Aspen Populus Tremula Research Articles

Coherent photosynthetic activity between deciduous arboreal trees.

The long-term time course of photosynthetic activity in arboreal trees of aspen Populus tremula L. and birch Betula pendula Roth species native for Kola Subarctic was observed through 2014–2017 yr vegetation seasons in terms of PAM (Pulse Amplitude Modulated) foliage chlorophyll fluorescence measurements in situ. The temporal pair- wise correlation chlorophyll fluorescence pattern between any leaf blades couple for the whole any single crone as well as for proximate tree crones was found. The abrupt temperature drops and other environmental changes promote transition to blades coherence, the most synchronicity between trees was observed in 2014th fall. The global synchronization between any leaf couple was often preceded by transition of the foliar blades photosynthetic activity in common coherent quasi-cyclic rhythm. It is suggested that mutual crone’s intra and inter temporal organization and cooperative assimilation promote resistance and optimal realization of adaptive species potential.

Haplotype-resolved genome assembly of Populus tremula × P. alba reveals aspen-specific megabase satellite DNA.

Populus species play a foundational role in diverse ecosystems and are important renewable feedstocks for bioenergy and bioproducts. Hybrid aspen Populus tremula × P. alba INRA 717-1B4 is a widely used transformation model in tree functional genomics and biotechnology research. As an outcrossing interspecific hybrid, its genome is riddled with sequence polymorphisms which present a challenge for sequence-sensitive analyses. Here we report a telomere-to-telomere genome for this hybrid aspen with two chromosome-scale, haplotype-resolved assemblies. We performed a comprehensive analysis of the repetitive landscape and identified both tandem repeat array-based and array-less centromeres. Unexpectedly, the most abundant satellite repeats in both haplotypes lie outside of the centromeres, consist of a 147 bp monomer PtaM147, frequently span >1 megabases, and form heterochromatic knobs. PtaM147 repeats are detected exclusively in aspens (section Populus) but PtaM147-like sequences occur in LTR-retrotransposons of closely related species, suggesting their origin from the retrotransposons. The genomic resource generated for this transformation model genotype has greatly improved the design and analysis of genome editing experiments that are highly sensitive to sequence polymorphisms. The work should motivate future hypothesis-driven research to probe into the function of the abundant and aspen-specific PtaM147 satellite DNA.

Suitability of European Aspen (Populus tremula) for Rehabilitation of Severely Polluted Areas

Suitability of European Aspen (Populus tremula) for Rehabilitation of Severely Polluted Areas

Подрост сосны обыкновенной (Pinus sylvestris L.) на отвалах месторождения хризотил-асбеста

The studies were carried out on the dumps of overburden rocks and tailings of poor ores of the chrysotile asbestos deposit. According to the scheme of forest site zoning, the studying area belongs to the pre-forest steppe district of pine and birch forests of the Zabaikal’ye plain province of the West Siberian plain forest site area. The survey sites were laid out on the terraces of the dump along the running lines. Undergrowth was counted at each survey site. It was classified by viability, size (small, medium, large), and life form (tree, bush, scrub). The provision with undergrowth of the indicated type of disturbed soils was defined and recommendations for measures aimed at accelerating the process of reforestation were given. Undergrowth on the dumps is represented by Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth.), aspen (Populus tremula L.), and goat willow (Salix caprea L.). Scots pine and silver birch are the dominant species in the undergrowth composition. Large share of Scots pine of scrub and bush form is the specific feature of the developing young growth. These specimens were found among small- and medium-sized undergrowth. It is the undergrowth of these heights that becomes an annual attrition without passing into the large-sized category. The latter is the main reason for faster conversion of the dumps into forest-covered area, for increasing the share of clay particles in the upper 50 cm thick dump layer, or for coating the dump surface by non-traditional fertilizers, in particular sewage sludge. It was noted that silvicultural trend in the dump reclamation on the chrysotile asbestos deposit is the most preferable. Scots pine should be preferred as the primary species for reclamation planning. For citation: Zaripov Yu.V., Zalesov S.V., Zalesova E.S., Popov A.S., Platonov E.P., Starodubtseva N.I. Scots Pine (Pinus sylvestris L.) Undergrowth on the Dumps of the Chrysotile Asbestos Deposit. Lesnoy Zhurnal [Russian Forestry Journal], 2021, no. 5, pp. 22–33. DOI: 10.37482/0536-1036-2021-5-22-33

