Stability of ponderosa pine provenance performance: results after 21 years in eastern South Dakota
1992
Schaefer, P.R. | Baer, N.W.
Present seed source recommendations for ponderosa pine throughout most of the Great Plains are based on provenance data of trees up to 15 years old. There are indications in the literature that these recommendations may change as test plantations get older. Height and survival of 69 provenances of ponderosa pine were recorded 5, 10, 15, and 21 years following field establishment in 1968. The three provenances forming the north central Nebraska cluster maintained a significant height superiority over the remaining clusters at all measurement dates. Age/age correlations for total height growth declined over time; however, all were highly significant and the correlation between ages 10 and 21 was quite strong (r = 0.76). However, relative to the plantation mean, the growth rate of the rapid early growers was decreasing, while that Of the slow early growers was increasing. Correlations between survival and growth rate were strong and highly significant at all ages, with the highest correlations for 5- or 70-year growth rate and 21-year survival (r = 0.74 and 0.75, respectively). If present growth trends continue, the historically strong age correlations for height growth will likely weaken. The impact on provenance recommendations should be minimal, because rapid early growth and long-term survival are the traits of interest.
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