Search Results (113)

Cavities are an essential structural element in forest ecosystems. In European forests, most cavities are excavated by the most numerous woodpecker species, the great spotted woodpecker (GSW) (Dendrocopos major). The impact of management practices on the availability of nesting sites for birds remains an important researched topic. Do the nesting sites of the GSW differ between protected and commercially managed areas? We analysed 173 GSW nesting sites in a large forest in Poland, divided into a national park and commercial forests. The aspen (Populus tremula) was the most preferred among tree species in both forest areas. In protected forests, cavities were less frequently excavated in the Scots pine trees (Pinus sylvestris) (10%) than they were in managed forests (30%). The significantly higher frequency of cavities excavated in a given tree in commercial forests suggests limited availability of suitable nesting trees. The GSW strongly preferred trees with wood softened by fungal decay for cavity excavation. Over 80% of all cavity trees were infested with wood-decaying fungi, with no differences between protection regimes. In commercial forests with a high proportion of pine trees, cavities can be excavated only in softened wood in the older stands. Protective recommendations include retaining more trees in poor health condition in commercial forests and ensuring an admixture of softwood tree species such as the aspen, birch (Betula sp.), and black alder (Alnus glutinosa) in commercial stands. Full article

Sawdust represents a locally available lignocellulosic resource that may complement ruminant diets during periods of forage shortage. This study evaluated the feeding value of birch (Betula pendula) sawdust subjected to physical and chemical processing using a stepwise experimental approach. Steam-exploded and fresh sawdust were treated with 0, 4% ammonia, or 4% sodium hydroxide in a 2 × 3 factorial design and initially evaluated by in vitro gas production, dry matter digestibility, and fermentation pH. Based on these results, selected materials were further assessed for rumen dry matter and fiber degradation using the in sacco technique in cannulated dairy cows, with untreated and ammonia-treated wheat straw included for comparison. In addition, steam-exploded sawdust was compared with wheat straw and grass silage for in vivo digestibility in sheep. A pilot study also tested aspen (Populus tremula) sawdust in lactating cow diets. Steam explosion substantially reduced fiber fractions, particularly hemicellulose, and increased residual carbohydrates, resulting in higher gas production and in vitro digestibility compared with fresh sawdust (p < 0.05). Ammonia treatment markedly increased crude protein content, whereas sodium hydroxide primarily increased ash concentration. In sacco, steam-exploded birch showed similar or higher ruminal dry matter and neutral detergent fiber degradation compared with ammonia-treated wheat straw, while untreated fresh birch remained largely undegraded. In vivo, steam-exploded sawdust exhibited greater organic matter digestibility and net energy than untreated wheat straw but remained less digestible than grass silage (p < 0.0001). A pilot feeding test with lactating dairy cows demonstrated good acceptance of untreated aspen sawdust as a partial roughage substitute under non-standardized conditions. Overall, the results indicate that steam-exploded sawdust has potential as a complementary roughage source for ruminants when conventional forages are limited. Full article

Intensive agriculture, ecosystem degradation, and declining soil quality highlight the urgent need for sustainable land use strategies. The cultivation of short-rotation woody crops (SRC), combined with fertilization using sewage sludge digestate (SSD), offers a promising approach to recycle nutrient-rich waste and promote soil organic carbon (SOC) accumulation. This study evaluated SOC concentrations, stocks and their spatial distribution in the 0–20 cm soil layer under SRC cultivation, with and without SSD fertilization, across contrasting soil types in Eastern Lithuania. The investigated soils included mineral (Luvisols (LV), Retisols (RT), Planosols (PL), Arenosols (AR)), organo-mineral (Gleysols (GL)), and organic soils (Histosols (HS)), representing textures from sand to peat and classified according to the World Reference Base for Soil Resources (WRB). Part I assessed baseline SOC variability in unproductive areas planted with hybrid poplars (Populus spp.) and hybrid aspen (Populus tremula × P. tremuloides) up to 20 years old. Part II examined SOC changes in three SRC fields of different ages (3–10 years), including unfertilized and SSD-fertilized stands. SOC concentrations increased consistently from mineral (1.14–1.80%) to organo-mineral (2.13–3.20%) and organic soils (6.37–17.53%). Heavier-textured soils accumulated more SOC than lighter soils, showing a strong positive correlation between SOC and soil texture (r = 0.82, p ≤ 0.01). SRC cultivation increased SOC across all soil types, while SSD fertilization further enhanced accumulation, with fertilized fields showing SOC increases of 0.50–1.07 percentage points and carbon stocks by 18.8–41.7 t ha⁻¹, compared with smaller increases in unfertilized fields. Spatial visualization of SOC further highlighted long-term accumulation patterns across soil types, confirming the trends observed under SRC cultivation and SSD fertilization. Full article

