Fast-growing hybrid aspen has been widely planted on former agricultural lands in Northern and Eastern Europe to produce pulpwood and sequester carbon into woody biomass. The biodiversity of mature hybrid aspen plantations has so far been rarely analysed. Moreover, the potential of hybrid aspen plantations to host flora typical of European aspen stands – recognised as biodiversity hotspots in Eurasian boreal forests – has not been evaluated. This study focused on two organism groups with contrasting habitat preferences – ground-dwelling herbs and epiphytic lichens. We sought to clarify how environmental and landscape factors influenced the diversity of herbs, lichens, and species characteristic of European aspen stands (EA species). Data were collected across 42 study plots within 20 hybrid aspen plantations in Estonia. Altogether, 162 herb species and 65 lichens were recorded, including 92 species also found in European aspen stands. The proportion of EA species was higher among lichens (86.2%) than among herbs (22.2%), reflecting a stronger legacy effect of former agricultural land-use on ground-dwelling species than on epiphytes. Responses of herb and lichen diversity to environmental variables differed. Richness of herbs was related to litter and stand characteristics. Compositional analyses also highlighted the role of soil-litter variables and stand structure in herb composition. Lichens responded to landscape-related variables. A greater extent of older forests around the study plots increased the richness of EA species. In conclusion, mature hybrid aspen plantations are relatively species-rich and can enhance landscape connectivity for forest species, particularly epiphytes, in agricultural landscapes.

Abandoned agricultural lands carry a legacy of soils contaminated with heavy metals from previous land use practices. Phytoremediation using fast-growing trees is widely used method for ecosystem restoration by accumulating heavy metals in aboveground biomass. In Northern Europe, where 1.8 to 2.6 million hectares of abandoned agricultural land can be afforested, the knowledge of fast-growing tree species' phytoremediation capacity is still poorly studied. This study examines the phytoremediation capacity after 20 years of afforestation of former agricultural lands with hybrid aspen plantations in hemiboreal Estonia, with a particular focus on the effects of different forest site type (Aegopodium, Dryopteris, Hepatica, and Oxalis) on heavy metal concentrations in topsoil and on bark and wood bioaccumulation factors. Soil, wood, and bark samples were collected from 24 sample plots to assess the allocation and accumulation of heavy metals in soil and biomass. The concentration of heavy metals in soil varied by site type, with waterlogged (Dryopteris) sites showing significantly higher levels of Cu, Fe, Ni, and Zn, whereas Cd and Mn were more concentrated in alkaline and dry (Hepatica) sites. The concentration of heavy metals in wood varied with tree size and age; smaller trees had significantly lower Cd, Cu, Fe, and Zn levels, while wood formed in the first decade of stand development showed higher concentrations of Cd, Cu, Mn, and Zn. Soil physical and chemical characteristics showed strong correlations with heavy metal bioaccumulation factors, particularly in bark. Soil pH negatively affected Mn bioaccumulation in all tree parts and Ni, Zn, and Cd in specific tissues, while soil P and available water content positively influenced metal uptake of trees. We found that the phytoremediation capacity of hybrid aspen plantations on former agricultural lands is controlled by soil properties and depends on tree size and age.

Afforestation of former agricultural land with silver birch (Betula pendula Roth) is increasingly promoted in Northern and Eastern Europe, yet its long-term effects on soil–plant heavy metal dynamics remain insufficiently understood. We assessed heavy metal accumulation in soil and woody biomass (stemwood and bark) 20 years after afforestation of former agricultural land at 11 plantations. Eleven elements (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, and Zn) were initially determined, but subsequent analyses focused on five elements (Cr, Cu, Fe, Mn, and Zn) consistently detected above the limit of quantification. Metal allocation between stemwood and bark and the influence of soil physicochemical properties (pH, P, K, Corg, Ntot, bulk density and available water content) were analyzed. We also examined relationships between soil metal concentrations, tree growth, and the distribution of metals between stemwood formed at early-age (1–10 years) and late-age (11–23 years). Heavy metal accumulation was primarily governed by soil properties, with pH, P, and K showing important relationships with bioaccumulation patterns, while the role of Corg varied among elements and substrates. No statistically significant evidence was found that elevated soil metal concentrations inhibited tree growth. Within stems, metal concentrations varied with wood age, with higher levels observed in early-age wood. Overall, the findings highlight the importance of soil properties in shaping heavy metal dynamics in birch plantations and provide insight into long-term trace metal allocation in forest ecosystems established on former agricultural soils, supporting sustainable afforestation and the evaluation of woody biomass for potential bioenergy use.

