Genetic Variation in Seedling Progeny of Ponderosa Pine Provenances

Abstract

Twenty-four characteristics were measured on seedlings of 80 natural stand seed provenances of ponderosa pine, during three growing seasons in a replicated experiment at Bessey Nursery in central Nebraska. ISODATA analysis using 13 traits provided a basis for grouping the 80 origins into a pattern of nine geographic clusters. Two of the clusters, California and the North Plateau (Oregon, Washington, Idaho, and western Montana), fit the description of Pinus ponderosa var. ponderosa. Other clusters, east of the Continental Divide including one Arizona source west of it, were described as Pinus ponderosa var. scopulorum and delineated into: (1) Transition between the two varieties in west central Montana; (2) Central Montana; (3) Central Rockies from north central Wyoming to south central Colorado; (4) Black Hills and surrounding High Plains from eastern Montana to western Nebraska; (5) Easternmost, low elevation in northern Nebraska; (6) Colorado Plains east of the Front Range; and (7) Southern Rockies from extreme southern Colorado through central New Mexico and Arizona. These geographic delineations provide new knowledge of the genetic variation in the large eastern range of this species and serve as convenient subdivisions for seed collections and growth prediction purposes.