Ectoedemia argyropeza (Zeller, 1839) sur Peuplier Tremble : traits de comportement inférés à partir de la distribution des traces d’activités subsistant sur les feuilles-hôtes (Lepidoptera, Nepticulidae)

Ectoedemia argyropeza on Aspen leaves: deciphering retrospectively some behavioural traits from the distribution of traces of the insect activities subsisting on host-leaves (Lepidoptera, Nepticulidae). Despite their usually small size, endotrophic insects —especially those whose larvae are mining into their host-leaves— exhibit patterns of behaviour that are often more elaborate than what is usually seen in many ectotrophic herbivorous insects. However, since it is generally difficult to capture properly these behaviours in the field, precisely due to the small size of these insects, it turns out to be more convenient attempting to uncover retrospectively some of these behaviours on the basis of their resulting traces which subsist on the host-leaves. In order to be able to infer reliable information from this retrospective approach, the examination of a substantial number of host leaves and the support of appropriate statistical tests are required. The present study concerns a species of microlepidoptera, Ectoedemia argyropeza, whose caterpillars are exclusively mining the leaves of Aspen (Populus tremula) and which is still further distinguished, in a remarkable manner, by the induction of a preliminary galling (“cecidian”) development stage. This unusual combination of life traits contributes to enrich the insect’s behavioural repertoire and therefore offers a more promising field of investigation. For this species, I more particularly focus on the way the artefacts resulting from the insect activities are distributed spatially, on (or in) the host leaf, namely: (i) the spatial distribution of eggs deposited on the host-leaf petiole, (ii) the hierarchy of preferential positioning of the caterpillar corridor in the section of the petiole, hypertrophied by the cecidogenic reaction, (iii) the hierarchy of preferential locations of mines in the host-leaf blade. Were also tested, on the one hand, the existence (or not) of paired relationships between each of the three categories of distributions mentioned above and, on the other hand, the degree of conformation of each of these different distributions to the bilateral symmetry of the leaf support. The behavioural aspects that can be tentatively inferred from the above information are subsequently discussed.

Inducing bark inclusions in branch junctions of aspen (Populus tremula L.) by bracing them with horticultural wire

ABSTRACT Branch junctions are typically strengthened by the production of dense wood with a tortuous grain pattern in their axils (axillary wood). The strong association found between natural braces in trees and bark-included branch junctions set below them suggests there may be a causal relationship: that if a branch junction receives little mechanical stimulation due to being naturally braced, little or no axillary wood will be formed and bark is occluded instead. To investigate this relationship, sixty branch junctions in young specimens of aspen (Populus tremula L.) were braced with horticultural wire and their development contrasted with sixty “controls” where no bracing was applied. After three years, 95% of the braced branch junctions exhibited included bark, whereas only one control junction developed included bark and that was found to be natural braced. This is the first recorded instance where bark-included junctions have been knowingly created by artificial means. The results point to a causal relationship between natural bracing and the formation of bark-included junctions, which has implications for tree management. This study also provides evidence that axillary wood should be categorised as a reaction wood, as its formation requires specific mechanical stimulation, and due to its distinct anatomical and mechanical properties.