Silver birch (Betula pendula) and hybrid aspen (Populus tremula × P. tremuloides) are widely planted tree species on former agricultural lands in Northern and Eastern Europe due to their fast growth, high biomass production and CO2 sequestration. As few comparative studies on the biodiversity of silver birch and hybrid aspen plantations have been carried out, we aimed to evaluate above- and below-ground diversity in silver birch plantations (SBs) and hybrid aspen plantations (HAs) and associate the trends with environmental variables. For this, we collected data on herbs, ground-dwelling bryophytes, epiphytic bryophytes, lichens, closed forest species and soil fungi from 10 SBs and 10 HAs (< 25 years of age) in Estonia. The richness and composition of herbs was similar in SBs and HAs, whereas all other groups differed either in species richness, composition or both. Overall, HAs hosted higher richness of ground-dwelling bryophytes and epiphytic lichens and lower richness of epiphytic bryophytes than SBs, which was associated with differences in litter and light conditions. The richness of closed forest species was similar between HAs and SBs and increased in correlation with the area of surrounding forests, whereas the compositions differed. The HAs hosted higher fungal richness of all soil fungi, as well as ectomycorrhizal, saprotrophic and plant pathogenic fungi and differed compositionally from SBs. Based on our findings, both birch and hybrid aspen plantations provide benefits with respect to biodiversity, as they support compositionally different assemblages of bryophytes, lichens, closed forest species and soil fungi.

Silver birch plantations on former agricultural lands grow faster than birch stands on forest land in Northern Europe. For optimal management decisions, there is a need to improve understanding of ecological processes such as competition in plantations where stand structure and soil conditions differ from native forests. We analyzed the effects of intraspecific competition on mortality and periodic annual increment during 15-21 years of age (PAI6) in silver birch plantations. We evaluated six individual tree competition indices (CI) and two competitor selection methods, and tested whether weighting competitor trees based on their cardinal direction from the subject tree would improve the goodness-of-fit of growth models based on CIs. Tree growth parameters were measured and tree locations were mapped in the 0.1 ha sample plots of 11 silver birch plantations. The best CI for predicting PAI6 was the sum of diameter ratios combined with the reverse search cone method for competitor selection. Reducing the weight of competitors toward north improved the performance of the best CI for below-average sized trees but not for above-average sized trees, thus size-class-wise estimation of CIs can be advantageous. Asymmetric CIs performed better than symmetric CIs suggesting that light competition was the prevailing mode of competition.

Coppice plantations have gained a high interest for biofuel production and carbon uptake in short rotation cycles. There is a limited knowledge how such intensive coppice management affects soil fertility and nutrients supply to maintain carbon sink. We studied ecosystem carbon and nutrients balance and allocation during a 5-year period in hybrid aspen coppice under different thinning methods in hemiboreal Estonia. The benchmark value for the changes was defined before the coppice emerged after the clear-cut of the previously planted hybrid aspen plantation. The studied systematical thinning treatments were as follows: corridor thinning with removal of 67% of the trees (CT), cross-corridor thinning with removal of 89% of the trees (CCT), and unthinned (UT) coppice. The UT and CT treatments resulted in a positive carbon balance at the ecosystem level. In all treatments, a decrease of soil acidity, organic C, total N, K, Mg and Mn contents, and an increase of soil Cu and B contents were observed in the 0–20-cm deep layer. The concentrations of leaf N, P, and K were higher in UT than in the two thinning treatments, indicating that the aspens had not entirely recovered from the changed root to shoot ratio 2 years after thinning, whereas the leaf mass fraction of medium- and small-sized trees had already increased. Bioenergy harvest from the UT site in a 5-year rotation would cause 5–18% removal of NPK from the total ecosystem pool. Overall, hybrid aspen coppice showed positive ecosystem carbon balance after the first 5-year period; however, further monitoring of soil properties is needed as we found decrease of soil organic C and nutrients concentrations in short term. Graphical Abstract

