Effect of browsing on willow in the Steel Creek grazing allotment

The Steel Creek drainage serves as both wildlife range (primarily moose and elk) and as a livestock grazing allotment. For some years there has been concern about the effect of browsing on willows. Dense clusters of twigs have formed at the end of branches; entire stems of some plants have died. As of 1996, the relative impacts attributable to each of the ungulate species had not been documented.

In 1997 a study was begun to determine: a) the current level of browsing, b) the history of past browsing pressure, and c) the relative roles of the different ungulate species. All areas surveyed in 1997 were found to be 100% intensely browsed as measured by the methods described in Keigley and Frisina (1998). A reconstructed history of aspen browsing indicated that browsing pressure increased sometime in the mid-1980s (Keigley and Frisina 1998: pp. 122-124). The intense aspen browsing occurred east of the Steel Creek Ranger Station in an area in which all livestock have been excluded for several years, thus indicating that wildlife were responsible. While the 1997 study indicated that wildlife had a significant impact on browse condition, no data were collected that documented the potential impact of livestock within grazed areas, or the combined impact of livestock and wildlife.

In 1998 we began a study of browsing impacts in the Steel Creek grazing allotment. The objectives of the study were to:

1. Determine willow growth potential,

2. Document the effect of browsing,

3. Document the response of willows to protection from browsing,

4. Determine the amount consumed each year,

5. Distinguish between the impacts of livestock and wildlife, and

6. Evaluate the consistency of the measurement methods.

View upstream from the study area. Salix geyerriana is the dominant willow species. Salix drummondiana and S. Boothii are less common; older individuals of both species grow to about 2-m tall. Salix bebbiana is much less common, and where present, is browsed close to ground level. The carcass of an old Bebb willow that had attained typical stature is located near the study area. Beaver are absent. The remains of relic beaver dams indicate that beaver were once an important hydrologic influence.