Preservation of Old Growth Forests has Surprise Environmental Benefit

In 1993, before concerns about climate change were as much in the public eye as they are today, forests on public land in the Northwestern United States came under the protection of the US Northwest Forest Plan. The goal of this plan was to preserve old growth forests from increasingly aggressive logging, and by doing so also protect endangered species like the Northern Spotted Owl. Today, researchers at Oregon State University and the USDA Forest Service Pacific Northwest Research Station have discovered that the plan has turned the forests into significant “carbon sinks,” areas which take in more carbon dioxide than they emit.


It may seem obvious that acres and acres of verdant forest have a positive effect on the environment, but in fact this is not always the case. When unprotected, the forests on public land were heavily logged. Although new trees were being planted, new growth emits more carbon dioxide than it takes in, making the area a source of carbon dioxide emissions. In the late 1980s and early 1990s, huge areas of both public and privately owned forest land were actually contributing to global warming.Under the US Northwest Forest Plan, however, harvesting dropped by 82 percent, and carbon emissions dropped too. The researchers used a combination of remote sensing and ecosystem monitoring to determine that the forests are taking in more carbon dioxide through photosynthesis than they are exuding through respiration, an unintended but positive side effect.

If managed properly, a forest can be logged while remaining carbon-neutral. The same study discovered that although harvesting on private lands has remained more or less at the same level, these privately owned forests have succeeded in becoming carbon neutral areas, a positive indicator for the feasibility of responsible, sustainable timber harvesting.

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