Effects of air pollution and climate change on forests of the Tatra Mountains, Central Europe

Abstract

Synergistic effects of air pollution, extreme weather conditions andbiotic agents related to global climate change have caused seriousdeterioration of forest condition in the Tatra National Park sinceearly 1990s. Atmospheric deposition of sulfate (SO(4)(2-)), nitrate(NO(3)(-)) and acidity (H(+)) are above the established criticalload limits for forests. In addition, ambient ozone (03) concentrationsare also elevated mainly due to a long-range transport of pollutedair masses. Ambient 03 concentrations have been monitored since 1992with active UV monitors and passive samplers showing significantdifferences along the elevational gradient. High O(3) values in springindicate a potential for O(3) stratospheric intrusion into troposphere.Ozone AOT40 index for protection of natural forest vegetation (10,000ppbh) is commonly exceeded in the middle of vegetation period. Acidicimpact may explain about 10-30% of a dieback observed in naturallyoligotrophic Norway spruce (Picea abies) ecosystems probably dueto acidification of soils leading to Al(3+), mobilization limitinggrowth of fine roots. This may cause weakened resistance of treesto wind throws frequently observed in the foothills of the TatraMountains. Seventy year-long observations of meteorological conditionsprovide a unique opportunity for comparing current status of theTatra forests within a context of long-term trends. Extremely highspring and summer temperatures, low precipitation and relative humidityobserved during last decade are new factors disturbing ecologicalstability of natural and man-made forests. Warm and dry vegetationperiods favor frequent bark beetle (Ips typographus) outbreaks affectinglarge areas of the Tatra forests.