Assessment of Siberian Forest Ecosystem Stability Against the Acidification

Abstract

In the perspective of worldwide agreement on atmospheric pollutants emission abatement it is very important to assess the forest ecosystem sensitivity to acid deposition in such a vast and forested area as the Asian part of Russia — Siberia. This region is situated between the Ural Mountains and the Pacific Ocean. At the present significant inputs of acid forming pollutants are related mostly to trans-regional and trans-boundary pollution from Europe because of circumpolar wind directions, which are predominant in the Northern hemisphere. In the future, ecosystem damage due to the atmospheric deposition in southern Siberian regions caused by trans-boundary pollutants transport from China is also possible. During last years, some research has been conducted to give quantitative estimates of Asian ecosystems sensitivity to acidity loading (Bashkin et al., 1995, 1996). These estimates have been based on semi quantitative approaches to the assessment of soil/ecosystem buffering mechanisms like chemical weathering, base cation and nitrogen uptake by vegetation, nitrogen leaching and denitrification. As usual, the input information for the calculation of the given parameters was based predominantly on expert conclusions. The uncertainty of both input parameters and output results was very great.