Commercial and noncommercial thinning studies in northern hardwoods on the Bartlett Experimental Forest, New Hampshire, began in 1932. One of the studies, still maintained today, consisted of several precommercial treatments at age 25 (1959) and a commercial treatment in 2003. Although economic returns from precommercial work appear somewhat marginal and require additional research, commercial thinning in northern hardwoods is clearly advisable--almost necessary because evenaged northern hardwoods offer a unique thinning opportunity: a component of shade-intolerant aspen and paper birch maturing in 50 to 70 years coupled with a component of long-lived species that will mature at age 100 to 120 years.
Leak, William B.; Yamasaki, Mariko. 2012. 80 Years of thinning research on northern hardwoods in the Bartlett Experimental Forest, New Hampshire. Res. Pap. NRS-20. Newtown Square, PA: U.S. Department of Agriculture, Forest Service, Northern Research Station. 8 p.