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permaculture - Re: [permaculture] questioning Douglas-fir thinning

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  • From: Toby Hemenway <toby@patternliteracy.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] questioning Douglas-fir thinning
  • Date: Thu, 13 Mar 2008 11:45:15 -0700


Marimike6@cs.com wrote:
Not certain of the status of Douglas firs on the West Coast. But lodgepole pine along the continental divide are nearly all dying or dead by now due to the practise of allowing uninhibited dense growth. Near-monocultural stands of these trees has encouraged the mother of all pine beetle infestations. Forest rangers have told me it could be a couple of centuries before the natural succession again returns these lodgepoles to the top of the ecological heap.
I've been re-reading my copy of Panarchy (by Lance Gunderson) and the pine-beetle infestation above reminded me of their story of the spruce budworm "damage." Forestry in much of North America is only old enough to have been through one cycle of the spruce budworm, which takes about 40-140 years, so when it happened everyone thought it was the end for spruce-fir forests, since it defoliated a good 80% of the trees in some places, with kills nearly as large.

It turns out that in young forests the budworms are visible to predators and are kept in check. This state is stable for many decades, but as the trees grow and foliage fills in, the larvae have more places to hide. They build to numbers that suddenly "release," in the language of complex adaptive systems, and kill large swaths of trees. This recycles enormous amounts of carbon into the soil, and in many ways sets the stage for the next generation of forests. The density of tree farms probably speeds up this cycle. Researchers are finding this kind of exploitation/release cycle in many places, such as the honey mushrooms that can kill hundreds of acres of forest. We see it as devastation, while it appears to be a very benevolent cycling that is on a scale a little too big, in both space and time, for us to grasp.

Toby
http://patternliteracy.com






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