Temporal and spatial development of critical loads exceedance of acidity to Polish forest ecosystems in view of economic transformations and national environmental policy

Abstract

Abstract Critical load exceedance is meant by definition as a quantitative measure of a potential risk of damage to ecosystems. Its temporal and spatial development for Polish forest ecosystems was a subject of a national scale study. Within this study critical loads of acidity were calculated and mapped and superimposed with sulphur and nitrogen deposition patterns of the last two decades. The resulting temporal and spatial development of critical load exceedances were subject to an analysis from the view of economic restructuring processes and environmental policy activities undergoing within this time span, historically significant for Poland and other eastern European countries. Calculations showed that deposition in excess of critical loads of acidification gradually increased in the period 1980–1989 while since 1990 a substantial decline was observed with a further downward trend kept to date. The major reason for this rapid decline was the considerable decrease in sulphur and nitrogen emissions observed in this period caused mainly by the transition from a centrally planned to free-market economy. Decline in energy production was the dominant factor controlling the observed emission trends and to a lesser extent by the implementation of effective air pollution abatement measures. Since the mid of 1990s energy production starts gradually to increase whereas the decreasing tendency in sulphur and nitrogen emission from the energy production sector got even intensified towards the year 2003. It might be concluded from this that the reported improvement in air quality in Poland was mainly due to the implementation of national emission reduction strategies well brought in line with the Gothenburg Protocol obligations and the EU directives. In spite of the resulting emission reductions some risk from acidification will remain. Therefore, effort should continue to abate emissions of acidifying pollutants of which nitrogen and specifically ammonia is the most challenging one.