Impact of air pollution on Scots pine stands growing in Poland on the basis of dendrochronological analysis

Air pollution and climate change are two key factors comprising the global change threat to forest health and sustainability. Intensive development of industry in the second half of the 20th century brought significant changes in the level of pollutants emitted into the atmosphere in Poland. Dry and wet deposition of toxic pollutants (mainly SO₂, NOx, & NH₃), continuing over more than 40 years, has caused serious damage to forest stands. One of the ways describing the effect of industrial emissions on forests is the tree-rings (dendrochronological) analysis, it has been used in our research. We present a brief description of the studies on impact of air pollution on growth of forest growing in the most polluted areas of Poland. The main aim is to evaluate of Scots pine stand degradation caused by the pollutants emitted from the one of biggest polluters of the environment in Poland for over 25 years (1966-1990). We found that pollutant emission caused disturbances of incremental dynamics and long-term strong reduction of growth. Scott pine growing in the vicinity of the nitrogen fertilizer factory showed a dramatic growth reduction after the beginning of the pollution period. Significant decrease in growth was observed for the majority of investigated trees (75%) to the end of the 1990s. The zone of destruction extends primarily in easterly and southern directions, from the pollution source, associated with the prevailing winds of the region. At the end of 1990s decreasing trend stopped and the wider tree-rings could be observed. This situation was related with a radical reduction of ammonia emissions and an improvement of environmental conditions. However, growth of damaged trees due to the weakened health condition is lower than the growth of Scots pine on the reference plot and trees are more sensitive to stressful climatic conditions, especially to drought.