Carrying Capacity: Concept and Critique
Key Points:
• The concept of carrying capacity has many meanings/definitions
• Many important management decisions are based on concepts of carrying capacity
• A critical perspective on the concept, its verbal and mathematical definitions, and its
applications are key to intelligent management and policy
Sources:
Caughley, G. and J. H. Lawton. 1981. Plant-herbivore systems. Ch. 7 in Theoretical Ecology (R. M. May, Editor).
Blackwell Sci. Publ.
McCullough, D. R. 1992. Concepts of large herbivore population dynamics. Pages 967-984 in Wildlife 2001:Populations
(Edited by D. R. McCullough and R. H. Berrett). Elsevier Applied Science.
Miller, K. V. and J. M. Wentworth. 2000. Carrying capacity. Ch. 7 in Ecology and Management
of Large Mammals in North America (S. Demaris and P. R. Krausman, Eds.), Prentice Hall.
Ricklefs, R. and G. L. Miller. 2000. Ecology. W. H. Freeman and Co.
Pierre-Francois Verhulst 1804-1849
Raymond Pearl 1879-1940
From Miller and Wentworth 2000
What is Carrying Capacity?
Originally modified from McCullough 1992
Problems with Definitions
K-Carrying Capacity
• KCC: does provide an understandable benchmark.
•Faulted on two issues:
• population may never reach KCC because of resources
that are limiting other than food resources
• KCC has high temporal variance so average value mean may not be useful
• HOWEVER, that other limiting factors exist does not mean that environmental limits do not exist.
“…relevant to distinguish between limits of the support capacity of the land,
the mortality imposed by human or natural predation…, or that combination…..
that determines the numbers of a population” (McCullough 1992)
• Does CC need to be constant? Isn’t the VAR(CC) important to understand and thus
provide guidance in using measures of CC in management?
I-Carrying Capacity ????
Carrying Capacity as an Equilibrium
Originally modified from Caughley 1979
Application of Carrying Capacity
with Environmental Variation
Originally modified from McCullough 1979
Carrying Capacity as a Useful Concept
In Ecology and Natural Resource Management???
Discussion led by Kaia and Todd:
Papers include Dhondt 1988 and McCleod 1997