Higher density means world forests are capturing more carbon
Forests in many regions are becoming larger carbon sinks thanks to higher density, U.S. and European researchers say in a new report.
In Europe and North America, increased density significantly raised carbon storage despite little or no expansion of forest area, according to the study, led by Aapo Rautiainen of the University of Helsinki, Finland, and published in the online, open-access journal PLoS One.
Even in the South American nations studied, more density helped maintain regional carbon levels in the face of deforestation.
The researchers analyzed information from 68 nations, which together account for 72 percent of the world’s forested land and 68 percent of reported carbon mass. They conclude that managing forests for timber growth and density offers a way to increase stored carbon, even with little or no expansion of forest area.
“In 2004 emissions and removals of carbon dioxide from land use, land-use change and forestry comprised about one fifth of total emissions. Tempering the fifth by slowing or reversing the loss of carbon in forests would be a worthwhile mitigation. The great role of density means that not only conservation of forest area but also managing denser, healthier forests can mitigate carbon emission,” says Rautiainen.
Co-author Paul E. Waggoner, a forestry expert with Connecticut’s Agricultural Experiment Station, says remote sensing by satellites of the world’s forest area brings access to remote places and a uniform method. “However, to speak of carbon, we must look beyond measurements of area and apply forestry methods traditionally used to measure timber volumes.”
“Forests are like cities – they can grow both by spreading and by becoming denser,” says co-author Iddo Wernick of The Rockefeller University’s Program for the Human Environment.
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  IMAGE:Forests in many regions are becoming larger carbon sinks thanks to higher density, US and European researchers say in a new report. In Europe and North America, increased density significantly…Click here for more information. |
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The authors say most regions and almost all temperate nations have stopped losing forest and the study’s findings constitute a new signal of what co-author Jesse Ausubel of Rockefeller calls “The Great Reversal” under way in global forests after centuries of loss and decline. “Opportunities to absorb carbon and restore the world’s forests can come through increasing density or area or both.”
To examine how changing forest area and density affect timber volume and carbon, the study team first focused on the United States, where the U.S. Forest Service has conducted a continuing inventory of forest area, timberland area and growing stock since 1953.
They found that while U.S. timberland area grew only 1 percent between 1953 and 2007, the combined national volume of growing stock increased by an impressive 51 percent. National forest density increased substantially.
For an international perspective, the research team examined the 2010 Global Forest Resources Assessment compiled by the UN Food and Agriculture Organization (FAO), which provides consistent figures for the years 1990 to 2010.
The data reveal uncorrelated changes of forest area and density. Countries in Africa and South America, which lost about 10 percent of their forest area over the two decades, lost somewhat less carbon, indicating a small rise in forest density.
In Asia during the second decade of the study period, density rose in 10 of the region’s 21 countries. Indonesia’s major loss of density and sequestered carbon, however, offset any gain in carbon storage in other Asian nations.
Europe, like the U.S., demonstrated substantial density gains, adding carbon well in excess of the estimated carbon absorbed by the larger forested area.
Says study co-author Pekka Kauppi, of the University of Helsinki, Finland, “With so much bad news available on World Environment Day, we are pleased to report that, of 68 nations studied, forest area is expanding in 45 and density is also increasing in 45. Changing area and density combined had a positive impact on the carbon stock in 51 countries.”
Related, see Earth’s biosphere is booming, CO2 the cause
Look what happened to atmospheric CO2 when trees with broad leaves evolved in the late Devonian / early Carboniferous:
Beerling and Berner 2005
From rbateman on June 6, 2011 at 8:58 pm:
I’ve likely made that observation before about forests in general, and it is self-evident to many, but for this article I believe the credit goes to Hoser.
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From Andy G55 on June 6, 2011 at 9:47 pm:
Not necessarily, and I knew that, but the difference should get swamped out with sufficient increases in woodland density. For example, it doesn’t seem likely you could support five times the density with the same amount of water consumption.
