Population Ecology

, 51:123

Density dependence in northern ungulates: interactions with predation and resources

  • Guiming Wang
  • N. Thompson Hobbs
  • Saran Twombly
  • Randall B. Boone
  • Andrew W. Illius
  • Iain J. Gordon
  • John E. Gross
Original Article

DOI: 10.1007/s10144-008-0095-3

Cite this article as:
Wang, G., Hobbs, N.T., Twombly, S. et al. Popul Ecol (2009) 51: 123. doi:10.1007/s10144-008-0095-3

Abstract

Variation in the abundance of animals has traditionally been explained as the outcome of endogenous forcing from density dependence and exogenous forcing arising from variation in weather and predation. Emerging evidence suggests that the effects of density dependence interact with external influences on population dynamics. In particular, spatial heterogeneity in resources and the presence of capable predators may weaken feedbacks from density dependence to growth of populations. We used the Kalman filter to analyze 23 time series of estimates of abundance of northern ungulate populations arrayed along a latitudinal gradient (latitude range of 40°–70°N) to evaluate the influence of spatial heterogeneity in resources and predation on density dependence. We also used contingency tables to test whether density dependence was independent of the presence of carnivores (our estimate of predation) and multiple regressions to determine the effects of spatial heterogeneity in resources, predation, and latitude on the strength of density dependence. Our results showed that the strength of density dependence of ungulate populations was low in the presence of large carnivores, particularly at northern latitudes with low primary productivity. We found that heterogeneity in elevation, which we assume acted as a surrogate for spatial heterogeneity in plant phenology, also reduced effects of density dependence. Thus, we show that external forces created by heterogeneity in resources and predation interact with internal feedbacks from population density to shape dynamics of populations of northern ungulates.

Keywords

Gompertz modelKalman filterLarge carnivoresLocal environmental variabilityPredationSpatial heterogeneity

Copyright information

© The Society of Population Ecology and Springer 2008

Authors and Affiliations

  • Guiming Wang
    • 1
  • N. Thompson Hobbs
    • 2
  • Saran Twombly
    • 3
    • 7
  • Randall B. Boone
    • 2
  • Andrew W. Illius
    • 4
  • Iain J. Gordon
    • 5
  • John E. Gross
    • 6
  1. 1.Department of Wildlife and FisheriesMississippi State UniversityMississippi StateUSA
  2. 2.Natural Resource Ecology LaboratoryColorado State UniversityFort CollinsUSA
  3. 3.Department of Biological SciencesUniversity of Rhode IslandKingstonUSA
  4. 4.Institute of Evolutionary Biology, School of Biological SciencesUniversity of EdinburghEdinburghUK
  5. 5.CSIRO Davies LaboratoryAitkenvaleAustralia
  6. 6.Office of Inventory, Monitoring and EvaluationNational Park ServiceFort CollinsUSA
  7. 7.Division of Environmental BiologyNational Science FoundationArlingtonUSA