Growth, Yield, and Value Projections for Black Walnut Interplantings with Black Alder and Autumn Olive

Abstract

Abstract Silvicultural practices to reduce managerial inputs, increase yields, and decrease rotation age for eastern black walnut contribute substantially toward making this species more attractive as a forestry investment. Height and diameter measurements of black walnut interplanted with European black alder or autumn olive were taken at ages 14 and 18 in fifth-acre plots at a location in southern Illinois. Black walnut had been planted by USDA Forest Service scientists at a 12 x 32-ft spacing. For the interplanted plots, three black alder or autumn olive were planted within the rows between the walnut trees at a spacing of 8 ft. Based on projections of average dbh, the autumn olive and walnut mixture possessed the highest estimated black walnut yields and return on investment. Average dbh values of 11 in. were projected for the interplanted walnut at age 31. In the black alder interplanting it was estimated that similar rates of growth would require 40 years. Estimated dbh for the control plantings did not reach merchantable sawlog size within the 80-year projection period. Interplanting black walnut with nitrogen-fixing tree species also is well adapted for marginal farmland and may provide landowners with returns that match or exceed those from other more intensively managed alternatives. North. J. Appl. For. 6:129-132, September 1989.