Influence of spacing and artificial pruning on the production of clearwood of Douglas-fir

Analysis of markets for Douglas-fir has shown that clearwood will probably command high values in the future. To evaluate the demand for high quality wood a review of spacing and artificial pruning techniques was made. Their effects on wood quality were also studied. Results of research conducted at the U.B.C. Research Forest and at Wind River, U.S.A. in the Gifford Pinchot National Forest are presented in order to define some relationships among spacing, branch morphology, tree growth and natural pruning. Times required to prune branches by various techniques were analysed. Results were incorporated in a simulation model PRUNE to estimate the volumes and costs of clearwood produced by various pruning methods. It now appears that early pruning of widely spaced Douglas-fir will show the highest return on investment. New data are needed, however, to determine any extra costs of stand tending and to quantify the savings in establishment costs associated with wide spacings. In order to define optimum strategies for Coastal Douglas-fir, analyses should be made of the sensivity of benefits from pruning to various cost and premium structures for sites likely to be managed intensively.Forestry, Faculty ofGraduat