Richard B. Keigley

A method for determining the onset year of intense browsing.

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. DOI:10.2458/azu_jrm_v56i1_keigley

Comment: Ungulate Herbivory of Willows on Yellowstone's Northern Winter Range: Response to Singer et al. (1994)

In a recent JRM article, Singer et al. (1994) report results of a willow (Salix spp.) study on the northern (ungulate winter) range of Yellowstone 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 judgement are more probable ones.

Aspen Height, Stem-girth and Survivorship in an Area of High Ungulate Use

An increase in ungulate population size potentially exposes aspen suckers, saplings, and trees to increased use. This study examined how stem height and girth influenced the selection of stems by ungulates for browsing, rubbing, and gnawing, and reconstructed the history of ungulate use for the study area. Transects were run through each of three aspen clones growing in southwestern Montana to determine height, circumference, and the surface area from which bark was totally and partially removed by rubbing and gnawing. Stems 20–250 cm tall were browsed. Stems 2–13 cm diameter were preferentially selected for rubbing and gnawing. The area of totally removed bark on dead saplings was twice the area of removed bark on live stems of similar diameter, suggesting that bark removal played a major role in the death of some stems. Based on an analysis of stem height and age, ungulate browsing was inferred to have increased from a light-to-moderate level to an intense level in 1991. The depth of scars was used to date scarring events. An increase in rubbing and gnawing was determined to have occurred about 1985. We concluded that elk were primarily responsible for the observed impacts. The combined effect of rubbing, gnawing, and browsing affects a broader span of ages compared to the effect of browsing alone. If prescribed fire is used to rejuvenate aspen stands, the resulting young stems should be protected from heavy browsing, rubbing and gnawing until they reach about 13 cm diameter and have grown out of the browse zone.

What is "natural"?: Yellowstone elk population? A case study

Ecology analyzes the structure and function of ecosystems at all points along the continuum of human disturbance, from so-called pristine forests to urban backyards. Undisturbed systems provide reference points at one end of the spectrum, and nature reserves and parks are highly valued because they can provide unique examples of such ecosystems. Unfortunately the concept of “natural” or pristine is not that easy to define. Indeed, although ecologists have considered pre-Columbian, western-hemisphere ecosystems to have been largely unaltered by human action, and have termed their state “natural” or “pristine,” evidence from archaeology challenges this view. U.S. and Canadian national parks are charged with preserving the “natural,” and thus need to be able to understand and manage for the “natural.” A pivotal “natural” question in Yellowstone National Park management is the size of the northern-range, wintering elk population at Park establishment in 1872, argued both to have been small and large. Integrating and quantifying several sources of evidence provides a consistent picture of a low population (ca. 5,000–6,000), largely migrating out of the northern range in winter, with little vegetation impact. If we accept this conclusion about what is natural for the Yellowstone ecosystem, then it dramatically alters how we view management alternatives for the Park, which currently supports a northern wintering herd of up to ˜ 25,000 elk.

How Perceptions About Naturalness Affect Science in Yellowstone National Park

ABSTRACT This paper describes a history of science and management on the Northern Range of Yellowstone National Park (YNP). In 1983 YNP began to shape public perceptions about management issues. In this case study, YNP shaped public perceptions to cause an unnatural condition (the appearance of the Northern Range was due to the extermination of wolves) to be portrayed as a natural condition (the appearance was due to climate change). Perception shaping can adversely affect the quality of science and influence the role of science in resource management. Perception shaping can have devastating ecologic consequences.