Photosynthesis Traits of Pioneer Broadleaves Species from Tailing Dumps in Călimani Mountains (Eastern Carpathians)

The reforestation and stable ecological restoration of tailings dumps resulting from surface mining activities in the Călimani Mountains represent an ongoing environmental challenge. To assess the suitability of different tree species for restoration efforts, photosynthetic traits were monitored in four broadleaf pioneer species—green alder (Alnus alnobetula (Ehrh.) K. Koch), aspen (Populus tremula L.), silver birch (Betula pendula Roth.), and goat willow (Salix caprea L.)—that naturally colonized the tailings dumps. Green alder and birch had the highest photosynthetic rate, followed by aspen and goat willow. Water use efficiency parameters (WUE and iWUE) were the highest for green alder and the lowest for birch, with intermediary values for aspen and goat willow. Green alder also exhibited the highest carboxylation efficiency, followed by birch. During the growing season, net assimilation and carboxylation efficiency exhibited a maximum in late July and a minimum in late June. The key limitation parameters of the photosynthetic process derived from the FvCB model (Vcmax and Jmax) were the highest for green alder and exhibited a maximum in late July, regardless of the species. Based on photosynthetic traits, the green alder—a woody N2-fixing shrub—is the most well-adapted and photosynthetically efficient species that naturally colonized the tailings dumps in the Călimani Mountains.

Root-Plate Characteristics of Common Aspen in Hemiboreal Forests of Latvia: A Case Study

Climate change will cause winds to strengthen and storms to become more frequent in Northern Europe. Windstorms reduce the financial value of forests by bending, breaking, or uprooting trees, and wind-thrown trees cause additional economic losses. The resistance of trees to wind damage depends on tree species, tree- and stand-scale parameters, and root-soil plate characteristics such as root-plate size, weight, and rooting depth. The root-soil plate is a complex structure whose mechanical strength is dependent on root-plate width and depth, as the root system provides root attachment with soil and structural support. In Latvia, the common aspen (Populus tremula L.) root system has been studied to develop a belowground biomass model, because information about root system characteristics in relation to tree wind resistance is scarce. The aim of this study was to assess the root-plate dimensions of common aspen stands on fertile mineral soil (luvisol). Study material was collected in the central region of Latvia, where pure mature (41–60 years old) common aspen stands were randomly selected, and dominant trees within the stand were chosen. In total, ten sample trees from ten stands were uprooted. The diameter at breast height (DBH) and tree height (H) were measured for each sample tree, and their roots were excavated, divided into groups, washed, measured, and weighed. The highest naturally moist biomass values were observed for coarse roots, and fine root biomass was significantly lower compared to other root groups. All root group biomass values had a strong correlation with the tree DBH. The obtained results show that there is a close, negative relationship between the relative distance from the stem and the relative root-plate depth distribution.

Identifying transcription factors that reduce wood recalcitrance and improve enzymatic degradation of xylem cell wall in Populus

Developing an efficient deconstruction step of woody biomass for biorefinery has been drawing considerable attention since its xylem cell walls display highly recalcitrance nature. Here, we explored transcriptional factors (TFs) that reduce wood recalcitrance and improve saccharification efficiency in Populus species. First, 33 TF genes up-regulated during poplar wood formation were selected as potential regulators of xylem cell wall structure. The transgenic hybrid aspens (Populus tremula × Populus tremuloides) overexpressing each selected TF gene were screened for in vitro enzymatic saccharification. Of these, four transgenic seedlings overexpressing previously uncharacterized TF genes increased total glucan hydrolysis on average compared to control. The best performing lines overexpressing Pt × tERF123 and Pt × tZHD14 were further grown to form mature xylem in the greenhouse. Notably, the xylem cell walls exhibited significantly increased total xylan hydrolysis as well as initial hydrolysis rates of glucan. The increased saccharification of Pt × tERF123-overexpressing lines could reflect the improved balance of cell wall components, i.e., high cellulose and low xylan and lignin content, which could be caused by upregulation of cellulose synthase genes upon the expression of Pt × tERF123. Overall, we successfully identified Pt × tERF123 and Pt × tZHD14 as effective targets for reducing cell wall recalcitrance and improving the enzymatic degradation of woody plant biomass.

