Search Results (1,665)

Structures made of wood are used extensively in applications that require mechanical reliability under variable environmental conditions. Several softwood species were investigated, including pine (Pinus sylvestris L.), spruce (Picea abies), and larch (Larix decidua). This study investigated the tensile deformation behavior of each species with a special focus on the mechanical energy demand of the tensile process. Samples were conditioned in an aqueous saline medium for defined exposure periods and compared with controls. The energy of deformation was determined from stress–strain relationships of tensile tests under identical loading conditions. Results indicate that saline conditioning alters the tensile response of the examined wood species in a species-dependent way. Tensile strength increased in pine wood after exposure, whereas spruce and larch showed different trends depending on conditioning duration. A wide range of tensile strengths was recorded for all samples, ranging from 5.4 MPa to 102.0 MPa. Controlled saline exposure significantly influences the mechanical behavior of softwood species, as indicated by the findings. Evaluating wood performance under modified environmental conditions, both deformation energy and strength parameters should be considered. The main novelty of this study is the introduction of an energy-based description of tensile deformation, in which the total tensile work is calculated from force–displacement relationships, enabling differentiation of specimens with similar tensile strengths but fundamentally different deformation and failure properties. A practical advantage of the proposed energy-based approach is that it provides additional insight into the deformation tolerance and failure behavior of saline-conditioned wood, thus enabling a more reliable assessment of material performance under unpredictable environmental conditions. Full article

This study focuses on the spatial variation in seed germination characteristics of Picea glauca and P. mariana, prominent and widespread species within the Canadian boreal forest. The main objective was to determine seed germination requirements of geographically distinct seed collections of P. glauca and P. mariana. A total of 73 collections of P. glauca and 62 collections of P. mariana were selected across Canada and tested for germination under various temperatures. Base temperature (T_b) and thermal time required to reach 50% germination (TH₅₀) were derived from thermal model parameters for all seed collections. Correlation analyses between seed germination traits, geographic, and climatic variables were conducted. Base temperatures for germination of P. glauca ranged from 5.2 to 11.9 °C while P. mariana had base temperatures ranging from 6.2 to 12.8 °C, indicating a broader temperature range for the former to initiate germination. Optimal germination temperatures ranged from 15 to 20 °C for P. glauca and from 17.5 to 30 °C for P. mariana. Thermal time requirements for 50% germination were higher for P. glauca than for P. mariana, indicating that the former takes longer to germinate under the same temperature conditions. Latitudinal-related variables such as temperature of sites had a stronger influence on germination relative to precipitation or potential evaporation and affected seed viability, final germination and germination capacity of all seed sources. Seed viability was lower in northern seed collections and germination capacity was diminished at lower temperatures for both species. The results from this study can be built into models predicting shifts in boreal forest species under climate change. Full article

Climate change is increasing forest vulnerability, and extreme disturbances such as windstorms can cause major economic and social losses. Forest recovery after such events often relies on salvage logging and extensive planting of seedlings produced in nurseries to rapidly restore forest cover. While effective, these interventions, particularly when applied over large areas, may also produce environmental impacts that are largely absent under spontaneous regeneration. Following the Vaia windstorm in northern Italy in 2018, several reforestation interventions were implemented to restore forest cover. We focused on one intervention and conducted a life cycle assessment to quantify its environmental impacts, using the planting of 800 four-year-old Norway spruce (Picea abies (L.) H. Karst) seedlings as the functional unit, combined with chipping on the site of forest biomass residues. The largest contributions were to global warming potential (443.91 kg CO₂ eq), human toxicity (167.72 kg 1,4-DCB eq), and freshwater ecotoxicity (142.43 kg 1,4-DCB eq). Seedling production and field establishment dominated these impact categories. Among field operations, manufacturing and transporting plastic shelters for seedling protection accounted for the highest share of global warming potential. Full article

