Washington Forest Health Issues in 2003
General Forest Conditions
The
USDA Forest Service regularly measures Washington’s forest size
and condition.
The
National Forests are monitored by the Forest Service (Region 6).State
and Private forest land is measured by the Forest Inventory and Analysis
group of the Pacific Northwest Research Station. Private landowners
also have their own inventory systems.
The
following information came from federal surveys completed between
1988 and 1997. Although a more recent cycle of inventory measurements
was completed for Washington in 2002, those data were not available
for reporting. The information will be updated in the 2004 Washington
Forest Health Highlights report and other more formal publications
that will be produced by the Forest Service.
Washington
has approximately 22 million acres of forest land which is dominated
by conifer species such as Douglas-fir, western hemlock and
ponderosa pine. Red alder, bigleaf maple and cottonwood are
the most important broadleaf species. Forests are classified
by "forest type" named for the dominant tree on the
site. |
Table
1: Number of acres of forest land by forest type.
1
Douglas-fir |
8,414,038 |
Western
hemlock |
2,685,372 |
Ponderosa
pine |
2,073,058 |
Red
alder |
1,403,420 |
Pacific
silver fir |
1,116,463 |
Nonstocked |
1,102,992 |
Mountain
hemlock |
928,213 |
Lodgepole
pine |
754,878 |
Grand
fir |
531,803 |
Subalpine
fir |
515,754 |
Western
redcedar |
508,696 |
Englemann
spruce |
348,331 |
Misc.
softwoods |
333,990 |
Western
larch |
304,468 |
Bigleaf
maple |
287,584 |
Misc.
hardwoods |
244,152 |
Unknown |
203,394 |
Cottonwood |
118,409 |
Total |
21,875,015 |
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In
addition to the number of acres covered, forests are measured
in the volume of wood present. A “cubic foot” of wood is a piece
of wood that is one foot tall, one foot wide, and one foot thick.
An eight-inch diameter log that is ten feet long contains about
3.5 cubic feet of wood.
The
live trees in Washington’s forests total approximately 72,256
million cubic feet of wood. Sixty percent of this wood is in
the major western Washington conifers Douglas-fir (29,514 million
cubic feet, 40.8%) and western hemlock (13,904 cubic feet, 19.2%).
The major eastern Washington conifers such as ponderosa pine,
grand fir and western larch contain much less wood, because
relatively dry eastern Washington forests have fewer trees,
smaller trees and cover less area. |
Table
2: Wood Volume in Washington Forest Types. 1
Douglas-fir |
29,514 |
Engelmann
spruce |
1,293 |
Grand
fir |
1,711 |
Lodgepole
pine |
1,868 |
Misc.
softwoods |
793 |
Mountain
hemlock |
1,787 |
Pacific
silver fir |
5,606 |
Ponderosa
pine |
3,275 |
Subalpine
fir |
1,380 |
Western
hemlock |
13,904 |
Western
larch |
880 |
Western
redcedar |
2,646 |
Bigleaf
maple |
1,113 |
Cottonwood |
280 |
Misc.
hardwood |
488 |
Red
alder |
5,404 |
Nonstocked |
239 |
Unknown |
74 |
Total |
72,256 |
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As
forest trees continue to grow, some also die. The ratio of mortality
(death) to growth provides information on whether forests are
increasing or decreasing. If growth is greater than mortality
then the ratio is greater than one and the forest volume is
increasing. If growth equals mortality then the ratio equals
one, and the forest volume is unchanged. If mortality is greater
than growth then the ratio is less than one, more trees are
dying and the forest live volume is decreasing.
The data
in Figure 3 indicate that some forest types are increasing in
volume and some are declining. The average ratio of mortality
to net growth in Washington, outside national, state, and municipal
parks is 2.68, indicating that growth is more than twice as
large as mortality. In Douglas-fir, western hemlock, western
redcedar and bigleaf maple forests growth is about four times
mortality. Lodgepole pine, grand fir and mountain hemlock forests
have growth that is about equal to mortality. Mortality exceeds
growth in Engelmann spruce and subalpine fir forests.
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In
addition to trees removed by logging and land clearing, insects,
diseases, fire, wind and a variety of other agents cause tree
death. In western Washington (Figure 4), when the cause of death
could be determined, it was most often attributed to physical
damage or fire, weather damage, and root disease. In eastern Washington
(Figure 5) trees were most often killed by physical damage or
fire, bark beetles, and root disease. |
|
- Hiserote,
B. and K.L. Waddell. 2003. The PNW – FIA Integrated
Database User Guide: Version 1.3. Internal Publication: Forest
Inventory and Analysis program, Pacific Northwest Research
Station. Portland, Oregon.
- Prepared
by Paul Dunham, Forest Inventory and Analysis program, Pacific
Northwest Research Station. Portland, Oregon. Re-formatted
by Jeff Moore, Washington Department of Natural Resources.
Olympia, Washington.
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