Abstract

Extrapolating ecological processes from small-scale experimental systems to scales of natural populations usually entails a considerable increase in spatial heterogeneity, which may affect process rates and, ultimately, population dynamics. We demonstrate how information on the heterogeneity of natural populations can be taken into account when scaling up laboratory-derived process functions, using the technique of moment approximation. We apply moment approximation to a benthic crustacean predator-prey system, where a laboratory-derived functional response is made spatial by including correction terms for the variance in prey density and the covariance between prey and predator densities observed in the field. We also show how moment approximation may be used to incorporate spatial information into a dynamic model of the system. While the non-spatial model predicts stable dynamics, its spatial equivalent also produces bounded fluctuations, in agreement with observed dynamics. A detailed analysis shows that predator-prey covariance, but not prey variance, destabilizes the dynamics. We conclude that second-order moment approximation may provide a useful technique for including spatial information in population models. The main advantage of the method is its conceptual value: by providing explicit estimates of variance and covariance effects, it offers the possibility of understanding how heterogeneity affects ecological processes

Published in

American Naturalist
2006, Volume: 167, number: 2, pages: 246-259
Publisher: UNIV CHICAGO PRESS

SLU Authors

• Leonardsson, Kjell

  • Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Fish and Aquacultural Science
Environmental Sciences related to Agriculture and Land-use


Publication identifier

DOI: https://doi.org/10.1086/499372

Permanent link to this page (URI)

https://res.slu.se/id/publ/21162