Environmental Management

, Volume 32, Issue 1, pp 152–169 | Cite as

Model-Based Assessment of Aspen Responses to Elk Herbivory in Rocky Mountain National Park, USA

  • Peter J. WeisbergEmail author
  • Michael B. Coughenour
Environmental Assessment


In Rocky Mountain National Park (RMNP), aspen (Populus tremuloides Michx.) has been observed to be declining on elk (Cervus elaphus nelsoni) winter range for many decades. To support elk management decisions, the SAVANNA ecosystem model was adapted to explore interactions between elk herbivory and aspen dynamics. The simulated probability of successful vegetative regeneration for senescent aspen stands declines sharply when elk densities reach levels of 3–5 elk/km2, depending on model assumptions for the seasonal duration of elk foraging activities. For aspen stands with a substantial component of younger trees, the simulated regeneration probability declines more continuously with increasing elk density, dropping below 50% from densities at 8–14 elk/km2.At the landscape scale, simulated aspen regeneration probability under a scenario of extensive seasonal use was little affected by elk population level, when this level was above 300–600 elk (25%–50% current population) over the ca. 107 km2 winter range. This was because elk distribution was highly aggregated, so that a high density of elk occupied certain areas, even at low population levels overall. At approximately current elk population levels (1000–1200 elk), only 35%–45% of senescent aspen stands are simulated as having at least a 90% probability of regeneration, nearly all of them located on the periphery of the winter range. Successful management for aspen persistence on core winter range will likely require some combination of elk population reduction, management of elk distribution, and fencing to protect aspen suckers from elk browsing.


Herbivory National park management Simulation models Ungulate population management Populus tremuloides Cervus elaphus Plant–animal interactions 


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We thank W. J. Ripple and two anonymous reviewers for providing helpful comments. W. Baker, T. Johnson, R. Monello, and F. Singer reviewed earlier versions of the manuscript. D. Barnett, G. Chong, M. Kaye, M. Khalkhan, R. Monello, C. Olmsted, M. Rock, W. Shepperd, F. Singer, T. Stohlgren and K. Suzuki provided critical data. This research was funded by Rocky Mountain National Park and EPA Project No. R827449-01-0.


