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SimSAGS 4.1 Read Me
& Introduction

Installation notes, the help system
and getting started

  • Thank you for your interest in SimSAGS 4.1, software to model a semi-arid grazing system.
  • To install the program simply insert the distribution CDR into your computer's CD drive and the installation should automatically start. If it fails to start automatically, or if you have downloaded the installation software from the website, find and run "SimSAGS4.1.EXE" manually.
  • All program files are copied to the program folder on your hard disk which you specify during installation. No peripheral or other files are copied to any other location on your computer.
  • The SimSAGS 4.1 Simulation project files (*.sgs) share the same format as Registry files (*.reg). Opening and updating a project file writes to your Registry under a SimSAGS 4.1 section. This section is self-contained and does not affect the other Registry settings nor working of your computer. The only other changes to the Registry are to register the file types for SimSAGS 4.1 Simulation (*.sgs) and SimSAGS 4.1 Output (*.out).
  • SimSAGS 4.1 does work on both win98 and winXP (and possibly still on win95) but you should be aware of an inconvenient Microsoft modification to registry file format. If you get this type of error message in win98 "Registry Editor cannot import drive:\path\filename.reg: The specified file is not a registry script." then you need to manually edit the sags4.sgs file (or whichever sgs file is causing the problem) in your installation directory (default is C:\Program Files\SimSAGS4.1) using the following steps:
    1. Open the sgs file using Notepad, and then change the header from Windows Registry Editor Version 5.0 to REGEDIT4.
    2. On the File menu, click Save

      • If you are using a Microsoft Windows NT-based OS, clear the Save as Unicode check box.
      • If you are using Windows 2000, change Encoding to ANSI.
    3. Exit Notepad.exe.
    There is official documentation for similar problems @ http://support.microsoft.com/?kbid=268774
  • A Help System is not bundled with this version of the SimSAGS 4.1 program as the online version will be updated and has the capacity for additional information beyond what could be distributed with the software. If you have an opinion on this or any other related topic please visit the forums to share your view.
  • The quickest way to introduce yourself to SimSAGS 4.1 is to try out a model. You can modify the default parameter set but it is recommended that you save your changes as a different project. There are also some example scenarios for you to work through and the following pointers to get you started, plus some troubleshooting tips.

    Getting Started

    SimSAGS 4.1 is the product of a decade's work, and was developed piecemeal in response to the current model application requiring the development work. So it may take a little while to familiarize yourself with all of it's features, most of which were introduced to facilitate that research. That does not stop being able to use the program immediately, but understanding the role of each parameter and the best way to use the investigative research tools will require some time investment. Because the model is automatically parameterized with the default parameter data set, all you have to do to run a simulation is press the play button. But it's more likely that you will want to change the defaults and specify your own simulation scenario. You do this by editing in the Parameter View window and then you can save your changes to your own simulation project files. Here is a tick list for what you need to think about:
    1. What is your site? You can set your site area in the Site section. The size of spatial grids can be set in the Spatial section along with the topographic character of your site. Alternatively, this can be explicitely defined by GIS import.
    2. How many iterations? The model works on a daily iteration and has the capacity to simulate precursory years to minimize the efffects of starting conditions. You set the simulation duration in the Time section.
    3. What rainfall? Perhaps the most important input data is daily rainfall. If you have say a 20-year sequence of daily rainfall data (N=20*365) for the simulation proper, then you can use the daily average (N=365) for the precursory simulation years. You set your rainfall data and other climatic parameters in the Climate section.
    4. What soil? Your soil profile can contain layers and sublayers, across which water infiltration is modelled. Soil structure and fertility (quality) can be set in the Soil section. You can adopt a default soil profile based on Charleville (Australia, LAT -26.42 LON 146.27 ELEV 305m) which actually has also worked very well for sites throughout Africa and Asia.
    5. Which plants? The model can be populated with a limitless number of plant types (as many as your computer can accomodate), of 5 generic types:
      • Annual Grass
      • Perennial Grass
      • Forb
      • Shrub
      • Tree
      Intial biomass can be set in the relevent section under Vegetation. Spatial distribution is either implicit (via stochastic allocation) or explicit (via GIS import).
    6. Which animals? The model can be populated with a limitless number of animal types. Distinguish between types using their mature male mass (MATR). For exampe, goat=53kg and cattle=476kg. The model is able to calculate several other parameters from this using body-size relations (allometry). You can set animal MATR in the relevent section under Animals.
    This is all you need consider, however, the other default parameters may not suit your simulation requirements so it is recommended that you familiarize yourself with the data in the Parameter View.

    Known Bugs and Issues

    • The Parameters View and GIS Control windows work best with larger screen resolutions as is the case for any serious GIS work where a large screen is recommended. See the Requirements sections for more details.
    • Crash on dropdown in graphical output during simulations. It has been necessary to force a simulation pause when the drop down menu is opened. The simulation can be restarted at the same progress point by clicking on the play button. FIX: set display variables prior to simulation or carefully click in combo box edit without pulling the menu down and use mouse roller button or cursor keys to scroll through the entries.
    • Intermittent "Invalid floating point operation" error. FIX: error handlers throughout the code catch most exceptions but if I've missed one please report it if it happens.

    Example Projects

    Installed in the projects folder below your main application directory (default is C:\Program Files\SimSAGS4.1\Projects)
    1. Example 1 - Kenya
      The welfare of Masai herders in the Kitengela Wildlife Dispersion Area is threatened by land use change; primarily, increased introduction of bomas and associated fences fragment tribal grazing land. There are also consequences for wildlife that utilize the area. Wildebeest travel through Kitengela to calving grounds in the south. It is envisaged that if there is sufficiently extensive boma development then the wildebeest migration may be blocked. Predictive modelling is being used to address these and other issues of primary concern for pastoralists in the region. Simulation scenarios can be constructed to include the suggested fragmentation of rangeland and migration routes.
    2. Example 2 - Mongolia
      There are an estimated 1.2 million gazelle in the Eastern Steppe. Rising unemployment has led to poverty and deteriorating livestock production systems, which in turn increase the pressure on natural resources, especially through wildlife poaching. Poachers illegally slaughter over 100,000 gazelles each year, threatening the steppe ecosystem and traditional culture. Since gazelles play a pivotal role in structuring the steppe's ecological landscape, ensuring their survival ensures sustainability of steppe biodiversity, ecological processes, and traditional culture.
    3. Example 3 - Australia
      A paddock study in Queensland. The Burdekin Catchment discharges 22 million tons of sediment into the sea each year, a lot because of the Queensland cattle industry. This soil is swept onto the Great Barrier Reef where life is harmed by muddy waters blocking the sunlight. Modelling is helping to work out how much damage is being done by farming, and what can be done to make improvements to benefit the cattle, the farmers and the Great Barrier Reef.

    Project Description

    To find out more about the project please visit the project website @ http://sags.bio.ed.ac.uk/

    J.F.Derry 03/2006