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The present study is the first attempt to carry out an inventory of greenhouse gas (GHG) fluxes in the forests of Estonia. The emission and uptake of CO as a result of forest management, forest conversion and abandonment of cultivated lands in Estonia was estimated. The removal of GHG by Estonian forests in 1990 exceeded the release about 3.3 times. Changes in the species composition and productivity of forest sites under various simulated climate change scenarios have been predicted by using the Forest Gap Model for the central and coastal areas of Estonia. The computational examples showed that the changes in forest community would be essential.2

To investigate the ecosystems on dunes, five typical dunes were selected in the coastal area of the Baltic Sea in southwest Estonia. To study ground vegetation species richness, species composition and horizontal structure, 251 quadrats of 1 m2 in size were established and descriptions of vascular plants, bryophytes and lichen species were provided. Topographical factors, soil horizons, soil pH and electrical conductivity, soil nutrients, soil moisture conditions and light conditions were determined. In total, 42 vascular plant, 43 bryophyte and 48 lichen species were recorded on five dunes. Vascular plant species richness and composition on forested dunes was dependent on the absolute dune height, zone and aspect of the slope, soil nitrogen, potassium and phosphorus content, soil pH and moisture, the cover of the bryophyte-lichen layer and light conditions. Regarding bryophyte and lichen layer species composition, important factors were the aspect of the dune, vascular plant species cover, light conditions, the thickness of the moderately decomposed organic soil horizon, soil pH, electrical conductivity and volumetric water content. Lichen species richness was highest on the slopes of the dunes, while bryophyte species richness was higher at the bottoms and decreased towards the tops of the dunes. Ground vegetation species richness and species' horizontal and vertical structure on forested dunes were highly dependent on topography-induced differences, aspect, height and zone of the dunes. The most important factors controlling the complex of ground vegetation were light conditions, soil water content, thickness of the moderately decomposed litter layer and soil potassium and calcium content. [ABSTRACT FROM AUTHOR]

The effects of clinker dust and wood ash on Norway spruce and Scots pine seedlings were compared in buried pots. Clinker dust (0.5 kg m−2) and wood ash (0.5 kg m−2) were applied to the surface of a nutrient-poor mineral soil. In the second year, the increase in soil pH by the dust and ash were larger than in the first year. Both alkaline treatments caused a large increase in the needle potassium (K) concentration. An excess of soil K relative to magnesium (Mg) was observed by decreased Mg concentration in needles shortly after treatment. However, Mg concentration in needles stayed in the sufficiency range. Current results confirmed earlier findings that despite a positive effect on base cation nutrition, wood ash has a low potential for increasing the biomass of forest stands on mineral soils due to the N limitation in these soils. [ABSTRACT FROM PUBLISHER]

Abstract: Characterisation of tree crown structure provides critical information to assess a variety of ecological conditions for multiple purposes and applications. The aim of investigation was to elucidate the influence of the alkaline soil on the formation of the crown of Norway spruce (Picea abies (L.) Karst.). The seven sample plots (0.05ha) with 75–90-year-old spruce stands of Oxalis–Myrtillus site type were selected at different distances from a cement plant influenced over 40years by alkaline dust pollution. The studies were conducted 13years after dust pollution had practically stopped. High pH values (6.1–7.8), large concentrations of dominant dust components (Ca, Mg, K) and a lower level of N and organic matter in the upper layers of soil within about 6km from the emission source compared to the unpolluted control area 30.4km from the source (pH 3.3) were found. Disbalance in mineral composition in needles and shoots was established, deficite in N and excess in Ca and K concentrations were brought about a great differentiation in growth and biomass formation between unpolluted and polluted trees. On the most polluted area the average height of trees and living crown, the length and dry mass of shoots and needles were lower, and average life span of needles were shorter than in unpolluted area, indicating an increased defoliation rate of the crown. [Copyright &y& Elsevier]

