Regeneration of northern hardwoods in the northeast with the shelterwood method.

Study plots (1/4 ac) were located in four northern hardwood stands in Vermont, and shelterwood canopy covers of 40, 60, 80, and 100%, and a control (no cutting) were established. Regeneration on small plots within the treated areas was sampled over a 3-year period and the composition of saplings determined after 6 years. While there were substantial increases in amount of regeneration under most canopy covers, there was no significant difference due to treatment. Some important trends, however, were evident. Sugar maple showed some increase in seedling density under most canopy densities with up to 68,000 new sugar maple seedlings per acre under 60% canopy cover. Yellow birch did best under 40 to 80% canopy cover and with good soil scarification. White ash increased under most densities but was best at about 80% canopy cover. Competitors, beech, striped maple, and hobblebush, increased under most densities. At about 60% canopy cover and less, raspberries and blackberries, pin cherry, and other shade-intolerant species increase in abundance. Among regeneration less than 3 ft tall after 3 years, preferred species outnumbered less preferred species by 5 to 1. Among regeneration over 3 ft tall when examined 6 years after treatment, the less preferred species, on average, outnumber preferred species by 2 to 1 (sugar maple 0-3430/ac, yellow birch 0-1920/ac, beech 200-2220/ac and striped maple 0-3130/ac). Most beech regenerations seemed to arise as root suckers. Small striped maple grew rapidly and assumed dominance among the regeneration when released. Northern hardwoods have diverse composition in the overstory, and much of the regeneration tallied after 3 years was already in place when the shelterwood cuts were made. Advanced regeneration as well as new regeneration is the key to success, or failure, if it is predominantly undesirable species. In implementing a shelterwood in northern hardwoods, 60 to 80% canopy cover seems good for most species. All trees below the main canopy should be cut to create a high canopy shade. Undesirable species should be controlled by cutting or possibly herbicides before or when the stand is cut, with additional treatment as necessary to maintain desired composition.