Sources

Hartmut Bossel's "System Zoo" models

This is a fantastic resource, and if the only thing we achieve is to make this widely available to students and researchers, then we would have done something really worthwhile.

It's a collection of c. 100 (!) models, all in System Dynamics (Vensim software), and most relating to ecology/environmental/society themes.

Each model has its own chapter in on of the 3 System Zoo books. A summary of the 3 books is available here. Google on

bossel system zoo amazon

to find out about book availability.

Robert has the full text for each of the 3 books as a Word document from Hartmut, and his permission to reproduce, and make available online, the text for each model in full, provided that the text is made available at the level of the individual models, rather than as the complete document. (This is to avoid making it easy for people to download the text, and thus avoid buying the books.)

A single zip file containing the Vensim code for each model (as a Vensim MDL text file) is available for download from here.

Shodor Vensim models

The Shodor Education Foundation is committed to the use of computational tools for improving education in maths and science.

Amongst its many resources is a collection of ecology-based System Dynamics models, implemented in Vensim and available for download as a Vensim MDL text file. They include a predator-prey model and a water-cycle model. The models are very simple, and should take only an hour or so to re-implement, once you see how to extract the equations from the MDL file (it's pretty obvious). Each model has an accompanying page of text, though this is rather brief and does not include (for example) the model diagram or sample results.

Andrew Ford's "Modeling the Environment"

Builds up from very simple (1 stock) to more complicated models. Models are implemented either in Stella or Vensim. Downloadable versions of Stella models require a copy of Stella in order to view them. Downloadable versions of Vensim models are in Vensim's MDL text format, which is usually enough to extract the model equations. Alternatively, the models can be re-implemented from the diagram/equations in the text of the book.

Book websites:

1st Edition (1999)

2nd Edition (2009)

Vanclay, Prabhu and Sinclair: "Realizing Community Futures"

"Through an easy-to-read narrative style and using real examples from Africa and Asia, this revolutionary book--part argument for the limitless power of human imagination and part practical manual for turning visions into reality--explains how to use a process of participatory modelling" to structure people’s learning and understanding of the natural systems they depend upon and how this can lead to better social and environmental outcomes."

Information about the book from the publishers (Earthscan) can be found here.

The book's website (including a downloadable version of the Johad model) can be found here.

Systemswiki model library

An open wiki, in which anyone can add a page describng a particular model.

http://www.systemswiki.org/index.php?title=SystemsWiki_Model_Library

Models come in various categories, of which "stock-and-flow" (System Dynamics) is the most relevant to us:

http://www.systemswiki.org/index.php?title=Category:Stock_%26_Flow

At the tme of writing this, there are some 100 pages in this section.

Note that some of these models are extremely simple, contributed by student beginners.

Some of the modes are implemented in Stella, and may include the downloadable Stella model (.stm file) Others are implemented in InsightMaker - the only other web-based System Dynamics modelling app - and you can run the model directly in the wiki page.

Tom Fiddaman's model library

http://models.metasd.com/

CIFOR - Centre for International Forest Research

There are several workshop reports which mention the use of Stella. Key people promoting the use of Stella seem to be Bruce ampbell, Mareike Sandker and Terry Sunderland. Googling on "cifor stella model" (without the quotes), and possibly one of these names, should provide entry points. There seem to be few concrete examples. There is a pdf from one workshop which includes a full model description: unfortunately, the actual text in this pdf has been messed up (readable but only just).

http://www.cifor.org/conservation/publications/pdf_files/Summary%20Yokadouma%20workshop.pdf

In fact, 4 models are available from the CIFOR "Virtual Toolkit" site for landscape models. This link is to the actual models themselves; search the upper pages to read more about their modelling process. I have downloaded the pdf for the Ghana model and uploaded it here, since it did not display properly when I opened it directly in my browser. I think it contains a complete description of the model (diagram+equations).

Two more models are available here.

And another one here.

Some scanned diagrams and equations from published papers

This strange source consists of the details (diagram, equations and results) for c. 6 models, scanned in from published papers. Some are in Stella notation, some in Odum's Energy Circuit Language (but should be readily re-expressible in System Dynamics).

You can download the document as a pdf if you sign in with your Facebook account (but check out their Terms and Conditions first...)

Ecosystem management model for Chile

This paper contains the Stella diagrams for a mid-complexity model, but not unfortunately the equations. Email the author?

