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LSC 405 - Simulation Modeling LECTURE NOTES J. Wu 1. Population Dynamics, Community Structure, and Disturbance The details of this model is documented in Chapter 14 of Grant et al. (1997). Definitions: r-selected species (or r-strategists): Species that reproduce early in their life span produce large numbers of usually small and short-lived offspring in a short period of time, and usually have inferior competitive ability. K-selected species (or K-strategists): Species that produce a few, often fairly large offspring invest a great deal of time and energy to assure offspring’s survival, and usually have superior competitively ability. (1) Model Objectives The General Objective: To facilitating understanding of the relationship among species life history characteristics, interspecific competition, and disturbance. Specific Objectives: To simulate the effects of the frequency of ecological disturbance on the dynamics of populations, and the number and types of species (r- vs. Kselected), in a community over 500 years. (2) Model Structure Use STELLA’s loop and tracing tools to help understanding model structure! A hypothetical ecological community in a 1-ha woodlot 2 K-selected (K1 and K2) and 3 r-selected species (R1, R2, and R3) Maximum annual per capita natality rates: higher for r-species than for K-species Minimum annual per capita mortality rates: same for both r- and K-species Species interaction (competition): One directional: negative impact of K-species on r-species 3 pairs of interactions: K1 on R1; K2 on R2; and K2 on R3 Competition is modeled through competition coefficients and effective population size (#indiv of a sp. + equivalent #indiv of its competitor sp.) Page 1 Lecture Notes for LSC 405 Simulation Modeling --- J. Wu Periodic disturbance that affects all populations, killing 90% newborns but not older adults Current population size of each species = 100 (3) Model Simulations To simulate the number and type of species present with the community over a 500-year period with the following scenarios: 1) Disturbance time intervals = 9999 yrs (a large number implies no disturbance) 2) Disturbance time intervals = 30 3) Disturbance time intervals = 25 4) Disturbance time intervals = 20 5) Disturbance time intervals = 15 6) Disturbance time intervals = 10 7) Disturbance time intervals = 5 (4) Sensitivity Analysis Initial population size Natality and mortality parameters Page 2