Forests' carbon capture abilities will peak in the future

Tiffany Stecker, E&E reporter
Published: Tuesday, April 3, 2012

American forests' capacity to hold carbon will peak in the next 10 to 40 years as it becomes harder for trees to recover from wildfires and pest infestation, the climate adviser to the Forest Service chief said yesterday.

In an interview with ClimateWire, climate change adviser David Cleaves said disturbances to forests would increase in the interior West, the interior of Alaska and the southeast of the country. Once forest stocks of carbon peak, they will remain steady for several years before declining.

"Carbon accumulations in forests are stabilizing," said Cleaves. Many areas are not reforesting as quickly and vibrantly as they could be, he added.

The Forest Service will elaborate on the findings in an upcoming Resources Planning Act assessment. The assessment reports on trends in renewable resources on forests and rangelands, as mandated by the 1974 act. In 1990, an amendment to the act was passed that required the incorporation of climate change predictions in the assessments.

According to a report by the Forest Service's Southern Forests Futures Program published last year, forests in the South will decline by about 23 million acres -- an area the size of South Carolina -- by 2060.

Forest carbon sequestration, trees' ability to absorb carbon and keep it out of the atmosphere, is an important factor for mitigating climate change. While forests will always sequester carbon, fires, insects and disease all drive the release of carbon, said Mark Ashton, a professor of forest ecology at the Yale School of Forestry & Environmental Studies. The age of trees in forests will also determine how well trees can hold carbon over time.

A move to the woods adds to the risk

"You can expect these large pulses of age classes to be affected all at once," said Ashton.

Mark Harmon, a professor of forest science at Oregon State University, said the key to the successful regeneration of future forests is probably moisture, which is why drier regions will see a decline in forest carbon stocks.

"The shorter the interval between disturbances and the longer the delay, the greater the effect," said Harmon. He added that dead trees and soil can also store carbon, even if the number of living trees declines. This can affect the numbers for carbon storage.

The urban areas that abut forests, zones known as the wildland-urban interface, will be the areas most affected, said Cleaves. As more and more people move to high-risk wildfire zones, recovery costs for wildfires have skyrocketed (ClimateWire, Oct. 26, 2010).

In addition to the Resources Planning Act assessment, the next National Climate Assessment, a report released by the U.S. Global Change Research Program, will include a chapter on the effect of climate change on forests. The assessment is expected to be released next year. The last one was completed in 2009.

The federal fire outlook predicted lower wildfire activity in the West this year than last year, specifically in states that saw significant damage in 2011, like Arizona and New Mexico (Greenwire, April 2).

Reprinted from ClimateWire with permission from Environment & Energy Publishing, LLC. www.eenews.net. 202-628-6500

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