Research Papers
Wild Ungulate Herbivory of Willow on Two National Forest Allotments in Wyoming

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Abstract

Willows (Salix) are important riparian plants and often used to indicate riparian condition. Many herbivores feed on willows, but there is limited information about willow browsing by wildlife except in national parks. This study was conducted to estimate wild ungulate herbivory of willow on two US Forest Service allotments in northern Wyoming and to compare these values to published estimates for national parks. We also compared total annual and seasonal willow utilization by wildlife between sites dominated by willows of different heights. The effects of height category, site, and season on willow utilization were determined with a repeated measures analysis. Four permanent willow utilization transects were established at each of six study sites per allotment on two allotments, in communities supporting planeleaf (Salix planifolia Pursh), Wolf's (Salix wolfii Bebb), Drummond's (Salix drummondiana Barratt ex Hook.), or Eastwood's (Salix eastwoodiae Cock. ex A. Heller) willow. Twenty-five twigs were marked per transect (distributed across 6–12 plants/transect). Lengths of marked twigs were recorded on four dates to estimate willow utilization for winter/spring, summer, and late summer/fall periods. Total annual willow utilization on one allotment (53%) was similar to published estimates for national parks (P  =  0.0864), whereas utilization for the other allotment (58%) was greater (P  =  0.0421) than national parks. Seasonal patterns of willow utilization differed among sites within height categories (P < 0.001). Total annual willow utilization by wildlife also varied by site within height category (P  =  0.0165) but was not greater for short (43–56%) versus tall (59–63%) willow communities. Wildlife browsing of willow in this study equaled, or exceeded, estimates for national parks, where concern has been expressed about willow community conditions. Generalizations about willow utilization for tall and short willow communities are problematic. Management decisions should be based on site-specific information as opposed to generalizations.

Resumen

Los sauces (Salix) son plantas importantes de las aéreas ribereñas y a menudo se utilizan para indicar la condición de esas áreas. Varios herbívoros ramonean estos sauces incluyendo el ganado y la fauna silvestre, pero existe poca información en relación al ramoneo de esta especie por fauna silvestre con excepción de los parques nacionales. Este estudio se realizó para estimar el ramoneo de los sauces por la fauna silvestre en dos sitios de USFS pastoreado por ganado o caballos en el Noreste de Wyoming y comparar estos valores a las estimaciones publicadas para los parques nacionales. También se comparó la utilización total por año, así como la estacional por la fauna silvestre entre sitios dominados por sauces a diferentes alturas. Se hizo un análisis de medidas repetidas para determinar los efectos de las categorías de la altura, sitio y estación en la utilización de los sauces. Cuatro transectos permanentes para medir la utilización de los sauces se establecieron en cada uno de los seis sitios del estudio por sección en las dos áreas. Veinticinco ramas se marcaron a lo largo de cada transecto (distribuidas a través de 6–12 plantas/transecto). La longitud de las ramas marcadas se registró durante 4 épocas para estimar la utilización de los sauces durante los periodos de invierno/primavera, verano, y finales de verano/otoño. La utilización total por año, en una de las áreas (53%) fue similar a las estimadas en las publicaciones de los parques nacionales (P  =  0.0864), mientras que para la otra área fue mayor (P  =  0.0421) con un (59%). En ambas áreas, los patrones estacionales de utilización del sauce fueron diferentes entre los sitios y entre las categorías de la altura. (P < 0.001). La utilización total anual del sauce por la fauna silvestre en ambos sitios presentó también una variación por sitio entre la categoría de altura (P  =  0.0165), pero no fue mayor para las comunidades pequeñas de sauces (43–56%) comparadas con las comunidades altas (59–63%). El ramoneo por la fauna silvestre en este estudio fue similar, y quizá exceda las estimaciones para los parques nacionales donde se ha tenido preocupación por la condición de la comunidad de los sauces. La generalización acerca de la utilización de los sauces para las comunidades altas y pequeñas es problemática. Las decisiones más apropiadas y efectivas de manejo y conservación se deben basar en información más en sitio-especifico contrario a generalizaciones.

Section snippets

INTRODUCTION

The importance of riparian ecosystems was captured effectively in a review by Kauffman and Krueger (1984) and has been reiterated many times (e.g., Schulz and Leininger 1990; Green and Kauffman 1995; Holland et al. 2005; Matney et al. 2005; Thorne et al. 2005). Because of their importance, the need to identify plants to indicate riparian zone condition has increased (Smith 1980; Kauffman and Krueger 1984), and willows (Salix) are often used in this manner (Martin 1978; Van Velson 1978; Platts

Study Areas

Two USFS grazing allotments in northern Wyoming were chosen as study sites for this project. Summer cattle grazing was permitted on both allotments, and wild, native ungulates had access to the study areas throughout the year.