Fast-growing Populus spp. are well-acknowledged to restore contaminated soils from heavy metals in industrial areas. Thus far, there is no knowledge about the phytoremediation capacity of Populus spp. plantations in hemiboreal Estonia conditions to restore industrially polluted areas. The objective of this study was to assess the soil contamination rate of heavy metals (As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb and Zn) and their uptake by mature hybrid aspen (Populus tremula × Populus tremuloides Michx.) in plantations in different industrial pollution areas (e.g. cement factory, oil shale mining). For the reference, industrially polluted plantations were compared with the low pollution area hybrid aspen plantation on former agricultural soil, which was influenced by fertilization and liming before afforestation. Twenty-one years after afforestation, soil samples were collected from the 0–10 cm topsoil layer. Aboveground biomass sampling was performed for bark and stem wood by ingrowth cores to separate wood formed during early (1–10 years) and late (11–21 years) stand development. Two decades after the afforestation of industrially polluted areas, the heavy metal concentrations in the soil were higher than the reference plantation and the standard reference for unpolluted soils in most cases. The highest concentrations of heavy metals in woody biomass were in the oil shale quarry spoil; because of poor growth, the accumulated pools in aboveground biomass were low. Cd differed from other metals and accumulated less in wood and more in bark. The concentration of heavy metals (Cd, Cr, Cu, Fe, Mn, Ni and Zn) was higher in the first decade of stand formation (1–10 years) than in the last 10 years (11–21 years). High pools of heavy metals were accumulated in aboveground biomass in the reference plantation, indicating the considerable removal of heavy metal residues from the previous fertilization and liming source with harvest. Two decades of afforestation with hybrid aspen is too short for complete ecosystem restoration from heavy metals in industrially polluted areas.

Treating peat with nutrient-rich ash significantly increases the content of different nutrients in the substrate. Such ash treatment promotes the revegetation of abandoned extracted peatlands. The aim of this study is to analyze the effect of wood ash (WA15 = 15 t ha−1 and WA10 = 10 t ha−1), oil shale ash (OSA8 = 8 t ha−1), and a mixture of wood ash and oil shale ash (WA10 + OSA8) on the revegetation (vascular plants and bryophytes) of the Puhatu abandoned extracted peatland in NE Estonia. The following results were obtained: (1) The MRPP tests indicate that there are compositional differences between the treatments. (2) Altogether, 23 vascular plant and 3 bryophyte species were recorded in the treatment areas. (3) Nine years after these ash treatments, the highest mean vascular plant species richness was recorded for WA15 (3.8 ± 0.3) and the lowest for OSA8 (2.0 ± 0.3). (4) A greater number of vascular plant species was observed in the WA15 area. (5) Mixed ash and wood ash had a significant effect on the amount of biomass in vascular plants. Treating with either wood ash or a mixture of ash ensured the rapid formation of vascular plants and bryophyte layers, contributing to the restoration of the abandoned peatland ecosystem.

Short-rotation forestry on former agricultural soils is a novel silvicultural system for producing woody biomass and mitigating climate change through CO2 uptake. However, tree plantations are often criticized for their low biodiversity and are sometimes referred to as "green deserts". We hypothesize that regarding biodiversity, the spontaneous natural regeneration of birch on former agricultural lands may be preferable to plantations. In this study, we compared soil fungal diversity and composition of fast-growing silver birch (Betula pendula Roth) plantations on former agricultural lands (n = 11) with naturally regenerated birch stands on former agricultural lands (n = 11) and native forest birch stands (n = 11) at the age of 21-28 years in hemiboreal Estonia. PacBio third-generation sequencing was carried out to analyse fungal species richness and composition in the soil samples. Sequencing of the fungal ITS region from 33 birch stand soil samples yielded 2830 fungal OTUs. We found that the total fungal species richness, per sample species richness, Shannon diversity index, and Pielou's evenness index did not differ significantly between the studied stand types. However, fungal community composition of both plantations and naturally regenerated stands on former agricultural lands differed significantly from the native forest stands, indicating that previous land use (agriculture vs. forest) had a stronger effect on fungal assemblages than the used regeneration method (planting vs. natural regeneration). The relative abundance of ectomycorrhizal and arbuscular mycorrhizal fungi was higher, and the relative abundance of saprotrophic fungi was lower in plantations than in native birch dominated forest stands. Soil chemical properties were found to be weak explanatory variables for describing soil fungal richness and composition. We identified historical surrounding forest cover, stand age, stand distance from a native forest, and soil Mg content as the factors significantly affecting soil fungal communities. These results indicate that fast-growing birch plantations established on former agricultural soils or naturally regenerated stands on such soils in the Northern Europe region harbour soil fungal diversity levels similar to those of same-aged native birch forests.