  1. Baker, D. L., Andelt, W. F., Burnham, K. P., Shepperd, W. D. 1999Effectiveness of Hot Sauce and Deer Away repellents for deterring elk browsing of aspen sprouts.Journal of Wildlife Management6313271336Google Scholar
  2. Baker, W. L., Munroe, J. A., Hessl, A. E. 1997The effects of elk on aspen in the winter range in Rocky Mountain National Park.Ecography20155165Google Scholar
  3. Ball, J. T., Woodrow, I. E., Berry, J. A. 1987A model predicting stomatal conductance and its contribution to the control of photosynthesis under different environmental conditions.Biggins, I. eds. Progress in photosynthesis research.Martinees NijhofDordrechtPages 221224Google Scholar
  4. Barnett, D. T., Stohlgren, T. J. 2001Aspen persistence near the National Elk Refuge and Gros Ventre Valley elk feedgrounds of Wyoming, USA.Landscape Ecology16569580Google Scholar
  5. Bartos, D. L., Campbell, R. B.,Jr. 1998Decline of quaking aspen in the Interior West—examples from Utah.Rangelands201724Google Scholar
  6. Bartos, D. L., Johnson, R. S. 1978Biomass and nutrient content of quaking aspen at two sites in the western United States.Forest Science24273280Google Scholar
  7. Bartos, D. L., Mueggler, W. F. 1980Influence of fire on vegetation production in the aspen ecosystem in western Wyoming.Boyce, M. S.Hayden-Wing, L. D. eds. North American elk: ecology, behavior, and managementUniversity of Wyoming PressLaramiePages 7578Google Scholar
  8. Beetle, A. A. 1974. Range survey in Teton County, Wyoming. Part 4—quaking aspen. Agricultural Experiment Station, Research Journal 31, Laramie, WY.Google Scholar
  9. Boone, R. B., Coughenour, M. B., Galvin, K. A., Ellis., J. E. 2002Addressing management questions for Ngorongoro Conservation Area, Tanzania, using the Savanna modeling system.African Journal of Ecology40138150Google Scholar
  10. Clarke, J. A., Olmsted, C. E., and Larkins K. 1994. Patterns of habitat use, movement, and distribution of elk adjacent to the eastern boundary of Rocky Mountain National Park. Summary report to Rocky Mountain National Park. Estes Park, Colorado.Google Scholar
  11. Coughenour, M. B. 1992Spatial modeling and landscape characterization of an African pastoral ecosystem: a prototype model and its potential use for monitoring droughts.McKenzie, D. H.Hyatt, D. E.McDonald, V. J. eds. Ecological indicators, Vol. IElsevier Applied ScienceLondonPages 787810Google Scholar
  12. Coughenour, M. B. 2001. Elk in the Rocky Mountain Park ecosystem—a model-based assessment. Final report to US. Geological Survey Biological Resources Division and US National Park Service, 132 pp.Google Scholar
  13. Ellis, J. E., Coughenour, M. B. 1998The SAVANNA integrated modelling system: an integrated remote sensing, GIS and spatial simulation modelling approach.Squires, V. R.Sidahmed, A. E. eds. Drylands: sustainable use of rangelands into the twenty-first centuryIFAD Series: Technical Reports.Pages 97106Google Scholar
  14. Ellis, J. E., Coughenour, M. B., Swift, D. M. 1993Climate variability, ecosystem stability and the implications for range and livestock development.Behnke, R.Scoones, I.Kerven, C. eds. Range ecology at disequilibriumOverseas Development InstituteLondonPages 3141Google Scholar
  15. Friend, A. D., Shugart, H. H., Running, S. W. 1993A physiology-based gap model of forest dynamics.Ecology74792797Google Scholar
  16. Gruell, G. E., and Loope L. L. 1974. Relationships among aspen, fire, and ungulate browsing in Jackson Hole, Wyoming, U S Department of Agriculture, Forest Service, Intermountain Region. Google Scholar
  17. Gysel, L. W. 1960An ecological study of the winter range of elk and mule deer in the Rocky Mountain National Park.Journal of Forestry58696703Google Scholar
  18. Hart, J. H., Hart, D. L. 2001Interaction among cervids, fungi, and aspen in northwest Wyoming.Shepperd, W. D.Binkley, D.Bartos, D. L.Stohlgren, T. J.Eskew, L. G. eds. Sustaining aspen in western landscapes: symposium proceedings.USDA Forest Service Proceedings RMRS-P-18, Rocky Mountain Research StationFort Collins, ColoradoPages 197205Google Scholar
  19. Hess, K. 1993Rocky times in Rocky Mountain National Park: an unnatural historyUniversity Press of ColoradoBoulderGoogle Scholar
  20. Hinds, T. E. 1985Diseases.DeByle, N. V.Winokur, R. P. eds. Aspen: ecology and management in the western United States. Technical Report RM-119.USDA Forest Service General Rocky Mountain Forest and Range Experiment StationFort Collins, ColoradoPages 87106Google Scholar
  21. Hobbs, N. T. 1996Modification of ecosystems by ungulates.Journal of Wildlife Management60695713Google Scholar
  22. Hobbs, N. T., Baker, D. L., Ellis, J. E., Swift, D. M. 1981Composition and quality of elk winter diets in Colorado.Journal of Wildlife Management45156171Google Scholar
  23. Jones, J. R., Schier, G. A. 1985Growth.DeByle, N. V.Winokur, R. P. eds. Aspen: ecology and management in the western United StatesGeneral Technical Report RM-119. USDA Forest Service Rocky Mountain Forest and Range Experiment StationFort Collins, ColoradoPages 1924Google Scholar
  24. Kay, C. E. 1993Aspen seedlings in recently burned areas of Grand Teton and Yellowstone National Parks.Northwest Science6794104Google Scholar
  25. Kay, C. E. 1997aIs aspen doomed?Journal of Forestry95411Google Scholar
  26. Kay, C. E. 1997bViewpoint: ungulate herbivory, willows, and political ecology in Yellowstone.Journal of Range Management50139145Google Scholar
  27. Larkins, K.F. 1997. Patrterns of elk movement and distribution in and adjacent to the eastern boundary of Rocky Mountain National Park. MS thesis. University of Northern Colorado, Greeley, Colorado. Google Scholar