Investigations in a 75-85-year-old Scots pine stand were performed on a territory influenced over 40 years by alkaline dust pollution (pH 12.3-12.7) emitted from a cement plant. Sample plots were located at distances of 2, 3, and 5 km E of the emission source and a control sample plot was selected on an unpolluted territory 38 km W of it. We studied soil properties and the anatomical structure, mineral nutrition, and pigments in Scots pine needles. The alkaline dust pollution has affected the biogeochemical cycling in the forest ecosystem, increasing the pH and total Ca, K, Fe, Mn, and Mg and decreasing N, C, organic matter, and C/N compared to the unpolluted soils. Alkalization and changes in the nutrient composition of soil had caused serious disbalances in nutrient availability and in the mineral composition of trees. Deficiency in foliar N and Mn and excess of K, Ca, and Fe contents had caused a decrease in the average chlorophyll concentrations. Carotenoids seemed to be more tolerant both to changes in soil and needle nutrient composition. The Ch1 a/Ch1 b ratio in needles was found to have declined. With the alkalization of the environment the total area of the needle cross-section, needle thickness, and mesophyll area had also decreased compared with control. Differences in the anatomical characteristics of needles between the polluted and unpolluted areas were significant in the oldest needles. The decrease of mesophyll was associated with the content of chlorophylls and correlated with N concentrations in needles. [ABSTRACT FROM AUTHOR]

Abstract: Studies were carried out in 1999, 2005 and 2007 in the area of Kunda cement plant in Northeast Estonia on sample plots 3km W and 2.5 and 5km E of Kunda. As control stands, two plots for pine and spruce were established in Lahemaa National Park (34–38km W of Kunda). The selected pine and spruce stands were 75–85-year-old Myrtillus site type, of 0.7–0.8 density and II quality class, with moderately dense or sparse understorey. The values concerning needle density and number of needle scars were higher for shoots formed in the period of higher pollution than for the shoots grown under a considerably lower pollution load. Although the cement dust pollution has notably decreased from year to year, the number of needle pairs per 1cm of the shoot was 1.8–2.1 times greater in the shoots formed in 1998 than in those formed in 2003, whereas the changes were statistically reliable. Possibly the low temperatures at the time of shoot and needle formation affected the density of needles on all sample plots, and thus the number of needles on shoots formed in 2003 was many times smaller. After the significant fall in the pollution load since 1996 the length growth of needles intensified around Kunda cement plant, at the same time no changes occurred in the length growth of needles in the control area. As compared to the data from 1998, the length growth of pine needles had improved, especially 2.5 and 5km E from the cement plant, needles being respectively 1.5 and 1.1cm longer than 6 years ago. The stimulation of the growth of pine and spruce needles 2.5 and 5km E of the cement plant may be a sign of a positive effect of reduced doses of cement dust in soil. The greater length of pine and spruce needles is the reason for the larger biomass of the needles. [Copyright &y& Elsevier]

Abstract: Relationships between climate and radial growth of Oxalis–Myrtillus-site type Norway spruce and Scots pine stands under different cement dust loads were investigated. Dendrochronological methods were used. Long-term alkaline (pH 13.2–12.7) dust pollution emitted over 40 years from a cement plant was the reason of alkalisation (pH 7.8–8.1) and high concentrations of K, Ca and Mg in soil of affected territories. Two study sites, Kunda and Malla (2.5 and 5.0km E from the emission source), were influenced by the dust emissions of the cement plant. Two other study sites, Eru (38km W) and Revoja (34km W), were situated on a relatively unpolluted area and served as control sites. The relationships between the radial growth and climate were almost similar on the control and dust-polluted sites. The climatic variables that had a significant effect on the radial growth of Norway spruce at both control and polluted sites were the temperature and precipitation of summer months of the current and preceding years. Specific to the Scots pine stands growing under dust pollution was a significant positive impact of the current spring temperature on the radial growth. A positive effect of precipitation during winter months on the radial growth was found at all sites. A significant negative effect of cement dust on the radial growth of Scots pine stands during the period of large amounts of dust emission (1966–1991) was detected. The effect of cement dust emissions on the radial growth of Norway spruce stands was also negative but weak. The decrease in the dust emissions since 1992 improved the growth conditions at pine stand sites. [Copyright &y& Elsevier]