Outbreaks of Ips hauseri, a major bark beetle pest in Central Asian Picea schrenkiana forests, have intensified under climate warming and prolonged droughts. However, the reproductive behavior and gallery construction strategies of this species remain poorly understood, limiting our ability to predict its population dynamics. Here, we dissected 219 galleries from infested spruce trees in Hami, Xinjiang, during an outbreak period (2024–2025). We identified 11 distinct gallery morphologies, with harem size (number of females per male) ranging from one to seven. Gallery length was positively correlated with egg production. Reproductive output peaked at a harem size of five, beyond which both gallery dimensions and fecundity declined. Host tree diameter at breast height (DBH) significantly influenced gallery complexity, with larger trees supporting more maternal galleries. Upward-oriented galleries were longer and contained more eggs than downward ones. Intraspecific competition, mediated by gallery adjacency and spatial orientation, strongly affected offspring development. Our results demonstrate that I. hauseri exhibits flexible gallery architecture and reproductive adjustments in response to resource availability and competition—a behavioral plasticity that likely contributes to its outbreak potential. Monitoring gallery morphology and harem size could enhance early detection and population forecasting for this increasingly damaging forest pest. Full article

Wind disturbance is the major driver of forest damage in Northern Europe, particularly during late autumn and winter when cyclonic activity might coincide with unfrozen soil conditions. We quantified the thermal regime of periodically waterlogged mineral soils in relation to snow cover thickness (SCT) in hemiboreal forests of Latvia. The study was conducted in 15 forest stands dominated by birch (Betula spp.), Scots pine (Pinus sylvestris L.), and Norway spruce (Picea abies (L.) H. Karst.) during two contrasting winters (2023/2024 and 2024/2025) across two regions differing in local climatic conditions. Soil temperature was monitored at 0, 10, and 20 cm depths, while SCT was measured at five points per plot. Linear mixed-effects models were used to assess the effects of air temperature, precipitation, region, season, and species composition to snow cover thickness (SCT) and effect of the other parameters to soil temperatures. SCT varied strongly between regions and seasons. Snow accumulation was lower in pine- and spruce-dominated stands compared to birch stands. Formation of snow layer increased soil temperatures at the surface, whereas SCT had a more pronounced insulating effect at depths of 10–20 cm, especially during prolonged snow cover (F = 15.43 − 54.25, p < 0.001). Heat transfer from deeper layers further enhanced thawing under waterlogged conditions. Snow cover significantly insulates soil in a depth-dependent manner, with its magnitude varying across regions and seasons. Promoting mixed-species stands and selecting deep-rooted species, such as birch, can enhance the formation of frozen soil, and thus soil–root anchorage, reducing wind damage risk on periodically waterlogged soils. Full article

Accurate spatial information on individual tree locations is essential for precision forestry, the integration of field and remote sensing data, and tree-level forest analyses. This study compared the positional accuracy and tree identification performance of four tree-mapping approaches: legacy paper maps, a pseudolite-based field positioning system (TerraHärp), drone-based laser scanning, and mobile laser scanning (MLS). The analysis was conducted in five long-term experimental forest sites in Lithuania, comprising pine- and spruce-dominated stands with varying stand densities. Tree locations derived from legacy maps and the TerraHärp system were compared to assess systematic and random positional discrepancies. TerraHärp-derived tree positions were subsequently used as a reference to evaluate the laser scanning-based methods. Positional accuracy was assessed using Hotelling’s T² test, root-mean-square error, and the National Standard for Spatial Data Accuracy (NSSDA), while spatial autocorrelation of deviations was examined using Moran’s I. The results indicated that discrepancies between TerraHärp and legacy maps were dominated by systematic horizontal shifts in the historical maps, whereas random positional variability was relatively small and consistent across stand types. Drone-based laser scanning showed a strong dependence of tree identification accuracy on stand density and mean tree diameter. Overall, CHM-based segmentation yielded more accurate tree identification than 3D point cloud segmentation, with mean F1-scores of 0.78 and 0.72, respectively. Positional accuracy varied by method, with the largest errors from CHM apexes and highest 3D point cloud points (mean NSSDA ≈ 1.8–2.0 m), improved accuracy using the lowest 3D cluster points (1.45–1.72 m), and the highest accuracy achieved using mobile laser scanning (mean NSSDA 0.76–0.90 m; >95% of trees within 1 m). These results demonstrate that pseudolite-based field mapping provides a reliable reference for high-precision tree location and for integrating field and laser scanning data in managed conifer stands. Full article