The dataset includes vascular plant, bryophyte and lichen species data and environmental data collected from 33 birch stands in Estonia representing three stand types with different restoration approach (birch plantations on previous agricultural land, naturally regenerated stands on previous agricultural land and birch stands on native forest land).

Fast-growing tree plantations on abandoned agricultural soils is a promising management system to sequester atmospheric CO2. However, the effects of fast-growing trees on the nutritional and organic carbon (SOC) status of soils degraded by agriculture, are poorly understood. We sampled the soil after 20 years in 10 silver birch plantations on former agricultural soils in hemiboreal Estonia to assess changes in soil chemical properties (SOC, N, C:N ratio, pHKCl, P, and K) in 10-cm vertical mineral soil layers to a depth of 30 cm and to determine the potential environmental drivers of plant-soil interactions. We observed no depletion of SOC or macronutrients in the upper 0–30-cm soil layer, but found some vertical shifts among the sublayers. The SOC concentration increased by 22

The properties of biomass-based fuel and combustion tests showed that logging residues are promising renewable energy sources. The data used in this study were collected from four clear-felling areas in Järvselja Training and Experimental Forest Centre, Southeast Estonia in 2013–2014. Logging was carried out by harvesters in Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies [L.] Karst.), silver birch (Betula pendula Roth.) and black alder (Alnus glutinosa L. Gaertn.) dominated stands with a small admixture of other tree species according to the cut-to-length method and logging residues were placed in heaps. The aim of this research is to assess different characteristics of logging residues (quantity, moisture content, energetic potential, ash content and amount) in clear-felling areas. The highest load of slash was measured on the birch dominated study site, where the dry weight of the logging residues was 29 t ha−1. Only the branch fraction moisture content on the black alder dominated site (35.4%) was clearly different from respective values on other sites (21.6–25.4%). The highest calorific value of the residues was assessed with the residues from the birch dominated site, where in moist sample it was 365 GJ ha−1 and in dry matter 585 GJ ha−1. The heating value of the fresh residues is highest in coniferous trees. The highest ash content in branch segments was registered for the black alder dominated site. Järvselja data indicate higher quality in conifer dominated sites, yet a higher load of logging residues in broadleaf dominated stands.

Alternatives to the restoration of cutaway peatlands include afforestation, energy forests, agricultural production, wetland restoration (restoration of peataccumulating function), reed canary grass (energy mower) or wild berries (blueberry, cranberry) cultivation, protected area for birds, and artifi cial lakes. Investigations made in several countries suggest that one of the most promising ways of regenerating cutaway peatlands is afforestation. The re-vegetation of Estonian cutaway peat production fi elds is mainly the result of natural processes, which are generally very slow: vegetation covers only 10–20% of a peat fi eld. Carbon dioxide is not bound anymore in cutaway peatlands where vegetation layer has been destroyed and therefore photosynthetical processes no more occur. Using biofuel ashes (wood ash, etc.) for the afforestation of cutaway peatlands helps to balance the content of nutrients in peat substrate, which improves the survival of planted seedlings and signifi cantly increases bioproduction. Drained and mined peatlands have become a signifi cant source of CO2 but stimulated woody biomass production can be helpful to balance CO2 emission from cutaway peatlands. Because of the limited resources of fossil fuels and negative impacts on the environment in recent decades alternative sources of energy have been actively looked for. In Scandinavia a lot of attention has been paid to fi nding possibilities for using biofuels. The situation in Estonia is that only very few types of ashes (for example certifi ed oil shale fl y ash with product name Enefi x) have been founded to be suitable for utilization and have been used for recycling in agriculture.

