A ponderosa pine-lodgepole pine spacing study in central Oregon: results after 20 years.

Abstract

The growth response after 20 years from an initial spacing study established in a ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and lodgepole pine (Pinus contorta Dougl. ex Loud.) plantation was measured in central Oregon. The study was designed to compare the growth rates of pure ponderosa pine, pure lodgepole pine, and a 50-percent mixture of each species planted at 6-, 9-, 12-, 15-, and 18-foot spacings. Diameter growth of pure ponderosa pine was greater than that of pure lodgepole pine at all spacings, although pure lodgepole grew faster in height than pure ponderosa. Growth of the mixed-species stands was generally intermediate. Both basal area and total cubic volume increment per acre increased at the narrower spacings, but diameter growth per tree was less. Volume yield in these plantations after 20 years was similar for the pure pine and mixed species except for a reduction in yield of the ponderosa pine at the 6- and 12-foot spacings.

Citation

Seidel, K.W. 1989. A ponderosa pine-lodgepole pine spacing study in central Oregon: results after 20 years. Res. Pap. PNW-RP-410. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 14 p