Abstract: The growth, aboveground biomass production and nutrient accumulation in black alder (Alnus glutinosa (L.) Gaertn.), silver birch (Betula pendula Roth.) and Scots pine (Pinus sylvestris L.) plantations during 7 years after planting were investigated on reclaimed oil shale mining areas in Northeast Estonia with the aim to assess the suitability of the studied species for the reclamation of post-mining areas. The present study revealed changes in soil properties with increasing stand age. Soil pH and P concentration decreased and soil N concentration increased with stand age. The largest height and diameter of trees, aboveground biomass and current annual production occurred in the black alder stands. In the 7-year-old stands the aboveground biomass of black alder (2100treesha−1) was 2563kgha−1, in silver birch (1017treesha−1) and Scots pine (3042treesha−1) stands respective figures were 161 and 1899kgha−1. The largest amounts of N, P, K accumulated in the aboveground part were in black alder stands. In the 7th year, the amount of N accumulated in the aboveground biomass of black alder stand was 36.1kgha−1, the amounts of P and K were 3.0 and 8.8kgha−1, respectively. The larger amounts of nutrients in black alder plantations are related to the larger biomass of stands. The studied species used N and P with different efficiency for the production of a unit of biomass. Black alder and silver birch needed more N and P for biomass production, and Scots pine used nutrients most efficiently. The present study showed that during 7 years after planting, the survival and productivity of black alder were high. Therefore black alder is a promising tree species for the reclamation of oil shale post-mining areas. [Copyright &y& Elsevier]

The content of nutrients in soil and needles of second-growth pines was studied on dunes of different relative height (23 m, 10 m, 5 m) in the coastal area of the Baltic Sea in South-West Estonia. Results give an insight into the nutrition status of pines on the plain and on the slopes and tops of dunes. The data obtained indicate that the logarithmic relationship is statistically significant between N, K, and Mg contents in the needles and soil and the height of the sample point on the dune. Deficiency of nutrients for the growth of pines, especially that of N and K, had developed on dunes. The study showed that on dunes the nutrition conditions and concentration of nutrients in needles depend significantly on the relative height of the growth site on the dune. [ABSTRACT FROM AUTHOR]

Anatomical features, including localization of lignin in needles of different age, were studied in Scots pines growing in extreme growth conditions (deficit of water and nutrients in soil) on dunes in South-West Estonia. Analyses showed that the anatomy and level of lignification depend on the location of sampled trees (in the plain, on slopes, or at the top of the dune) and needle age. It was found that the average total cross-section area of needles of the trees growing on the dune decreases with age. Also the areas of xylem, sclerenchyma, and mesophyll are the largest in current-year needles. Needles of trees growing on the slope of a dune have the greatest proportion of sclerenchyma, xylem, and mesophyll in the total area of the cross-section. Their proportion is the smallest on the top of the dune. Lignification starts already in the current year and first in xylem. The structure of lignin changes over years being more compact in older needles. [ABSTRACT FROM AUTHOR]

Sandy soil in a tree nursery was treated with wood ash (0.25, 0.5, or 1.0kg m-2 untreated for control). The influence of different treatments on the carbohydrate concentration and dynamics in needles was estimated. The increase in the pH of soil due to wood ash application correlated with the reduction in the needle hexoses (glucose and fructose). The ratio of fructose to glucose in treated trees often exceeded 2-3 times the respective hexose ratio in untreated trees. The sucrose concentration was not significantly influenced by the soil pH and wood ash. The starch concentration tended to be smaller in treated trees. The results suggest that carbohydrate reserves in needles could be reduced by wood ash during the growing period. The accumulation of soluble carbohydrates by winter did not depend on the treatment. [ABSTRACT FROM AUTHOR]

