Romualdas Juknys

Tree-ring analysis for the assessment of anthropogenic changes and trends.

Investigation of Pine (Pinus sylvestris L.)annual radial increment (width of annual tree rings) was carriedout in the surroundings of one of the largest pollution sources inLithuania – Jonava Nitrogen Fertilizers Plant. The main objectiveof investigation was to analyse different sides of anthropogenictransformations of tree-ring series in the polluted environment:changes in tree growth intensity; variance changes in tree-ringseries; changes in the relations with natural external factors.Three different periods of tree reaction to the environmentalpollution were singled out – fertilization period, depressionperiod and recovery period since annual emissions were essentiallyreduced. The variance of tree-ring series has increased severaltimes in the polluted environment. Reaction of trees to the impactof climatic factors (temperature, precipitation) has changedsignificantly in the polluted environment and their sensitivity hasalso increased.

The impacts of heavy metals on oxidative stress and growth of spring barley

Oxidative stress is accepted to play a significant role in stress symptoms, caused by different stressors in a variety of organisms. In this study seedlings of spring barley (Hordeum vulgare L.) were exposed to a wide range of copper, zinc, chromium, nickel, lead and cadmium concentrations in order to determine the relationships between heavy metals-induced oxidative stress and plant growth inhibition. All investigated heavy metals induced an essential increase in lipid peroxidation and a reduction of dry biomass along with an increase in metal concentration in the nutrient solution. A very close and statistically significant exponential relationship between lipid peroxidation and growth inhibition was detected in this study. According to the results of analysis of variance (ANOVA), the intensity of nonspecific oxidative stress is identified as the main factor of barley growth inhibition, explaining 75% of total variance. Almost 10% of growth inhibition is attributed to the specific impact of heavy metals. The most pronounced increase of malondialdehyde content and growth inhibition was observed in Cu and Cd treatments, whereas the lowest changes in observed indicators were detected after exposure to Zn and Pb.

Dynamic response of tree growth to changing environmental pollution

Long-term investigations of Scots pine (Pinus sylvestris L.) growth were carried out in the vicinity of one of the biggest air pollution sources in Lithuania—mineral fertilizers plant “Achema.” It is detected that initial stages of the dynamic tree response to the external stress factors in the polluted environment with an increased quantity of nitrogen compounds have started with a stimulation stage, followed by a gradual transition to a depression of growth. The recovery of the damaged stands took place along with the reduced environmental pollution, and the overdraft of the “normal” annual increment was a characteristic feature of all the investigated stands. This phase is still continuing for the most damaged stands. A very high individual variability of the tree growth response to the environmental impact is a characteristic feature of the damaged Scots pine stands. The homeostatic mechanisms of the survived trees stipulated reaching approximately the same or even higher growth rate as prior to the depression period, and the tree growth rate before the depression period can serve as the most powerful predictor of tree growth recovery capacity under the reduced environmental pollution. Crown defoliation is the next most important predictor of individual tree recovery capacity. Lower stand density and lower competition cause higher recovery capacity of damaged trees. The conclusion is made that a reduction in the environmental pollution on the local and regional scale and especially a decrease in emissions and deposition of sulfur and nitrogen compounds caused the recovery of damaged forests. These trends should be taken into account while analyzing and modeling forest dynamics. Interaction of environmental pollution and climatic factors is very important for the response of tree growth to the environmental stressors.

Did the Ambient Ozone Affect Stem Increment of Scots Pines (Pinus sylvestris L.) on Territories under Regional Pollution Load? Step III of Lithuanian Studies

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.

Eco-efficiency: trends, goals and their implementation in Lithuania

Abstract Paper aims to explore the progress in eco-efficiency and the course of decoupling of environmental impact from economy growth in Lithuania during 1990–2008. For better interpretation of ongoing changes in eco-efficiency the concept of double decoupling was applied. Decoupling of resource consumption from economy growth is considered as primary decoupling, and decoupling of environmental pollution from resource consumption is considered as secondary decoupling. Energy intensity is treated as indicator of primary decoupling and pollution intensity as indicator of secondary decoupling. Over investigated period an essential primary decoupling took place and final energy intensity was reduced approximately 2.5 times in Lithuania and has converged to the level of EU-15 on average. Transition to the market economy, shift to the modern technologies, increased energy prices and structural changes of Lithuanian economy are considered as the main drivers for this achievement. Progress in secondary decouplin...

Changes in the sensitivity of agricultural plants to the impact of ozone and UV-B radiation in simulated warmer climate conditions@@@Kultūrinių augalų jautrumo ozonui, UV-B spinduliuotei ir dirbtinai sukurto šiltesnio klimato sąlygoms pokyčiai

The sensitivity of agricultural crops and weed to the impact of ozone and UV-B radiation was evaluated according to changes in their dry biomass and concentration of photosynthetic pigments. Pisum sativum L., Raphanus sativus L. and Phleum pretense L. were most sensitive to the impact of ozone in current climatic conditions (350 ppm of CO2 and 21 °C day/14 °C night temperatures). The sensitivity of all test crops to the impact of ozone decreased significantly under warmer cli matic conditions – 700 ppm of CO2 and 25 °C day/19 °C night temperatures. Pisum sativum L. and Chenopodium album L. appeared to be most sensitive to the impact of UV-B radiation under current climatic conditions. Changes in the sensitivity of plants to the impact of UV-B radiation under warmer climatic conditions were not as pronounced as those for ozone, and were highly species-dependent. Sensitivity to the impact of UV-B radiation under warmer climatic conditions decreased for Lycopersicon esculentum Mill. and Chenopodium album L. and increased for Raphanus sativus L. and Phleum pretense L.

The role of oxidative stress in spring barley cross-adaptation to different heavy metals

ABSTRACT The aim of this study is to investigate the possibilities and the mechanisms of spring barley (Hordeum vulgare L.) cross-adaptation to different heavy metals after hardening with ozone (O3), drought and UV-B radiation. Dry shoot biomass, accumulation of superoxide (O2˙−) and malondialdehyde (MDA), and activities of enzymes superoxide dismutase (SOD), glutathione reductase (GR) and catalase (CAT) were measured after hardening and heavy metal treatments. Seedlings, exposed to ozone and drought prior to copper (Cu) treatment, showed significantly increased tolerance to this heavy metal. The most possible causes of cross-adaptation to this redox-active heavy metal, which triggered very strong oxidative stress in nonhardened barley seedlings, were increased CAT activity, mitigation of O2˙− accumulation and lipid peroxidation. Cross-adaptation to cadmium (Cd) was induced only by drought hardening. In this case, however, adaptation had lower effect on antioxidative enzymes, did not altered O2˙− accumulation and even slightly increased the intensity of lipid peroxidation. The study reveals that stimulation of CAT activity and mitigation of oxidative stress are the main reasons for plant adaptation to Cu; whereas cross-adaptation to Cd, heavy metal with much lower oxidative capacity, is determined by the mechanisms that are not related to oxidative stress directly.