The aim of the study was to compare the amount of epicuticular waxes of Norway spruce and Scots pine needles from the area of cement production in Kunda. The amount of Norway spruce waxes decreased under air pollution influences and with ageing. The quantity of waxes of Scots pine needles showed an increasing tendency in the polluted area and in one-year-old needles compared with the current-year ones. A rapid decrease in the amount of waxes was established also in the older needles of Scots pine

The present paper is based on experiments carried out with black spruce in the industrial area North-East Estonia. Two-year-old seedlings of black spruce were planted in a sample plot affected by a cement plant and by oil-shale processing enterprises and in an unpolluted control sample plot in 1990. At the end of the experiment in 1997 it was ascertained that the impact of industrial alkaline air pollution complexes resulting in the alkalisation and chemical deviations of growth conditions retards the height growth of trees and brings about a decrease in their biomass. The sturdiness quotient was higher and the Dickson quality index was lower than the control, indicating serious damages of trees under air pollution. Increasing share of needles in the total biomass in polluted areas in comparison with control trees suggest that compensation mechanism were started in trees to increase the assimilating mass in order to survive under stress. The state of young black spruces in alkalised industrial areas shows unsuitability of using this species in industrial areas

It was ascertained that the content of soluble sugars, starch and ratios between different forms of carbohydrates varied in the trees growing in areas affected by industrial production in Kohtla-Jaerve and Kunda. The ratio of soluble sugars to starch is a good indicator of the state of trees in industrial areas. This ratio depends on the level of air pollution. In the studied areas a strong relationship between the content of soluble sugars and N, Mg and K was observed in the needles of Norway spruce

The research was conducted in 1990-99 in forest observation sites in the neighbourhoods of industrial enterprises of Kohtla-Jaerve-Johvi and the cement plant of Kunda and in the control area in Lahemaa National Park. Differences between the radial increments of conifers growing under pollution and in a relatively unpolluted area were estimated. The stands selected for investigation were similar as to their edaphic conditions and forest survey indicators. The high sensitivity of conifers to long term emissions of pollutants into the atmosphere from oil shale based power engineering and chemical industry, production of building materials and fertilisers and other industrial enterprises in the investigation area is expressed as changes in the radial increment of trees with the changes depending on the pollution load and alterations in precipitation and soil

The highest defoliation in Estonia has continually been assessed in Scots pine though a permanent improvement of crown conditions of the trees has been observed since 1992. In 1996-99 there was a slight increase in the defoliation of Norway spruce and the steady decrease in defoliation, observed in 1989-95 stopped. The decrease in the defoliation of the Norway spruce is more noticeable in north-western and northern Estonia. Only 9.4 per cent of the Norway spruces and 8.9 per cent of the Scots pines were defoliated more than 25 per cent in 1999. The age of trees seems to have a great impact on both defoliation and discoloration of Norway spruce. Defoliation of older Norway spruces is higher than that of younger ones. Only 37 per cent of the older trees were defoliated less than 11.5 per cent and the proportion of such trees has decreased over the last four years. From Norway spruces younger than 60 years as many as 86 per cent of the trees were defoliated less than 11 per cent. In 27 sample points the Norway spruces had secondary shoots, in 16 points the proportion of the trees with secondary shoots was 10 per cent in 1999. In total the health state of the deciduous trees was markedly better than that of the conifers. For example, the share of healthy birches was 96 per cent in 1999

Prolonged effects of the multicomponent air pollution complexes emitted from the cement production in Kunda and oil shale processing in Kohtla-Jaerve, North-East estonia, on the forest ecosystems are discussed. It was found that atmospheric input substantially affects biogeochemical cycling in forest. The comparatively high concentrations of alkaline dusts and ash and various gaseous pollutants in the atmosphere of the investigated areas over 40 years have caused qualitative and quantitative changes in the forest soil, soil water and precipitation and in the state of forest and trees. Although the levels of air pollutants emitted by the industry have seriously decreased in recent years, alkalisation of the growth environment of trees is still essential in some regions. Alkalisation of soil and soil water in the vicinity of Kunda and Kohtla-Jaerve complicated mineral nutrition processes and disbalanced mineral elements composition in tissues, which resulted in a decrease in the increment and quality of trees

