Stand density in many
old-growth stands in southern Oregon has increased significantly
in the past 50+ years as shade-tolerant conifers and hardwoods
have invaded following the exclusion of fire. These understory
trees sometimes form "fuel ladders" that make the old-growth
trees (many of them over 300 years old) susceptible to stand-replacing
fires. Also, this increase in stand density and the corresponding
competition by younger trees may make old trees susceptible
to loss of vigor and pathogen or insect-related mortality, especially
during periods of drought. Reducing stand density in existing
old-growth stands may prolong the life of old trees by increasing
their ability to resist wildfire and reducing competitive
stress. The purpose of this study is to determine the response
of old-growth trees to past thinnings and to assess the use
of thinning as a mechanism to increase vigor in old-growth trees
while reducing the potential for severe fires in old-growth
stands. Results should help forest managers determine appropriate
silvicultural treatments to preserve or at least increase the
longevity of old-growth trees.
For additional information about this completed study see the
2000
CFER Annual Report. (2.7 MB)
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