Date of Award


Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)


Forest Resources


Robert G. Wagner


The long-term effect on the development of spruce-fir stands in Maine from combinations of herbicide (Glyphosate, Triclopyr, 2,4-D, 2,4,5-T, MSMA, Picloram, Water, and Control) and precommercial thinning (PCT and no PCT) treatments was examined 22 years after herbicide application and 13 years after PCT. The mean IRR for the herbicide treatments with no thinning was 8.2%. For PCT only the IRR was 6.3%. The mean IRR for plots receiving both herbicide and PCT treatments was 5.8%. Therefore, the rate of return for both herbicide and PCT and combinations of the two treatments would be acceptable to many investors.