NEPA--Environmental Assessment

Treatment of noxious weeds would continue whether livestock grazing occurs or not. Livestock
would no longer be indirectly contributing to the spread of weed populations by creating conditions
that foster establishment of weeds, such as patches of bare soil, and reductions in vegetative cover
and competition.
There would be no impacts from permitted livestock grazing to threatened, endangered, proposed,
candidate, or sensitive plant species because there would be no permitted livestock grazing under
this alternative.
Alternative 2
Under this alternative, livestock grazing intensity (defined in Alternative 1) would be low in most
places. Sheep would graze (consume the leaves and shoots of plants) and sometimes overgraze (the
continued utilization of an excessive amount of the current years plant growth which exceeds the
recovery capacity of the plant) forage plants in the project area (particularly forbs), which would
decrease the photosynthetic abilities of the grazed plants by decreasing the leaf areas necessary for
performing this function (Heitschmidt and Stuth 1993, Caldwell et al. 1981, Briske and Richards
1995). Defoliation would cause a reduction of carbohydrate pools within the root systems of the
grazed plants, which would reduce root growth and nutrient absorption. A reduction in
photosynthesis and carbohydrate pools would decrease plant vigor and productivity and decrease the
grazed plants chances for survival by decreasing their ability to reproduce, compete, and withstand
drought, disease, fire, and grazing (Briske and Richards 1995).
A significant decrease in the abundance and vigor of plant species due to sheep grazing and
trampling (which often occurs at bedgrounds) would decrease the amount of ground cover
(vegetation and litter) and increase the amount of bare soil, which could reduce infiltration (Lull
1959, Smith 1967, Dadkhah and Gifford 1981), and increase runoff and erosion (Lull 1959, Orr
1975, Dunford 1954, Smith 1967, Forsling 1931).
This alternative would result in ecological conditions that are similar to current conditions since the
livestock grazing intensity, timing, and the rotation grazing system would remain the same. Since
sheep spend most of their time in the turf type, the potential for adverse effects from sheep grazing
would be greater there compared to the other alpine vegetation types. But adverse effects to plants
and soils from sheep grazing and trampling in all the vegetation types in the project area (including
the turf type, riparian areas, and wetlands) would be minor. Adverse effects to plants and soils from
sheep trailing and sheep bedgrounds would likely continue, but they would be minor. Also under this
alternative, the desired conditions for BLM lands and Forest Service lands would continue to be met.
Noxious weeds would continue to be present in the analysis area under this alternative. Permitted
livestock would continue to be one of the factors in the spread of noxious weeds, along with the
other sources of weed spread. As with Alternative 1, the spread of noxious weed populations would
be more dependent upon treatment intensity than upon livestock grazing.
There would be no impacts to threatened, endangered, proposed, or candidate plant species from
livestock grazing associated with these alternatives because there are none of them in the project
area and no habitat for them in the project area.
Potential effects of these alternatives to Sensitive Species Eriophorum altaicum var. neogaeum,
Parnassia kotzebuei, Machaeranthera coloradoensis, Cryptogramma stelleri, Carex viridula,
Eriophorum chamissonis, Eriophorum gracile, and Gilia sedifolia include injury or death to
individuals resulting from trampling or foraging by sheep, and disturbance to the habitat of these
species due to trampling by sheep which may also create conditions that are conducive to the
establishment of invasive plant species that can compete with native species for habitat resources,
which could lead to a decrease in the number of individuals of these species if they are present. It is
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