Short-term effects of different doses (0.25 and 0.5 kg m-2) of wood ash fertilization in a field experiment in a 20-year-old Scots pine stand on a nutrient-poor sandy soil (Arenosol) was studied in North Estonia. Soil chemical properties, nutrient accumulation, soluble carbohydrates, starch, hemicellulose, cellulose, and lignin were used as biochemical indicators for the assessment of the state of trees from 2000 until 2005. Changes in the soil upper horizon (30 cm) showed an increase in the pH and in the concentrations of K, Ca, B, Mg, and other elements, except N, after treatment. Statistical relationships were found between the doses of wood ash used in the treatment and the mineral composition of the soil. Changes in soil properties brought about changes in nutrient accumulation into trees and the needle diagnosis showed an essential increase in the K, Mg, Fe, Mn, and Zn concentrations in needles. No statistically significant changes were observed in the concentrations of soluble carbohydrate (tendency to decrease), starch (tendency to increase), and structural carbohydrates, but a somewhat higher accumulation of cellulose and lignin was registered in the needles of Scots pine. The effect of wood ash on carbohydrate metabolism and lignin synthesis seemed to depend on the seasonal development stage of needles and climatic conditions. [ABSTRACT FROM AUTHOR]

Abstract: Short-term effects of different doses of wood-ash application (0.25kgm−2; 0.5kgm−2; control without treatment) on soil chemical properties, tree growth and lignin concentration was investigated in a young Scots pine (Pinus sylvestris) forest stand in northern Estonia from 2000 until 2003. Changes in the soil upper horizon (30cm) showed an increase of pH and concentration of available K, Ca and P and a decrease of N after treatment. Later, from the second year after treatment, a decrease of P was found if compared to the control. The changes in the Mg concentration were very small at the beginning of the experiments, but an increase in the Mg concentration in soil was established a year after the treatment. Statistically significant stimulation of lignification in shoots was found after wood-ash treatment, but the pattern of seasonal changes in the rate of lignin concentration in needles and shoots was similar to control. It was found that the increase of Klason lignin as a result of wood-ash application correlated negatively with N and positively with K, Mg and Ca in soil. The diameter increment of pines had a negative correlation with lignin concentrations in shoots and needles. The increment of stem biomass, diameter and height was stimulated, but not significantly, by the wood-ash dose of 0.25kgm−2. [Copyright &y& Elsevier]

Oil shale mining and processing in northeast Estonia have brought about several ecological problems. The mined oil shale is used as fuel in power stations and in processing plants producing crude oil and about 40 manufactured articles. Pollutants emitted from oil shale processing and chemical plants include SO 2 , CO, NO x , oil shale fly ash, and organic compounds in which aromatic and aliphatic hydrocarbons, phenols, formaldehyde, etc., are represented. Pollution has caused changes in the condition of the forest ecosystem and the chemical character of soil and ground water. The condition of coniferous forest sites was investigated in 1995–1998. Because of the high concentration of alkaline fly ash in the air, the pH of rain water is somewhat elevated (pH = 7.0–7.1) and exceeds the level regarded as normal for rain water. The analysis of the soil samples showed that the concentrations of Ca, Mg and K, which dominate in the solid fraction of the pollutant mixture, are high, being respectively 18, 14, and 4 times as high as the control. The increases in the concentrations of K, Mg, Cu, Pb, and Ni in stemwood reflect increases in the regional oil shale fly ash deposition. Conifers influenced by high levels of air pollution emitted from the oil shale industry are characterized by retarded growth of needles and shoots and radial growth as a result of disturbances in their mineral nutrition and imbalance in their mineral composition. [ABSTRACT FROM AUTHOR]

Spatial partitioning of nutrients in the canopy of Pinus sylvestris L. was evaluated quantitatively and morphological differences between different canopy layers were studied in 45-55-year-old trees in a Myrtillus site type forest stand. A significant variation was revealed in the biomass and growth of pine needles and shoots, density of needles, and number of buds on shoots between different canopy layers. The mass and length of shoots depend significantly on the content of N, K, and Ca in spring, before budbreak. In autumn, when growth has stopped, the content of nutrients plays a less significant role. [ABSTRACT FROM AUTHOR]