Forest Cover Changes in the Center of East European Plain Over the Last 150 Years

Changes in forest cover in the center of the East European Plain (Central Russian Upland) from the end of the 19th century to the end of 20th century have been assessed. Over that period, forest cover has increased in the northern part of the studied territory and declined in the southern part. After the end of the 1990s and beginning of 2000s, increases in forest cover occurred within the subzones of mixed coniferous–broad-leaved forest, while in the southern regions it has hardly manifested at all. The fallow land overgrowth rate, without any anthropogenic interference, has been determined for the Central Russian Upland (from 10 to 50% of fallow area has been covered by forest vegetation over a period of 10 years), decreasing gradually in from west-northwest to east-southeast. Special attention is paid to the forests that grew on nonforested lands over a period of 150 years. This process occurs everywhere in the northern part of the Upland and along the river valleys in the southern part. The forest structure of newly formed forests is studied as well (deciduous, mixed, pine, and spruce). In the southern parts of the Central Russian Upland, the newly grown forests are mostly pine plantations. The analysis of the field data suggests that, in the Central Russian Upland, within the broadleaved forests subzone, fallows are usually overgrown with birch (Betula pendula), or, less frequently, with aspen (Populus tremula). On the western and southwestern slopes, the overgrowth occurs with broadleaved (Querqus robur and Acer platanoides), small-leaved (Populus tremula), and steppe species (Prunus spinosa, Malus praecox, and Pyrus pyraster). In the south, overgrown fallows are dominated by steppe or adventive species (Acer negundo).

Carbon and Nitrogen Isotope Composition of the Wood of Pinus sylvestris, Betula pendula and Populus tremula

Proportions of 13C/12C and 15N/14N isotopes were identified in different woody compartments of birch (Betula pendula Roth), pine (Pinus sylvestris L.) and aspen (Populus tremula L.) trunks in preforest-steppe and pine-birch forests of the Middle Urals using mass spectrometry. The data were analyzed and interpreted from the perspective of the biochemical processes of carbon and nitrogen metabolism in leaves, cambial tissue, trunk wood, branches, roots, and soil. A lighter isotopic composition of carbon is characteristic of the leaves and trunk cambium. The trunk wood is characterized by a basal trend for 13C enrichment. The 13C/12C ratio corresponds to the nitrogen content in the trunk wood tissues, indicating metabolic control of carbon fractionation in woody plants. The isotope composition of nitrogen in the trunk cambium was significantly depleted in 15N (δ15N varies from –1.5 to –3.5‰) and δ13C (δ13C varies from –28.3 to –25.8‰). Meanwhile the sapwood (δ15N varies from –2.6 to 1‰ and δ13C varies from –27.5 to –27.1‰) and heartwood (δ15N varies from –2.5 to –3.5‰ and δ13C varies from –26 to –24.5‰) were more enriched in 15N and 13C. The significant difference between the values of 13C and 15N isotope discrimination consequently in the different woody compartments of trunk should be taken into account when interpreting data of wood organic matter in the context of paleoclimate.

Analysis of adsorption of heavy metals from water solutions by wood of selected domestic species using X-Ray Fluorescence (XRF)

Analysis of adsorption of heavy metals from water solutions by wood of selected domestic species using X-Ray Fluorescence (XRF).The aim of this study was to analyze the absorption of three specific heavy metals from model water solution by wood species from domestic Polish forests. This paper focuses on XRF method to determine metal content in samples. European aspen (Populus tremula L.) and Black locust (Robinia pseudoacacia L.) have been chosen. Firstly, shavings were prepared and soaked with standard solutions of lead (II) nitrate, cadmium nitrate and mercury (II) chloride for 7 days. Then, the material was dried and reduced to ashes using muffle furnace. Finally, content of absorbed metal was marked (XRF) and analyzed with a view to initial contents of metal ions in standard solutions. It was established, that the higher the concentration of mercury in standard solution is, the higher impulse counts is obtained for European aspen. This reversal of the dependence is noticeable for second analyzed species.

