Growth of Ponderosa pine poles thinned to different stocking levels in central Oregon.

This paper presents 15-year results of one installation of a west-wide study of growing-stock levels in even-aged ponderosa pine. Growth was related to growing-stock level in a 65-year-old pole stand on an above average site. Periodic growth is presented for 10 years after the initial thinning and for 5 years after a second thinning to six assigned growing-stock levels.Annual growth in diameter during the 5 years after initial thinning ranged from an average of about 0.28 inch at the lowest growing-stock level to 0.10 at the highest. These rates increased slightly during the following decade, but differences between growing-stock levels remained about the same. These growth relations resulted in much larger trees at the lower growing-stock levels 15 years after the initial thinning.