Critical loads of acidity for forest ecosystems of North Asia

Critical loads of acidity were calculated using the PROFILE model to assess the forest ecosystem sensitivity to acid deposition in the Asian part of R ussia - Siberia. The main input parameters and the output were mapped. At p resent atmospheric inputs of acid forming pollutants to the study territory are mainly related to transregional and transboundary pollution from Europ e. It was shown that the most sensitive to acid loading are ecosystems of t he Tundra zone and of the East Sayan mountains' coniferous forests with dys tric cambisols and gleysoils, critical loads of actual acidity (CL(Ac)) = 0 -0.3 keq/ha/yr. The most tolerant ecosystems are ecosystems of deciduous fo rests with podsoluvisols, luvisols and humic luvisols of South Taiga zone i n West Siberia, CL(Ac) = 3.5-7.0 keq/ha/yr. Generally the values of critica l loads are increasing from the North to the South and from the East to the West following the bioproductivity, annual soil temperature and alkalinity of deposition increases.