NUTRITION STATUS OF DOUGLAS-FIR (PSEUDOTS UGA-MENZIESII [MIRB] FRANCO) FROM DANISH AND GERMAN SITES IN COMPARISON WITH THE AREA OF ORIGIN

The nutrition status of 10- to 25-year-old Douglas firs was investigat ed on a total of 14 Danish and German trial plots. Cumulative frequenc y distributions were developed for the N, P, K, Ca, Mg and Mn contents In needles, which were compared with corresponding results of needle analysis investigations on Douglas fir from the Pacific North America region. N nutrition showed distinct differences. In Central Europe Dou glas fir responds to high N inputs with high N concentrations in the n eedles. Here N concentrations in needles (first whorl) vary from 12.4 mg/g to 26.2 mg/g. The mean value of distribution is 16.6 mg/g, and th us by 5.1 mg/g higher than in the area of origin. The ranges of nutrie nt element contents determined in the Central-European investigation a rea for Ca (1.8 to 4.8 mg/g) and Mg (0.8 to 1.7 mg/g) are narrower com pared with the natural range of this tree species. With P contents bet ween 0.8 and 2.9 mg/g and K concentrations between 4.5 and 11.6 mg/g t he needles appear to have similar contents as have those in North Amer ica. The measured Mn concentrations in needles (first whorl) range fro m 0.2 to 2.1 mg/g on the Danish and German plots. The Mn concentration s determined on the American trial plots clearly fall below these cont ents with 0.01-0.8 mg/g. This is interpreted as an effect of stronger soil acidification on Danish and German trial plots. The investigated Douglas firs show distinct variations in N and Mn concentrations compa red to those in the area of origin. This may be attributable to nutrit ional imbalances based on anthropogenic causes or acidification.