Teacher Notes

This model simulates climate-driven bark beetle outbreaks. Compared to the basic “Bark Beetle Outbreaks” model, which presents students with the impact of temperature and droughts on bark beetle outbreaks, this model separates the effects of rising temperatures on beetle reproduction and survival. This model also allows students to explore the impacts of different forest management strategies, such as sanitation cutting and salvage cutting.

Grades: 6-12;

NGSS Standards: MS-LS2-1; MS-LS2-4; MS-LS2-5; HS-LS2-1; HS-LS2-2; HS-LS2-7

HOW IT WORKS & HOW TO USE IT

Climate-driven Bark Beetle Outbreaks

Agents:

There are two types of agents: beetles and host trees.

Model Rules:

The model has 289 patches (light brown squares). Each patch may grow one pine tree.
Bark beetles follow pheromone to find their host tree. They always first infest the tree with the strongest pheromone (i.e., max pheromone) and are not fully occupied (i.e., attack < 50).
If no pheromone is sensed, bark beetles attack a mature tree (i.e., with a size no smaller than 1.75) nearby and release pheromones to attract other dispersing beetles.
Once infesting a tree, each bark beetle produces 2 offspring beetles and counts as 2 attacks on the tree. When the average temperature rises in summer, some beetles may produce another 2 offspring beetles.
Beetles may live two hypothetical years and die after reproduction. Each year, 49% of the beetles die during winter. When the average temperature rises in winter, fewer beetles die.
Trees become reddish after receiving 35 attacks and die after getting 50 attacks. Droughts will lower the tree defense threshold from 50 to 45, 40, or 35.
Every empty patch grows a new pine tree at a chance of 5% each year.

THINGS TO NOTICE & TRY

Can you identify an outbreak in the model? How?
How many outbreaks may occur over 150 years when there are no droughts and no increases in temperatures?
How many outbreaks may occur over 150 years when there are droughts and increases in temperatures?
How do droughts and/or rising temperatures affect the number of dead trees?
How does cutting down trees affect the outbreak occurrences and tree loss?

data collection

CREDITS AND REFERENCES

Dr. Lin Xiang created this module at the University of Kentucky in 2022. If you mention this model in a publication, we ask that you include the citations below.

Xiang, L. (2022). Climate-driven Bark Beetle Outbreaks. Department of STEM Education, University of Kentucky, Lexington, KY.

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