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Yes, it is possible for a user to define the age distribution at the start of a run. A few notes about age distributions:
1. If the age distribution is not set by the user, then the age of each cell is automatically randomized between the starting and ending age of its corresponding state class. For state classes with no ending age, the initial age is set to the starting age.
2. The user can define the age distributions of a ST-Sim simulation by adding rows with specific age ranges to the Initial Conditions Distribution datasheet. To access these datasheets, select the Scenario Properties from the Library Explorer pane, and navigate to the Initial Conditions tab. Within this tab, there are options to set initial conditions for both Non-Spatial and Spatial simulations.
3. For Non-Spatial simulations, you can customize the age distributions by accessing the Non Spatial property within the Initial Conditions tab. If you right-click in the Distribution table, a context menu will appear, and you can choose to add the Age Min and Age Max columns to your table. You can then set your desired age distributions for desired combinations of state class and strata. Note that records for the same stratum and state class can be repeated to refine the starting age distribution. Cells in the landscape are assigned to this distribution according to the relative amount column. Once assigned to a specific record, the age of the cell is randomized using a uniform distribution between the Age Min and Age Max values for that record. See an example below:
4. For Spatial simulations, select the Spatial datasheet within the Initial Conditions tab. In this datasheet, under the Age column, you can select a raster file to set the initial ages for each cell in your landscape: