This paper aims to integrate existing information on effects of air pollution on main forest tree species of economic importance, mainly on growth and reproduction. Gaps in knowledge and areas for future research will be identified

Following the objective to provide an overview on the spatial and temporal variation in forest condition on a European scale, an extensive systematic survey on more than 6000 so called Level I plots throughout Europe is carried out. Results show a recuparation of crown condition in the mid nineties and a resuming deterioration with nearly a quarter of the sample trees classified as damaged in 2001. Results of statistical evaluations explain the observed variation mainly by weather extremes, insects, fungi and indirect effects of air pollutants via soil acidification or changes in the nutritional status of trees

Significant correlations (p0.05) were found between the concentration of elements in the c needles and the distance of the sites from nitrogen ferilizer factory (NFF): the amounts of C, K, Mg, Zn, and Rb in the c+1 needles were increasing, whereas concentrations of N, P, Al, Mn, Cu, Ni, Sr and Cd were decreasing alongside the transect from NFF. Statistical analyses performed on logarithms and estimation of components of variance by maximum likelihood has shown that the age of the needles and the sites were the most important, while year of sampling was much smaller source of variance. Only a few significant differences were found comparing the amount of elements in Scots pine needles collected in four-year space

The investigation was carried out in three areas characterised by different levels and types of PAHs emission. The difference in total amount of PAHs in pine needles from investigated areas was accompanied by a significant changes in mutual ratio of PAHs with different number of rings

We aim to differentiate the various visible leaf symptoms in the field survey with microscopical methods, and to better know, how the leaf, tissue and cell response differs between injury from ozone, heavy metals (both oxidative stress) and biotic infections

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 need to assess the role of terrestrial ecosystems in the global C cycle and the potential change of this role as the atmospheric concentration of CO2 increases attracted considerable scientific attention over the recent decade. In order to assess ecosystem responses as a whole and to evaluate the potential role of forests and tree communities as a carbon sinks, the below-ground response to increasing levels of CO2 must be addressed

Emissions, especially of SO2 and to a certain degree of NOx have been reduced markedly in Slovakia during the 90s. Problems related to climate change and especially ozone are increasingly growing. The aim was to evaluate the long-term air pollution effect on forest ecosystems in mountain area with prevailing distribution of spruce through evaluation of spruce needle surface structure in relation to mineral nutrient status of trees. According to strong relationship between the coefficient of epicuticular wax degradation (Q) and accumulation of S and other elements it can be suggested that evaluation of needle surface structure by means of Q well reflects the surface status of needles

Increased ozone sensitivity of larger soil-growing trees with growth in the multi-year exposure was a result of several interactive senescence-related physiological factors: lower net photosynthesis to stomatal conductance ratio at the end of the growing season promoted high ozone uptake and low photosynthetic carbon gain, leading to onset of visible injuries and impaired bud formation. This was expected to affect negatively the early growth of the next year foliage, This clone showed a major change in allocation pattern during the early ontogeny at the expense of foliage growth towards the stem height increase

The attention was focused on the diameter increment of beech timber forest growing on the partial plots with various stand density. The individual parts of the originally homogenous stand, were subjected to regeneration cutting of various intensity resulting in several partial plots. On the different partial plots we found different proportions of trees belonging to the individual diameter classes. We also found that the differences between the individual plots were statistically very significant. Beech is a tree species which is capable to continue creating considerable light increments even long after the stand opening