Various effects of the expression of the xyloglucanase gene from Penicillium canescens in transgenic aspen under semi-natural conditions

BackgroundRecombinant carbohydrases genes are used to produce transgenic woody plants with improved phenotypic traits. However, cultivation of such plants in open field is challenging due to a number of problems. Therefore, additional research is needed to alleviate them.ResultsResults of successful cultivation of the transgenic aspens (Populus tremula) carrying the recombinant xyloglucanase gene (sp-Xeg) from Penicillium canescens in semi-natural conditions are reported in this paper for the first time. Change of carbohydrate composition of wood was observed in transgenic aspens carrying the sp-Xeg gene. The transformed transgenic line Xeg-2-1b demonstrated accelerated growth and increased content of cellulose in wood of trees growing in both greenhouse and outside in comparison with the control untransformed line Pt. The accelerated growth was observed also in the transgenic line Xeg-1-1c. Thicker cell-wall and longer xylem fiber were also observed in both these transgenic lines. Undescribed earlier considerable reduction in the wood decomposition rate of the transgenic aspen stems was also revealed for the transformed transgenic lines. The decomposition rate was approximately twice as lower for the transgenic line Xeg-2-3b in comparison with the control untransformed line Pt.ConclusionA direct dependence of the phenotypic and biochemical traits on the expression of the recombinant gene sp-Xeg was demonstrated. The higher was the level of the sp-Xeg gene expression, the more pronounced were changes in the phenotypic and biochemical traits. All lines showed phenotypic changes in the leave traits. Our results showed that the plants carrying the recombinant sp-Xeg gene do not demonstrate a decrease in growth parameters in semi-natural conditions. In some transgenic lines, a change in the carbohydrate composition of the wood, an increase in the cell wall thickness, and a decrease in the rate of decomposition of wood were observed.

Substrate specificity among Diptera in decaying bioenergy wood: can they be conserved by the same measures as are currently applied to beetles?

Although threatened by forestry, our knowledge concerning saproxylic insects is strongly biased towards well-known orders, mainly beetles (Coleoptera). The beetles have, therefore, formed the basis on which conservation measures of other groups have been formulated. Despite being more species-rich, the Diptera have been rather neglected. Moreover, our limited knowledge of the Diptera suggests that their demands on the dead wood substrate differ markedly from that of coleopterans. We tested if this is true by comparing the substrate requirements of dipteran and coleopteran species by analysing the affinities of species assemblages for logging residues differing in age, size, and tree species. Insects were reared out from the same samples of bioenergy wood from clear-cuts in Sweden. 15 species of Brachyceran flies were compared with 56 species of Coleoptera. We found the average level of specialisation to be similar between the two groups, but the dipterans had (contrary to the expectations) a higher proportion of specialists. Affinities for differently aged wood were similar. More dipterans than beetles were associated with the coarsest wood (diameter 9 cm–15 cm). More dipterans than beetles tended to be associated with aspen (Populus tremula), while Coleoptera tended to be more associated than Diptera with oak (Quercus) and spruce (Picea abies). We conclude that most recommendations for conserving the saproxylic beetle fauna also seem to benefit dipterans, but that the dipterans might be even more sensitive to which qualities of the wood that is preserved. The high conservation value of aspen is already recognised and our results for dipterans strengthen this. The high incidence of many dipteran species in logging residues suggests that many dipterans use sun-exposed environments.

Interspecific Variability of Water Storage Capacity and Absorbability of Deadwood

The aim of the study was to determine the water storage capacity and absorbability of deadwood of different tree species with varying degrees of decomposition. Coniferous (Silver fir—Abies alba Mill.) and deciduous (Common hornbeam—Carpinus betulus L., Common ash—Fraxinus excelsior L., Common alder—Alnus glutinosa Gaertn., and Common aspen—Populus tremula L.) species were selected for the research. The study focuses on the wood of dead trees at an advanced stage of decomposition. Deadwood samples were collected at the Czarna Rózga Nature Reserve in central Poland. Changes over time of the water absorbability and water storage capacity of deadwood were determined under laboratory conditions. The research confirmed the significance of the wood species and the degree of wood decomposition in shaping the water storage capacity and absorbability of deadwood in forest ecosystems. Fir wood was characterized by having the highest water storage capacity and water absorbability. Among deciduous species under analysis, aspen wood was characterized by having the highest water storage capacity and absorbability. Our research has confirmed that deadwood may be a significant reservoir of water in forests.

