Douglas-fir provenance trials established 1961 in northwestern Germany: findings at the age of 38 years
2012
Weller, A., Nordwestdeutsche Forstliche Versuchsanstalt, Göttingen (Germany)
The Douglas-fir provenance trials established on 14 sites in northwestern Germany in 1961 are the basis for a comparison of 26 North American Douglas-fir provenances. The following assessment criteria were formulated: (1) How do the provenances differ with respect to total volume growth after 38 years? (2) Can climate-induced variations be observed in provenance values? (3) Do provenances differ in regard to branchiness? Because of non-orthogonal trial set-ups and plot-related influences, overall trial sites analysis called for a standardisation of interval-scaled primary data. Relative rank classes were calculated on the basis of a mean plot value. With respect to total volume growth, the provenances Tenas Creek (D47) as well as Molalla (D74) and Timber (D41/59) proved provenances with stable and outstanding productivity. Among the tested local climate elements long-term annual mean temperature, mean annual precipitation and height above sea level only the influence of long-term annual mean temperature is statistically relevant for productivity. Beside hardy ecotypes, which adapt to a wide spectrum of differing plot climates (e.g., Molalla [D74]), there are provenances with poor adaptive capabilities that react sensitively to local climatic conditions (e.g., Salmon Arm II [D46]). For the criterion fine-branchiness, the provenances Conrad Creek (D43), Ashford (D67) and Gold Hill (D83) show the best, the provenances Detroit (D76), Carson (D87) and Salmon Arm II (D46) the poorest results.
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