Abstract:

The influences of rising temperature on the chemical composition of seepage water of acidified forest soils under high soil water content conditions were investigated for 1.5 years with undisturbed soil columns sampled from a strongly acidified 60-year-old Norway spruce (Picea Abies Karst .) at Solling, Germany.After watering with throughfall gathered at Solling the seepage water was sampled and analysed weekly.With an increase of the mean temperature during the investigation period from 12.3 ℃ to 15.5 ℃, the mineralization rate of soil organic matter was accelerated markedly; the concentration and leaching of SO₄^2-and N_org as well as C_org were increased obviously; the concentration and leaching of Al³⁺ and NO₃^- were decreased significantly; the concentration and leaching of NH₄⁺,HPO₄^2-,Cl^- and the Ca²⁺/Al³⁺ ratio of the seepage water were increased only slightly; the concentration and leaching of H⁺ were decreased slightly; however, the concentration of base cations and their percentage in the sum of all cations were not obviously afftected by the rising temperature.The lowering of net nitrification rate caused by the acceleration of denitrification under higher temperature seems to be the decisive process for the decrease of Al³⁺concentration.To summarise, the Al³⁺ toxicity was moderated in a certain degree by the rising temperature, the nutrient situation of base cations was not improved.

Key words: Forest soil, Percolating water, Element balance, Temperature, Climate change