Conclusion

 

In the final project, I updated published Infestation Pattern Simulation ABM model published by (Kautz et al., 2014) in NetLogo environment, leading to creation of Influence of Clustering model.

 

The aim of the model is to simulate the bark beetle spreading over forested landscape with altering cluster level of weakened trees. Cluster extend is defined by its radius value. At every cluster level scenario, the total amount of weakened trees remains equal, merely the amount of cluster, their extent and location are altered. At the end of simulation run, the system level variables are recorded as beetle infestation success, amount of infested trees and maximum infestation distance. Simulations were repeated 10 times to detect the results variability.

 

The results indicate that beetle infestation success is not related to clustering level. However, the broader the cluster is, beetles are more dispersed over available wind-fallen trees and thus aggregation needed to overpass tree resistance is more difficult to accomplish. Beetle mortality is thus higher in more clustered spots. Surprisingly, maximum tree infestation distance increase with rising cluster dimension.

 

These results should not be predictable using only linear deterministic approaches, thus highlight the necessity of importance of ABM in bark beetle – tree system interactions.