Aim of the study: To investigate terrestrial bryophyte and lichen species richness and environmental factors affecting the composition of species. Area of the study: Four Boreal zone fixed dunes were selected in the coastal area of the Baltic Sea in southwest Estonia. Material and methods: Non-metric multidimensional scaling was performed to analyse distribution patterns and environmental factors like canopy cover, photosynthetically active radiation, soil organic horizon thickness and decomposition rates, soil volumetric water content, soil pH and electrical conductivity and soil nutrients correlated with bryophyte and lichen species composition. Main results: Thirty bryophytes and 22 lichens were found on 232 sample plots, the most frequent species were Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens (Hedw.) Schimp., Dicranum polysetum Sw. ex anon., Cladonia arbuscula (Wallr.) Flot. and Cladonia furcata (Huds.) Schrad. The lichen species richness was highest on the slopes of the dunes and decreased towards the bottoms and tops; bryophyte species richness was higher on the bottoms and decreased towards the tops of the dunes. Research highlights: The composition of bryophytes and lichens is significantly influenced by the aspect and the location on the dune, light conditions, soil pH, soil salinity (measured as electrical conductivity) and volumetric water content, thickness of moderately decomposed organic horizon and vascular plant species cover. Keywords Inland dunes; terrestrial bryophyte and lichen communities; environmental factors; topography.

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 m 2 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.

Use of biofuel ashes for the afforestation of cutaway peatlands helps to balance the content of nutrients in peat substrate, which improves the survival of planted seedlings and increases significantly bio-production. The purpose of this study was to investigate the effect of fertilization with alkaline ashes on the above-and belowground biomass formation of four-year-old Silver birch (Betula pendula Roth) and five-year-old Scots pine (Pinus sylvestris L.) stands on a cutaway peatland. Five treatments were established: three mixtures with different proportions of wood ash (10-15 t ha(-1)) and oil shale ash (10-15 t ha(-1)), pure oil shale ash (10 t ha(-1)) and control (unfertilized plot). Three years after fertilization with ashes the content of phosphorus was up to 150 times and that of potassium 23 times higher in the peat substrate treated with ashes than on the control plot. The growth and biomass formation varied among treatments and depends strongly on the content of P and K in the growth substrate. The best results were observed on plots of Silver birch treated with mixed ashes; there the seedlings annual height increment was 2-3 times (first year), 5-7 times (second year) and 8-9 times (third year) greater than on the control plot. The effect of mixed ashes on the annual height increment of Scots pine was weaker: the annual height increment was 1.4 times (first year), 3 times (second year) and 5 times (third year) greater than on the control plot. The effect of pure oil shale ash on the growth and biomass formation of trees was the smallest. The greatest root collar diameter increment of birch and pine was observed on the third vegetation period. Roots formed the largest part of the total Silver birch biomass, followed by stem, branches and leaves. At the end of the third year after treatment the largest part of the biomass of Scots pine was allocated to the needles, followed by roots, stem and branches. The biomass and biomass production were the greatest on the plots treated with mixed ashes, especially on the WA15+ OSA10 and WA15+ OSA10 treatments. The total bioproductivity of birch was until 4 times intense than in the case of pine. The average current annual biomass production of Silver birch and Scots pine stands were respectively 0.17-0.21 t ha(-1) and 0.3-0.56 t ha(-1) (mixed ashes), 0.04 t ha(-1) and 0.16 t ha(-1) (OSA10) and 0.02 t ha(-1) (control).

