In the Detritus Inputs and Removal Treatment (DIRT) field experiments established at the Síkfőkút Site (northern Hungary) in October 2000, an experimental approach was applied to study long-term effects of litter quality and quantity on pH and nutrient mobility of soil in a Quercetum petraeae-cerris forest. Our previous results have suggested that decreases in organic matter content, total N, Ca2+ and Mg2+ concentrations in the soil are the consequence of the reduction in forest litter production induced by climate change and the resultant soil degradation over a longer period. An eight-year litter manipulation demonstrated a relation between soil pH and Mg2+ and Ca2+ concentrations in the soil. The reduction of litter production resulted in a decrease of the soil pH which occurred due to the decreasing Mg2+ and Ca2+ inputs into the soil, and consequent reduction of soil buffering capacity against the acidifying effects of the acidic intermediates of litter decomposition and humus compounds. If the litter production increases as a result of climate change, it should be accompanied by increasing C, total N, Ca2+ and Mg2+ contents in the soil and soil pH, with a positive effect on the soil organic matter and fertility. However, this scenario is rather unlikely as our results indicated decreasing litter production in the measurement period.