From the University of Michigan
U-M ecologist: Future forests may soak up more carbon dioxide than previously believed
![36944_web[1]](http://wattsupwiththat.files.wordpress.com/2011/10/36944_web1.jpg?quality=83 "36944_web[1]")
An aerial view of the 38-acre experimental forest in Wisconsin where U-M researchers and their colleagues continuously exposed birch, aspen and maple trees to elevated levels of carbon dioxide and ozone gas from 1997 through 2008. Credit: David Karnosky, Michigan Technological University
ANN ARBOR, Mich.—North American forests appear to have a greater capacity to soak up heat-trapping carbon dioxide gas than researchers had previously anticipated.
As a result, they could help slow the pace of human-caused climate warming more than most scientists had thought, a U-M ecologist and his colleagues have concluded.
The results of a 12-year study at an experimental forest in northeastern Wisconsin challenge several long-held assumptions about how future forests will respond to the rising levels of atmospheric carbon dioxide blamed for human-caused climate change, said University of Michigan microbial ecologist Donald Zak, lead author of a paper published online this week in Ecology Letters.
“Some of the initial assumptions about ecosystem response are not correct and will have to be revised,” said Zak, a professor at the U-M School of Natural Resources and Environment and the Department of Ecology and Evolutionary Biology in the College of Literature, Science, and the Arts.
To simulate atmospheric conditions expected in the latter half of this century, Zak and his colleagues continuously pumped extra carbon dioxide into the canopies of trembling aspen, paper birch and sugar maple trees at a 38-acre experimental forest in Rhinelander, Wis., from 1997 to 2008.
Some of the trees were also bathed in elevated levels of ground-level ozone, the primary constituent in smog, to simulate the increasingly polluted air of the future. Both parts of the federally funded experiment—the carbon dioxide and the ozone treatments—produced unexpected results.
In addition to trapping heat, carbon dioxide is known to have a fertilizing effect on trees and other plants, making them grow faster than they normally would. Climate researchers and ecosystem modelers assume that in coming decades, carbon dioxide’s fertilizing effect will temporarily boost the growth rate of northern temperate forests.
Previous studies have concluded that this growth spurt would be short-lived, grinding to a halt when the trees can no longer extract the essential nutrient nitrogen from the soil.
But in the Rhinelander study, the trees bathed in elevated carbon dioxide continued to grow at an accelerated rate throughout the 12-year experiment. In the final three years of the study, the CO2-soaked trees grew 26 percent more than those exposed to normal levels of carbon dioxide.
It appears that the extra carbon dioxide allowed trees to grow more small roots and “forage” more successfully for nitrogen in the soil, Zak said. At the same time, the rate at which microorganisms released nitrogen back to the soil, as fallen leaves and branches decayed, increased.
“The greater growth has been sustained by an acceleration, rather than a slowing down, of soil nitrogen cycling,” Zak said. “Under elevated carbon dioxide, the trees did a better job of getting nitrogen out of the soil, and there was more of it for plants to use.”
Zak stressed that growth-enhancing effects of CO2 in forests will eventually “hit the wall” and come to a halt. The trees’ roots will eventually “fully exploit” the soil’s nitrogen resources. No one knows how long it will take to reach that limit, he said.
The ozone portion of the 12-year experiment also held surprises.
Ground-level ozone is known to damage plant tissues and interfere with photosynthesis. Conventional wisdom has held that in the future, increasing levels of ozone would constrain the degree to which rising levels of carbon dioxide would promote tree growth, canceling out some of a forest’s ability to buffer projected climate warming.
In the first few years of the Rhinelander experiment, that’s exactly what was observed. Trees exposed to elevated levels of ozone did not grow as fast as other trees. But by the end of study, ozone had no effect at all on forest productivity.
“What happened is that ozone-tolerant species and genotypes in our experiment more or less took up the slack left behind by those who were negatively affected, and that’s called compensatory growth,” Zak said. The same thing happened with growth under elevated carbon dioxide, under which some genotypes and species fared better than others.
“The interesting take home point with this is that aspects of biological diversity—like genetic diversity and plant species compositions—are important components of an ecosystem’s response to climate change,” he said. “Biodiversity matters, in this regard.”
###
Co-authors of the Ecology Letters paper were Kurt Pregitzer of the University of Idaho, Mark Kubiske of the U.S. Forest Service and Andrew Burton of Michigan Technological University. The work was funded by grants from the U.S. Department of Energy and the U.S. Forest Service.
Some of the trees were also bathed in elevated levels of ground-level ozone, the primary constituent in smog, to simulate the increasingly polluted air of the future.
——————————
I was told the air was improving not getting “increasingly polluted.”
Mike says:
October 14, 2011 at 8:20 am
====================================
Cyanobacteria mostly, they are everywhere
I thought the Druids were the only ones who tortured trees in the name of religion?
See how they have some stands planted in a ring? I haven’t seen that since I lived in the UK. A Forester explained it to me. They’d plant an Ash and let it grow for a few years. Then plant pine trees in a ring around it. Since the Pines grow faster, the Ash would lose its lower limbs and grow straight up with very few branches along its length. These made great masts for the Royal Navy.