  28. Milchunas, D. G., Lauenroth, W. K., Chapman, P. L., Kazempour, M. K. 1989Effects of grazing, topography, and precipitation on the structure of a semiarid grassland.Vegetatio801123Google Scholar
  29. Mueggler, W. F. 1989Age distribution and reproduction of intermountain aspen stands.Western Journal of Applied Forestry44145Google Scholar
  30. National Park Service.1988Management policiesUS Department of the InteriorWashington, DC.Google Scholar
  31. Olmsted, C.E. 1977. The effect of large herbivores on aspen in Rocky Mountain National Park. PhD thesis. University of colorado, Boulder, Colorado. Google Scholar
  32. Olmsted, C.E. 1997. Tweny years of change in Rocky Mountain National Park elk winter range aspen. Unpublished report to Rocky Mountain National Park. Estes Park, Colorado.Google Scholar
  33. Peinetti, R. 2000. Riparian willow dynamics and their interaction with environmental and biological factors in the elk winter range of Rocky Mountain National Park (Colorado) – a multi-scale analysis. PhD thesis. Colorado State University, Fort Collins, Colorado.Google Scholar
  34. Ripple, W. J., Larsen, E. J. 2000Historic aspen recruitment, elk, and wolves in northern Yellowstone National Park, USA.Biological Conservation95361370Google Scholar
  35. Ripple, W. J., Larsen, E. J., Renkin, R. A., Smith., D. W. 2001Trophic cascades among wolves, elk and aspen on Yellowstone National Park’s northern range.Biological Conservation102227234Google Scholar
  36. Romme, W. H., Turner, M. G., Wallace, L. L., Walker., J. S. 1995Aspen, elk, and fire in Northern Yellowstone National Park.Ecology7620972106PhD thesis. Colorado State University, Fort Collins, Colorado.Google Scholar
  37. Romme, W. H., Turner, M. G., Gardner, R. H., Hargrove, W. W., Tuskan, G. A., Despain, D. G., Renkin, R. A. 1997A rare episode of sexual reproduction in aspen (Populus tremuloides Michx.) following the 1988 Yellowstone fires>Natural Areas Journal171725Google Scholar
  38. Ruark, G.A. 1985. Biomass, net primary production, and nutrient distribution in successionary Populus tremuloides Michx. stands on an entic haplorthod in nort-central Wisconsin. PhD thesis. University of Wisconsin, Madison.Google Scholar
  39. Schier, G. A. 1975. Deterioration of aspen clones in the middle Rocky Mountains. Research Paper INT-170. USDA Forest Service, Intermountain Forest and Range Experiment Station, Ogden, Utah.Google Scholar
  40. Shepperd, W. D. 1990A classification of quaking aspen (ASPENCLS) in the Central Rocky Mountains based on growth and stand characteristics.Western Journal of Applied Forestry56975Google Scholar
  41. Shepperd, W. D. 1993. Initial growth, development, and clonal dynamics of regenerated aspen in the Rocky Mountains. Research Paper RM-312. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado.Google Scholar
  42. Shepperd, W. D. 1996. Response of aspen root suckers to regeneration methods and post-harvest protection. Research Paper RM-RP-324. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, Colorado.Google Scholar
  43. Singer, F. J., Mark, L. C., Cate., R. C. 1994Ungulate herbivory of willows on Yellowstone’s northern winter range.Journal of Range Management47435443Google Scholar
  44. Singer, F., Elliott, T., Coughenour, M., Welker, J., Valentine, D., Williams, S., Zeigenfuss, L., Alstad, K., Menezes, R., Peinetti, R., Barnett, D., Cates, R., and Zou, J. 1998. Large mammalian herbivores, plant interactions, and ecosystem processes in five national parks. Third Annual Report on Cooperative Agreement 1445-0009-94-1074, Subagreement 2, to Midcontinent Ecological Science Center, Biological Resources Division of US Geological Survey, Fort Collins, Collins.Google Scholar
  45. Spalinger, D. E., Hobbs, N. T. 1992Mechanisms of foraging in mammalian herbivores: new models of functional response.American Naturalist140325348Google Scholar
  46. Stevens, D.R. 1979. Effect of elk on vegetation in Rocky Mountain National Park. Unpublished report to Rocky Mountain National Park.Google Scholar
  47. Stohlgren, T. J., Chong, G. W., Kalkhan, M. A., Schell., L. D. 1997Multiscale sampling of plant diversity: effects on minimum mapping unit size.Ecological Applications710641074Google Scholar
  48. Suzuki, K., Suzuki, H., Binkley, D., Stohlgren, T. J. 1999Aspen regeneration in the Colorado Front Range: differences at local and landscape scales.Landscape Ecology14231237Google Scholar
  49. Wang, J. R., Zhong, A. L., Comeau, P., Tsze, M., Kimmins, J. P. 1995Aboveground biomass and nutrient accumulation in an age sequence of aspen. (Populus tremuloides) stands in the Boreal White and Black Spruce Zone, British ColumbiaForest Ecology and Management78127138Google Scholar
  50. Weisberg, P. J., Hobbs, N. T., Ellis, J. E., Coughenour, M. B. 2002An ecosystem approach to population management of ungulates.Journal of Environmental Management65181197Google Scholar
  51. White, C. A., Olmsted, C. E., Kay., C. E. 1998Aspen, elk and fire in the Rocky Mountain national parks of North America.Wildlife Society Bulletin26449462Google Scholar
  52. White, C. A., Feller, M. C., and Bayley, S. 2003. Predation risk and the functional response of elk-aspen herbivory. Forest Ecology and Management (in press).Google Scholar
  53. Wolff, J. O. 1978Burning and browsing effects on willow growth in interior Alaska.Journal of Wildlife Management42135140Google Scholar

Copyright information

© Springer-Verlag New York, Inc. 2003

Authors and Affiliations

  1. 1.Mountain Forest Ecology Group, Department of Forest SciencesSwiss Federal Institute of Technology, ETH-Zentrum HG F21.5, CH-8092 ZurichSwitzerland
  2. 2.Natural Resource Ecology LaboratoryColorado State UniversityFort Collins, Collins, 80523-1499, USA

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