Effects of excessive ammonium deposition on the nutritional status and condition of pine needles

摘要: In the southeastern part of Netherlands many Scots pine (Pinus sylvestris L.) trees show signs yellowing. To investigate whether there is a relation between this phenomenon and high ammonium deposition, needle soil samples were analyzed. Soil from discoloured forests contained more extractable nitrogen than healthy stands, whereas differences in pH values small. Needles yellow had higher levels total needles green as well severe imbalances Mg, K+ P relative to N. The amount leaf pigments was substantially lower diseased trees, but they much quantities free arginine, which accounted for major nitrogen. This may be an indication overload. linkage excessive nutrition observed process yellowing discussed.