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Stump removal is a novel potential source of woody biomass for renewable energy in the Nordic and Baltic countries. In Estonia, a prospective resource of Norway spruce ( Picea abies ) stumps is available for bioenergy. The main aims of the present study were to estimate the biomass and volume of harvested spruce stumps; also to evaluate nutrient and carbon loss from a site due to stump removal; and to estimate the effect of stump harvesting on soil respiration. In this pilot study an allometric model was elaborated for estimation of the biomass and volume of harvested stumps. The volume of harvested spruce stumps reached up to 130 m 3 ha −1 and potential energy content amounted to 290 MW h ha −1 . The average calorific value of different stump and root fractions varied between 19.0 and 19.3 kJ g −1 and there was no significant difference between the stump fractions. The weighted average density of the harvested spruce stumps was 430 kg m −3 . Fertile automorphic forest types were selected for this pilot study and the nitrogen (N) storage removed from clear-cuts with stumps was not appreciable, being 1.2–4.4%, in comparison with soil N storages. Removed phosphorus (P) accounted for 8–28% of total soil lactate soluble P and removed potassium (K) accounted for 6–23% of the soil K storage. The loss of carbon (C) made up 11–33% of the soil C storage. However, the concentration of lactate soluble P evidently reflected the balance between solubilized and assimilated P in the soil rather than actual P limitation. Hence, at fertile sites stump removal does not caused considerable N and C depletion, however, removal of P and K may be appreciable compared with corresponding soil storage values. Stump harvesting did not increase soil respiration intensity. Total annual soil respiration at the Oxalis site type was 4.9 and 5.1 t C ha −1 yr −1 in the uprooted and control plots, respectively. At the Myrtillus site type the respective values were lower, 3.7 and 3.9 t C ha −1 yr −1 . Also soil heterotrophic respiration in the Oxalis site type was practically the same at the uprooted and control sites, being 3.3–3.2 t C ha −1 yr −1 . However, in the Myrtillus site type the values of the heterotrophic respiration efflux was higher from the control plots than from the uprooted plot, at 2.5 and 1.8 C ha −1 yr −1 , respectively. Norway spruce stumps are a potential bioenergy resource in Estonian forests and stump harvesting at fertile autotrophic sites does not cause problems in terms of depletion of nutrients and carbon from the ecosystem. [ABSTRACT FROM AUTHOR]

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]

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: 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]