Element turnover in a heavily damaged Norway spruce ecosystem influenced by N deposition

Abstract

Element budgets of a heavily damaged Norway spruce ecosystem at Hohe Matzen in the Fichtel Mountains/FRG were studied over 3 years. The trees show severe symptoms of decline and Mg deficiency. The soil is a typic Dystrochrept derived from granite with sandy texture, high stone content, and low base saturation. The budgets show high releases of N, S and Al from the ecosystem as a result of input, buffering and turnover processes. After an increase of proton fluxes in the organic surface layer, a strong reduction of protons in the B horizon was found. This process was accompanied by the release of Al, whereas reactive Al(OH)3 was exhausted in the A horizon. The low ANC is also shown in pH-stat.-titrations. The data indicate a strong mineralisation in the humus layer, which results in a net release of NH4, SO4 and TOC. Nitrification takes place mainly in the A horizon. With respect to the N-budget, the ecosystem is approaching the state of N saturation. The processes of N turnover lead to an internal proton production exceeding the atmospheric input, and thus contributing to soil acidification.

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