Understanding patterns and processes in models of trophic cascades

Research output: Contribution to journalArticle

68 Citations (Scopus)

Abstract

Climate fluctuations and human exploitation are causing global changes in nutrient enrichment of terrestrial and aquatic ecosystems and declining abundances of apex predators. The resulting trophic cascades have had profound effects on food webs, leading to significant economic and societal consequences. However, the strength of cascades – that is the extent to which a disturbance is diminished as it propagates through a food web - varies widely between ecosystems, and there is no formal theory as to why this should be so. Some food chain models reproduce cascade effects seen in nature, but to what extent is this dependent on their formulation? We show that inclusion of processes represented mathematically as density-dependent regulation of either consumer uptake or mortality rates is necessary for the generation of realistic “top-down” cascades in simple food chain models. Realistically modelled “bottom-up” cascades, caused by changing nutrient input, are also depend on the inclusion of density-dependence, but especially on mortality regulation as a caricature of e.g. disease and parasite dynamics or intra-guild predation. We show that our conclusions, based on simple food chains, transfer to a more complex marine food web model in which cascades are induced by varying river nutrient inputs or fish harvesting rates.
LanguageEnglish
Pages101–114
Number of pages14
JournalEcology Letters
Volume17
Issue number1
Early online date27 Oct 2013
DOIs
Publication statusPublished - 30 Jan 2014

Fingerprint

trophic cascade
food chain
food webs
food web
intraguild predation
mortality
nutrient
density dependence
nutrient enrichment
nutrients
global change
terrestrial ecosystem
aquatic ecosystem
eutrophication
parasite
predator
predation
climate
uptake mechanisms
predators

Keywords

  • bottom-up
  • food chain
  • food web
  • predator-prey
  • density-dependence
  • simulation
  • model
  • harvesting
  • top-down

Cite this

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Understanding patterns and processes in models of trophic cascades. / Heath, Michael R.; Speirs, Douglas C.; Steele, John H.

In: Ecology Letters, Vol. 17, No. 1, 30.01.2014, p. 101–114.

Research output: Contribution to journalArticle

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