Determining the Potential Vulnerability of Northwestern Maine to the Eastern Spruce Budworm
- Mercier, Wilfred J.
Maine Image Analysis Lab, School of Forest Resources, The University of Maine
The eastern spruce budworm (Chorisoneura fumiferana (Clem.)), a native pest to the northeast United States and eastern Canada, has historically infested these regions every 30 to 50 year causing widespread defoliation and mortality of balsam fir (Abies balsamea) and spruce (Picea spp.) trees in these regions. With the next expected outbreak rapidly approaching for the state of Maine it seems prudent to make an attempt to examine the potenital vulnerability of Maine's current forests to this pest.
A spatially explicit spruce budworm vulnerability model was developed and applied to an approximately 4 million acre (1.6 million hectare) study area in northwestern Maine. This model was based primarily on data products derived from Landsat imagery. A second model with no spatial aspects (nonspatial model) was then derived based on Forest Inventory and Analysis (FIA) data.
These two models each have their own strengths and weaknesses. The spatial model was constructed out of information that has limited amounts of detail but had the advantage of being tied to actual locations in space. The nonspatial model on the other hand had more detailed information, but this information was not tied to any specific location in space. As it seemed that these two models complemented each other quite well, a process was derived to relate these two models to each other in order to create an improved spatial product. The results of this process was a spatially explicit model that reflected the more detailed information present in the nonspatial model.
This particular model estimates that over 25% of the study area is highly vulnerable to the spruce budworm. A qualitative analysis of the vulnerability map shows both large extensive areas of high risk as well as smaller pockets of high risk interspersed within large areas of low risk.
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