and Second Growth >
Thanks to the many forest scientists
who have spent time studying the forests of Oregon, pioneers
and homesteaders who have recorded the landscape through
journals and pictures, we have a good idea today of what
our forests looked like earlier this century even back
to the mid-1800s!
||A forest worker
approaches the stem of a large, old Douglas-fir tree,
found in old growth forests of western Oregon.
Forest scientists Bill Ripple and Tom
Spies, their colleagues, and their predecessors, have been
looking to the past in order to understand the forests of
the present. With their work, we can see how our landscape
constantly changes, with or without human impacts.
| Let's talk about
old growth, using western Oregon (everything west
of the crest of the Cascades) as an example.
It is estimated that before
1840, the era considered "prelogging," between
40 to 60 percent of the forests of western Oregon were over
200 years old and had characteristics of old
growth forests. Large-scale, infrequent disturbances
like wildfires, insects and disease, windstorms, and human
activities, all combined to create a mix of younger forests
in the remaining forest lands. How big were some of these
disturbances? Well, in 1849 the Siletz fire in western Oregon
burned around 800,000 acres of forest that equates to
1,250 square miles, or a strip of land 11 miles wide, from
Eugene to Portland! Several other wildfires
over the last 150 years have also demonstrated the magnitude
of disturbance in this forest cycle, including the 240,000
acre Tillamook burn in the early '30s. As a result of these
disturbances the old growth in westside forests moved across
the forests over long periods of time. This is the cycle
of life in western Oregon forests.
As populations and demand for both
land and timber increased with the westward migration, so
did the harvest of large, old trees. Today, the amount of
naturally regenerated forests 80 yrs and older is about
3.2 million acres on federal land (additional amounts of
"late successional forest" occur on state and
private lands but these do not add much to the total). The
amount of forest considered old growth is considerably less.
In one analysis of the Coast Range
it is estimated that less than 10% of the federal lands
contain forests over 200 years old. Other estimates put
the amount of old growth at 10-20% of its level at the time
of Euroamerican settlement in the mid 1800's. It is important
to remember that the actual amount of old growth is not
known because of differences in definitions of "old
growth" and inventory methods. Also, the amounts of
old growth are least in the Coast Range and most in the
Oregon Cascades and Klamath areas.
Similar to the natural disturbances
caused by fire, insects and disease, and windstorms, today's
management activities of logging and burning remove forest
stands in patches. Unlike fire, insects, disease and windstorms,
however, logging tends to remove most of the live wood,
leave smaller and more uniform patch sizes, and is repeated
every 50 to 70 years catastrophic wildfires revisit western
Oregon forests with intensity to replace old growth forests
every few-hundred years.
Old growth forests play an important
role in the cycle of life and resources for the plant, animal,
and human communities of Oregon. As we learn more about
the old growth forests of Oregon, we as forest workers,
land managers, and forest land owners can better manage
for old growth characteristics should we decide to. Features
associated with old growth such as large live trees, large
standing snags, and woody debris on the forest floor, can
be incorporated into both even-aged and uneven-aged stands.