Virumaa has the richest forest resources in Estonia. The area covered with forests in Virumaa amounts to 51.3 per cent (total in Estonia 49 per cent). Pine, birch and spruce forests dominate. A large part of forests are under technogenous pressure (oil-shale mining, power engineering etc.). The total amount of all the fellings in 1999 was 1.061 million cubic metres (in Estonia totally 6.704 mln. cubic metres). The volume of fellings has reached the critical level close to the annual increment of forests. Therefore, the volume of cutting down forests should not be increased

The influence of air pollution from a cement plant on chlorophylls and carotenoids of the needles of Scots pine and Norway spruce was studied on the sample plots established at different distances from the emission centre in 1992, 1994 and 1999. No essential difference was observed in pigment concentrations in needles between 1992, when the emission of cement dust from the plant was very high, and 1999, when dust pollution had practically stopped. The negative influence on the synthesis of pigments in needles occurred through the alkalisation of soil and disbalances of mineral nutrients accumulation into the organism

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

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

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

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

The paper is based on the data of geochemical mapping of the humus horizon of soil and geochemical monitoring of soil carried out in 1986-94. These data have been supplemented with results of later investigations. The authors describe the formation of parent rock of soil in NE Estonia and its major geochemical features. The main plant nutrient elements and those having a negative influence of plant growth and the development of animate nature in the case of their elevated concentration in soil are observed. Components are areal distribution of technogenous atmospheric pollution falling on the ground surface in NE Estonia are also dealt with. The chemical composition of the humus horizon of soil in NE Estonia is variable, the variation coefficient of several elements exceeding 100 per cent. The trends of lateral changes in the concentration of elements are accidental. Such heterogeneity is mainly due to great variability of parent rocks of soil. Glacial deposits formed from Proterozoic crystalline rocks of Fennoscandian origin, as well as the Vendian and Paleozoic sedimentary rocks, among the latter mineralised or ore-bearing varieties, Dictyonema shale and phosphorite. Mean concentrations of elements in the humus horizon of NE Estonian soils are close to the respective concentrations of the whole Estonian territory, but differ considerably from the mean concentrations of all continents

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

Forty-five macrolichen species were registered on 29 forested sample plots in Laeaene- and Ida-Viru counties in North-East Estonia. Analysis of the macrolichen species distribution indicated and impact of air pollution on the epiphytic lichen cover. The presented distribution maps demonstrate that lichen species belonging to different ecological groups by substrate requirements respond differently to air pollution. Lichen species diversity was analysed by means of species richness, diferent diversity measures including the Shannon-Weaver Diversity Index, and characterised by the sum of species abundances. Alpha diversity of epiphytic macrolichens for the study area is 8.3 (s.d. 5.5), beta diversity 5.4, and the Shannon-Weaver Diversity Index varied from 0 to 1.189. Variations in the lichen community demonstrated the existence of a steep local air pollution gradient oriented from north-east to south-west