Also unmanaged woodland areas tend to grow rather thick rather fast. I’m on the edge of a forest, and from when my parents built this house a half century ago they have photos showing this whole hilltop area was cleared off for farmland. It’s a battle keeping the trees from overtaking this small piece of property. But the atmospheric CO2 concentration rise is slow and leisurely in comparison. The growth rate of forest density, and area when allowed, far outstrips the rate of CO2 rise, thus the increase in the effect I noted (FCA) should be happening.
Alexander Feht says:
June 6, 2011 at 10:31 pm
I always wondered if agricultural cultivation of vast barren lands by man, going on for thousands of years, has ever been taken into account as an important CO2-absorbing and climate-moderating factor by those who, like IPCC and Dr. Ira Glickstein, are so fond of playing games with the formulas.
It may very well be that human activity, in the final reckoning, is more beneficial than it is destructive, as opposed to the purely hypothetical “natural state” of the planet.
I have wondered the same. Wheat and many other crops farmed on a very large scale are monocot grasses which have the C4 type of photosynthesis, more efficient than the Hatch-Slack C3 photosynthesis of dicot plants (e.g. trees). Therefore, if you clear forest for instance and replace it with a grass type agriculture, then the net result could well be more fixation of CO2 from the atmosphere, not less. (But turn it into a shopping mall and parking lot and thats another story.)
Thus agriculture globally is essentially a process of transferring atmospheric CO2 to human biomass. Thus if the extreme environmentalists were ever to realise their utopian agenda of human population reduction, it could have an unexpected outcome for atmospheric CO2.
So, forests are becoming larger carbon sinks? That to me means that we might end up sending more billions to countries with huge forests under REDD:
“Under the [REDD] scheme, a value would be placed on every ton of carbon that rain forests soak up.”
http://www.dailymail.co.uk/news/article-1335367/Starving-orangutans-forced-villages-look-food-rainforest-destroyed.html
Gotta give these redistributionist leftists credit for finding yet another way to squeeze more billions out of us…
Increased density of stocking, as several have commented here, isn’t all that it’s cracked up to be. I am a professional forester with 30+ years experience. Much of the increase in density of stocking in the US is due to the laissez-faire attitude of the USDA Forest Service, essentially walking away from management of more than 190 million acres of National Forest lands.
Increased density of stocking, up to a point, does indeed increase biomass and thus, carbon “sequestration.” However, these increases also lead to more decadent, fire prone forests (google Biscuit and B&B Fires in Oregon).
All trees require sunlight upon their leaves to actively conduct photosynthesis and grow. Dense forest has more shade and eventually, even shade tolerant species (true firs, hemlock, e.g.) begin to lose leaves and reduce growth. If this continues long enough, trees become stressed and much more prone to insects and diseases, and eventually, stand replacing fires. This is exactly the legacy that the policies of the USDA Forest Service is leaving – more and more over-mature, overly dense, decadent, and burned up forests, especially in the US West.
So, while some “researcher” may model on the computer that denser forests sequester more carbon, a simple math exercise, increased density if left to it’s own devices, is terrible for long term forest health.
Professor Pekka Kauppi of Helsinki University, a co-author of the study, said: ‘People worry about forest area, and that’s quite correct. But if you want to know the carbon budget, it cannot be monitored observing only the changes in area. It is more important to observe this change in forest density.’
Hasn’t Joe Romm been saying this very same thing about Arctic sea ice for years now? Funny how it’s come full circle to bite him in the ass now. How is the ice thickness doing now anyway?
MrC
Lew Skannen says:
Plants sucking up carbon? Outrageous!! The EU wants us to pay for expensive machines to do that….
And they call them ‘trees’:
http://thebreakthrough.org/blog/2008/03/18/synthetic%20trees.jpg
This is a pet peve of mine. There’s a difference between a sink and a store. Once the forest reaches max biomass density it is no longer a significant sink. In fact, due to the actions of insects and decay, it produces methane as it consumes co2. So, a mature forest is not a good thing for ghg reduction. On the other hand, if there’s a big forst fire, then some of the carbon is converted into char, which is somewhat longer-lived in the soil.