The application of natural polysaccharides and their sulfated derivatives have already been successfully implemented in the pharmaceutical and food industries, in particular. The present study is concerned with modifying a predominant polysaccharide in the composition of spruce wood, galactoglucomannan (GGM), by sulfation via a urea-sulfamic acid complex in a 1,4-dioxane medium. By varying the sulfation process duration from 30 to 180 min, six novel GGM sulfate samples with different degrees of substitution (DS) of 0.4–1.2 were obtained and studied with a combination of modern physicochemical methods: elemental analysis, Fourier transform infrared (FTIR) spectroscopy, and gel permeation chromatography (GPC). It has been revealed that the sulfation of GGM proceeds without degradation of the main polymer chain, as evidenced by the shift in the main peak toward the high-molecular-weight region in the GPC curves. Moreover, modification of the polysaccharide leads to a significant transformation of the molecular conformation from a dense sphere to a random coil (α from 0.30 to 0.76). Furthermore, it has been determined that sulfate-substituted groups of the GGM tended to decrease the scavenging capacity of the 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals. However, the 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assay showed an increase in the free radical inhibitory capacity of sulfated polysaccharides. This is attributed to the structural and conformational properties of the polysaccharide sulfate derivatives. The maximum anticoagulant activity (ACA) of sulfated GGM (SGGM) is 21.19 ± 2.89 IU/mg and increases with increasing sulfation duration. Full article

Mixed forests provide several ecosystem service benefits, and they also often show higher productivity than pure forests. In mixed forests, several interactions among tree species occur, with size-symmetric and size-asymmetric competition being particularly important. We studied diameter growth of European beech in pure stands and in mixtures with oak, maple, pine, spruce, fir, and spruce and fir combined on extremely diverse beech sites in Slovenia, using forest inventory sample plots (n = 26,793, 500 m² each). For each mixture, we developed models of 10-year individual tree diameter increment (id) using natural splines and incorporating tree, competition, stand, site, and climate variables that were mainly gathered in regular forest inventories. Competition was represented using simple indices: stand basal area (BA) for size-symmetric competition, basal area of overtopping trees (BAL) for size-asymmetric competition, and reduced competition due to harvesting (CUT). The models revealed differences among mixtures and a strong influence of competition. Id was among the lowest in pure stands and substantially higher in mixtures, indicating strong intraspecific competition. Overall, size-symmetric competition was more influential, but size-asymmetric competition appeared important in some mixtures. We recommend growing beech in mixtures with other species and applying a forest management approach that accounts for competition symmetry, which proved crucial in each mixture. Full article

Wood, which is flammable, is commonly used as a building material and can be improved using a suitable surface treatment. A promising coating solution is polyurea, featuring properties like flexibility, mechanical resistance, resistance against water, etc., but it is also easily flammable. Expandable graphite (EG) is effective as a flame retardant and environmentally suitable. In this study, we studied the suitability of polyurea improved with EG. Spruce wood samples with dimensions of 50 mm × 40 mm × 10 mm were divided into eight groups, each including five samples. Each group was subjected to two applications of polyurea and EG in various combinations to examine the best combination with the lowest mass loss. The second component of the experiments aimed to examine the effectiveness of EG, which was applied in different weights. During the experiments, samples were thermally loaded in an apparatus for 10 min, where a heat flux of 30 kW·m⁻² was applied to the sample surface and the mass loss was continuously recorded. Lastly, thermal analysis was performed. The best results were observed for the combination of NEOPROOF mixed with 0.3 g of EG covered with NEODUR. The thermal analysis results revealed substantial differences: NEOPROOF, a polyurea, had only one degradation step, while NEODUR, which also contained polyurethanes, decomposed in several steps. Full article

