Young Spruce-Fir Forests Released by Herbicides I. Response of Hardwoods and Shrubs

Abstract

Abstract Responses of shrubs and hardwoods to 9 aerial herbicide treatments were evaluated in a replicated conifer-release experiment in a 7-year-old spruce-fir clearcut in west-central Maine. All herbicides and rates of application reduced hardwood and shrub cover by 50% or more in year 9, 2 years after treatment. Cover more than 1.5 m tall was nearly eliminated by treatments with triclopyr amine (Garlon 3A®), glyphosate (Roundup®), or a high rate of 2,4,5-T. Phenoxy herbicides (2,4-D and 2,4,5-T) led to short-term reductions in birches, maples, aspen, and raspberry, and little change in willows. Pin cherry was also controlled by these treatments but died out before year 16, regardless of whether it was sprayed. Untreated controls increased in total cover by about 50% between years 7 and 9 and also in abundance of cover >1.5 m tall. Much cover less than 1.5 m tall was left by all treatments other than triclopyr at a high rate. By the 16th year, major differences in height and cover still existed between all treatments and the controls. North. J. Appl. For. 9(4):126-130.