Study: Large, old trees in decline

Dec 06, 2012

(Phys.org)—The largest living organisms on the planet, the big, old trees that harbour and sustain countless birds and other wildlife, are dying. A report by three of the world's leading ecologists in today's issue of the journal Science warns of an alarming increase in deathrates among trees 100-300 years old in many of the world's forests, woodlands, savannahs, farming areas and even in cities.

"It's a worldwide problem and appears to be happening in most types of forest," says lead author Professor David Lindenmayer of the ARC Centre of Excellence for (CEED) and Australian National University.

"Large are critical in many natural and human-dominated environments. Studies of ecosystems around the world suggest populations of these are declining rapidly," he and colleagues Professor Bill Laurance of James Cook University, Australia, and Professor Jerry Franklin of Washington University, USA, say in their Science report.

"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 ."

Prof. Lindenmayer says they were first tipped off to the loss of big old trees while examining Swedish forestry records going back to the 1860s. Then a 30-year study of Mountain Ash (Eucalyptus regnans) forest in Australia confirmed not only that big old trees were dying en masse in , but also perishing at ten times the normal rate in non-fire years—apparently due to drought, , logging and other causes.

Looking round the world, the scientists found similar trends at all latitudes, in California's , on the African savannahs, in the rainforests of Brazil, the of Europe and the boreal forests of the far north. Losses of large trees were also pronounced in agricultural landscapes and even cities, where people make efforts to preserve them.

"It is a very, very disturbing trend. We are talking about the loss of the biggest on the planet, of the largest flowering plants on the planet, of organisms that play a key role in regulating and enriching our world," says Professor Bill Laurance of James Cook University.

"Large old trees play critical ecological roles. 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.

"Big trees supply abundant food for numerous animals in the form of fruits, flowers, foliage and nectar. Their hollows offer nests and shelter for birds and animals like Australia's endangered Leadbeater's Possum (Gymnobelideus leadbeateri)—and their loss could mean extinction for such creatures.

"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," he says.

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, says Prof. Jerry Franklin.

"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 adds.

The researchers liken the global loss of big trees to the tragedy that has already befallen the world's largest mammals, such as elephants, rhinos, tigers and whales, cautioning that almost nowhere do conservation programs have the time-frames lasting centuries, which are needed to assure the survival of old trees.

"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 imperilled," they warn.

They call for an urgent world-wide investigation to assess the extent of big tree loss, and to identify areas where big trees have a better chance of survival.

Their paper "Rapid Worldwide Declines of Large Old Trees, by David B. Lindenmayer, William F. Laurance and Jerry F. Franklin appears in today's issue of the journal Science.

Explore further: Research team helps develop new forecast systems for northern Gulf of Mexico

More information: DOI: 10.1126/science.1231070

Journal reference: Science search and more info website

Provided by ARC Centre of Excellence for Environmental Decisions

4.2 /5 (6 votes)

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Caliban
2.7 / 5 (7) Dec 06, 2012
Number one as culprit, I am certain, is logging. The timber companies in America(I'm sure this holds true elsewhere), see any and all old-growth forest as nothing more than vertical stacks of cash, which makes them a permanent target for the unceasing efforts of the timber industry to gain access to in order to rapaciously exploit these inhabitants of the Commons.

A single old-growth tree can represent thousands upon thousands of board feet of lumber and other derived products, which is available for no more effort or expense than to cut it down and haul it to the mill. And this is why the effort to gain access to such timber never ends--the profit margin they represent is phenomenal.

Especially so, since we taxpayers cover the costs of roadbuilding, upkeep, fire control and remediation of the Public Lands from which they are harvested.

Sustainable-forest sourced timber is much less profitable, even though it is still massively so, but this just isn't enough to satisfy that greed.
RealScience
3.9 / 5 (7) Dec 06, 2012
Another culprit is fungi. Around here many of the old trees (beeches, maples, elms, ashes and even poplars) are dying due to fungi brought in from other parts of the world.
In a few generations the trees will have resistance, but for big trees a few generations can be hundreds of years.
SamB
1.5 / 5 (8) Dec 06, 2012
Funny but larger older humans are also in decline... Sounds like a trend of some sort.
extinct
2.5 / 5 (11) Dec 07, 2012
identifying the problem is one thing, but admitting that it is our own fault? hah, never! slave to the ego, all the way to extinction
Ojorf
2.3 / 5 (9) Dec 07, 2012
You don't have to stress any tree much to make it susceptible to all kinds of maladies and old trees are even more sensitive.
Changes in climate are putting stress on many plants everywhere.
Semmster
2 / 5 (4) Dec 07, 2012
we're next. it's about time. natural justice.
Anonym
1.8 / 5 (10) Dec 07, 2012
Consider the source. Even if you haven't been paying close attention, you may have noticed that there is a new scare story every day and certain academic centers in the UK, Australia, Germany and the US are responsible for most of them. It's almost as if they've been tasked (and funded) with the mission of repeating the mantra until we have all internalized it: "People are killing the planet and must be stopped!" Old old news, this. The overpopulation meme goes back 200 years, and experience shows that its premise is false. People are adaptive and so is the planet. Both will get through this period of adjustment; already we have seen large reductions in emissions and in the growth of energy consumption in developed countries, and this trend is accelerating. It is not necessary to place very real economic hardship on the poor and the middle class because of fears created by the rich (Al Gore, Maurice Strong et al) using primitive and clearly inaccurate climate models.