© 1986 Heron Publishing—Victoria, Canada
Foliar mineral composition, fertilization and dieback of Norway spruce in the Belgian Ardennes
H. J. van Praag (1) and F. Weissen (2)
1. Centre for Forest Research, Soil Ecology Section, Faculty of Agronomy, B-5800 Gembloux, Belgium / 2. Department of Forestry, U.C.L., Louvain-La-Neuve, B-1348 Gembloux, Belgium / Received October 25, 1985
Summary
Needles from healthy Norway spruce (Picea abies (L.) Karst.) at Willerzie in the West Ardennes and from trees with symptoms of dieback at Langesthal in the East Ardennes
were analyzed by age class for mineral composition. Both stands were on acid oligotrophic soils. At Willerzie, needles were
sampled from plots fertilized 12 to 17 years earlier (dolomitic lime plus N, P and K) as well as unfertilized plots. Effects
of fertilization included increased levels of calcium, manganese, phosphorus, and copper and reduced levels of total sulfur,
sulfate-S, sulfate-S:total S, potassium and aluminum. Levels of calcium, magnesium, copper and boron were low at both sites
and, at Langesthal, calcium and magnesium may have been deficient. Sulfur level was normal at Willerzie, but at Langesthal,
mean sulfur content for needles of all age classes was 198 mg 100 g–1 dry weight, a level that may be toxic. In older needles, the N:S ratio at Langesthal was below the threshold value of eight
reported to be necessary for healthy growth. Other symptoms of stress observed were high sulfate-S:total S and nitrate-N:total
N ratios. At Langesthal, manganese level was probably adequate although only one-fifth the level at Willerzie. Levels of aluminum
and iron were very high at both sites. Most of the iron and much of the aluminum occurred as a surface deposit that could
be removed by washing the needles in chloroform.