Alternatives to the restoration of cutaway peatlands include afforestation, energy forests, agricultural production, wetland restoration (restoration of peataccumulating function), reed canary grass (energy mower) or wild berries (blueberry, cranberry) cultivation, protected area for birds, and artificial lakes. Investigations made in several countries suggest that one of the most promising ways of regenerating cutaway peatlands is afforestation. The re-vegetation of Estonian cutaway peat production fields is mainly the result of natural processes, which are generally very slow: vegetation covers only 10–20% of a peat field. Carbon dioxide is not bound anymore in cutaway peatlands where vegetation layer has been destroyed and therefore photosynthetical processes no more occur. Using biofuel ashes (wood ash, etc.) for the afforestation of cutaway peatlands helps to balance the content of nutrients in peat substrate, which improves the survival of planted seedlings and significantly increases bioproduction. Drained and mined peatlands have become a significant source of CO2 but stimulated woody biomass production can be helpful to balance CO2 emission from cutaway peatlands. Because of the limited resources of fossil fuels and negative impacts on the environment in recent decades alternative sources of energy have been actively looked for. In Scandinavia a lot of attention has been paid to finding possibilities for using biofuels. The situation in Estonia is that only very few types of ashes (for example certified oil shale fly ash with product name Enefix) have been founded to be suitable for utilization and have been used for recycling in agriculture.

Different environmental factors were studied to determine which factors influence the species richness, composition and structure of vascular plants in Pinus sylvestris L. forests in a fixed dune landscape in south-western Estonia. In addition to site topographic factors, different environmental parameters were investigated. Thirty-four vascular plant species were recorded in 232 quadrats. The most abundant species was Vaccinium vitis-idaea L., which was in 82.8% of quadrats, followed by Vaccinium myrtillus L. (74.1%), Melampyrum pratense L. (71.1%) and Deschampsia flexuosa (L.) Trin. (69.8%). The multiple response permutation procedure (MRPP) showed considerable differences in species composition at the bottoms of dunes compared with that on the slopes and at the tops of dunes. Indicator species analysis (ISA) determined species exhibited characteristics specific to zone: V. myrtillus had the highest indicator value at the bottoms of dunes; Calluna vulgaris L., at the tops. Soils were Haplic Podzols, and the presence of humus horizon depended on zone. Soil conditions on the dunes were variable and site specific, in general, soils at the bottoms of the dunes were more acidic and moist compared with those of the slopes and tops of the dunes, and the nutrient content decreased toward the dune tops. According to non-metric multidimensional scaling (NMDS) and linear mixed model analyses, species coverage, composition and richness were controlled by site-specific factors such as absolute height, location and aspect of the quadrat on the dune; soil nitrogen, potassium and phosphorus contents; soil pH and moisture; light conditions; and the thickness of the litter horizon.

Eighty-one cutaway peat production fields with a total area of about 9000 ha exist and were studied in Estonia in 2005–2015. Only a very small number of the fields (seven) have been restored—either afforested or used for growing berries. The re-vegetation of Estonian cutaway peat production fields is mainly the result of natural processes, which are generally very slow due to an unfavourable water regime or a too thin remaining peat layer. The fields are mostly covered by cotton grass and birches. Often sparse vegetation covers 15–20% of a peat field, but some fields have turned into heaths or grasslands with plant coverage up to 60%. However, due to changes in environmental (mainly hydrological) conditions and peat characteristics (mainly peat type), these areas can also be new niches for several species. A number of moss species new to or rare in Estonia, e.g. Pohlia elongata, Ephemerum serratum, Campylopus introflexus and Bryum oblongum, were recorded.

Trees in cutaway peatland are growing in difficult conditions. Fertilization with nutrient-rich wood ash helps improve growth conditions. Photosynthesis and carbohydrate concentration along leaf anatomy were studied on plots treated with 10 and 5 t ha−1 wood ash (WA10 and WA5) and on untreated (Control) plot to explain the physiological background of the differences in tree growth. The leaves from WA10 had the largest leaf area, total thickness, the thickest mesophyll and also significantly larger average values of all anatomical parameters of the shoots. The photosynthetic assimilation was significantly higher on treated plots at 200 and 400 ppm CO2 levels. In leaves on the treated plots, the sucrose concentration was lower while that of starch was higher than in trees on untreated soil. The differences in the maximum photosynthesis were relatively small. At unit ground, the leaf area provided for a wood ash-treated tree an efficient surface for CO2 assimilation, light interception and some starch storage during the growing period.