Chuck Nolan says:
October 14, 2011 at 8:34 am
Some of the trees were also bathed in elevated levels of ground-level ozone, the primary constituent in smog, to simulate the increasingly polluted air of the future.
——————————
I was told the air was improving not getting “increasingly polluted.”
_________________________________________________
Yeah, I spotted the same straw-man and wondered about it. Having said that, this is a long-term experiment (12 years mentioned and it may have been a while with the paper in review – since it doesn’t exactly support CAGW), so maybe this was one of the justifications for the original grant and they are just quoting from the application.
Ozone at ground level has been reduced significantly by the various clean air acts around the world – even though the EPA is still pretending that it is deadly in order to reduce it further.
I have been saying this for a few years now.
More carbon dioxide is OK.
http://www.letterdash.com/HenryP/more-carbon-dioxide-is-ok-ok
“Some of the initial assumptions about ecosystem response are not correct and will have to be revised,” said Zak, a professor at the U-M School of Natural Resources”
Precisely, theories in biology are skewed to satisfy Malthusian underpinnings. I knew this result before the tests and I’m only a mining geologist/engineer. I based my certainty on the certainty that biologist/ecologists assume the path to disaster is short- which, as you can see has some prediction skill (that they are wrong)
but we might cause another mini ice age
Anecdotal but relavent. 50 year-old McIntosh apple tree next to my mom’s house in upstate New York. Biggest crop of apples ever last fall. Only thing that changed is in previous winter the old gas furnace (vintage 1965) was replaced with a new one which has intake and exhaust pipes positioned about 4′ off the ground at the side of the house whereas the old furnace exhausted out the roof chimney high above the ground and had no separate intake pipe.
Long story short the exhaust blows right about onto the trunk of that apple tree from about 12 feet away.
I am a little confused when I hear that when trees and plant-life dies the carbon they absorbed while growing is immediately released into the atmosphere. How can this be if those 100 foot seams of coal in Wyoming that were formed 300 million years ago were from decaying vegetation. If this is true than we have the ability to sequester carbon for millions of years.
“Zak stressed that growth-enhancing effects of CO2 in forests will eventually “hit the wall” and come to a halt. The trees’ roots will eventually “fully exploit” the soil’s nitrogen resources. No one knows how long it will take to reach that limit, he said.”
Sooo….
The Amazon Rain Forest must have hit the “fully exploit” wall long ago. Indeed the entire tropical and sup-tropical growing areas of the world must be in distress due to lack of nitrogen.
When will they all die off?
I smell a new grant application….
Prob’ly some legumes snuck in there and fixed it for ’em. (That’s why eating them is so productive of potent GHGs.)
“Zak stressed that growth-enhancing effects of CO2 in forests will eventually “hit the wall” and come to a halt. The trees’ roots will eventually “fully exploit” the soil’s nitrogen resources.
Zak my boy, you should have taken the nitrogen-from-the atmosphere 101 option in your undergrad studies. Nitrogen makes up 80% of the atmosphere and it falls in the rain, is sucked in by soil bacteria, and is especially efficiently pulled in by legumes growing in the soil. A thunderstorm causes a rich blast of nitrogen for the soil. Did you ever stop to think how the “nitrogen resources” in the soil got there in the first place? Oh well, there will be a timely re-discovery of this by plant scientists before too long. Hey the just worked out that CO2 is beneficial.
What the narrowly focused scientists and enviro-radicals of today usually don’t consider in their thought process is that trade-offs usually come into play in the real world. For example, there are numerous leguminous and non-leguminous forest undercover plant species that are capable of symbiotically producing nitrogen in a readily available form for plant uptake. Unfortunately, they are also palatable to many forest critters. If we overseeded forests with these species to increase nitrogen, eventually we would have to shoot the proliferating Bambi’s.
People who say that the forests can take care of themselves, might do well to have a look at the following, also by University of Michigan. Their deforestation figures are based on remote sensing.
http://www.globalchange.umich.edu/globalchange2/current/lectures/deforest/deforest.html
Actinorhizal plants are dicotyledons distributed among four angiosperm orders (Fagales, Cucurbitales, Fabales and Rosales), 8 families and 24 genera (Betulaceae: Alnus; Casuarinaceae: Gymnostoma, Casuarina, Allocasuarina, Ceuthostoma; Coriariaceae: Coriaria; Datiscaceae: Datisca, Elaeagnaceae: Eleagnus, Hippophae, Shepherdia; Myricaceae: Myrica, Comptonia; Rhamnaceae: Colletia, Discaria, Kenthrothammus, Retanilla, Talguenea, Trevoa, Ceanothus; Rosaceae: Dryas, Purshia, Cowania, Cercocarpus, Chamaebatia). Actinorhizal species are trees or shrubs, except for the genus Datisca.
Many are common plants in temperate regions like alder, bayberry, sweetfern, Avens, mountain misery and Coriaria. Some Elaeagnus species and Sea-buckthorns produce edible fruit.
