MAKING SIMULATIONS
Making a simulation involves the following steps:
1.
2.
3.
4.
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6.
Identify a working directory
Select a zone–geographic area
Load any user modified system knowledge files
Load a landscape
Set simulation parameters
Run simulation
IDENTIFY A WORKING DIRECTORY
The first step is to identify the working directory. This is the area where you want output files sent
to and may also be where you have the input file for the landscape you wish to simulate. File > Set
Working Directory opens a dialog box to allow the user to browse to the desired location (Figure
17).
Note: Do not put working files in the installation directory that the installation of SIMPPLLE
created.
The working directory is saved when SIMPPLLE is closed. The next time SIMPPLLE is started, the
saved directory is recalled.
SELECT A ZONE—GEOGRAPHIC ZONE
After the zone is loaded, its name is displayed on the screen as the Current Zone, and the New
Area button is enabled.
After the zone has been loaded, the option to load a new area is now available.
Loading the saved file from a previous simulation can be used to create additional reports, GIS files
that were not created at the time of the initial simulation, or reports for a saved file from a set of
multiple simulations (see “System Output” section). All the landscape files are identified by an area
(*.area) extension. Landscape files containing the results of a simulation can be loaded as a
previously simulated area and have a “*.simdata” extension.
SET SIMULATION PARAMETERS
To run a simulation, select Run Simulation.
This will bring up the Set Simulation Parameters screen, which contains a number of choices for the user
to select.
Number of Simulations can be set from one to one hundred. Multiple sets of 100 simulations can be
made if desired. An option in Excel spreadsheets provides for combining the output files from
multiple sets of simulations. The limit on the Number of Time Steps is 10,000. The Simulation
Method can be set to Stochastic, Highest, or Stand Development.
Invasive Species Logic must match the geographic area being used. At this time, only ColoradoPlateau
and Eastside Region One have logic for predicting invasive species.
The time steps can be set as yearly or decade. The default is decade. To change the time steps to
yearly, check the Yearly Time Steps box. The three grassland geographic areas must use a yearly time
step. There is no user choice.
Fire Suppression must be checked, or no fire suppression logic is used. If the Fire Suppression box
is checked, Discounted Cost is enabled, and the user can chose to have the system calculate and
discount suppression costs at the rate specified.
If Ownership and Special Area are attributed in the landscape file, the option to have the output file of
“*-ls.txt” stratified by these levels can be chosen by selecting Track Ownership or Track Special
Area. These can only be selected for multiple simulations.
For a single simulation, no output files are automatically created and saved so no file names have
to be entered in the Results Output Options. If multiple simulations are made, some output files
are automatically created using a prefix file name provided by the user.
If multiple simulations are being made, a directory has to be identified for the output files. The prefix
for this directory name is also used as a prefix for all files names. Unless the GIS Update/Spread
Files box is checked, the only GIS files generated for the multiple simulations will be those that
provide the basis of making probability maps. The update files showing the changes in all attributes
and disturbance processes by time step by simulation will not be generated unless this box is checked.
The spread files that show the origin and spread of the spreading disturbances such as wildfire will
not be generated unless this box is checked. Checking this box can result in a very large number of
files being created. Often, the approach is not to check it, generating only the probability files. After
an analysis of the multiple
simulations, the user can select an individual simulation, reload it and generate the update and
spread GIS files. However, this is possible only if the simulations were made without discarding
unnecessary simulation data.
Simulation choices involve Memory Saving Options that are based on trying to keep SIMPPLLE’s
system requirements appropriate for the type of PCs in common use at the field level in many
organizations. The simulation results can be written to a database or past time step data can be
discarded. There is a minimum of how many time steps to keep in memory. Some of the logic
associated with disturbance probabilities looks back to use disturbance and treatment history. The
default and minimum is set at 10 time steps. For the Eastside Region One zone, the
minimum must be set to 20 time steps for logic that is associated with the conifer encroachment
process.
The All States Report requires the detailed data for each plant community for all time steps and if the
simulations are made discarding data, the reports must be run during the simulation. If simulation data
is not discarded, these reports can be run after the simulations.
The Tracking Species Report is designed to be used in two cases: where some plant communities
have pathways that are defined by percentages of individual species, and where invasive species are
being simulated.
RUN SIMULATION
After all parameters have been set, click Run Simulation within the Set Simulation Parameters
screen.