Please note: This research Programme is no longer active
The Modelling Team
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
modelís 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
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:
Dept of Biology
The University of York
PO Box 373
Tel: +44 (0)1904 328559
Note: SIM is designed to run on IBM compatible PCs running Microsoft
Windows 9x, 2000, Me, NT and XP.
||Microsoft Word Document
||Provides information on how to use the software, as
well as details of the model itself. You are advised to read
this file before using the software.
file - executable
||exe file (Application)
||Running this application will automatically install
SIM on your computer. Download it to a destination folder of your
choosing on your PC. When you run the programme you will be taken
through a simple series of steps to install SIM.
file - Zip file
||Zip file (compressed file)
||This is a Zipped version of the installation
executable programme and is provided as an alternative file should you
experience problems downloading the exe file. You will need a copy of
WinZip in order to unpack this file.
If you experience problems downloading, installing or
running the software, please contact Jon Pitchford (details above) for
The modelling team
|University of York
||University of Cambridge
Berg M, DeRuiter P, Didden W, Jansen M, Schouten T, and Verhoef H
(2001) Community food web, decomposition and nitrogen mineralization in a
stratified Scots pine forest soil. OIKOS 94, 130-142.
Fitter AH, Gilligan CA, Hollingworth K,
Kleczkowski A, Twyman RM, Pitchford JW and the members of the
NERC Soil Biodiversity Programme (2005) Biodiversity and ecosystem
function in soil Func. Ecol. (in press).
Hunt HW, Coleman DC, Ingham ER, Ingham RE, Elliott
ET, Moore JC, Rose SL, Reid CPP and Morley CR (1987) The detrital food web
in a shortgrass prairie. Biol. Fert. Soils 3, 57-68.