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Caribou – Wolf Interactions OmMQ5Fc.

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Presentation on theme: "Caribou – Wolf Interactions OmMQ5Fc."— Presentation transcript:

1 Caribou – Wolf Interactions http://www.youtube.com/watch?v=nK1J OmMQ5Fc

2 Issues with Simulations Realistic Movement –Moving toward desired areas –Keep animals from getting “stuck” Validation Boundary conditions –What happens at the edges? Disappear/die (need immigration as well) Reverse direction Wrap to the other side (not realistic) Model stability Model complexity/Performance

3 Moving Toward Desired Areas Use Distance Raster –Desired area: Spawning ground, feeding grounds –Destination is desired area –Pixels with lower cost are closer to desired area –Animals move to adjacent pixels with lower cost

4 Moving Through Networks Use polylines with network nodes Move in direction (or against) of polylines Need to make decisions at nodes

5 Getting “Stuck” Certain conditions arise and animals can become stuck and just move back and forth –Add additional randomness –Examine environmental layers for unrealistic values Streams not flowing perfectly down hill Bays not connected with the ocean

6 Validation Run models over and over again Record locations, births, deaths, feeding –Create probability surfaces Validate against existing datasets –Are observations/measurements within the predicted areas? –Could use likelihood/AIC…

7 Model Stability Density dependence –Most species struggle more when crowded –Reduces food availability, increases disease –Places a control the number of individuals Balancing birth rates and death rates Realistic lifecycles, predation rates

8 Model Complexity Typically there are lots of agents Need to keep the behaviors and attributes simple The group behaviors are typically more complex than expected from the individuals Model a population –Convert “groups” of individuals to populations when they cluster

9 Monte Carlo-Markov Chain Markov Chain: –A series of states of being that have probabilities associated with transitions (i.e. the state is not deterministic but has some stochastic component).

10 Performance Select the right resolution for rasters –High enough to be realistic –Low enough for speed –May have to just simulate a smaller area than desired.

11 3D and Temporal Simulations are almost always temporally based 3D is common but requires more hardware/time –Also requires special software and 3D data

12 Ecological Modeling Water, carbon, nutrient cycling Trophic models Population models Predator/Prey Disease wsu.edu

13 Sustainable Fisheries www.niwa.co.nz

14 Can operating rooms in Second Life teach real doctors? - Discover World of Warcraft Sims

15 Tools NetLogo HexSim MASON Multi-Agent Simulation Toolkit Repast Programming! –Python –Java Books: “Agent-Based Models of Geographical Systems”

16 Envision – Policy Simulation

17 Simulations Parameterization –Based on mechanisms/theories –Typically include random effects –“Tweeked” to fit reality Validation –Run over observed space and time Do simulated measures match observed? –Run it over and over Observed fit into “Confidence interval”?

18 Simulations Startup: –Either simulate a known situation –Or, run until reaches an expected state Stability –Populations tend to breed out of control or die out over time –Build in realistic limitations

19 NetLogo Environment for 2D simulations Easy to program OpenSource, free Was a “kids” language Now used for education, visualization, simple simulations Can install outside “Program Files” Run NetLogo.exe See included Tutorials

20 NetLogo – Model Interface

21 NetLogo Design NetLogo is a world made up of: –Turtles: The agents that move –Patches: Agents that do not move (i.e. grass, buildings, roads) –Links: Connections between turtles –Observer: Oversees the action

22 Ecological Modeling Combination of cellular automata and individually based models: Grid of cells (raster) Individuals

23 NetLogo - Code

24 HexSim Visit Hexsim.net to download Decompress the folder Can run “Hexsim.exe” from within the folder without other installation See the “Examples” on the HexSim website to get started –The User’s Guide has good information on how HexSim works

25 HexSim Basics Set the workspace: –HexSim -> Set Workspace –Select a “*.grid” file Double click on a scenario to “open” –Adds a tab for that scenario –“Scenario” menu items work on the currently selected tab View spatial data: –In the “Spatial Data” panel, open items –Double-click on “-> 1” to show the data

26 HexSim Basics Select “Scenario -> Run Simulation” Save an XML file for the run Click “Start” in the window that is displayed These examples are not yet parameterized so you may need to modify them to do something interesting

27 Comparison of Software http://en.wikipedia.org/wiki/Comparison_ of_agent-based_modeling_software

28 Simulation Modeling Plate tectonics: –http://www.youtube.com/watch?v=ryrXAGY 1dmE Wolf simulation game –https://www.youtube.com/watch?v=idr0A- yl56Q

29 Possible Simple Models Fire w/fire fighters Zombies and humans Reef fish Wolves and elk Invasive species (w/managers)


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