Experiment suggests limitations to carbon dioxide 'tree banking'August 07, 2007SAN JOSE, CALIF. -- While 10 years of bathing North Carolina pine tree stands with extra carbon dioxide did allow the trees to grow more tissue, only those pines receiving the most water and nutrients were able to store significant amounts of carbon that could offset the effects of global warming, scientists told a national meeting of the Ecological Society of America (ESA). These results from the decade-long Free Air Carbon Enrichment (FACE) experiment in a Duke University forest suggest that proposals to bank extra CO2 from human activities in such trees may depend on the vagaries of the weather and large scale forest fertilization efforts, said Ram Oren, the FACE project director. "If water availability decreases to plants at the same time that carbon dioxide increases, then we might not have a net gain in carbon sequestration," said Oren, a professor of ecology at Duke's Nicholas School of the Environment and Earth Sciences.
"In order to actually have an effect on the atmospheric concentration of CO2, the results suggest a future need to fertilize vast areas," Oren added. "And the impact on water quality of fertilizing large areas will be intolerable to society. Water is already a scarce resource. " In a presentation delivered on Tuesday, Aug. 7 by Heather McCarthy, Oren's former graduate student, eight scientists working at the FACE site reported on the daily administrations of 1 1/2 times today's CO2 levels and how it has changed carbon accumulations in plants growing there. The Department of Energy-funded FACE site consists of four forest plots receiving extra CO2 from computer-controlled valves mounted on rings of towers, and four other matched plots receiving no extra gas. Trees in the loblolly pine-dominated forest plots that were treated produced about 20 percent more biomass on average, the researchers found. But since the amounts of available water and nitrogen nutrients varied substantially from plot to plot, using averages could be misleading. "In some areas, the growth is maybe 5 or 10 percent more, and in other areas it's 40 percent more," Oren said. "So in sites that are poor in nutrients and water we see very little response. In sites that are rich in both we see a large response." The researchers found that extra carbon dioxide had no effect on what foresters call "self thinning" -- the tendency of less-successful trees to die off as the most-successful grow bigger. "We didn't find that elevated CO2 caused any deviation from this standard relationship," said McCarthy, now a postdoctoral fellow at the University of California, Irvine. Also unchanged by the CO2 enrichment were the proportions of carbon atoms that found their way to various components of plant systems -- wood, leaves, roots and underlying soil. Only a few of those components will store carbon over time, noted Oren and McCarthy. "Carbon that's in foliage is going to last a lot shorter time than carbon in the wood, because leaves quickly decay," McCarthy said. "So elevated CO2 could significantly increase the production of foliage but this would lead to only a very small increase in ecosystem carbon storage." Duke University | |||||||||||||||||||||
|
Related Carbon Dioxide Current Events and Carbon Dioxide News Articles Bold traveler's journey toward the center of the Earth The first ecosystem ever found having only a single biological species has been discovered 2.8 kilometers (1.74 miles) beneath the surface of the earth in the Mponeng gold mine near Johannesburg, South Africa. RAND study: Alternative fossil fuels have economic potential Alternative sources of fossil fuels such as oil sands and coal-to-liquids have significant economic promise, but the environmental consequences must also be considered, according to a RAND Corporation study issued today. Arctic soil reveals climate change clues Frozen arctic soil contains nearly twice the greenhouse-gas-producing organic material as was previously estimated, according to recently published research by University of Alaska Fairbanks scientists. Deep biosphere research points to new methods for recovering petroleum Miles below us, deep within Earth's crust, life is astir. Organisms there are not the large creatures typically envisioned when thinking of life. NASA study finds rising Arctic storm activity sways sea ice, climate A new NASA study shows that the rising frequency and intensity of arctic storms over the last half century, attributed to progressively warmer waters, directly provoked acceleration of the rate of arctic sea ice drift, long considered by scientists as a bellwether of climate change. Gas from the past gives scientists new insights into climate and the oceans In recent years, public discussion of climate change has included concerns that increased levels of carbon dioxide will contribute to global warming, which in turn may change the circulation in the earth's oceans, with potentially disastrous consequences. Emissions rising faster this decade than last The latest figures on the global carbon budget to be released in Washington and Paris today indicate a four-fold increase in growth rate of human-generated carbon dioxide emissions since 2000. Green coffee-growing practices buffer climate-change impacts Chalk up another environmental benefit for shade-grown Latin American coffee: University of Michigan researchers say the technique will provide a buffer against the ravages of climate change in the coming decades. Cranking up the volume-- Sounds travel farther underwater as world's oceans become more acidic It is common knowledge that the world's oceans and atmosphere are warming as humans release more and more carbon dioxide into the Earth's atmosphere. However, fewer people realize that the chemistry of the oceans is also changing--seawater is becoming more acidic as carbon dioxide from the atmosphere dissolves in the oceans. Carbon sinks: Issues, markets, policy With reducing carbon emissions on the national agenda, a group of expert panelists will discuss methods, markets, testing and policy issues on how carbon sinks or carbon sequestration may be used to reduce atmospheric CO2. More Carbon Dioxide Current Events and Carbon Dioxide News Articles |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||