Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
The analysis assumes that the vegetation treatments include medium and small tree thinning and that
the fuel reduction treatments include understory pre-treatments (thinning trees less than four (4) inches
dbh). The analysis also assumes that any medium or small tree thinning would reduce canopy closure
levels to 30 percent or less and thereby removing it as thermal cover. It further assumes that pretreatment
activities degrade thermal cover by eliminating that portion of the canopy that can benefit
deer, specifically trees greater than five (5) feet in height. It is quantified as a reduction of 10 percent of
the canopy cover. Reductions were applied to the optimal and acceptable cover categories. Those
acreages where post-treatment cover levels were reduced to either the marginal or non-cover categories
are displayed in the “post-treatment cover reductions” columns for each alternative. The analysis does
not include or reflect the retention of 10 (Alternative 2) or 20 percent (Alternative 3) of each treatment
unit in an untreated state for acceptable thermal cover. This is because these retention clumps or
patches are to be distributed across the treatment unit to meet a variety of objectives, such as hiding and
thermal cover, structural and vegetative diversity, and cannot be assumed to exclusively provide
thermal cover. Under Alternative 3, 100 percent of existing optimal thermal cover patches would be
retained regardless of distribution.
In the long-term, more than 10 years, continued growth in forested areas would be expected to result in
a continuing increase in canopy closure levels and potentially increasing the amount and distribution of
thermal cover. Alternative 1 would be expected to experience the greatest increase in the number of
acres having canopy closures greater than 30 percent. Alternatives 2 and 3 would have smaller acreage
increases with most or all associated with untreated areas that are near 30 percent canopy closure at the
present time.
The risk of bark beetle attack and the subsequent long-term loss of thermal cover would be greatly
reduced on treated acres. As thermal cover levels increase, the risk of bark beetle attack also increases.
Assuming that efforts to minimize the risk of bark beetle attack through stand density management
would continue into the future, it is unlikely under either action alternative that thermal cover levels
would be allowed to reach current levels. It is therefore also unlikely that the current LRMP objective
of 30 percent thermal cover in deer winter range would ever be met or sustained on a large scale.
Similarly, increasing fuel loadings, including the development of ladder fuels and the retention of
flammable shrub species, also would continue to place existing and developing thermal cover at risk of
loss or destruction, particularly over the long-term.
Cumulative Effects -Thermal Cover -There are no identified cumulative or cumulatively significant
effects associated with the implementation of any of the current or on-going activities in conjunction
with Alternatives 1 and 3. The seasonal area closure from December 1 to March 31 will reduce the
harassment and stress to deer during the colder winter months, which should improve their health and
survivability by maintaining more body fat. [See above section for cumulative effects / cover]
Measurement Standard - Bitterbrush Age/Structure Ratio
The LRMP requires that a mixture of shrub age classes be provided in Deer Habitat (M7-14) to ensure
good forage availability for mule deer. The LRMP goal is to optimize habitat conditions within the
Deer Habitat allocation. Additionally, the Integrated Fuels Management Strategy (1998), which was
done in cooperation with the Oregon Department of Fish and Wildlife, recommended a ratio of 1/3 rd .
early, 1/3 rd . mid and 1/3 rd . late age/structure stages of bitterbrush as a desired condition in Deer Habitat.
Table 3-12 compares the acres of the various fuel reduction treatments by alternative within the
planning area. The analysis assumes that tree thinning would result in the conversion of approximately
25 percent of the existing bitterbrush acres to an early stage. Thinning combined with a follow-up
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