Biomass allocation and nutrient content of hybrid aspen clones grown on former agricultural land in Finland

ABSTRACT Vegetatively propagated hybrid aspen (Populus tremula × P. tremuloides) is one of the fastest growing tree species in Finland. To study clonal variation in element concentrations in wood, bark and branches, and the amount of elements bound in above-ground biomass, seven clones were selected from a field trial in Southern Finland, when the trees were 13 years old. Significant clonal differences in the growth and allocation of biomass in stem wood, stem bark and branches were found. On average, the biomass consisted of 56% of stem wood, 10% of stem bark and 34% of branches. The clone with the highest total biomass production also had the highest fraction of biomass allocated to branches (43%). The study also revealed significant clonal differences in the concentrations of most of the studied elements in wood, bark and branches, and in the amounts of elements bound in the leafless above-ground biomass. For most of the elements, the highest concentrations were found in the stem bark followed by branches. Hybrid aspen bark was especially rich in Ca compared to some other broad-leaved tree species. There were also significant clonal differences in the amount of heavy metals (Cd, Cu and Zn) bound in the biomass.

Сучасний стан дубових насаджень Східного Полісся

За матеріалами лісовпорядкування проаналізовано лісовий фонд Східного Полісся, зокрема розподіл площі дубових насаджень за походженням, групами віку, типами лісу та категоріями лісів. Досліджено лісівничо-таксаційні показники дубових лісів регіону в розрізі їхнього походження. Представлено результати досліджень особливостей розподілу площ і запасів дубових насаджень у різних категоріях лісів. Виявлено розбалансованість вікової структури дубових насаджень із суттєвим переважанням середньовікових насаджень незалежно від їхнього походження, а також пристиглих дубняків природного походження і молодняків насіннєвого штучного походження. Запропоновано проведення лісогосподарських заходів у дубових лісах Східного Полісся щодо оптимізації вікової структури насаджень і забезпечення їхнього відновлення природним насіннєвим шляхом.

Полевые испытания размноженных in vitro клонов осины (Populus tremula L.): рост, продуктивность, качество древесины, генетическая стабильность

The widespread introduction of highly productive and rot-resistant forms and hybrids of aspen (Populus tremula L.) into the forest production is constrained by the lack of effective methods of their vegetative reproduction. Achievements of modern forest biotechnology enable in vitro cloning of economically valuable aspen genotypes and obtain planting material for plantation forest growing. The study of the manifestation features of valuable traits and genetic stability of in vitro clones propagated in the field (ex vitro) is important for the development of effective and reliable propagation methods that guarantee the preservation of the genetic and economic value of parent trees for their sustainable and targeted reproduction. The results of genetic stability evaluation, growth dynamics, productivity and wood quality of three in vitro propagated aspen clones (6/3, 15/01, and 20/4) in the field are presented. Micropropagation was carried out by direct organogenesis using hormone-free nutrient media. According to the results of 17-year field trials, clones demonstrate good growth and sufficiently high productivity of stands; preserve the growth characteristics of parent trees, showing no signs of somaclonal variability. At the age of 17, the average height of the trees was 18–20 m; the strunk diameter was 25–30 cm; the trunk volume was 0.391–0.553 m3; the timber volume was 111–227 m3/ha at trees placing 4×4 and survival rate 44–71 %. High genetic stability of clones in vitro and ex vitro was revealed based on the results of analysis of microsatellite loci, ploidy level and mixoploidy. It is shown that the triploid clone 15/01, which has high myxoploidy level, is characterized by a higher preservation and better wood quality attributes (wooddensity and fiber length) than diploid clones. This is probably due to the optimal balanced ratio of cells with different ploidy levels (triploid, diploid, and aneuploid), which provides the most effective expression of genes in specific environmental conditions.For citation: Mashkina O.S., Shabanova E.A., Varivodina I.N., Grodetskaia T.A. Field Trials of in vitro Propagated Aspen Clones (Populus tremula L.): Growth, Productivity, Wood Quality, and Genetic Stability. Lesnoy Zhurnal [Russian Forestry Journal], 2019, no. 6, pp. 25–38. DOI: 10.17238/issn0536-1036.2019.6.25