Tree-related microhabitats (TreMs) are small features on living or dead trees that offer habitat, shelter, breeding sites, or food for many organisms, making them useful indicators of forest-dwelling species. Despite increasing research on TreMs in Europe, most published studies have focused on temperate regions, leaving a relative paucity of data from hemiboreal forests. In our research, we aimed to fill the knowledge gap, offering insight into the occurrence patterns and factors influencing TreM diversity in the hemiboreal region. We analyzed data from the National Forest Inventory in Latvia, comprising information on 168,839 trees across 5653 sample plots. The most common TreMs were bark loss (6.1% of trees), bryophytes (2.6%), and perennial polypores (2.6%). TreMs occurred more frequently on deciduous than on coniferous trees, on larger trees (diameter at breast height more than 60 cm), and on dead trees compared to living ones. Forest type and signs of recent cutting also had significant effects on TreM richness at both the tree and plot scales, whereas forest protection status was significant only at the plot scale. TreMs such as buttress-root concavities and ivy or liana cover, which are common in temperate Europe, had a low relative occurrence in our study. The occurrence of specific TreM forms was strongly tree-species dependent: exudates were much more common on live Picea abies (4.0%) than on other species, whereas Populus tremula had a higher occurrence of fruiting bodies of saproxylic fungi and slime moulds (2.0%). The highest occurrence of crown deadwood was observed on Quercus robur. Overall, dead trees play a particularly important role, providing both a higher total number of TreMs and certain TreM types more frequently. Given their high TreM richness, dead and large trees represent important structural components supporting biodiversity in hemiboreal forests. Full article

Epiphytic corticolous lichens are vital components of forest ecosystems, yet their species composition and distribution patterns along altitudinal gradients in the Populus tremula forests of Barluk Mountain National Nature Reserve, Xinjiang, China, remain understudied. This study analyzes the diversity and distribution of epiphytic corticolous lichens in these forests along an altitudinal gradient. Field research was conducted at six sites (940–1450 m) from June to July 2023–2024, with samples collected from 576 quadrats on 48 Populus tremula trees. Lichen identification involved morphological, anatomical, and chemical analyses. Data on cover and frequency were analyzed to calculate importance values (IV), diversity indices, and floristic similarity (Sørensen’s index). NMDS and TWINSPAN were used to explore distribution patterns along the altitude gradient. In total, 28 epiphytic lichen species were identified, with diversity indices peaking at 1040 m. Dominant species exhibited significant variations in IV across altitudes (P < 0.05), and NMDS/TWINSPAN revealed distinct community clustering associated with elevation. Sørensen’s index indicated a low similarity (<30%) between the highest and lowest altitude sites. This study provides a baseline for biodiversity conservation and forest management in arid and semi-arid land mountain ecosystems. Full article

Developing sustainable and eco-friendly approaches to plant propagation, development, and protection is a common goal for the scientific community. Plant cell culturing enables us to obtain plant clones and produce biomolecules under controlled conditions. The same principle can be applied to the harvesting of extracellular vesicles (EVs). These nanosized structures are key players in cell communication and stress response by carrying, protecting, and delivering important biomolecules. Raising interest in the scientific community, EVs have been successfully tested as nanocarriers for therapeutics and biotechnology. However, despite their potential, there remains a gap in research on scalable, reliable sources for EV production. Our goals were to optimize EV production and isolation from induced poplar callus cell lines (Populus tremula × P. alba) and load these with RNA to validate their functionality as nanocarriers. We were able to isolate 2.5 × 10¹⁰ EVs/g, highlighting the potential for these lines to be mass-produced. Furthermore, RNA loaded into EVs through electroporation was internalized into Botrytis cinerea hyphae, reassuring their potential in protecting and delivering cargo. Our findings contribute to EV characterization and demonstrate that RNA delivery through EV transport could be a safe and effective method for future EV-based technologies in plant protection. Full article

