Growth Data for 29 Years from the California Elevational Transect Study of Ponderosa Pine

Ponderosa pine progenies from parents restricted in latitude but spanning 7.000 feet of elevation show significant growth differences in plantations at low-, mid-, and high-elevation test sites. At low- and mid-elevation sites tree heights and diameters of progenies from high-elevation parents were the smallest; those from the low-elevation parents. intermediate: and those from mid-elevation seed parents. largest. At the high­ elevation site. trees from mid- and high-elevation sources grew equally well, whereas trees from low-elevation parents showed poorest growth. The variation associated with elevation zone of parent trees accounted for 8 percent of the total experimental varia­ tion. About 9 percent of the total was attributed to the interaction between parent tree elevational zones and plantations. Height rankings of progenies for different ages showed little change over the 29-year growth period of the study in low- and mid­ elevation test sites. But at the high-elevation test site, height means for zone groups shifted with age as the relative heights of the higher elevation progenies increased. Forest Sci. 19:31-39.