engleski

Atmospheric deposition measurement in the lowland forest ecosystem of Pokupsko basin in Croatia

Background and Purpose: The chemistry of atmospheric deposition and its transformation in contact with vegetation are of great importance in understanding its effects on forest. Evaluation of the damage caused by atmospheric pollution, acid loads, climate change and other factors influencing forest condition are of great interest in large-scale monitoring programme like the UN-ECE ICP Forests. Following its methodologies, the flux of ions from atmosphere and the relationship between them in a permanent ICP Forests plot (number 110), the lowland forests of Pedunculate oak and Common hornbeam in Croatia were investigated on yearly basis. The following criteria were investigated in order to assess the condition of lowland forest of Croatia: relationship among ions, difference among different samples typology, the flux of ions in the plot, and comparison between actual and critical loads of acid components. Materials and Methods: Bulk open field deposition and throughfall deposition were sampled using a continuously exposed collector. The samples were collected biweekly during one year. The variables examined in the laboratorywere as follows: pH, conductivity concentration of anions (chloride, nitrate, sulphate, phosphate) and cations (ammonium, sodium, potassium, calcium and magnesium). Data validation and statistical analyses were performed. Results: The results showed that the chemistry of bulk deposition was strongly influenced by natural sources, such as sea water components (sodium, chloride, magnesium and partly by sulfate), and soil dust that contains ions (potassium, calcium, magnesium and sulfate) of local origin. The ionic concentrationswere higher in throughfall than the respective bulk values due to interaction of rain water with vegetation. The increase involved main ions, with the exception of calcium and magnesium. The actual loads of acidifying and nitrogen compounds showed much lower values than the critical load for both types of samples. Conclusions: This multifunctional monitoring programme offers a very good tool to record the extent and intensity of risk factors and to monitor and assess the reactions of forest ecosystems. The flux of acid and nitrogen ions measured in the lowland forest did not exceed critical loads. It was, therefore, still not influencing the stress in the lowland forest ecosystem. New challenges arising from air pollution, biodiversity loss and climate change effects on forests and the increasing importance of forests as a source for renewable resources render joint efforts necessary to maintain the ICP Forests monitoring

atmospheric deposition; bulk open field; ICP Forest; throughfall; lowland forest ecosystem

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