Contribution of Ambient Ozone to Changes in Scots Pine Defoliation. Step II of Lithuanian Studies

This study aimed to explore if changes in peak ozone (O3) concentrations may reinforce the phytotoxic effects of air concentration of acidifying compounds and their deposition, as well as unfavorable climatic factors on pine crown defoliation. Forty-eight pine stands with more than 8000 sample pine trees have been monitored annually. The impact of sulfur dioxide (SO2) on pine defoliation was found to be the most significant. The impacts of peak O3 concentrations, acid deposition, and amount of precipitation were considerably lower, whereas the impact of air temperature, the least. Contribution of peak O3 concentrations to the integrated impact of acid deposition and amount of precipitation on pine defoliation was most significant, whereas the contribution to the impact of acidifying air compounds, mainly SO2, was the least. No synergetic effect between peak O3 concentrations and high temperature during vegetation period was detectedVytauto Didžiojo universitetasŽemės ūkio akademij

The seasonal variability of air pollution effects on pine conditions under changing climates

The multiple-stressor effects of air pollution, nutrient and water availability are the key issues of present forest ecosystem research. However, too little is known about the seasonal effect of pollutants on tree crown defoliation and their interaction with changes in climate. Therefore, data on seasonal variation in air pollution, including surface ozone, deposition of acidifying compounds and meteorological conditions, were tested against pine defoliation to identify the periods when the effect of the considered contaminants is most pronounced. The findings of the study revealed that a higher level of air concentrations of acidifying pollutants and their deposition was observed during the dormant period, with the exception of only ΣNH4+ air concentrations and their monthly deposition. An increase in precipitation over the vegetation period and mean monthly temperature from September to December, as well as a decrease in temperature and precipitation over the remaining months of the dormant period represented the climate change condition over the 14-year period in the observed region. Detected changes in the considered parameters during the dormant period were found to be most significant to changes in pine crown defoliation. Therefore, we concluded that climate changes, if they occur by the detected scenarios, should mitigate the negative effect of air pollutants and acid deposition on pine crown conditionVytauto Didžiojo universitetasŽemės ūkio akademij

N deposition, balance and benefit in the forest ecosystem of main landscape types of Lithuania

Sulphur emissions have declined in Europe by 67% since the early 1980s due to enactment of strict pollution control strategies, whereas nitrogen emissions have remained fairly constant. Consequently, the effect and benefits of nitrogen deposition remain among the most relevant ecological issues. The presented data reveal the trends of nitrate and ammonium concentrations in the air, their wet deposition and concentrations in soil water, ground and runoff water as well as the trends of different components of forest biota in areas where integrated monitoring stations have been operating since 1994. Data on nitrogen concentrations in the soil, ground and surface waters were analysed in relation to air nitrogen concentrations and their deposition. Changes in tree crown defoliation, and abundance, and diversity of the soil micro-arthropods, stream macro-invertebrates and small mammals were analysed in relation to concentrations of N compounds in studied substances in an effort to estimate N deposition benefits in forest ecosystems. N balance in areas studied revealed that the amount of nitrogen inflow into the system was very high in comparison with its elimination from the catchments. Approximately 1000 N kg/km(2) in LT01 and 600 N kg/km(2) in LT03 are accumulated in the investigated ecosystems per year. But, the relationship between condition of the conifers and air N compounds and their deposition was more significant than between N concentrations in soil and groundwater. N concentration in the studied substances resulted in more significant changes in abundance of soil micro-arthropods, stream macro-invertebrates and small mammals than in their diversityVytauto Didžiojo universitetasŽemės ūkio akademij