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 detected

Trend in Ambient Ozone and an Attempt to Detect Its Effect on Biota in Forest Ecosystem. Step I of Lithuanian Studies

The presented study aimed to explore the relationships between ambient ozone (O3) and tree defoliation, specific diversity, and abundance of soil microarthropods, stream macroinvertebrates, and small mammals (mainly rodents) in order to test the hypothesis that changes in the considered objects of the forest ecosystem could be related to changes in ambient O3, concentration of which is below critical level. The observations were carried out from 1994 at three integrated monitoring stations. The obtained data revealed that only peak O3 concentrations (from 125–215 μg·m-3) had significant effect on changes in the considered components of forest biota

Integrated effect of environmental changes on forest ecosystems in Lithuania: Strategies for adaptation to and mitigation of the main threats of global climate change

Field-measured forest productivity and its time series are crucial to understanding the impact of climate change on the main tree species increment and stand productivity in general. In this study, the causative relationships between environmental factors, such as O3 fluxes and tree ring width formation, including stem sap flow intensity, in the prevalent Lithuanian tree species (Picea abies (L.) Karst, Pinus sylvestris L., Betula pendula, and Betula pubescens ) growing under different nutritional and moisture conditions in northeastern Lithuania were examined. We hope that this information will help us assess a trees capacity to adapt to and mitigate recent global clima te changes. Continuous monitoring of the tree stem increment from annual to hourly scales was crucial for this study. The obtained data revealed that Norway spruce trees are appropriately adapted to current climatic conditions in temperate forests. Even du ring a drought episode, spruce stem increment exceeded the increment of the rest of the studied tree species; therefore, they had the highest water use efficiency compared to the rest of the tree species in the study. O3 fluxed through the stomata at an ho urly scale, stimulating the stem shrinking process more intensively than inhibiting the swelling process, but only for pine and birch trees. Spruce trees demonstrated the highest sensitivity to O3 because O3 significantly affected the stem swelling process. Pine trees were less sensitive to O3 damage, and birch trees were the least affected. Reduced tree growth intensity and the weak relationship between birch tree radial increment and the main meteorological parameters indicate that birch trees have the lo west adaptive capacity to recent environmental changes of the tree species in this study

Did the Ambient Ozone Affect Stem Increment of Scots Pines ( Pinus sylvestris

This study aimed to explore if changes in stem increment of Scots pines (Pinus sylvestris L.) could be related to changes in ambient ozone concentration when the impact of tree dendrometric parameters (age, diameter) and crown defoliation are accounted for. More than 200 dominant and codominant trees from 12 pine stands, for which crown defoliation had been assessed since 1994, were chosen for increment boring and basal area increment computing. Stands are located in Lithuanian national parks, where since 1994–95 Integrated Monitoring Stations have been operating. Findings of the study provide statistical evidence that peak concentrations of ambient ozone (O3) can have a negative impact on pine tree stem growth under field conditions where O3 exposure is below phytotoxic levels