Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
the Opine planning area. The current type acres and percentages are based on the 1995 photointerpretation
layer in the district GIS database.
Table 3-21 Historic and Current Timber Type Acreages and Structural Stages
PAG Size Group
Lodgepole
Pine
Ponderosa
Pine
Structural
Stage
Timber
Atlas Acres
3-39
Timber Atlas
Type Percent
Current
Type Acres
Current
Type Percent
Seedlings/Saplings 0&1 * 0% 1,082 10.4
Poles 2&3 5,033 92.3 4,062 38.9
Mature 4,5,6,7 418 7.7 5,300 50.7
LP Totals 5,451 100 10,444 100
Seedlings/Saplings 0&1 858 4.3 7,009 26.7
Poles 2&3 1,299 6.6 10,117 38.6
Immature (12-21”) 4&5 2,239 11.3 3,272 12.5
Mature 6&7 15,391 77.8 5,807 22.2
PP Totals 19,787 100 26,205 100
During the past 30 years, approximately 5,250 acres or approximately 14.3 percent of the forested acres
within the planning area have had one or more silvicultural treatments implemented. Of these acres,
approximately 3,190 acres (approximately 60 percent of the previously treated acres) have had more than
one entry. Of those 3,190 acres, 215 acres have had two commercial timber harvest entries; the remaining
2,975 acres have had a non-commercial silvicultural treatment such as precommercial thinning or
reforestation activities implemented.
A total of 10,645 acres, approximately 29 percent of the forested acreage in the planning area, are rated as
being at moderate to high risk for bark beetle attack because they have canopy closures of 25 percent or
greater.
Effects
Bark Beetle Risk
Alternative 1: Under Alternative 1, none of the acres rated as moderate to high risk for bark beetle attack
10,645 acres, would have stand densities reduced. The likelihood of a landscape level bark beetle
epidemic is highest under this alternative. No measurable change in the number of acres at risk would be
expected during the next 5 to 10 years. It poses the greatest risk of loss of habitat for species that require
more dense stands and higher canopy closure levels, especially over the long-term. Assuming no
disturbance from wildfire or insect attack in the long-term, the number of acres rated as moderate to high
risk would be expected to increase as stands currently rated as low risk due to low stand densities and
canopy closure levels, experience increases in density levels and canopy cover. In stands comprised of
large diameter, older aged trees overtopping dense understory, the increasing stress associated with the
increasing competition for space, nutrients, and water would result in continued and increasing mortality
of the larger overstory trees. Structural diversity would be reduced or lost. The presence of dense stands
would also continue horizontal fuel continuities, which when combined with continued vertical fuels,
would retain the high risk of a high intensity ground and/or crown fire and result in increasing the risk of
damage or destruction to existing and proposed new facilities and site improvements.
Alternatives 2 and 3: Both reduce the risk of a landscape scale bark beetle epidemic. Alternative 2 and 3
would treat 43 percent (4,625 acres) and 47 percent (4,964 acres) respectively of the 10,645 forested acres
currently rated as moderate or high risk of bark beetle attack. Post-treatment stocking levels under both
alternatives are expected to keep beetle risk levels in treated stands at low to moderate levels for 20 to 30
years before re-entry would be required to again reduce canopy coverage to achieve low to moderate risk
levels. In stands with large diameter or mature and old growth aged trees, reduced stocking levels would
reduce the competition for available resources resulting in reduced stress levels, increased vigor, and