Tree nutrition of Norway spruce as modified by liming and experimental acidification at the Höglwald site, Germany, from 1982 to 2004

From 1982 to 2004 the elemental concentrations of current, current+1, and current+2 year old needles of a mature spruce stand were investigated at the N-saturated, acidified, but healthy Höglwald site. The control was compared with a liming, experimental acid irrigation, acid irrigation + liming, normal irrigation, and normal irrigation + liming treatment. Liming was performed in 1984, and irrigation from 1984-1990. High year to year variations were found for most of the elements in all treatments, especially for K ("deficient" to "high"). Despite the N saturation of the ecosystem, needles showed no N-overfeeding of the trees. N, Mg, K, Fe concentrations showed no clear treatment effects. Twenty years after liming a lowered P availability is indicated, which was more pronounced in older needles. Ca concentrations increased after liming, while Al decreased. The elemental concentrations of the acid irrigated treatment did not differ significantly from the normal irrigated or control treatment.