in the dry forests of western North America declined dramatically over the last century because of selective logging, uncharacteristically severe wildfires, and other causes,” he said.
The pervasive loss of large trees was also found in both agricultural and urban landscapes, where citizens typically make efforts to preserve them.
“In agricultural landscapes, large old trees can be focal points for vegetation restoration; they help connect the landscape by acting as stepping stones for many animals that disperse seeds and pollen,” Laurance explained.
In addition to the roles they play in our daily lives, older trees also impact the ecosystem on both a local and global scale.
“Large old trees play critical ecological roles,” added Laurance. “They provide nesting or sheltering cavities for up to 30% of all birds and animals in some ecosystems. They store huge amounts of carbon. They recycle soil nutrients, create rich patches for other life to thrive in, and influence the flow of water within landscapes and the local climate.”
In their report, the scientists partly blame the decline of large mammals over the past few hundred years to this widespread loss of older trees. They suggest that conservation programs often have time frames that are simply too short and should instead focus on strategies based time frames that are centuries — rather than decades — long.
“Just as large-bodied animals such as elephants, tigers and cetaceans have declined drastically in many parts of the world, a growing body of evidence suggests that large old trees could be equally imperiled,” they wrote.
“Research is urgently needed to identify the causes of rapid losses of large old trees and strategies for improved management. Without “¦ policy changes, large old trees will diminish or disappear in many ecosystems, leading to losses of their associated biota and ecosystem functions,” the research team concluded.