Air pollutants (oil shale fly ash, gases, organic compounds) emitted by the oil shale industry in Kohtla-Jaerve, North-East Estonia, have caused changes in the growth conditions of forest ecosystems. Compared with the period before 1990 the pollution load in the area investigated has fallen drastically; however, this has not resulted in an essential improvement in growth conditions of trees. Morphological analysis of 80-year-old Picea abies (L.) Karst. and Pinus sylvestris L. growing on sample plots (6) in the polluted area and in the control area showed that air pollution has had a temporally and spatially variable effect on the parameters characterising the state of trees: length growth, weight and dry matter content needles and shoots, density of needles on shoots and radial increment of trees. The length growth of Scots pine needles and shoots proved to be one most suitable parameters indicating the influence of air pollution, although not in all sample plots investigated. The results for fresh and dry weight of needles revealed great differences between sample plots. The biomass of the shoots of Norway spruce was notably greater in the immediate vicinity of Kohtla-Jaerve than in the control. The Scots pines and Norway spruces whose shoots showed inhibited length growth had greater density of needles on shoots with difference from the control being respectively up to 33 per cent and 16 per cent. The effect on the radial increment of Norway spruces was especially strong in the immediate vicinity of pollution sources but it fell rapidly with distance from them

Element concentrations in the xylem wood of Scots pines (Pinus sylvestris L.) growing in different soil and pollution load conditions at Narva-Joesuu and Haeaedemeeste, Estonia, were studied for temporal trends with respect to soil properties. The upper horizons of the Haeaedemeeste stand soil profile were strongly acidic compared with those of Narva-Joesuu, which were weakly acidic. Element concentrations for K, Ca, Mg, Mn and Zn in upper soil horizons were higher at the Narva-Joesuu stand and for Pb at Haeaedemeeste. Concentrations of xylem elements Mg, K, P, Pb and Cu were higher in the Narva-Joesuu sample and of Ca, Mn and Zn in the Haeaedemeeste sample. The concentrations of xylem elements except for K, Mg and Cu were poorly associated with those in soil. The increasing concentrations of Ca, K, P and in the Narva-Joesuu sample during the last decades can be explained by the larger amounts of emissions of the oil-shale fly ash by the neighbouring thermal electric power stations. Thus, the alteration of the concentrations of these elements in the xylem offer a promise for determining deposition-mediated changes in the environment

To study the impact of air pollution on the growth of conifers sample plots were established at different distances and directions from the Kunda cement plant. The plots included stands of 70-80-year-old Scots pine and Norway spruce. Although emission of alkaline cement dust had decreased in the second half of the 1990s analyses of soil samples collected to characterise the growth substrate of trees showed that the pH value of the humus horizon of weakly podzolised temporarily overmoist sandy soils was within the radius of 3 km from the cement plant 2.0-2.9 times as high as that of the control plots in Lahemaa National Park. To ascertain the effect of alkaline environment on the growth of conifers the length (cm) of the needles and shoots formed in 1996-99, dry and wet mass (g) of 100 needles, dry matter content of needles(per cent) and density of needles on shoots were measured. The results obtained were compared with data from 1992 if possible. Both pine and spruce were found to be sensitive towards cement dust pollution and alkalised environment; however, the impact on different morphological parameters was different. As compared to the control, the strongest inhibition of growth was revealed in the sample plot situated 2.5 km east from the cement plant. Conifers on sample plots 2 km west from the emission source showed more vigorous growth than the control. As compared with data from 1992, some improvement in the growth of pine and spruce was observed

The greatest sources of atmospheric emissions of alkaline dust and SO2 in Estonia are the soil shale based power plants and the cement production. In the vicinity of oil sale processing and chemical plants the organic pollutants, as well asammonia, H2S etc. are also found in the ambient air. Temporal changes in emission amounts and in atmospheric air pollution levels in North-East Estonia since 1960 until today (1997-98) are discussed. During the period of 1989-98 the emissions from power plants decreased about 2.5 times and those from cement production up to 40 times. In 1960-89 oil shale fly ash was the prevalent factor of air pollution, most notably in north-eastern and northern parts of the region. Since 1990-91 the proportion of SO2 has increased in the balance of alkaline and acidic components in some industrial areas. Zonation of landscapes on the basis of air pollution and the critical loads of pollutants for forest trees and Sphagnum are discussed