Synthetic anthelmintic drugs not only contribute to the development of pathogen resistance and environmental pollution but also to the development of pathogen resistance. Therefore, identifying the anthelmintic properties of widely used medicinal plants could be of great practical interest to veterinary and human medicine. In our experiment, we evaluated the in vitro survivability of the noninvasive and invasive (L_1–2 and L_3, respectively) larvae of Strongyloides papillosus and Haemonchus contortus subject to aqueous solutions of ethanolic tinctures of traditional medicinal plants (46 species). Most of the plant species we studied belonged to the families Asteraceae (Achillea millefolium, Arctium lappa, Artemisia absinthium, Bidens tripartita, Calendula officinalis, Cynara cardunculus var. scolymus, Echinacea purpurea, Helichrysum arenarium, Inula helenium, Matricaria chamomilla, Silybum marianum, Tanacetum vulgare, Taraxacum officinale, Tragopogon porrifolius), Rosaceae (Agrimonia eupatoria, Fragaria vesca, Sanguisorba officinalis), and Lamiaceae (Leonurus cardiaca, Mentha × piperita, Origanum vulgare, Salvia officinalis, Thymus vulgaris). Other plant families were represented by 1–3 species: Fabaceae (Glycyrrhiza glabra, Hedysarum alpinum, Trifolium pratense), Salicaceae (Populus nigra, P. tremula, Salix alba), Fagaceae (Quercus robur), Betulaceae (Betula pendula), Juglandaceae (Juglans regia), Rhamnaceae (Frangula alnus), Acoraceae (Acorus calamus), Apiaceae (Foeniculum vulgare), Caprifoliaceae (Valeriana officinalis), Cucurbitaceae (Cucurbita pepo), Equisetaceae (Equisetum arvense), Ericaceae (Vaccinium vitis-idaea), Gentianaceae (Centaurium erythraea), Hypericaceae (Hypericum perforatum), Malvaceae (Althaea officinalis), Plantaginaceae (Linaria vulgaris, Plantago major), Poaceae (Zea mays), Polygonaceae (Polygonum aviculare), and Ranunculaceae (Nigella sativa). We determined Artemisia absinthium, Inula helenium, Matricaria chamomilla, Salvia officinalis, and Populus nigra, whose aqueous solutions of alcohol tinctures demonstrated nematocidal properties. The other plants we studied did not affect the viability of parasitic nematode larvae. Full article

Urban tree biodiversity represents a valuable natural resource. However, some fast-growing tree species with limited esthetic value play an important ecological role by colonizing degraded areas, such as closed landfills. Our observations indicate that trees like Betula pendula (Roth), Acer negundo (L.), and Populus tremula (L.) reached the size of adult trees in less than 30 years after the landfill’s closure in the 1990s, forming a nature area similar to a natural forest. A resident survey conducted among the inhabitants of Zgierz confirmed that the lack of space provides opportunities for various forms of recreation. The example analyzed indicates a trend that can be replicated in other cities with minimal human intervention and low financial costs for landfill reclamation. The case study presents an ecological approach to managing degraded sites, where nature determines the quality of the soil environment by eliminating pollutants from the residential surroundings. Furthermore, the research framework provides a basis for developing future models for cleaning up urban landfill sites and promoting placemaking. This pilot study shows a model for old landfills in Europe with well-developed spontaneous vegetation that can be transformed into recreation and sports facilities in the urban areas with industrial past times. Full article

Eurasian aspen (Populus tremula L.) is a tree species with recognised ecological and economic importance for both natural and plantation forests. For the fast cloning of selected aspen genotypes, the method of plant propagation through in vitro culture (micropropagation) is often recommended. The efficiency of this method is related to the use of shoot-inducing chemical growth regulators, among which cytokinins, a type of plant hormone, dominate. Although cytokinins can inhibit rooting, this effect is avoided by using cytokinin-free media. This study sought to identify concentrations and combinations of growth regulators that would stimulate one type of P. tremula organogenesis (either shoot or root formation) without inhibiting the other. The investigated growth regulators included cytokinin 6-benzylaminopurine (BAP), auxin transport inhibitor 2,3,5-triiodobenzoic acid (TIBA), auxins indole-3-acetic acid (IAA) and indole-3-butyric acid (IBA), gibberellin biosynthesis inhibitor paclobutrazol (PBZ), and a gibberellin mixture (GA₄/₇). Both BAP and TIBA increased shoot number per P. tremula explant and decreased the number of adventitious roots, but TIBA, in contrast to BAP, did not inhibit lateral root formation. However, for the maintenance of both adventitious shoot and root formation above the control level, the combination of PBZ and GA_4/7 was shown to be especially promising. Full article

