Students may use this model to explore effects of different factors on the carrying capacity of a hypothetic elk population.
Grades: 6-12;
Students may use this model to explore effects of different factors on the carrying capacity of a hypothetic elk population.
Grades: 6-12;
Within each 'tick,' a simulation time unit, elk wander, eat and reproduce in the habitat. They gain energy from grass and lose energy when wandering and reproducing. They die when their energy is used up.
Step 1: Start the simulation.
Press the "Setup/Reset" button to generate a population of elk in the simulation.
Input the number of ticks you want to investigate the simulation, e.g., 100 or even 1000000.
Press the 'Run/Pause' button to run or pause the simulation. The simulation will stop at the defined tick. Input a large number if you would like to observe the simulation longer.
Step 2: Observe the results
Examine how the number of elk changes over time in the output monitors and the real-time graph.
STEP 3: Test the impacts of different factors
Adjust the slider value to see how different factors affect the elk population size.
FOUR FACTORS
Food: Grass is elk's only food resource in this simulation. When a patch of grass is consumed, the square becomes black. The grass will regrow at a certain rate based on temperature. Note the amount of grass is finite, even though grass regrows at a 100% rate. Can you tell why? If you turn on 'infinite-grass?' patches will remain green, and therefore grass supplies become infinite.
Environment: Temperature affects the grass growth rate. What will happen if it is too cold or too hot? The habitat size often determines the amount of food resources available. How do you think the habitat size affects the elk population?
Predator: You may introduce or remove wolves in this simulation. Once introduced, a wolf will prey on an elk it encounters. Wolves do not reproduce in this simplified world. This is nice because you may explore how a certain number of wolves affect the elk population.
Other herbivores: Many other species also consume grass. What will happen if you introduce rabbits, another grass-eater, here? To simplify the simulation, the introduced rabbits do not reproduce. You may use the corresponding slider to adjust the number of rabbits. In this simplified world, wolves do not prey on rabbits.
THINGS TO TRY
Students may explore how carrying capacity is influenced by four types of factors. There are at least ways to explore:
A longitudinal study: While simulation is running, adjust a certain factor and see how carrying capacity changes over time.
Design an experiment: Collect data systematically to examine the effects. For example, keep other factors the same, test the effects of temperature at 10, 20, 30, 40, and 50 degree Celsius.
Dr. Lin Xiang creates this module at the University of Kentucky in 2019. If you mention this model in a publication, we ask that you include the citations below.
Xiang, L. (2019). Carrying Capacity. Department of STEM Education, University of Kentucky, Lexington, KY.
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