Before beginning the land-cover change simulation, the user can specify input parameters to the simulation. The user selects the input parameters from the LUCAS Setup Menu (recall Figure ).
The user first chooses the watershed on which the land-cover change simulation will be run. In this example, the Little Tennessee River Basin is selected. To select this particular watershed, the user places the pointer (by moving the mouse) over the watershed name in the Watershed scrolled list and double clicks. The text field is highlighted upon selection. The LUCAS interface retrieves the watershed selection and updates the Scenario scrolled list based on the watershed choice, as the scenarios are developed for each watershed. The LOCATION_NAME environment variable is then set to the appropriate value based on the watershed selected by the user.
Next, the user can select the mapset directory in which output maps are saved. The Mapset selection list contains only directories into which the user can write files because of ownership rules. In our example, the only possible selection for mapset is macintyr because that is the only directory in which user macintyr has ownership. The MAPSET environment variable used by the underlying analysis software is set to the highlighted value on the Mapset scrolled list.
The Scenario scrolled list contains the list of pre-defined scenarios which are available for the selected watershed. There are sixteen pre-defined scenarios for the Little Tennessee River Basin watershed. A description of these scenarios is provided in Appendix . Because all sixteen scenarios can not be displayed in the Scenario scrolled list at once, a scrollbar has been placed to the right of the Scenario scrolled list by the XmScrolledList widget. The user can change the scenario titles displayed in the list by moving the mouse to place the pointer over the scrollbar, pressing the left mouse button to grab the location indicator on the scrollbar, and moving the mouse to modify the scenario names displayed. In this example, scenario 1 is selected from the list of scenarios. Scenario 1 is the land-cover change based on the historical transition probabilities for the period 1986-1991 applied to both public and private land [B92]. For this example simulation, we will be constructing a future landscape on which the landcover will change based on patterns recorded between the years 1986-1991. The resulting landscape will appear as it could if the same land-use decisions are made as were for the years 1986-1991. The environment variables LUCAS_SCENARIO and LUCAS_STATS are set according to the scenario selected from the Scenario scrolled list to communicate this information with the underlying analysis software.
Several simulations are run in order to gather statistically valid results [WTF94] from the simulation. In this example, the simulation will be run ten times, so ten replicates are chosen from the Number of Replicates scale widget. The user can select the number of replicates by moving the pointer with the mouse to the indicator on the Number of Replicates scale widget, pressing the left mouse button to grab the indicator on the scrollbar, and moving the mouse to modify the number of replicates. The value selected by the user for replicates is communicated to the analysis software by the LUCAS_REPLICATES environment variable.
To predict how the landscape will look in 100 years, 20 timesteps are selected from the Number of Timesteps scale widget. The user chooses the number of timesteps in the same manner in which the number of replicates are selected. The value chosen for the number of timesteps is communicated to the analysis software by the LUCAS_TIMESTEPS environment variable.
No maps will be saved in this example, so the default of 0 maps saved is not altered on the Number of Maps Saved per Replicate scrollbar. The number of maps to be saved is communicated to the analysis software by the LUCAS_MAPS_SAVED environment variable.
In this example, landscape change will be based on a pixel-based model. Since pixel-based is the default method of simulating landscape change, the value for landscape change is not altered on the Landscape Change selection box. The method of landscape change is communicated to the analysis software by the LUCAS_PIXEL_PATCH environment variable.
For this example, the simulation will begin in the year 1991 and will simulate landscape change 100 years into the future. Since the default value in the Beginning Map selection box is 1991, the value for beginning map is not altered. The selection for the beginning map year is indicated to the underlying analysis code in the title of the selected scenario.
No species are selected for this simulation. If the user wants to see the effect of the resulting landscape with respect to species biodiversity, the user would choose values from the Species scrolled list. The selected species are communicated to the analysis code by the LUCAS_SPECIES environment variable.
After selecting values for all of the setup information, the user presses the Run Simulations push button located at the bottom of the setup window, invoking the underlying analysis code (see Figure ). The LUCAS Analysis Status window (see Figure ) is displayed indicating the current status of the analysis in progress.
Figure: LUCAS Setup Menu with values for simulation.
Figure: LUCAS Analysis Progress Status window.