The transition to sustainable energy sources has intensified interest in lignocellulosic biomass (LCB) as a feedstock for second-generation biofuels. However, the inherent structural recalcitrance of LCB requires the utilization of an effective pretreatment to enhance enzymatic hydrolysis and subsequent fermentation yields. This manuscript presents a novel, single-step, and optimized nitrogen explosive decompression system (NED 3.0) designed to address the critical limitations of earlier NED versions by enabling the in situ removal of inhibitory compounds from biomass slurry and fermentation inefficiency at elevated temperatures, thereby reducing or eliminating the need for post-treatment detoxification. Aspen wood (Populus tremula) was pretreated by NED 3.0 at 200 °C, followed by enzymatic hydrolysis and fermentation. The analytical results confirmed substantial reductions in common fermentation inhibitors, such as acetic acid (up to 2.18 g/100 g dry biomass) and furfural (0.18 g/100 g dry biomass), during early filtrate recovery. Hydrolysate analysis revealed a glucose yield of 26.41 g/100 g dry biomass, corresponding to a hydrolysis efficiency of 41.3%. Fermentation yielded up to 8.05 g ethanol/100 g dry biomass and achieved a fermentation efficiency of 59.8%. Inhibitor concentrations in both hydrolysate and fermentation broth remained within tolerable limits, allowing for effective glucose release and sustained fermentation performance. Compared with earlier NED configurations, the optimized system improved sugar recovery and ethanol production. These findings confirm the operational advantages of NED 3.0, including reduced inhibitory stress, simplified process integration, and chemical-free operation, underscoring its potential for scalability in line with the EU Green Deal for bioethanol production from woody biomass. Full article

Soil pollution is a global threat that seriously affects biodiversity in (agro)ecosystems and may compromise water and food quality. Therefore, the ability of tree species (Populus tremula, Salix caprea, and Betula pendula) to accumulate and phytoextract specific toxic heavy metals from soil was investigated. The study was conducted in and near relict mining areas of Freiberg (Germany) and sampling sites selected according to their spatial location relative to potential sources of metal(loid)s. The concentrations of geogenic (P, Fe, Mn, Ca) and pollutant (Pb, Cd, Zn, As) elements in soil and the present trees were measured using ICP-MS. The highest total soil concentrations of As (8978 µg g⁻¹) were found within the Davidschaft mining area, and for soil Pb, both in the Davidschaft vicinity (328 µg g⁻¹) and mining area (302 µg g⁻¹). Unexpectedly, the highest soil Zn (0.64 mg g⁻¹) and Cd (3.5 mg g⁻¹) concentrations were found in Freiberg city Forest. The lowest soil concentrations of pollutants (As, Cd, Pb, and Zn) were recorded for Seifersdorf. Total soil P was highest in Colmnitz, but Ca, Mn, and Fe concentrations were very similar across all sites. The available concentration of all measured toxic elements in the soil generally decreased in the order Davidschaft > Davidschaft vicinity, Colmnitz > Seifersdorf = Freiberg city forest. All studied tree species had higher concentrations of the essential elements in leaves than in branches. Generally, higher values of bioaccumulation coefficients (especially for Cd) were found for Salix caprea compared with Populus tremula and Betula pendula. Full article

Plant U-box E3 ubiquitin ligases (PUBs) serve as crucial regulators of protein degradation and are fundamentally involved in plant developmental processes and stress response mechanisms. Despite their well-characterized roles in model plant species, the PUB gene family in the hybrid poplar (Populus alba × P. tremula var. glandulosa) remains poorly understood. By conducting a comprehensive genome-wide analysis, we identified 152 PUB genes in poplar and phylogenetically classified them into five distinct clades based on a comparative analysis with Arabidopsis thaliana and tomato PUB homologs. The structural characterization revealed that numerous PagPUB proteins possess additional functional domains, including ARM and WD40 repeats, which are indicative of potential functional diversification. Genomic distribution and synteny analyses demonstrated that the expansion of the PUB gene family predominantly resulted from whole-genome duplication (WGD) events, with evolutionary constraint analyses (Ka/Ks ratios < 1) suggesting strong purifying selection. An examination of the promoter region uncovered an abundance of stress-responsive cis-elements, particularly ABRE and MYB binding sites associated with abiotic stress and hormonal regulation. Transcriptome profiling demonstrated both tissue-specific expression patterns and dynamic regulation under diverse stress conditions, including drought, salinity, temperature extremes, and pathogen infection. Our findings provide the first systematic characterization of the PUB gene family in poplar and establish a valuable framework for elucidating their evolutionary history and functional significance in environmental stress adaptation. Full article

