Scientists from Microsoft Research and the United Nations Environment Programme World Conservation Monitoring Centre (UNEP-WCMC) are developing the first general-purpose computer model of whole ecosystems, across the entire world. In a recent Nature article (Time to Model all Life on Earth), the authors argue that this type of model could radically improve our understanding of the biosphere and inform policy decisions about biodiversity and conservation.
General ecosystem models, or GEMs, are the ecological equivalent of general circulation models (GCMs), widely used in climate change science to simulate the physics and chemistry of the Earth's atmosphere. Scientists from Microsoft Research and UNEP-WCMC argue that GEMs could capture the broad-scale structure and function of any ecosystem in the world by simulating processes – including feeding, reproduction and death – that drive the distribution and abundance of organisms within the ecosystems. Such an approach could provide a way to base future conservation policy on an understanding of how ecosystems actually work.
Applied to African savannas, for instance, GEMs could be used to model the total biomass of all plants, the grazing animals that feed on them, the carnivores that feed on the grazers and so on – mapping the flows of energy and nutrients within the food chain over time. Within this food chain, organisms would be grouped not by species but by their key functional characteristics: plants, birds, mammals, warm blooded, nocturnal and so on. By encoding processes such as feeding, reproduction, death and migration into simple mathematical and computer models, ecologists could model what happens to the various groups over time. Such information could underlay metrics, such as the diversity of animals, to assess the savannas' health. Ecologists could explore how these measures of health might change in response, for example, to climate change or poaching.
GEMs however are not restricted to African savannas: they can be applied to forests, lakes or remote parts of the oceans, providing a common framework for understanding and managing ecosystems.
Over the past two years, Microsoft Research and UNEP-WCMC have built a prototype GEM for terrestrial and marine ecosystems. Called The Madingley Model, it uses real data on carbon flows as a starting point. The development of this project demonstrates that building realistic GEMs is possible with scientific publications of the results pending.
Commenting in Nature, the Madingley Model scientists argue that GEMs have the potential to support and guide conservation policy. However, significant challenges remain in constructing robust, trustworthy models. For example, ecological systems do not have the equivalent of the precise laws used by climate scientists and there is a paucity of data with which to constrain and test GEMs. Nonetheless, the Madingley Model scientists argue that attempting to build such models will help ecologists to discover what they need to know to fully understand ecosystems.
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