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 RNH4 ? 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 condition.
The present study aimed to detect sensitivity of beech trees (Fagus sylvatica L.) to meteorological parameters and air pollution by acidifying species as well as to surface ozone outside their north-eastern distribution range. Data set since 1981 of Preila EMEP station enabled to establish that hot Summers, cold dormant, and dry and cold first-half of vegetation periods resulted in beech tree growth reduction. These meteorological parameters explained 57% variation in beech tree ring widths. Acidifying species had no significant effect on beech tree growth. Only ozone was among key factors contributing to beech stand productivity. Phytotoxic effect of this pollutant increased explanation rate of beech tree ring variation by 18%, that is, up to 75%. However, due to climate changes the warmer dormant periods alone are not the basis ensuring favourable conditions for beech tree growth. Increase in air temperature in June-August and decrease in precipitation amount in the first half of vegetation period should result in beech tree radial increment reduction. Despite the fact that phytotoxic effect of surface ozone should not increase due to stabilization in its concentration, it is rather problematic to expect better environmental conditions for beech tree growth at northern latitude of their pervasion.
European beech is a successful tree species outside its distribution range in northeastern Europe, where Prussian foresters introduced it mainly into Scots pine stands. This forest management practice resulted in new issues related to the sensitivity of European beech to current environmental changes in areas outside its natural range. We hypothesized that recent global environmental changes promoted the northeast migration of European beech outside its distribution range in Europe. To test this hypothesis, dendrochronological analysis of beech tree ring series was performed for eight sites located in Poland, Lithuania and Latvia. Frost in winter months and heat in June, along with drought in the vegetation period, limited beech tree growth outside its natural distribution range in northeast Europe. Higher air concentration of surface ozone and sulphur deposition level reinforced the negative effect of the detected key meteorological variables on beech growth, while higher air concentrations and deposition of nitrate had a positive effect. These factors explained about 50% of the total variation in increment indexes of beech trees at sites on the northeasren edge of their range. The observed trends of beech growth over the last 25 years has determined favorable conditions for planting this tree species outside its natural range in northeastern European forests.
a r o n ] IUS †, GINTARAS PIVORAS †, BENIUS BENDORAVI[ C c a r o n ] IUS †, DALIA [ S c a r o n ] OPAUSKIEN[ E d o t ] ‡, DALIA JASINEVI[ C c a r o n ] IENE ‡, IEVA BAU[ Z c a r o n ] IEN[ E d o t ] §, IRENA EITMINAVI[ C c a r o n ] IUT[ E d o t ] ¶, K STUTIS ARBA[ C c a r o n ] IAUSKAS ¶ AND REDA MA[ Z c a r o n ] EIKYT[ E d o t ] ¶ †Lithuanian University of Agriculture, LT-53362 Kaunas dstr.,
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