Pulse pressure (PP) reflects ventricular stroke volume and arterial compliance, but its utility as a marker of cardiac disease in animals is not well established. This study evaluated the association between PP and echocardiographically confirmed cardiac abnormalities in dogs and horses and assessed its potential in pre-anesthetic evaluation. Clinical and echocardiography examination of 20 dogs and 20 horses was sufficient for inter-group comparisons and assignments to a Cardiac group (echocardiographically confirmed cardiac disease) or a Control group (healthy animals). Non-invasive oscillometric blood pressure was measured, and PP was calculated. Animals with cardiac abnormalities showed significantly higher PP but not mean arterial blood pressure (MAP) compared with healthy subjects. In horses, PP was approximately 22 mmHg higher in the Cardiac group (p = 0.042), while in dogs, the increase was 25 mmHg (p < 0.001). Regression analysis confirmed cardiac status as an independent predictor of elevated PP (p = 0.001) with excellent and good discriminatory performance between healthy and diseased dogs (AUC = 0.90; 95% CI: 0.77–1.00) and healthy and diseased horses (AUC = 0.81; 95% CI: 0.61–1.00), respectively. These results suggest that PP may serve as a sensitive and practical hemodynamic indicator of underlying cardiac disease. Full article

The search for antagonistic microorganisms as alternatives to chemical pesticides is an urgent priority in sustainable agriculture. Previously, we isolated several bacterial isolates from spruce plants, and one of them, identified as Bacillus atrophaeus R7PjV2-12, showed strong antagonistic properties against plant pathogens such as Magnaporthe oryzae, Fusarium avenaceum, and Erwinia billingiae. Given its strong fungicidal properties, we decided to sequence the complete genome of this bacterium to determine how it can inhibit fungal growth. The whole genome size of B. atrophaeus R7PjV2-12 was 4,127,644 bp with 4032 open reading frames. B. atrophaeus R7PjV2-12 genome possessed clusters of secondary metabolites with a complete set of genes with 100% similarity representing clusters of biosynthesis of bacillin, bacillibactin, subtilosin A, and fungicin, which indicates the studied strain’s ability to synthesize these substances. Thus, this paper has shown and discussed the potential importance of B. atrophaeus R7PjV2-12 for biocontrol of pathogenic microorganisms in agriculture. Full article

Forest fertilization is commonly used to enhance tree growth and carbon (C) sequestration, especially in nutrient-poor boreal forests. However, it also poses several environmental risks, including shifting ground vegetation community composition and a reduction in species diversity. This study evaluated how ground vegetation species composition responded to forest fertilization with ammonium nitrate and wood ash across forest stands with varying dominant tree species, age groups, and site types. Ground vegetation assessment was performed during the one to three years following fertilizer application. We conducted detrended correspondence analysis (DCA) to examine compositional differences in ground vegetation between control and fertilized plots and to identify ecological factors underlying dataset variation. Ordination was based on species percentage cover data, with soil chemical parameters and stand inventory metrics providing environmental context for interpreting the results. Additionally, permutational multivariate analysis of variance (PERMANOVA) was conducted to evaluate whether vegetation composition differed across the experimental design factors. Forest site type and stand developmental stage were the primary drivers of understory composition, with fertilization effects being statistically significant but ecologically modest (0.9–14.2% of variation explained by fertilization in PERMANOVAs). Wood ash treatments showed greater compositional divergence from controls than ammonium nitrate alone. Fertilization effects varied with stand age, with significant responses in middle-aged and pre-mature Norway spruce stands but not in young stands. Despite modest compositional changes, fertilization achieved substantial productivity gains (volume increment increases of 20–60% compared to controls depending on species and site conditions), suggesting that moderate fertilization for timber production can be implemented without dramatic changes to ground vegetation. These results reflect short-term responses (1–3 years after fertilization) and should therefore be interpreted as early ecological effects rather than long-term ecosystem changes. Full article

