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The graph I made shows the frequency between the total number of ash trees and the total number of ash trees infected by emerald ash borer (EAB). Each dot on the graph represents one of the 5, 25X25 foot plots containing ash trees. I included a trendline and r^2 value to assess how strong the correlation, if any, existed between my predictor and response variable. I was surprised to see my data indicates there seems to be no correlation between the two variables (very low r^2 value). In my methodology, I was not able to notice signs of EAB presence with full certainty so I expect the general rate of infestation is higher among all plots. My results underestimated infestation rates because it was limited to what I could see with my eyes (eg. larval galleries, fissures in the bark, woodpecker foraging). D-shaped exit holes are the first sign of EAB presence, however, Burr et. al note this occurs 2 years after trees are already infected. This is to say many of the trees I noted as “not-infected” might indeed be infected. Without the ability to girdle trees at the conservation area I visited, my results are not completely accurate. When I made my observations noting the signs of emerald ash borer infestation in the trees, it appeared that younger saplings were not affected by emerald ash borer even amidst other trees that showed clear signs of infestation (eg. D-shaped emerald ash borer exit holes). After some research, I came across the work of Klooster et. al which noted that by 2009, 99% of ash trees in the Upper Huron area of southeast Michigan had been killed -largely by EAB- but those that remained were younger saplings. In the future, I think it would be beneficial to do the same study but based on trees that were planted at the same time /naturally came into seed around the same time to see if there is a relationship between density of a plot and infestation rate. These areas would be characterized by the absence of younger saplings. Additionally, I would use other methods to ensure better accuracy in EAB detection (eg. tree girdling to expose hidden larval galleries and remote sensing methods to notice early canopy loss of EAB infected trees).
Burr, S. J., McCullough, D. G. and T. M. Poland. 2018. Density of Emerald Ash Borer (Coleoptera: Buprestidae) Adults and Larvae at Three Stages of the Invasion Wave. Environmental Entomology 47. https://doi.org/10.1093/ee/nvx200
Klooster, W. S., Gandhi, K. J. K., Long, L. C., Perry, K. I., Rice, K. B. and D. A. Herms. 2018. Ecological Impacts of Emerald Ash Borer in Forests at the Epicenter of Invasion in North America. Forests 9. https://doi.org/10.3390/f9050250
