Economic Analysis of Growth Effects of Thinning and Fertilization of Lodgepole Pine in Alberta, Canada

Abstract

Abstract This study examined the economic profitability of eight combinations of thinning and fertilization treatments applied to 40-year-old natural stands of lodgepole pine (Pinus contorta Dougl. Var. latifolia Engelm) in Alberta, Canada. The eight treatments, consisting of four levels of nitrogen fertilizer application (0, 180, 360, and 540 kg ha−1) and two levels of thinning (thinned and unthinned), were applied in 1984 in a randomized complete block design with factorial treatments and nine replications per treatment. The diameters and heights of all trees on the experimental plots were measured in 1984, 1989, 1994, and 1999. A simple factorial analysis of variance (ANOVA) with the 1984 volume as a covariate showed that both fertilization and thinning increased volume growth significantly. Economic analyses showed that thinning without fertilization was the most profitable treatment combination. The ranking of profitability was based on the soil expectation value and assumed that the thinnings had a commercial value. If thinnings had no market value, then the unthinned treatments were more profitable than their corresponding thinned ones. The profitability ranking was robust for real discount rates of 4 to 10%. To improve economic profitability, fertilization of lodgepole pine should be carried out when the stands are in an optimal stand density range for the site to ensure that the increased growth is concentrated on the most valuable trees with the best growth potential.North. J. Appl. For. 22(4):254–261.