Forest trees significantly affect human life. The spread of pathogens, including bacterial ones, poses a serious threat to their health. Despite this, however, the species composition and distribution of pathogenic bacteria, as well as the etiology of common diseases affecting forest trees, remain virtually unstudied. In this study, we, for the first time, describe different species of Pseudomonas and Pantoea as new etiological agents associated with the symptoms of leaf spotting and wood darkening on Acer tataricum L., Fraxinus pennsylvanica L., Ulmus minor Mill. Ulmus laevis Pallas. and Populus tremula L. For the identification of bacteria species, we used an integrated approach based on the characterization of their morphology, biochemistry, physiology and genetics. Phylogenetic analysis was performed using multilocus typing for five genes for Pseudomonas and six genes for Pantoea. Leaf spotting on A. tataricum, F. pennsylvanica, U. minor and U. laevis was shown to be caused by Pseudomonas cerasi, Pseudomonas congelans, Pseudomonas graminis, Pseudomonas syringae and Pantoea agglomerans both in monoinfection and coinfection. Wood darkening in U. minor U. laevis and P. tremula was found to be associated with the presence of Pantoea sp. and P. agglomerans. The coinfection of forest trees with bacteria of the genera Pseudomonas and Pantoea indicates a complex mechanism of interaction between the two populations, which will be the subject of future studies. Full article

The Short Internodes-Related Sequence (SRS) family is a class of transcription factors unique to plants that are essential for controlling their growth, development, and stress responses. Nevertheless, information regarding the characterization and biological function of poplar SRS family members remains limited. In this study, we identified 10 members of the SRS gene family in the genome of Populus tremula using bioinformatics, distributed on seven chromosomes and named PtSRS01-PtSRS10 based on their locations. Our phylogenetic analysis results indicated that PtSRS genes can be categorized into five subfamilies and that members of each subfamily have similar gene structures and motifs. Collinearity analysis indicated that the expansion of the PtSRS gene family is caused by segmental duplication and is influenced by purifying selection during its evolutionary process. Cis-acting element analysis revealed that PtSRS was enriched in cis-acting elements related to growth and development, light response, hormone induction, and stress response. Quantitative real-time PCR revealed that drought and salt (NaCl) treatments affected the expression of several PtSRS genes, with PtSRS04 and PtSRS05 being the two genes with the most significant expression levels, with PtSRS04 showing a 700-fold increase in relative gene expression level after 8 d of drought stress and the PtSRS05 gene showing a 38-fold increase in gene expression level at 48 h of NaCl stress, suggesting that they could be crucial in salt and drought stress. The results presented herein provide a theoretical basis for subsequent in-depth studies on the involvement of poplar SRS gene family members in drought and salt stress resistance. Full article

This study presents a novel approach to analyzing forest regeneration dynamics by integrating a Markov chain model with Multivariate Time Series (MTY) decomposition. The probabilistic tracking of age-class transitions was combined with the decomposition of regeneration rates into trend, seasonal, and irregular components, unlike traditional deterministic models, capturing the variability and uncertainties inherent in forest ecosystems, offering a more nuanced understanding of how Scots pine (Pinus sylvestris L.) and other tree species evolve under different management and climate scenarios. Using 20 years of empirical data from the Lithuanian National Forest Inventory, the study evaluates key growth and mortality parameters for Scots pine, Spruce (Picea abies), Birch (Betula pendula), and Aspen (Populus tremula). The model for Scots pine showed a 79.6% probability of advancing from the 1–10 age class to the 11–20 age class, with subsequent transitions of 82.9% and 84.1% for older age classes. The model for Birch shown a strong early growth rate, with an 84% chance of transitioning to the next age class, while the model for Aspen indicated strong slowdown after 31 years. The model indicated moderate early growth for Spruce with a high transition in later stages, highlighting its resilience in mature forest ecosystems. Sensitivity analysis revealed that while higher growth rates can prolong forest stand longevity, mortality rates above 0.33 severely compromise stand viability. The Hotelling $T^2$ control chart identified critical deviations in forest dynamics, particularly in years 13 and 19, suggesting periods of environmental stress. The model offers actionable insights for sustainable forest management, emphasizing the importance of species-specific strategies, adaptive interventions, and the integration of climate change resilience into long-term forest planning. Full article