Bark Beetle Epidemic
This model helps students make sense of forest ecosystem dynamics and explore the interactions among bark beetles, host trees and a few environmental factors through developing and using a model, collecting and interpreting data, constructing explanations and engaging in argument from the evidence.
HOW TO USE
NetLogo version: 6.0.2 or higher
1. Choose a small or large forest to start
2. Choose how long to run the model
3. Observe changes in bark beetles and forests over time
HOW IT WORKS
- Bark beetles use spruce trees as food and shelter.
- Bark beetles produce offspring and then die.
- They only attack big spruce trees. When a spruce tree is attacked by many beetles, it turns orange and eventually die.
- New spruce trees grow up every year.
- when temperature rises, bark beetles develop faster and may produce more than once. Less beetle larvae die in a warmer winter.
- When drought becomes severer, it takes less beetles to kill a host spruce. No relationships are defined between temperature and severity of drought in this simulation (even it is likely in reality).
- When increasing tree diversity, another type of tree grow in the forest, which bark beetles cannot use as food and shelter.
Days 1-2: Ask questions to obtain information
Students learn about the bark beetle outbreak phenomenon, observe the specimens of tree bark and bark beetle, ask questions, and read to obtain information about the bark beetle life cycle and the interactions between bark beetles and host trees.
Days 3-4: Develop and use a model to investigate changes in populations
Students conduct a kinesthetic activity to model and understand the interaction between bark beetles and trees and reveal the dynamic nature of the changes over time.
Day 5:Analyze data to identify possible disruptions to the forest ecosystem
Students analyze climate data collected by scientists to identify a rise in global temperatures over the past several decades.
Days 6~7: Use a computer model to investigate the impacts of climate change on bark beetle populations
Students carry out an investigation on the effect of rising temperatures on the severity of bark beetle outbreaks by collecting data at five different mean temperatures.
Day 8: Construct a written argument supported by evidence
Students constructed a written argument about the cause of recent bark beetle outbreaks using the evidence and information from the unit.
*The sequence above only focus on the effect of rising temperature on bark beetle outbreak. Similar design can be apply to have students investigate the effect of drought or tree diversity of bark beetle outbreak.
CREDITS & REFERENCES
This unit was designed by
April Mitchell, Science Coach, Salt Lake City School District
Dr. Lin Xiang, Assistant Professor of Science Education, University of Kentucky
The NetLogo model was developed by Dr. Lin Xiang at Weber State University. If you mention this model in a publication, we ask that you include the citations below.
Xiang, L. (2017). Bark Beetle Epidemic. Zoology Department, Weber State University, Ogden, UT. https://sites.google.com/view/3d-science-abm/ecology/bark-beetle-epidemic