By Mark Kinver -- 
Ecologists have seen a sharp increase in the number of trees dying
Old growth trees in western parts of the US are probably being killed as a result of regional changes to the climate, a study has suggested.
Analysis of undisturbed forests showed that the trees' mortality rate had doubled since 1955, researchers said.
They warned that the loss of old growth trees could have implications for the areas' ecology and for the amount of carbon that the forests could store.The findings have been published in the journal Science.
"Data from unmanaged old forests in the western US showed that background mortality rates have increased rapidly in recent decades," the team of US and Canadian scientists wrote.
"Because mortality increased in small trees, the overall increase in mortality rates cannot be attributed to ageing of large trees," they added.
"Regional warming and consequent increases in water deficits are likely contributors to the increase in tree mortality rates."
Water woes
After ruling out a variety of other possible factors, including insect attacks and air pollution, the researchers concluded that regional warming was the dominant contributor.
Scientists fear the die-back could be a signal of worse to come
"From the 1970s to 2006, the mean annual temperature of the western US increased at a rate of 0.3C to 0.4C per decade, even approached 0.5C," they observed.
"This regional warming has contributed to widespread hydrological changes, such as declining fraction of precipitation falling as snow, declining snowpack water content, earlier spring snowmelt and a consequent lengthening of summer drought."
The team, led by the US Geological Society (USGS), examined data from 76 temperate forest stands older than 200 years, which contained almost 59,000 trees.
Over the study period, which stretched back to 1955, more than 11,000 trees died.
The researchers reported that the increased mortality rate affected a range of species, different sized trees, and all elevations.
"The same way that in any group of people, a small number will die each year; in any forest, a small number of trees will die," explained co-author Phil van Mantgem, a USGS ecologist.
"But our long-term monitoring shows that tree mortality has been climbing, while the establishment of replacement trees has not."
Carbon store
The change in the forests' dynamics, the team noted, was going to have an impact on the forests' ecology and carbon storage capabilities.
"We may only be talking about an annual tree mortality rate changing from 1% a year to 2%, but over time a lot of small numbers add up," said co-author Professor Mark Harmon from Oregon State University.
He feared that the die-back was the first sign of a "feedback loop" developing.
As regional warming caused an increased number of trees to die, there would be less living trees to absorb carbon dioxide from the atmosphere.
Yet there would be an increased proportion of decaying trees, releasing the carbon that had been locked away inside the trees' wood.
Warmer temperatures might also increase the number and prevalence of insects and diseases that attack trees, the team added.
They used the example of recent outbreaks of tree-killing bark beetles in the US, which have been linked to a rise in temperatures.
Another member of the team, Dr Nate Stephenson, said increasing tree deaths could indicate a forest that was vulnerable to sudden, widespread die-back.
"That may be our biggest concern," he warned.
"Is the trend we're seeing a prelude to bigger, more abrupt changes to our forests."
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Comments: 18
No contradiction Col. As climate warms, pine beetles move into previously immune forests. Such destruction of forests accelerates CO2 release into the atmosphere, creating a "positive feedback". The more warming, the more beetle infestations (and dead trees), the more CO2, the more warming....
Mountain pine beetle and forest carbon feedback to climate change
You have to start listening to what science is saying about this, and not confuse the issue with contributions to mega-wildfires. But even there, the chief federal firefighter recently noted the contribution of climate change to western mega-wildfires:
__________
"You know, there are a lot of people who don't believe in climate change," Pelley remarks.
"You won't find them on the fire line in the American West anymore," Tom Boatner says. "'Cause we've had climate change beat into us over the last ten or fifteen years. We know what we’re seeing, and we're dealing with a period of climate, in terms of temperature and humidity and drought that's different than anything people have seen in our lifetimes."
Insects, Trees, and Climate: The Bioacoustic Ecology of Deforestation and Entomogenic Climate Change
Testimony of
Dr. John A. Helms
Professor Emeritus of Forestry
University of California, Berkeley,
and 2005 President of the Society of American Foresters
before the Senate Committee on Energy and Natural Resources
on Scientific Assessment of Effects of Climate Change on Wildfire
Western U.S. Bark Beetles and Climate Change
People have to get over the political and corporate hype with climate change and look at the facts.
It is going to be expensive cleaning up our act but we did it and we need to undo it.