The Greybull allotment (lat 44°02′N, long 109°19′W) on the Greybull District, Shoshone National Forest is located in the Absaroka Mountains approximately 40 km west of Meeteetse, Wyoming. This allotment has an area of 14 769 ha divided into 12 management units determined

Cattle Utilization of Willow During the Study

No cattle were present on the Greybull allotment at any time during this study. Therefore, all willow utilization reported for this allotment is a result of wildlife herbivory. Cattle used three of six sites on the Paintrock allotment during this study, and it was assumed that all willow utilization measured while cattle were in a particular study site was a result of cattle browsing even though wildlife may have also browsed willows. Cattle were not on the Paintrock allotment before the summer

DISCUSSION

Management and conservation of riparian willow communities should consider herbivory by all large ungulates using the area. This study focused on quantifying wildlife utilization of willow, which required quantification of willow herbivory by cattle at three of the six Paintrock sites. Willow utilization measured while cattle were present for 2–18 d confirms that it is important to consider livestock use of willow, as is often done. However, willow herbivory by wild ungulates in areas other

IMPLICATIONS

The degree of willow utilization by wildlife observed in this study equaled or exceeded that reported in national parks, where significant concern has been expressed about riparian willow community conditions. Zeigenfuss et al. (2002) concluded that “reducing elk numbers and/or reducing elk concentrations will result in increases in willow productivity and heights of willow” in national parks, and suggested that fencing some willow communities in parks may be necessary. It is clear that

ACKNOWLEDGMENTS

Special thanks to Fred Lindzey, Tom Wesche, and Bill Laycock for their valuable input in the planning stages of this study. Numerous individuals from the Pitchfork and Hyatt ranches and the Forest service made this research possible and enjoyable, especially Jack and Lili Turnell, Joe and Tracy Thomas, Louis and Rebecca Abar, Ray and Ruth Mills, Paula and Bill Grigsby, Wes and Margaret Hyatt, Lon and Jana Timberman, Jeff and Jean Petty, Dustin Cushman, Joe Hicks, and Dave Morris. We also

LITERATURE CITED (66)

  • ChaddeS.W. et al.

    Tall willow communities on Yellowstone's Northern Range: a test of the “Natural-Regulation” paradigm

  • ConroyS.D. et al.

    Willow planting success as influenced by site factors and cattle grazing in northeastern California

    Journal of Range Management

    (1991)
  • DahlemE.A.

    The Mahogany Creek watershed—with and without grazing

  • DornR.D.

    Moose and cattle food habits in southwest Montana

    Journal of Wildlife Management

    (1970)
  • DornR.D.

    Vascular plants of Wyoming

    (1992)
  • DunrudC.R.

    Volcanic rocks of the Jack Creek area, southeastern Absaroka range Park County, Wyoming [thesis]

    (1962)
  • EngemanR.M. et al.

    The use of repeated measurement designs in field studies

  • GaffneyW.S.

    The effects of winter elk browsing, South Fork of the Flathead River, Montana

    Journal of Wildlife Management

    (1941)
  • GirardM. et al.

    Classification of riparian communities on the Bighorn National Forest. Denver, CO, USA: US Department of Agriculture Forest Service R2-RR-97-02. 308 p

    (1997)
  • GirdenE.R.

    ANOVA repeated measures

    Newbury Park, CA, USA: Sage Publications. 77 p

    (1992)
  • GreenD.M. et al.

    Succession and livestock grazing in a northeastern Oregon riparian ecosystem

    Journal of Range Management

    (1995)
  • GundersonD.R.

    Floodplain use related to stream morphology and fish populations

    Journal of Wildlife Management

    (1968)
  • HansenP.L. et al.

    Riparian dominance types of Montana

    (1988)
  • HarryG.B.

    Winter food habits of moose in Jackson Hole, Wyoming

    Journal of Wildlife Management

    (1957)
  • HeroyW.B.

    Geology of the Shell Canyon area, Bighorn Mountains, Wyoming [dissertation]

    (1941)
  • KauffmanJ.B. et al.

    Livestock impacts on riparian ecosystems and streamside management implications—a review

    Journal of Range Management

    (1984)
  • KauffmanJ.B. et al.

    Effects of late season cattle grazing on riparian plant communities

    Journal of Range Management

    (1983)
  • KayC.E.

    Viewpoint: ungulate herbivory, willows, and political ecology in Yellowstone

    Journal of Range Management

    (1997)
  • KnopfF.L.

    Wildlife considerations in seasonal grazing of riparian zones

  • KovalchikB.L. et al.

    Effects of cattle grazing systems on willow-dominated plant associations in central Oregon

  • KufeldR.C.

    Foods eaten by the Rocky Mountain elk

    Journal of Range Management

    (1973)
  • MartinS.C.

    Evaluating the impacts of cattle grazing on riparian habitats in the National Forests of Arizona and New Mexico

  • McMillanJ.F.

    Some feeding habits of moose in Yellowstone Park

    Ecology

    (1953)
  • Cited by (1)

    Research was funded in part by the Wyoming Water Resources Center, the Hyatt Ranch, the Pitchfork Ranch, the WesMar Grazing Management Trust Fund, the SRM Hyatt Trust, the Wyoming Agricultural Experiment Station, and the Dept of Renewable Resources, University of Wyoming.

    At the time of the research, the senior author was research assistant, Dept of Rangeland Ecology and Watershed Management, University of Wyoming, Laramie, WY 82071, USA.

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