Early Growth of Ponderosa Pine Ecotypes in Michigan

Key Points

Growth rates varied among ponderosa pine ecotypes, with Pacific Northwest trees being the tallest at age 8 years, suggesting regional adaptation.
California-Oregon origins faced severe winter injuries, leading to decreased growth rates, while Southern origins exhibited the most lammas growth.
Differences in foliar concentration of nutrients like N, K, P, Ca, and B allowed for the separation of coastal and interior varieties of ponderosa pine.
Significant within-ecotype variation was observed, indicating that environmental factors at the place of origin affect growth but don't explain all variations.

Abstract

Abstract A 57-origin provenance study of Pinus ponderosa includes three test plantations in southern Michigan. Relative growth rate changed from age 2 to 8, primarily because of severe winter injury to California-Oregon trees and slight winter injury to Arizona-New Mexico origins. At all test sites trees from the Pacific Northwest were tallest at age 8. All hardy origins had about 4 branches per whorl. Southern origins produced the most lammas growth. Coastal var. ponderosa and interior var. scopulorum could be separated by bud scale color, bud scale appression, and foliar concentration (highest in var. ponderosa ) of N, K, P, Ca, and B. Waxy bloom on young twigs continued to be a diagnostic character of the Arizona-New Mexico ecotype. Most differences among ecotypes could be related to environment at place of origin, but the considerable amount of within-ecotype variation could not be so related.

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