Downloading SIM
The Modelling Team
References

Introduction
A key output of the NERC Soil Biodiversity Programme is SIM (Stable Isotope Modelling), a Windows-based program that provides the user with the facility to design food webs and simulate ¹³C pulse labelling experiments over a specific duration. SIM has been developed through a contract let to a team of from the Universities of Cambridge and York. The model and the software was produced based on data and observations made during the Soil Biodiversity Programme. Programme researchers were consulted on the model and software at a number of workshops hosted by the modelling team. 

The basic food web model is based on that described in Hunt et al. (1987) and Berg et al. (2001). To this basic framework has been added the facility to simulate ¹³C pulse experiments through the food web, enabling the user to validate the model’s outputs against newly available stable isotope data (Fitter et al. 2005). The underlying food web model envisages the soil ecosystem as a network of connected boxes, each box corresponding to a species or functional group and the connections representing directed trophic linkages between them. The central assumption is that the biomasses in all functional groups remain constant over time (the default unit of time is one year in the software) so that, for each functional group, one can assert biomass gained = biomass lost. The implementation of this basic principle across the web uniquely defines all the carbon flows. In practice, the situation is more complicated, involving mortality, variable prey preferences, and production and assimilation efficiencies.

SIM can be downloaded from this page - see below. An user guide describing how to use the model is also available.

For further information about SIM please contact:

Jon Pitchford
Dept of Biology
The University of York
PO Box 373
York
YO1 5YW

E-mail: jwp5@york.ac.uk
Tel: +44 (0)1904 328559