Material balances in pine/oak stands close to urban agglomerations

Foresters report substantial needle loss by pine trees (Pinus sylvestris L.) in the forests of Berlin (West). Air pollution is often regarded as the cause of these damages, though the exact mechanisms of its influence is not known. The central element in the understanding of the effects of gaseous air pollutants, acid deposition and soil acidification is the measurement of input, output and cycling of nutrients and pollutants, and the flux of carbon within the ecosystem. Leaf gas exchange as the key for the carbon budget of the stand, and the distribution of dry matter and minerals in the tree layer, are investigated in the botanical part of an ecosystem analysis in the Berlin forest. Methods and first results are reported here. (orig.)