Do you have some information you are hiding on us or is this just more GOP denial?
I need something that proves what I am posting is lies and made up propaganda from some mythical group.
Trees thrive on CO2. It is what they "breathe" They release oxygen so we can breathe.
The men on the fire line know exactly what caused the fire and why those trees are dead. You will not find a person in Montana that is all that fond of todays crop of tree huggers.
Mythical group. There is nothing mythical about Environmentalists. Tree Hugger is probably a local term for them, I don't know. When they stopped the Forest Service from cutting roads into the back country to fight fires and stopped the program to stop blight they condemed the forests of Montana and other states to the destruction of our forrests.
affected areas of Global Warming
An Inconvenient Truth’ Scientific Analysis
Did you deliberate misunderstand what I wrote, or are you just so biased that you honestly cannot comprehend it? Your statement addresses nothing that I pointed out. Nothing. The rest of your obvious bias against environmentalism doesn't warrant any comment. It speaks for itself.
I will say, however, that even if you despise environmentalists, there is a difference between environmentalism and science. You did know that, didn't you?
Scientific evidence is another thing and just because some people feel that a group is on the wrong track, scientific proof cannot be denied by intelligent people or the world would still think the earth is flat and you could sail off the end of it and the sun revolves around the earth lol. That is what Bush brought us to but that part (thank god) is over.
Before we make foolish statements on global warming we need to look at the real scientific evidence and make sound judgements. people are destroying the environment and people will have to clean it up or see their future generations suffer because they feel they have to follow a political party line or be just to stubborn to look at the truth and stay in the dark ages, anyway the future is being made by us now and we either clean up our act or suffer the consequences.
While environmentalists advocate for ways to address climate change, the research, data, predictions and recommendations are all about science. Col. wouldn't object to science that contributes to his standard of living, so why would he object to science, which "very likely" would prevent a significant decline his kids'/grandkids' standard of living?
Personally I am on your side all the way Steve. I do not understand how anyone would want to knowingly make their own family suffer the effects of what will happen if we do not clean up our act.
Its the real scientific knowledge that counts not the political hype. If the liberals took a stand against the global warming issue the GOP would automatically side with the global warming facts.
Whenever we allow politicians to interfere with real knowledge we only make life harder for our self and the public is the one that always does the suffering not the environmental rapists that take all and live in their atmospheric controlled castles. Its the same when a politician wants to hang a war victory on their chest, who pays the price our children or the war monger? Its always stand up for MY cause and to hell with the real truth of the matter.
First, the ethical question has nothing to do with being "holier than thou". I can scarcely think of anything we do in our lives, which does not have an ethical component. There are very few decisions we make, individually and collectively, which do not affect the well-being of others. That makes ethics a central issue in most decisions we make. Conservatives, most of whom purport to be Christian, should understand that (do unto others as you would have them do unto you).
Second, I wonder about references to "reality", which, of course, are never backed with evidence. Evidence is science. So I consider these "reality" statements simple rhetorical "proclamations" (Col.'s "bunk" statement). In other words, "skeptics" seem to confuse their proclamations with "reality", kind of like many religious people confuse their particular religion with "God".
I could go further into philosophical notions of "reality", but it would be too far afield from this topic. Suffice it to say that climate change advocacy rests on 1. science and 2. ethics. It is highly logical (that is to say, not emotional - unlike non-evidence-based proclamations re: "reality). The logic is simple:
Global warming is/is not real. (Science suggests it is*)
Global warming is/is not caused by humans. (Science suggests it is*)
Global warming will/will not affect future generations. (Science says it will*)
"Skeptics" have/do not have kids/grandkids.
"Skeptics" care/do not care about the future well-being of their kids/grandkids.
*No scientific organization in the world disputes the IPCC Reports.
That's the ethical question. Denial is apparently a way to avoid the issue.
Jack: "Whenever we allow politicians to interfere with real knowledge we only make life harder for our self and the public is the one that always does the suffering not the environmental rapists that take all and live in their atmospheric controlled castles."
Elections have consequences, and I look forward to an administration/congress that again listens to science, instead of industrial lobbyists.
Jack: "Its the same when a politician wants to hang a war victory on their chest...."
The military, folks like Col., usually cannot afford to think in those terms (although I know of a few, who have started since the Iraq disaster).