Effects of Planting Density on Early Growth of Giant Sequoia (Sequoiadendron giganteum)

Abstract

Abstract Almost no information exists for stocking and growth of young giant sequoia (Sequoiadendron giganteum) plantations. This study measured 2,086 giant sequoia seedlings, planted at true spacings of 7 to 20 ft, over a period of 7 yr. Compared to other species that have been studied, giant sequoia shows remarkably early and extensive effects of intertree competition. Unlike results for other species, spacing substantially affects early height growth of sequoia. A general least squares model showed that crown width, stem diameter, and height increased linearly with the natural log of spacing distance at 4, 5, and 7 yr after planting (all P-values < 0.0001). By 7yr, trees at wide spacing (14-20 ft) were showing 45-78% wider annual diameter growth and 29-67% higher annual height growth than trees at one-half each respective spacing (7-10 ft). Results indicate that for close initial planting densities (7-12 ft spacings), early precommercial thinning (before 7 yr after planting) may be required to avoid intertree competition. West. J. Appl. For. 14(2):65-72.