Carbon sequestration need not be the chief aim. It suits me fine to say we’re reforesting for the sake of reforesting.
All of this begs the (naive) question, “But don’t commercial timber industries plan ahead, planting the trees they will soon harvest in big, like, nurseries, replanting the ones they have already cut?”
The Weyerhaeuser website is so green it hurts your eyes, but I imagine they are more interested in the “back end” of their investment, namely the harvest.
http://www.weyerhaeuser.com/
Even if capitalists do want to undertake replanting projects for (some future?) profit, my sense is that ultimately, they will have to navigate government bureaucracies, cooperate with government agencies to build roads, and to cut, and even take government subsidies to alleviate front-end losses. Where would they plant? What responsibility would they have for maintaining their “crops” of trees? How will they ultimately harvest their (or the government’s, or the private land owner’s) trees?
And why is it that right now, if you’re a lumberjack, you’re not “o.k.”:
http://www.timberharvesting.com/2011-logging-business-survey-big-squeeze/
“Future forests may soak up more carbon dioxide than previously believed”
Translation: The countries of the South with huge forests will be able to get larger international financial transfers from developed countries to store their carbon under REDD.
Oh, ferchrissakes. Of course trees “soak up” carbon dioxide. But they call it “food.”
The irony is that companies like weyerhaeuser who replant the trees they take down are villified by the same crowd that thinks CO2 is killing the planet. Talk about your carbon sinks, just think of all the carbon that is tied up in the wood of our houses.
How much carbon would there be in a live tree (and leaves) weighing (say) 10 tonnes? Does anybody know?
for the flatlanders among us: i’m really glad to see this topic come up. for nearly a half century i have heard the idiots screaming that you shouldn’t cut trees as they are gone forever. well they aren’t. i fought fire in western montana in my college summers and the trees that i planted as side work in 1962 were cut down and made into houses in bakersfield in 1995. it was part of a replanting cycle administrated by the USFS and paid for by the timber sales on govt. land. i believe that those areas have been replanted since.
the largest contributer to tree ring width is WATER!!!! trees that grow in oregon near the coast where it rains a lot grow about an inch a year in diameter, where trees that grow in the montana/idaho forest areas grow about a quarter of that. same tree species, better sunlight in the montana stands, same ground….. the height is pretty much forced by the densty of the stand of trees, the closer they grow the taller the faster they grow. it’s easy to tell, just look at a logging truck from each area.
for those who continue to snivel: You mow your lawns, DON’T YOU.
in actuallity some of the major factors in tree loss is drought and bugs. drought and bugs kill the trees, then they dryout and sooner or later a lightining strike sets the whole mess on fire. quarter million acre fires or larger. (the country is so large that unless the fire comes withing a few miles of some of the larger towns not to many people notice.) it happens half a dozen times in ten years.
the ecologists stand by and tell people that its their fault because they built their house within 70 miles of a lightning strike. this causes a considerable amount of bad feeling……. but that doesn’t slow the greenies down. as most of them live in the college towns quite a ways away. they’re not not to hard to miss as they usually have bullet holes in the trunks of their cars from stealing christmas trees off of private land.
C
I’d like to see a comparison of grassland vs forest. I would think the grassland environment could soak up even more carbon dioxide than a forested one. Grasslands can carry on photosynthesis for more months of the year than forests, and though they don’t store quantities of carbon as wood, the soils beneath them tend to accumulate very large volumes of organic matter which probably exceeds the volume of wood for a given acre of forest land.
Lord-luv-a-duck, have all you gone out of your gourds? Why have you bought into this “storing/saving/soaking up carbon(-dioxide)” bushwah? Do you actually believe it’s important, efficacious, a good thing?
Dig up limestone, roast it in coal-fired kilns, maximize atmospheric CO2. It pays big time in improved agriculture. As opposed to “carbon reduction”, which is lose-lose-lose-…. all the way down.
And “pollution” from other hydrocarbons is well-controlled in affluent societies, and is FAR cheaper than gutting energy infrastructure and consumption. So let’s make everyone affluent. There’s a plan that will actually work!
Get real.
What is this about soaking up CO2? Doesn’t anyone else worry about how little of it there is?
I was looking at a long distant past graph the other day, and noticed that the dinosaurs flourished when there was a very high level of CO2 – between 1,200ppm and 2,000 ppm. The dinosaurs were supposed to have been wiped out by a meteorite, but could it be that when CO2 dropped below 1,200 ppm or thereabouts 60 million years ago, the huge vegetation on which they lived was starved of the previously abundant CO2, and the dinosaurs starved. All life shrank. That always puzzled me..
Stikes me that if CO2 drops much lower, the vegetation on which we live will shrink and we will all be extinct as well.
I’d be willing to bet that, push comes to shove, that Photosynthesis is far more efficient at storing heat energy from the Sun than a trace gas floating in the atmosphere. For every CO2 molecule, there are 3,000 other molecules about. That’s mighty weak, but then so is CO2 trace gas warming theory.