Logging destabilizes forest soil carbon over time, Dartmouth study finds

December 02, 2014

HANOVER, N.H. - Logging doesn't immediately jettison carbon stored in a forest's mineral soils into the atmosphere but triggers a gradual release that may contribute to climate change over decades, a Dartmouth College study finds.

The results are the first evidence of a regional trend of lower carbon pools in soils of harvested hardwood forests compared to mature or pristine hardwood forests. The findings appear in the journal Global Change Biology Bioenergy. A PDF of the study is available on request.

Despite scientists' growing appreciation for soil's role in the global carbon cycle, mineral soil carbon pools are largely understudied and previous studies have produced differing results about logging's impact. For example, the U.S. Forest Service assumes that all soil carbon pools do not change after timber harvesting.

The Dartmouth researchers looked at how timber harvesting affects mineral soil carbon over 100 years following harvest in the northeastern United States, where soils account for at least 50 percent of total ecosystem carbon storage. Mineral soils, which underlie the carbon-rich organic layer of the soil, make up the majority of that storage, but are sometimes not included in carbon studies due to the difficulty in collecting samples from the rocky, difficult terrain. The researchers hypothesized that the mineral soil carbon would be lower in forests that had been harvested in the last century than in forests that were more than 100 years old. They collected mineral soil cores from 20 forests in seven areas across the northeastern United States and compared the relative amounts of carbon in the soil from forests that were logged five years ago, 25 years ago, 50 years ago, 75 years ago and 100 years ago.

The results showed no significant differences between mineral soil carbon in the older versus harvested forests. But there was a significant relationship between the time since forest harvest and the size of the carbon pools, which suggested a gradual decline in carbon across the region that may last for decades after harvesting and result in increased atmospheric carbon dioxide.

"Our study suggests that forest harvest does cause biogeochemical changes in mineral soil, but that a small change in a carbon pool may be difficult to detect when comparing large, variable carbon pools," says lead author Chelsea Petrenko) (formerly Vario), a doctoral candidate in the Graduate Program in Ecology and Evolutionary Biology and a trainee in Dartmouth's IGERT program for Polar Environmental Change. "Our results are consistent with previous studies that found that soil carbon pools have a gradual and slow response to disturbance, which may last for several decades following harvest."

A previous Dartmouth study found that clear-cutting releases detectible amounts of carbon stored in deep forest soils, challenging the notion that burning woody biomass for energy is more carbon-neutral than fossil fuels. "Mineral soil, which is the most significant ecosystem carbon pool in temperate forests, should be studied more closely before the carbon neutrality of bioenergy from local wood in temperate forests is asserted," says Petrenko, whose research focuses on the biogeochemistry of warming ecosystems and the impact on climate change.
-end-
Available to comment are Chelsea Petrenko at Chelsea.L.Petrenko.GR@dartmouth.edu and senior author Andrew Friedland, a professor of Environmental Studies at Dartmouth at Andrew.J.Friedland@dartmouth.edu.

Broadcast studios: Dartmouth has TV and radio studios available for interviews. For more information, visit: http://www.dartmouth.edu/~opa/radio-tv-studios/

Dartmouth College

Related Climate Change Articles from Brightsurf:

Are climate scientists being too cautious when linking extreme weather to climate change?
Climate science has focused on avoiding false alarms when linking extreme events to climate change.

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.

Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.

Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.

Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.

Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.

A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.

Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).

Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.

Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.

Read More: Climate Change News and Climate Change Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.