Several investigations about air pollution impact on forests have been carried out in Slovenia during last thirty years, mainly using the Norway spruce (Picea abies [L.] Karst.) as the main bioindication species, but there is a lack of information about common beach (Fagus sylvatica L.) condition, the most important forest tree species in Slovenia and in Zasavje area. The assessment of air pollution effect on beech based on stress physiological indicators of foliage, macronutrients level in beech leaves and by assessment of crown defoliation was carried out altogether with necessary soils analyses of the selected beech stands. On the basis of all parameters it can be concluded that the worst condition of beech trees in Zasavje is due to high level of air pollution, mainly by sulphur dioxide and not by deficiency of macronutrients or unfavourable state of soils

The biological effects of both elevated CO2 and N deposition on model ecosystem were investigated in the Birmensdorf open-top chamber facility. Each of the 16 chambers was divided into two compartments with a ground area of 3 msub2 and filled with natural unfertilized forest soils from two sites (one acidic, the other calcareous). Elevated CO2 significantly increased O and Zn concentrations in beech leaves and those of Zn in spruce needles on the calcareous soils. Enhanced N deposition also led to a dilution of nutrients and increased N contents

The phenolic compounds showed different responses to fertilization. Fine roots of beech showed a significant decrease of (-) epicateching (84-99%) and pecatannol (78-98%) with nitrogen fertilization. Fine roots of fertilized Norway spruce showed decreased concentrations of 4-hydroxyacetophenone (33-48%), p-coumaric acid (44-64%), and pecatannol (36-61%). Concentration of p-hydroxybenzoic acid and protocatechuic acid were significantly higher in no fertilized roots. However in both tree species fertilization had no effect on vanillin and quercetin concentration in fine roots. It is suggested that roots of beech and Norway spruce are more susceptible to attacks of pathogens when they are exposed to impact of nitrogen

The magnesite plants Jelsava and Lubenik emitted in the 80s 30 000 tons of magnesite dust and heavy metals and 4000 tons of SO2 per year, what caused an extreme damage to the vegetation in the area around of about 500 km2. For the determination of 3 zones of endangerment we used pollution index values. In each pollution zone we demarcated experimental plots and carried out soil analyses. Forest stands polluted by magnesite dust belong to alkaline air pollution type

Taking into account the results of environmental monitoring in forest ecosystems (European Level I- and II-Programme) showing high degrees of soil acidification and still a widespread exceedance of critical loads by deposited sulphur and nitrogen compounds, the programme of differentiated forest protection liming should continue with site specific doses. On the other hand the programme to restore forest ecosystems with higher stability and to a large extent balanced nutrient cycles has to be carried out in order to minimize internal acid-generating processes

Two field exercises for the assessment of foliar visible ozone symptoms were performed during the "2nd UN/ECE ICP-Forests Intercalibration Course on the Assessment of Ozone Injury on European tree Species" organised by the WSL in collaboration with the University of Florence, Linnaea ambiente, and the PSU. The exercises were conducted at the Lattecaldo OTC research facility in Southern Switzerland and on the Moggio Level II plot in Northern Italy from 22-24 August 2001. 48 participants represented 21 countries. There are given objectives and results and conclusions from both sites

Frequency and intensity of wildfire occurrences are dramatically increasing worldwide due to global climate change, having a devastating effect on the entire ecosystem including plants. Moreover, distribution of fire-smoke can influence the natural environment over very long distances, i.e. hundreds of kilometres. Dry plant matter contains 0.1–0.9% (w/w) sulphur, which is mainly released during combustion into the atmosphere as sulphur dioxide (SO₂) resulting in local concentrations of up to 3000 nL L⁻¹. SO₂ is a highly hazardous gas, which enters plants mostly via the stomata. Toxic sulphite is formed inside the leaves due to conversion of SO₂. Plants as sessile organisms cannot escape from threats, why they evolved an impressive diversity of molecular defence mechanisms. In the present study, two recent wildfires in Germany were evaluated to analyse the effect of SO₂ released into the atmosphere on deciduous trees: the Meppen peat fire in 2018 and the forest fire close to Luebtheen in 2019. Collected leaf material from beech (Fagus sylvatica) and oak (Quercus robur) was examined with respect to detoxification of sulphur surplus due to the exposure to elevated SO₂. An induced stress reaction in both species was indicated by a 1.5-fold increase in oxidized glutathione. In beech leaves, the enzymatic activities of the sulphite detoxification enzymes sulphite oxidase and apoplastic peroxidases were increased 5-fold and a trend of sulphate accumulation was observed. In contrast, oaks did not regulate these enzymes during smoke exposure, however, the constitutive activity is 10-fold and 3-fold higher than in beech. These results show for the first time sulphite detoxification strategies of trees in situ after natural smoke exposure. Beech and oak trees survived short-term SO₂ fumigation due to exclusion of toxic gases and different oxidative detoxification strategies. Beeches use efficient upregulation of oxidative sulphite detoxification enzymes, while oaks hold a constitutively high enzyme-pool available.

Rigorous studies on long-term changes of heavy metal distribution in forest soils since the implementation of emission controls are rare. Hence, we resampled 97 old-growth beech stands in the Vienna Woods. This study exploits an extensive data set of soil (infiltration zone of stemflow and between trees area) and foliar chemistry from three decades ago. It was hypothesized that declining deposition of heavy metals is reflected in soil and foliar total contents of Pb, Cu, Zn, Ni, Mn and Fe. Mean soil contents of Pb in the stemflow area declined at the highest rate from 223 to 50 mg kg−1 within the last three decades. Soil contents of Pb and Ni decreased significantly both in the stemflow area and the between trees area down to 80–90 cm soil depth from 1984 to 2012. Top soil (0–5 cm) accumulation and simultaneous loss in the lower soil over time for the plant micro nutrients Cu and Zn are suggested to be caused by plant uptake from deep horizons. Reduced soil leaching, due to a mean soil pH (H2O) increase from 4.3 to 4.9, and increased plant cycling are put forward to explain the significant increase of total Mn contents in the infiltration zone of beech stemflow. Top soil Pb contents in the stemflow area presently exceed the critical value at which toxicity symptoms may occur at numerous sites. Mean foliar contents of all six studied heavy metals decreased within the last three decades, but plant supply with the micro nutrients Cu, Zn, Mn and Fe is still in the optimum range for beech trees. It is concluded that heavy metal pollution is not critical for the studied beech stands any longer. Microsites, affected by beech stemflow, are very useful for studying the legacy of high atmospheric heavy metal deposition.