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.

Historical accounts, park records, and biologists' observations indicated that wintering elk in Yellowstone's northern range were present in low numbers prior to and at park establishment in 1872; increased to 20,000-35,000 by the early 1900s when they heavily impacted the northern-range ecosystem; and declined to 3,172 censused animals in 1968 due to park control efforts. In 1967, the park announced a politically coerced natural-regulation policy terminating park control; and in 1971 posed a natural-regulation ecological hypothesis stating that northern-range elk had been numerous prior to 1872, had not risen to 20,000-35,000 in the early 1900s, and would stabilize at moderate numbers following recovery from control efforts without significantly affecting the northern-range ecosystem. Archaeological and historic evidence, park records, and censuses begun in the 1920s indicate a northern herd of ~5,000-6,000 in 1872, increasing to ~20,000-35,000 in the early 1900s, declining to a censused number of 3,172 in 1968 in response to control efforts, increasing to a census-based number of 21,071-25,920 in the 1980s and 1990s, then declining somewhat after 2000. This book reviews critically the published and unpublished records to test the natural-regulation hypothesis and propose a conceptual model of the northern-range ecosystem with inferences from system changes associated with the four stages of elk abundance, inside-outside exclosure comparisons, and system comparisons inside and outside park boundaries.

In a recent JIinl article, Singer et al. (1994) report results of a willow (S&X spp.) study on the northern (ungulate winter) range of YeIlowstone National Park (YNP) and immediate vicinity. The authors measured production, forage quality, moisture stress, and tannin content of growth shoots, all in relation to ungulate browsing, browsing-induced architectural variation, and altitude. In our view, the evidence presented does not support a number of the major inferences drawn, and in fact points to what in our judgment are more probable ones.

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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