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Program Flow


SIMPDEL program flow is illustrated in Figure 3. Input files are read by subroutine input, and simulation variables initialized in initsim. Hydrology and vegetation updates are performed once every seven days by subroutines hydrology and vegetation. The deer component is simulated daily by subroutine deer, which invokes dage, drepro, and dforage, in sequence. Subroutine dage increments deer ages daily for deer under two months of age, and monthly for all others, and calls ddisperse for all male deer turning eighteen months of age. Subroutine ddisperse simulates the dispersal process by randomly selecting dispersal locations and analyzing the locations for suitability. The reproduction process is handled by drepro, which simulates deer mating and fawn birth, and calls ddisperse for all male deer whose mothers are giving birth to new fawns. The foraging process is comprised of subroutines dforage, dmove, dgraze, and dmovelow. Subroutine dmove locates a new 500m grid cell position with available forage and dgraze simulates deer grazing on the 100m grid cells within the selected 500m cell. Subroutine dmovelow selects a 500m grid cell along a deer's maximum travel distance perimeter, and is called only after no high or medium quality forage is found. Finally, after each deer's foraging process is completed, subroutine dgrow updates the deer's body weight based on daily energy expenditures and invokes dmortality if death results from weight loss or other factors.

Michael W. Berry (
Wed Oct 11 14:53:18 EDT 1995