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From the Editors of E/The Environmental Magazine
Trees to Combat Climate Change
Plant these species to pull excess carbon dioxide from the air
Which trees are best to plant to help fight global warming?
Tim C., Perrineville, NJ
Trees are important tools in the fight to stave off global warming because they absorb and store the key greenhouse gas emitted by our cars and power plants, carbon dioxide, before it has a chance to reach the upper atmosphere where it can help trap heat around the Earth’s surface.
While all living plant matter absorbs carbon dioxide as part of photosynthesis, trees process significantly more than smaller plants due to their large size and extensive root structures. In essence, trees, as kings of the plant world, have much more woody biomass to store carbon dioxide than smaller plants, and as a result they are nature’s most efficient carbon sinks.
Tree species that grow quickly and live long are ideal carbon sinks, according to the U.S. Department of Energy. Unfortunately, these two attributes are usually mutually exclusive. Given the choice, foresters interested in maximizing the absorption and storage of carbon dioxide (known as carbon sequestration) usually favor younger trees that grow more quickly than their older cohorts. However, slower growing trees can store much more carbon over their significantly longer lives.
Scientists are busy studying the carbon sequestration potential of different types of trees in various parts of the U.S., including eucalyptus in Hawaii, loblolly pine in the Southeast, bottomland hardwoods in Mississippi and poplars in the Great Lakes.
“There are literally dozens of tree species that could be planted depending upon location, climate and soils,” says Stan Wullschleger, a researcher at Tennessee’s Oak Ridge National Laboratory who specializes in the physiological response of plants to global climate change.
Dave Nowak, a researcher at the U.S. Forest Service’s Northern Research Station in Syracuse, New York, has studied the use of trees for carbon sequestration in urban settings across the United States. A 2002 study he co-authored lists the common horse-chestnut, black walnut, American sweetgum, Ponderosa pine, red pine, white pine, London plane, Hispaniolan pine, Douglas fir, scarlet oak, red oak, Virginia live oak and bald cypress as examples of trees especially good at absorbing and storing carbon dioxide. Nowak advises urban land managers to avoid trees that require a lot of maintenance, as the burning of fossil fuels to power equipment like trucks and chainsaws will only erase the carbon-absorption gains otherwise made.
Ultimately, trees of any shape, size or genetic origin help absorb carbon dioxide. Most scientists agree that the least expensive and perhaps easiest way for people to help offset the carbon dioxide that they generate in their everyday lives is to plant a tree any tree, as long as it is appropriate for the given region and climate. Those who wish to help larger tree planting efforts can donate money or time to the National Arbor Day Foundation or American Forests in the U.S., or to the Tree Canada Foundation in Canada.
For more information:
• American Forests: www.americanforests.org.
• National Arbor Day Foundation: www.arborday.org.
• Tree Canada Foundation: www.treecanada.ca.
Got an environmental question? Send it to: EarthTalk, c/o E/The Environmental Magazine, P.O. Box 5098, Westport, CT 06881; submit it at www.emagazine.com/earthtalk/thisweek: or e-mail [email protected]. Read past columns at: www.emagazine.com/earthtalk/archives.php.