w oody plants are an important component of rangeland habitat, providing food and shelter for animals that range in size from moose to warblers to insects. Because of this importance, land managers are paying increased attention to browse trends. In this two-part article, we describe how browse trend is assessed at the Mt. Haggin Wildlife Management Area in southwestern Montana.Located south of Anaconda, Montana (Fig. l), winters are extremely cold and windy at the Mount Haggin Wildlife Management Area. The annual precipitation is Fig. 2. Willow co~nrnzinityprovides critical habitat for wildlife. about 20 inches, much of which occurs as snow.

A survey based on browsing related architectures indicated that browsing level had increased at the Mt. Haggin Wildlife Management Area. We describe a technique for determining the year in which the increase in browsing level occurred. The technique is based on the analysis of stems old enough to have experienced the early period of light browsing; the onset year of intense browsing was determined by using dendrochronology to date the formation of twig clusters produced by intense browsing. Stems from 20 Geyer willow (Salix geyeriana Anderss.) plants were analyzed from each of 6 study sites. Mean onset years at the 6 sites ranged from 1983.1 to 1988.4; the mean onset year for all 6 sites was 1985.4 ± 0.5 SE (N = 120). The reconstructed history was used to evaluate the relationship between moose (Alces alces) number and browse trend. From 1976 to 2000, the winter trend census of moose increased from 7 to 56. The onset of intense browsing in 1985 occurred when 23 moose were counted.

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