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Genetic Variation in the Height-Diameter Ratio in Scotch Pine

A range-wide provenance test including seed from 110 parts of the species' natural range was established in 1961 in three Michigan plantations. The trees were measured in 1973-1974, shortly after crown closure. At that time the plantation in the Upper Peninsula averaged 12.7 ft. tall and 3.3 in. diameter-at-l-foot; the two plantations in the Lower Peninsula averaged 23.9 and 23.2 ft. tall and 6.0 and 6.2 in. diameter, respectively. The average height/diameter ratio (feet/feet) was 54:1 in all three plantations. The six tallest seedlots (30 percent taller than average) were from Belgium, northern France, West Germany, and eastern Czechoslovakia. Their height/diameter ratio varied from 50:1 to 54:1 (differences not significant); all six were among the eight largest in diameter. Thus, selection for rapid volume growth can be done on the basis of either height or diameter. Trees from the north (northern Sweden, Siberia, and the Ural Mountains) grew at very slow to moderate rates (40 to 90 percent of average). Such trees were more slender than average, having height/diameter ratios of 56:1 to 58:1. The stockiest trees (i.e., lowest height/diameter ratios) were from Spain, Greece, Turkey, and northern Italy (average height/diameter ratios of 44:1, 49:1, 50:1, and 50:1, respectively). Those races grew at moderate rates (80 to 100 percent of average) and are among the best for Christmas tree production from the standpoints of foliage color and needle length.

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Author(s): Johnathan W. Wright

Publication: Tree Improvement and Genetics - Lake States Forest Tree Improvement Conference - 1975