Biomass and nutrient relationships ofBetula pendula, Fagus sylvatica, Picea abies andAbies alba with varying nitrogen and sulphur additions in a pot experiment | Wachstum und Ernährung von Birke, Buche, Fichte und Tanne bei unterschiedlichem Stickstoff- und Schwefelangebot im Gefäßversuch

The effects of varying nitrogen (N) and sulphur (S) additions on biomass growth and nutrient relationships of silver birch(Betula pendula), European beech(Fagus sylvatica), Norway spruce(Picea abies) and silver fir(Abies alba) were investigated in a two-year factorial experiment. Saplings were grown in pots filled with 7 kg of a sand-loam mixture, to which KH₂PO₄ and Mg acetate were added. N and S treatments were applied each year in five equidistant levels (0 to 0.25 g N per pot, equivalent to 0 to 80 kg N ha⁻¹ as NH₄NO₃, and 0 to 0.64 g S per pot, equivalent to 0 to 200 kg S ha⁻ as H₂SO₄) in order to simulate present and future conditions of soil chemistry with special respect to soil acidification in the Erzgebirge (East Germany).Aboveground growth was markedly enhanced with increasing N fertilization, with maximum response in birch and minimum response in beech and fir trees. High levels of S restricted growth of beech, spruce, and fir. However, the growth-stimulating effect of N was only given for low levels of S addition, and growth restriction due to S was only found under high N fertilization. With rising levels of N fertilization, leaf N contents increased, and contents of S, K, and Mg decreased. The contents of N, S, K, Mg, Mn, and Al in leaves increased consistently with elevated S addition. Growth stimulation by N fertilization resulted in dilution of S only in leaves of beech and reduced contents of K (spruce, fir) or Mg (birch, beech). Growth retardation as a consequence of high S addition increased contents of K, Mg, and Al in leaves of beech, spruce, and fir. Potassium may be an important counterion under sulphate accumulation in needles especially of spruce and fir, and Mg in leaves of beech. Nutritional relationships of birch are only marginally affected by experimental additions of N and S, whereas the nutritional status of beech, spruce, and fir was severely affected.