[MCN] How logging contributes to climate destabilization

Lance Olsen lance at wildrockies.org
Mon Apr 18 10:29:48 EDT 2016

Clear-cutting destabilizes carbon in forest soils, Dartmouth study finds

HANOVER, N.H. - Clear-cutting loosens up carbon stored in forest 
soils, increasing the chances it will return to the atmosphere as 
carbon dioxide and contribute to climate change, a Dartmouth College 
study shows.

The findings appear in the journal Soil Science.

Soil is the world's largest terrestrial carbon pool. In northern 
hardwood forests in the United States, mineral soil pools store up to 
50 percent of total ecosystem carbon. Logging and other land-use 
changes are a major cause of soil carbon release, but there has been 
recent interest to further understand soil carbon dynamics in 
forested ecosystems after logging. This is of particular importance 
in the northeastern U.S. because of the great potential for the use 
of biomass as part of a diversified renewable energy portfolio.

The Dartmouth researchers explored whether clear-cutting changes the 
strength of the chemical bonds of carbon stored in mineral soils in 
hardwood forests in the northeastern United States. Clear-cutting 
involves harvesting all timber from a site at once rather than 
selectively culling mature trees. Carbon is stored in soil by binding 
only to certain soil structures.

The researchers collected soils from recently clear-cut forests and 
from older forests, and pulled carbon from the soil in a sequence of 
gentle to stronger extractions. The results showed that mature forest 
stands stored significantly more soil organic carbon in strongly 
mineral-bound and stable carbon pools than did soils from cut stands.

"Clear-cutting forests has an effect of mobilizing the carbon, making 
it more likely to leave the soil and end up in the atmosphere," says 
senior author Andrew Friedland, a professor of environmental studies. 
"These findings are important because differences in the relative 
distribution of carbon in organo-mineral pools in mature and cut 
forests may inform our understanding of soil organic matter stability 
and bioavailability, microbial decomposition and carbon dioxide 
production in ecosystems after clear-cutting."
The global climate change agreement brokered in Paris in December by 
195 nations will come into effect two years earlier than originally 
planned, the top United Nations climate diplomat predicted.

Even so, she said the deal had come "10 years too late," and that the 
world is now at "two minutes to midnight."

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