Effects of Bigleaf Maple Sprout Clumps on Diameter and Height Growth of Douglas-Fir

Abstract

Diameter and height growth of 7- to 11-yr-old Douglas-fir (Pseudotsuga menziesii) were examined in relation to bigleaf maple (Acer macrophyllum) competition. Growth models were developed for plantations in Oregon and Washington by joining a distance-dependent model with a model that excluded competition effects. The fitted equations were based on Douglas-fir size at plantation age 7 yr and distance from the stump and crown diameter of the bigleaf maple clump. The models suggest that bigleaf maple clumps between 5.7-14.6 m from planted Douglas-firs decrease the latter's dbh and height growth, and that this decrease becomes greater with increasing size of the clump. A procedure is suggested to use the models to guide vegetation management prescriptions on sites with bigleaf maple sprout clumps. West. J. Appl. For. 10(1):5-11.