Environmental Assessment

AFFECTED ENVIRONMENT & ENVIRONMENTAL CONSEQUENCES CHAPTER 3
broadcast burn or a follow-up dripline burn would result in the conversion of approximately 75
(broadcast burned) and 40 (dripline burned) percent of existing bitterbrush acres to an early stage. A
broadcast burn with no thinning is assumed to result in the conversion of approximately 70 percent of
the existing bitterbrush acres to an early stage whereas a dripline burn without thinning would result in
the conversion of approximately 40 percent of those acres. Thinning with mowing or mowing without
thinning are assumed to result in the conversion of approximately 80 percent of the bitterbrush acres to
an early stage.
The late and decadent classes contain a large portion of the bitterbrush population, almost two thirds
(approximately 65 percent). The desired condition over the long-term is to have approximately one
third each in the early, mid, and late/decadent classes per INFMS and MA 7 goal to “optimize” habitat
conditions.
Table 3-13 summarizes the acreage and percentage of bitterbrush by age class and structure resulting
from implementation of each of the alternatives. Table 3-14 summarizes by WRHU LRMP land
allocation, alternative, and age class/structure category, the projected changes in age class/structure
associated with proposed vegetation and fuel reduction treatments under Alternatives 2 and 3.
Nine (9) percent of the planning area, 4,998 acres, has plant associations that have no potential for
bitterbrush. The remaining 49,625 acres either currently have bitterbrush present or have the potential
for it to be present. The figures in the table reflect only the acres with bitterbrush present or have the
potential to have it present. Due to the rounding of numbers, percentages and acres may not total 100
percent or 49,625 acres.
Table 3-13 Bitterbrush Age Class/Structure by Alternative
• Age
Class/Structur
e Stage
• Alt 1 • Alt 2 • Alt3
Acres Percent Acres Percent Acres Percent
• Early 12,734 • 26 22,922 • 46 21,234 • 43
• Mid • 4,871 • 10 • 2,279 • 5 • 2,589 • 5
• Late 15,387 • 31 11,668 • 24 12,380 • 25
• Decadent 16,633 • 34 12754 • 26 13,324 • 27
Alternative 1 (Bitterbrush Age/Structure Ratio): Under Alternative 1, 65 percent of the bitterbrush
acres, 32,020 acres would remain in the late seral stage (late and decadent age class/structure groups).
This is almost double the desired level of 1/3 rd of the acres being in this stage. Both the early, with
12,774 acres (26 percent) and the mid, with 4,878 acres (10 percent) would remain below the desired
goal of 1/3 rd of the acres in each seral stage.
Under Alternative 1, there would be no thinning or fuel reduction treatments and therefore, no existing
bitterbrush acres would revert to an early seral stage. Bitterbrush would continue to be concentrated in
the late and decadent age class and structural stages. The percentage of the bitterbrush in these two
classes would continue to increase in the long-term. Percentage would decrease in both the early and
mid classes over the long-term and assuming no large scale wildfire.
3-27