Growth Response of Even-Aged Ponderosa Pine Related to Stand Density Levels in Arizona
Dense stands of slow-growing ponderosa pines responded significantly to release. Forty-three-year-old stands, with an average stand density of 5,844 stems per acre and average dbh of 2.6 inches, were thinned in 1962 to test six residual growing stock levels (GSL) with numerical indices representing future basal areas in sq. ft. per acre ranging from 30 to 150. Net dbh periodic annual increment (PAI) was 4.6 times greater at GSL-30 and 2.2 times greater at GSL-150 during the first five years alter thinning than the pre-thinning rate. The net PAI in terms of square toot basal area and cubic foot volume increased significantly with increased GSL up to GSL-80, and then tapered off or decreased with increased GSL. Height increased insignificantly with increased stand density. Crown width increased most on trees in the lowest density stands. The PAI of the 100 largest trees per acre showed improvement in diameter, basal area and volume with increasing growing space.
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Document Type: Journal Article
Affiliations: Principal Silviculturist, Rocky Mtn. Forest and Range Exp. Sta., U.S. Forest Service, Stationed at Flagstaff, Ariz., in cooperation with Northern Arizona University
Publication date: 01 December 1971