Modeling forage potential for red deer (Cervus elaphus): a tree-level approach

Red deer (Cervus elaphus) are mixed feeders that consume both herbaceous and woody plants. As a consequence, intensive browsing on trees where red deer populations are particularly dense often leads to serious conflicts between the interests of forestry and hunting stakeholders. Therefore, understanding the density of deer that forest system can bear requires the ability to measure amount of potential forage provided by non-commercial tree species within a stand that serve as forage. Our objective was to build models that estimate forage potential (i.e., maximum biomass edible and accessible for consumption by red deer per tree) based on tree size [i.e., stem base diameter (d0)]. We developed models for three tree species commonly consumed by red deer in Central Europe, aspen (Populus tremula), goat willow (Salix caprea) and rowan (Sorbus aucuparia). To construct models of forage potential, we harvested 380 young (age of 2–15 years) trees on 14 sites in the Western Carpathians of Slovakia. Tree biomass was first divided into three components (stem bark, branches and foliage), each of which was subdivided into edible and non-edible portions based on branch diameter and height from the ground and then dried and weighed. We then quantified edible biomass by tree species, tree component and season (growing vs. dormant). The total amount of tree mass (forage potential) that could be consumed by red deer generally increased with tree size, but the relative contributions of different tree components varied by tree size, tree species and season. Our models predicted that the maximum forage potential per tree was ~ 500 g in aspen, 350 g in goat willow and 300 g in rowan in summer, and nearly 500 g in aspen, 300 g in goat willow and 250 g in rowan in winter. Together with theoretical knowledge and practical experience, our forage potential models can be used to help forest and wildlife managers both to better measure edible tree biomass for red deer populations and how edible tree biomass might be used to minimize the risk of deer damaging commercially valuable trees.

Impact of deadwood decomposition on soil organic carbon sequestration in Estonian and Polish forests

Key messageThe deadwood of different tree species with different decomposition rates affects soil organic carbon sequestration in Estonian and Polish forests. In warmer conditions (Poland), the deadwood decomposition process had a higher rate than in cooler Estonian forests. Soil organic matter fractions analysis can be used to assess the stability and turnover of organic carbon between deadwood and soil in different experimental localities.ContextDeadwood is an important element of properly functioning forest ecosystem and plays a very important role in the maintenance of biodiversity, soil fertility, and carbon sequestration.AimsThe main aim was to estimate how decomposition of deadwood of different tree species with different decomposition rates affects soil organic carbon sequestration in Estonian and Polish forests.MethodsThe investigation was carried out in six forests in Poland (51° N) and Estonia (58° N). The study localities differ in their mean annual air temperature (of 2 °C) and the length of the growing season (of 1 month). The deadwood logs of Norway spruce (Picea abies (L.) Karst.), common aspen (Populus tremula L.), and silver birch (Betula pendula Roth) were included in the research. Logs in three stages of decomposition (III–V) were selected for the analysis.ResultsThere were differences in the stock of soil organic carbon in two experimental localities. There was a higher soil carbon content under logs and in their direct vicinity in Polish forests compared to those in the cooler climate of Estonia. Considerable differences in the amount of soil organic matter were found. The light fraction constituted the greatest quantitative component of organic matter of soils associated with deadwood.ConclusionA higher carbon content in surface soil horizons as an effect of deadwood decomposition was determined for the Polish (temperate) forests. More decomposed deadwood affected soil organic matter stabilization more strongly than less decayed deadwood. This relationship was clearer in Polish forests. Higher temperatures and longer growing periods primarily influenced the increase of soil organic matter free light fraction concentrations directly under and in close proximity to logs of the studied species. The slower release of deadwood decomposition products was noted in Estonian (hemiboreal) forests. The soil organic matter mineral fraction increased under aspen and spruce logs at advanced decomposition in Poland.