Fisheries management models

The FAO publication Introduction to Tropical Fish Stock Assessment - Part 1: Manual contains equations and code snippets for a large number of models relating to fisheries management. See especially teh following chapters:

8. PREDICTION MODELS

9. ESTIMATION OF MAXIMUM SUSTAINABLE YIELD USING SURPLUS PRODUCTION MODELS

10. MULTISPECIES/MULTIFLEET PROBLEMS

(Each chapter is a separate pdf.)

It's a terrific resource, and it would be a real contribution to fisheries management in developing countries if we could provide these models in an easily-accessible form, by converting them and adding them to our model database.

Thanks to Wilson Mhlanga, a lecturer in the Department of Environmental Science, Bindura University of Science Education, Zimbabwe, for pointing us to this publication.

Ecopath foodweb modelling tool

Ecopath is an ecosystem modelling tool primarily concerned with quantifying and modelling foodwebs. It has been around for a long time now, and Ecopath-based foodweb studies have now been undertaken in many countries. Many of these models, and the associated publication, are available in the Models section of the Ecopath web site.

Until recently, Ecopath models assumed steady-state - that is, they did not attempt to capture ecosystem dynamics. These models can be represented in System Dynamics terms - you just have constant flows on the flow paths - but that lead sto uninteresting (and unrealistic) results if you actually simulate the behaviour of the model.

However, they have now added two dynamic-modelling modules: Ecosim for non-spatial dynamics and Ecospace for dynamic spatial modelling. I have not yet explored these tools, to see how they map on to System Dynamics (for Ecosim) and Simile (for Ecospace).

There is a great opportunity here for a student or group of students with an interest in trophic ecology and foodwebs. You could become the specialists in finding out more about Ecopath/Ecosim/Ecospace; you could interact with the software developers and with users to see if they are prepared to make their models available, and you could undertake the conversion of these models. This is actually likely to be the technically-easiest task of any body involved in STEEMI, since the models (judging from Ecopath) have a very stylised and uniform nature, so you are unlikely to keep on finding new modelling techniques etc.

Thanks to Wilson Mhlanga, a lecturer in the Department of Environmental Science, Bindura University of Science Education, Zimbabwe, for alerting us to Ecopath and the Lake Kariba model implemented in it.

Because EcoSim is likely to be a great source of easily-converted ecosystem models, I have made a separate page for listing these models as they are discovered. Please add references to any EcoPath or EcoSim models you find to that page.

MIT-UAlbany System Dynamics PhD Research Colloquia

If someone has the time, could you go through the files for the various talks in the various colloquia listed here, and identify any models which are described in sufficient detail (perhaps with attached Vensim or Stella diagram and equations) to enable them to be re-implemented? I have seen at least one (fisheries model in the 9th colloquium).

Steve Hurst: A System Dynamic Model of the Canadarago Lake fishery zip file containing Powerpoint slides, abstract and Vensim .mdl file

Richard Dudley's models

Analysis of natural resource management policy issues, especially those linked to international development / international relations. Small-Scale fisheries management. Management oriented fisheries research. System dynamics investigations of natural resource and related policy issues.

See http://earth01.net/RGDudley/dudspbs.html

Contains both papers and model source files.

Internatiomal Futures

Not sure just how much of a model is in here (as opposed to database lookup), but worth looking at.

http://www.ifs.du.edu/introduction/ifs.aspx

Dave Bice's Earth System models in Stella

Dave Bice, at Penn State University, has produced a terrific collection of Stella models and associated teaching material, around a general geoscience theme, in most cases at a global level (e.g. global carbon cycle; global climate, Daisyworld). The models are all reasonably simple System Dynamics models (in most cases, 1-5 stocks). They are all implemented in Stella, and the model diagram and equation listing is available for all the models (some 19 in total), which makes them ideal targets for conversion.

An overview of his models can be found here. This has links to further detailed notes on the various models.

The models are available for running in a web browser. They are stored in Dave's personal model repository at Forio, the online simulation site. Selecting a model gives you access to a run-time environment, along with input sliders and graphs to show model behaviour: note that there may be multiple graphs, stacked on top of each other (click on the triangle symbol in the bottom-left to move to the next graph).

Buttons are provided for seeing the model diagram and the equations: use both if you are going to re-implement the model. Note that the text window for the equations might be rather small. If this is the case, right-click in it, select "Select All", then select "Copy", then paste into a word processor.

French modelling course - Vensim models

http://formationhg.free.fr/dossier%20ge%CC%81omatique/formaterre_nov2006/modeles/

Need someone to check this out, and move around the directory structure, to see how useful this resource is.

Note: this page is a web directory listing, as are the other pages. When I (RM) visited in Oct 2012, there was a really irritating floating banner ad on the top of each page (for water features, or all things, in my case).