Cutting-derived Salix dasyclados Wimm. were grown on soil containing high amounts (2 kg m[sup-2] in year 1 + 1 kg m[sup-2] in year 2) of dust from filters of a cement plant. The pH of the treated soil was increased from 6.5 (control) to 7.6. Soluble sugars, starch, and chlorophylls in leaves of spring flush shoots were analysed during the vegetative growth of the second year of treatment. The lower hexose content in the leaves of treatment trees was approximately balanced by their higher sucrose content. Maltodextrins and starch were not affected significantly and no fructans were found. The effect of treatments on chlorophyll a and b was neglible. Total biomass was significantly lower than in control trees without any change in the partitioning of biomass between different parts of the trees. [ABSTRACT FROM AUTHOR]

The article presents a preface of the October 2005 issue of the "Scandinavian Journal of Forest Research."

A preface for the June 2006 issue of the journal "Proceedings of the Estonian Academy of Sciences, Biology, Ecology," is presented.

Two-year-old seedlings of Picea abies L., P. glauca L. and P. mariana L. were planted in a sample plot subjected to high concentrations of cement dust and in an unpolluted (control) area in 1990. In 1994, the six-year-old trees were dug up in the pre-bud-break period for morphological assessment. Comparison of biomass formation and the lengths of different organs of the trees showed that alkalization of the growth substrate (pH 8.1) and the high level of dust pollution load (600-2400 g m-2 yr-1) are serious factors inhibiting height growth by 61%, the length of shoots and needles by 75 and 28%, respectively, and the dry weights of roots by 88%, stems by 90%, shoots by 91% and needles by 55%. The ratio of roots to shoots dry weights increased in all species of spruces under stress. P. mariana was the most sensitive to dust pollution impact and alkalization of theenvironment. [ABSTRACT FROM AUTHOR]

To investigate the ecosystems on dunes, five typical dunes were selected in the coastal area of the Baltic Sea in southwest Estonia. To study ground vegetation species richness, species composition and horizontal structure, 251 quadrats of 1 m2 in size were established and descriptions of vascular plants, bryophytes and lichen species were provided. Topographical factors, soil horizons, soil pH and electrical conductivity, soil nutrients, soil moisture conditions and light conditions were determined. In total, 42 vascular plant, 43 bryophyte and 48 lichen species were recorded on five dunes. Vascular plant species richness and composition on forested dunes was dependent on the absolute dune height, zone and aspect of the slope, soil nitrogen, potassium and phosphorus content, soil pH and moisture, the cover of the bryophyte-lichen layer and light conditions. Regarding bryophyte and lichen layer species composition, important factors were the aspect of the dune, vascular plant species cover, light conditions, the thickness of the moderately decomposed organic soil horizon, soil pH, electrical conductivity and volumetric water content. Lichen species richness was highest on the slopes of the dunes, while bryophyte species richness was higher at the bottoms and decreased towards the tops of the dunes. Ground vegetation species richness and species’ horizontal and vertical structure on forested dunes were highly dependent on topography-induced differences, aspect, height and zone of the dunes. The most important factors controlling the complex of ground vegetation were light conditions, soil water content, thickness of the moderately decomposed litter layer and soil potassium and calcium content.

The study was aimed at the quantitative evaluation of the temporal and spatial partitioning of non-structural carbohydrates and needle biomass in a canopy of Scots pine (Pinus sylvestris L.) growing in a Myrtillus site type forest stand (predominant in Estonia). The tree canopy was divided into ten equal layers and the material for the spatial partitioning of the investigated characteristics was sampled from all layers. Our findings revealed a significant variation in morphology and in the partitioning of carbohydrates in needles in different layers of the canopy. The study of the temporal dynamics of carbohydrates showed that starch content in needles started to increase in early spring before budbreak, which was accompanied by a decline in soluble carbohydrates. In October, the starch content of needles was low, but the concentration of soluble sugars started to increase attaining a maximum in winter. Regression analysis indicated that before budbreak, the partitioning of soluble sugars in different canopy layers was relatively weakly correlated with the height of the layer; however, a strong correlation was observed for starch. In autumn, when the growth of trees stopped and daily temperatures decreased, the allocation of soluble sugars was correlated with the height of the canopy layer.