Foliage chemistry

Aims assess the nutritional status of trees and the dynamics of nutrients reveal possible pollutant-related stress The chemistry of the foliage – in this case spruce needles – reveals the nutritional status of the tree. At nitrogen saturation, e.g., the concentration of the amino acid arginine may increase dramatically. Simultaneously nitrate ions may leach and take with them cations such as potassium and magnesium. With shortage of these ions the trees will suffer from deficiency . At sites with large nitrogen deposition also deficiency in phosphorous, boron and copper may appear. Needles from the upper part of the spruce crown are sampled once a year in winter. For this is used a long pole equipped with a cutting pruner head at the top and a line between the head and the bottom. At each site ten trees distributed evenly over the area are sampled. The needles are analysed at different laboratories with regard to (1) arginine, (2) major nutrients and heavy metals and (3) C, N, S. Foliage samples of Norway spruce are taken once a year during late winter when the trees are dormant and the amounts of elements stable.   Variables total P, C and N; S, K, Ca, Mg, Na, Al, Mn, Fe, Cu, Zn, Pb, Cd, Hg, arginine

Twigs with living needles are clipped from the light-exposed part of the tree by means of a coal-fibre rod which can be extended to 20 meters. The needles of the last two years are analysed. (Gammtratten.)