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R.B. Keigley

Publications and source records attributed to R.B. Keigley.

10 recordsLinked to original sources
USGS2008

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.

Northwest Science↗
USGS2008

Browse evaluation of tall shrubs based on direct measurement of a management objective

The monitoring of Geyer willow was based on the following management objective: Browsing will prevent fewer than 50 percent of Geyer willow shrubs from growing taller than 3 m . Three questions were addressed: (1) Is browsing a potential factor? (2) If so, can young plants grow taller than 3 meters? (3) If not, is browsing the dominant factor? All shrubs were intensely browsed. With a post-browsing growth rate of 5.0 cm per yr, no shrub could grow 3 m tall. Analyses of stem growth rate excluded dominant roles for climate and plant vigor. Browsing and stem age were the dominant factors that limited growth to 3 m tall.

Montana↗
USGS2003

A method for determining the onset year of intense browsing

McAuliffe studied the factors limiting seedling establishment of a common Sonoran Desert tree, Cercidium microphyllum, at three sites in bajada habitat in Arizona and Mexico. Distribution patterns of Cercidium seedlings in both habitats were random when seedlings emerged, however, seedling distribution in bajadas quickly became non-random and associated with other perennial plants. Seedlings closely associated with (rooted under) shrubby perennial vegetation survived because they had some protective cover and were not grazed by rabbits, however, future survival of these seedlings may be reduced due to competition with the protective plants. The authors concluded that herbivory was the main factor limiting the establishment of Cercidium microphyllum seedlings in the bajada habitats in the Sonoran desert.

Montana↗
USGS2002

Assessing browse trend at the landscape level Part 1: Preliminary steps and field survey

Woody 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. Willows are currently heavily browsed, but there is evidence that browsing pressure was lower in the past. Heavily-browsed 14-inch-tall plants grow in close proximity to 16-foot-tall plants, the tallest stems of which are unbrowsed. The 16-foot-tall stems are older than the 14-inch-tall stems, and apparently grew through the browse zone when browsing pressure was lower than its current level. An increase in browsing pressure would be consistent with the increase in the moose population that occurred over the past 3 decades.

Rangelands↗
USGS2002

Assessing browse trend at the landscape level Part 2: Monitoring

In Part 1, we assessed browse trend across a wide geographic area of Mt. Haggin Wildlife Management Area by conducting surveys of browsing-related architectures. Those data were qualitative. Below we describe the periodic collection of quantitative data from permanently marked locations; we refer to this phase of the trend assessment program as "monitoring." Trend was monitored by three methods: 1 Repeat photography. 2 Comparison of the height of live stems with the height of stems killed by browsing (LD Index). 3 Net annual stem growth rate (NAGRL3). The photography provides an assessment of trend from the comparison of photographs taken at intervals of a few years. The LD Index and NAGRL3 measurements provide an immediate assessment of trend.

Rangelands↗
USGS2001

The condition of browse plants at the Theodore Roosevelt Memorial Ranch (TRMR)

The Theodore Roosevelt Memorial Ranch (TRM), owned and operated by the Boone and Crockett Club, spans 6,000 acres along the Rocky Mountain East Front. The ranch is located west of Dupuyer, Montana, on the forks of Dupuyer and Scoffin Creeks. Each fall, mule deer migrate from the Bob Marshall Wilderness and adjacent Lewis and Clark and Flathead National Forests to the ranch and adjacent private lands. Winter counts and classifications have been conducted since the mid-1970’s by Montana Fish, Wildlife & Parks personnel. In addition to mule deer, domestic livestock, whitetailed deer and elk compete for space and forage on the winter range. Browse species such as chokecherry, aspen, serviceberry, red osier dogwood, horizontal juniper, and willows are utilized by all ungulates in the area. The Dupuyer Creek winter range shows evidence of severe over-browsing on these species. Coincidentally, mule deer and elk populations have historically been higher here than other areas along the mountain front. Over the past 22 years, mule deer densities have been calculated at over 75 deer per square mile over the entire winter range and up to 200 per square mile on the TRM itself. Winter ranges are occupied from mid-November through May. Winter counts are conducted in January and again in March to assess fawn and adult survival. An average of 2,100 mule deer are surveyed annually, with fawn/doe ratios of 71, fawn/adult ratios of 54, and buck/does ratios of 33 (ratios are expressed as animals per 100 does or adults). Mule deer migrate back to higher elevation summer ranges in mid- to late-May, traveling as far north as Glacier National Park and westward to the South Fork of the Flathead River. Less than 15 percent of the wintering population remains along the mountain front during the summer. Movements back to winter range may occur in early October, with the majority of animals present by November 15th. As background for a more comprehensive study, we collected data in September and October 1999 from which to assess the impact of ungulates on browse plants. There were three general objectives: 1) determine the current level of browsing intensity, 2) reconstruct histories of browsing, and 3) determine the effect of browsing on rate of stem growth.

Montana↗
USGS2000

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.

Wyoming↗
USGS2000

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.

Montana↗
USGS2000

Elk, beaver, and the persistence of willows in national parks: comment on Singer et al. (1998).

Singer et al. (1998) propose that the decline in populations of beaver (Castor canadensis) in Yellowstone National Park (YNP) has caused willow to be more vulnerable to browsing by clk (Alces alces). I do not believe that their scenario correctly characterizes the relationship between elk and willow in YNP The authors developed their hypothesis based on 2 sets of observations. One was an experiment that compared willow growth in YNP to that in Rocky Mountain National Park (RMNP). Current annual growth was clipped from plants at 0%, 50%, and 100% levels in each of 4 years (1992–1995). From RMNP plants in 1 exclosure were used (Beaver Meadows); in YNP plants in 3 exclosures were treatcd (Junction Butte, Lamar East, and Lamar West; L.C. Zeigenfuss, personal communication). A second set of observations, which included additional sites in RMNP measured the growth and stature of browsed and unbrowsed plants. Singer et al. (1998) reported response to the clipping experiment in their Table 5. Even under the most severe clipping treatments, willow height and annual production were maintained in RMNP willows but declincd in YNP willows. Willows in RMNP responded to the 50% clipping treatment by increasing the level of chemical defenses (tannins and phenolics), whereas the chemical defenses of YNP willows remained relatively constant. The authors surmised that 1) enhanced vigor may enable a plant's terminal leader to grow out of ungulates' reach and 2) increased production of chemical defenses may deter herbivory. Singer et al. (1998) concluded that the betweenpark differences were directly related to better growing conditions in RMNP compared to YNP The better growing conditions in RMNP were attributed to: 1) higher effective precipitation, 2) more beaver activity, 3) more beaver dams in drainages, and 4) higher water tables near streamsides. There are several reasons the experiment conducted by Singer et al. (1998) does not support these conclusions.

Colorado, Wyoming↗