title: Emergent global patterns of ecosystem structure and function from a mechanistic general ecosystem model.
abstract: Anthropogenic activities are causing widespread degradation of ecosystems worldwide, threatening the ecosystem services upon which all human life depends. Improved understanding of this degradation is urgently needed to improve avoidance and mitigation measures. One tool to assist these efforts is predictive models of ecosystem structure and function that are mechanistic: based on fundamental ecological principles. Here we present the first mechanistic General Ecosystem Model (GEM) of ecosystem structure and function that is both global and applies in all terrestrial and marine environments. Functional forms and parameter values were derived from the theoretical and empirical literature where possible. Simulations of the fate of all organisms with body masses between 10 µg and 150,000 kg (a range of 14 orders of magnitude) across the globe led to emergent properties at individual (e.g., growth rate), community (e.g., biomass turnover rates), ecosystem (e.g., trophic pyramids), and macroecological scales (e.g., global patterns of trophic structure) that are in general agreement with current data and theory. These properties emerged from our encoding of the biology of, and interactions among, individual organisms without any direct constraints on the properties themselves. Our results indicate that ecologists have gathered sufficient information to begin to build realistic, global, and mechanistic models of ecosystems, capable of predicting a diverse range of ecosystem properties and their response to human pressures.
authors.affiliation: United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom; Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Michael B J
authors.initials: MB
authors.lastname: Harfoot
authors.affiliation: United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom; Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Tim
authors.initials: T
authors.lastname: Newbold
authors.affiliation: United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom; Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom; Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Derek P
authors.initials: DP
authors.lastname: Tittensor
authors.affiliation: Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Stephen
authors.initials: S
authors.lastname: Emmott
authors.affiliation: United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom.
authors.forename: Jon
authors.initials: J
authors.lastname: Hutton
authors.affiliation: Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Vassily
authors.initials: V
authors.lastname: Lyutsarev
authors.affiliation: Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Smith
authors.affiliation: United Nations Environment Programme World Conservation Monitoring Centre, Cambridge, United Kingdom; School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Jörn P W
authors.initials: JP
authors.lastname: Scharlemann
authors.affiliation: Computational Science Laboratory, Microsoft Research, Cambridge, United Kingdom.
authors.forename: Drew W
authors.initials: DW
authors.lastname: Purves
mesh_terms: D002980:Climate; D003198:Computer Simulation; D055669:Ecological and Environmental Phenomena; D004463:Ecology; D017753:Ecosystem; D004777:Environment; D057232:Global Warming; D006801:Humans; D008954:Models, Biological; D008962:Models, Theoretical
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