Bark beetle infestations and other natural disturbances have increasingly affected Norway spruce (Picea abies (L.) Karst.) forests across Europe resulting in devaluation and decreased applicability of woody biomass of such trees. The aim of this research was to investigate the extractive content of bark beetle-attacked and dead wind-damaged Norway spruce trees relative to healthy trees, in order to assess their potential for extractives recovery. After harvesting, three discs were dissected along the stem height of each tree, and samples of sapwood, heartwood, knots, and bark were collected. Sequential extraction of the samples was performed using cyclohexane and acetone–water mixture in an accelerated solvent extractor. Lipophilic and hydrophilic extractives were determined gravimetrically, while total phenols and proanthocyanidins were measured by UV–Vis spectrophotometry. Results showed that knotwood contained the highest amounts of hydrophilic extractives and total phenols among investigated tissues. Knots of healthy trees contained the highest amount of hydrophilic extractives (52.4% w w⁻¹), while knots of dead wind-damaged trees contained significantly higher content of total phenols (8.8% w w⁻¹). The total phenols in bark beetle-attacked and healthy trees were 7.1% w w⁻¹ and 7.2% w w⁻¹, respectively. The sapwood and heartwood of dead wind-damaged trees had higher content of hydrophilic extractives (3.4% and 2.3% w w⁻¹) than healthy and bark beetle-attacked trees. Bark from healthy trees contained more total phenols (2.7% w w⁻¹) than bark of bark beetle-attacked trees, while proanthocyanidin contents in bark were comparable among three groups of trees. Our findings revealed that woody biomass from bark beetle-attacked and dead wind-damaged Norway spruce trees contains significant levels of phenolics, indicating high potential for extracting valuable compounds in biorefineries. Full article

The spatial localization of plant secondary cell wall polymers is a controversial issue. A relief of parallel-organized cellulose microfibrils was discovered, on the surface of which spherical nanoparticles were visualized. Spherical nanoparticles with a diameter of 20–50 nm were isolated using size exclusion chromatography from an aqueous extract of differentiating xylem of Norway spruce and visualized by SEM and AFM. The composition of isolated nanoparticles was determined by pyrolytic GC-MS, ¹H NMR spectroscopy, and nitrobenzene oxidation, followed by separation of the products by liquid chromatography. Lignin was detected in the isolated nanoparticles already at the stage of cell wall formation. The hypothesis about the intracellular synthesis of lignin was proposed based on the results obtained. Lignin in the form of a lignocarbohydrate complex is formed not in the cell wall, but inside the cell. The formation of lignin–carbohydrate complexes occurs in Golgi apparatus and vesicles, which discharged into the inner surface of the cell wall simultaneously with the deposition of cellulose microfibrils. A new model of the structure of secondary cell wall postulates the formation of cellulose microfibrils surrounded by lignin–carbohydrate spherical complexes having a carbohydrate shell and an aromatic core. Full article

The probability that female bagworms (Lepidoptera: Psychidae) are in mating time-in (live pheromone calling) was recorded in three bagworm species: Oiketicus kirbyi in a Costa Rican oil palm plantation in 1993–1994; Metisa plana in Malaysian oil palm plantations during five consecutive generations of bagworms in 1996; and Thyridopteryx ephemeraeformis on ornamental trees in the Midwest United States. Because females entirely reproduce within their bag (mate attraction, copulation, and oviposition), it is possible to assess the mating success of time-out females (dead individuals from an ongoing generation that either mated or died as a lifelong virgin) and incidence of calling females that may or may not mate before death. Synchronous larval development and discrete (non-overlapping) generations imply a declining proportion of live calling females over time in all three bagworm species: ‘young’ calling females prevail in the early season as opposed to a majority of time-out (post-reproductive) females in the late season. Calling females are long-lived relative to males (one-day lifespan) and thus expected to mate as adults when abundance of males is high and/or female longevity exceeds three days. A low mating success of calling females is associated with extreme protogyny (early season male shortage; O. kirbyi in 1994) or late adult emergence in populations at the edge of the distribution range (T. ephemeraeformis at latitudes > 41° N in 2019). Full article