Forests in Western U.S. out of balance
Colorado forests are dangerously overpopulated. Can they be restored to healthy conditions?
Wednesday, May 11, 2011 - 00:17
DWARF MISTLETOE: Parasites such as dwarf mistletoe are increasingly found in unhealthy forests. (Photo: Will Geller)
Forests in Colorado are under threat — threat of populations that are, in some places, ten times more dense than natural forest structure. But what is natural?
Forest ecologists have learned that many forests in the West evolved with frequent, low-intensity fires. These fires were periodically started by lightning or ignited by Native Americans in order to clear the forest of fuel build-up, replenish nutrients and sustain diverse landscapes and ecosystems.
Ponderosa pine forests in the West are beginning to look like massive monocultures. Hundreds, possibly thousands, of trees of similar ages are packed together in a single acre. This is very different from what forests in the West looked like in pre-colonial times. Decades of fire suppression and the spread of grazing animals has changed the structure of the forest.
Restoration ecologists recommend a combination of manual thinning and prescribed burning. The goal is to restore the self-sustaining processes of the forest. Frequent low-intensity burns are ideal, letting our forests become overcrowded, with very few open spaces, is not. Dense thickets will burn with high-intensity, devastating crown fires. These high-intensity fires are the type that leave behind a moonscape and deposit siltation into the watershed.
Many are not comfortable with the idea of forests being more open. The belief "the more trees, the better" is incorrect from an ecosystem and forest health perspective. It is important to realize that fires will burn one way or another. The hope is that we won't have massive, damaging fires caused by a changed forest structure.
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