Search Results (55)

European beech wood has low natural resistance to microbial attacks especially when it is exposed outdoors. We looked at ways of improving this by applying three hydrophilic extracts from other species known for their ability to inhibit fungal growth. We prepared oak heartwood and black locust bark extracts by accelerated-solvent extraction with aqueous methanol and freeze-drying, and obtained black wattle bark hot-water extract commercially. The molecular size of the phenolic components and associated saccharides in the extracts were determined by size-exclusion chromatography (SEC). We found that two extracts improved beech wood durability even at low concentrations (5 wt.% solution); the most effective extract was black wattle extract. The worst performance, by black locust bark extract, was attributed to the presence of small-molecule phenolics. The total phenolic content was up to 9× lower than that reported for fresh extracts. Even though the extracts were not stored specifically to preserve the original phenolic content, we found that two were still effective as fungal inhibitors. Full article

Forest structure, including trees, deadwood and tree-related microhabitats, is a key determinant of forest biodiversity. Their relative contribution in shaping local (alpha) biodiversity and its variation (beta) between sites remains unclear. We assessed how forest characteristics shape alpha and beta diversity of beetle communities in mixed silver fir–beech forests within the Vallombrosa Nature Reserve (Tuscany, Italy). We sampled 47 circular plots recording single-tree attributes, deadwood volume and decay stage, and the occurrence of tree-related microhabitats. Beetle assemblages were surveyed using window flight traps, yielding over 11,000 individuals belonging to 187 species, 20% of those known from central-southern Italian forests, 58% of which were listed in the Italian Red List of Saproxylic Beetles and 10% of which were threatened. Statistical models (GLMs and GDMs) revealed that alpha diversity was driven by fine-scale features, including tree species composition, microhabitats (cavities, bark, epiphytes) and deadwood diversity. In contrast, beta diversity was shaped by stand structure and inter-stand heterogeneity. Our results highlight the need for conservation strategies that simultaneously maintain tree-level heterogeneity and secure variation across the landscape. Management should therefore combine retention of microhabitats and diverse deadwood substrates with promotion of structurally diverse, mixed stands to sustain beetle diversity at multiple spatial scales. Full article

Forests in Croatia are characterized by higher levels of biodiversity in species composition. Three significant events occurred in Croatian forests over the past ten years, all of which have a common denominator—sanitary felling. The challenge in the sustainable development of forests started with the ice storm of 2014 that amounted to damage and raised costs in forest stands to EUR 231,180,921. The second challenge was in 2017 when the bark beetle outbreak occurred in the Gorski Kotar region. In December 2017, a windstorm in the same area caused damage to approximately 500,000 m³ of wood stock. The third climate extreme was in the summer of 2023 when three storms with strong winds and heavy rain damaged even-aged forests of common beech and pedunculated oak. The damage was substantial: 3,954,181 m³ of timber was mostly broken and destroyed across 21,888.61 ha of area, and the most damage was in the pedunculate oak forests of Slavonia, i.e., Quercus robur subsp. Slavonica, at 1,939,175 m³. For the main meteorological stations in lowland Croatia, data on precipitation amounts (mm) and wind speeds (m/s) were collected for the period 1981–2023, and the results of our analysis for the last decade are presented. Meteorological drought was analyzed using the rain anomaly index RAI. Data regarding open space fires in the Mediterranean karst area of Croatia were collected from the Croatian Firefighting Association, and the calculation of the burned area index (BAI) was determined. Throughout the entire area of Gorski Kotar County, a sample of permanent plots was set and used to assess the extent of forest damage from the ice storm in 2014 and for the establishment of permanent monitoring of the recovery of trees and forests damaged by the ice storm. The monitoring of bark beetles in the Gorski Kotar region started in 1995 and is still in progress. The aftermath of bark beetle outbreaks in two uneven-aged silver fir stands was studied after a bark beetle outbreak and a sanitary felling of 4655.34 m³. In the area of lowland Croatia, a statistically significant and positive correlation was found between sanitary fellings, maximum wind speeds, and rain anomaly indices in even-aged forests. In conclusion, sustainable development will be at risk due to difficult recovery, rising costs, and overall climate change in the years to come. Full article

The enhanced use of wood residues from the timber industry contributes to mitigating the global climate crisis. Currently, bark, a by-product of the timber industry, is primarily burned for thermal energy generation. However, with the growing demand for lignocellulosic products and the emphasis on extending life cycles, it would be more beneficial to prioritize substantial uses of bark over thermal utilization. Although numerous methods for substantial bark utilization have been explored, a significant untapped potential remains. The extractives obtained through water extraction, for instance, can be applied to various further uses like biopolymers or medical applications. This study investigates the impact of hot water extraction on the mechanical and physical properties of bark-based panels, with the aim of extending the life cycle of tree bark and its valorization in bio-based composites. The findings demonstrate that hot water extraction can enhance the bending properties (modulus of rupture, modulus of elasticity) of bark-based panels. Additionally, the extractives obtained from the process have potential applications in the pharmaceutical and adhesive industries. The study also includes an LCIA that highlights the differences between the three scenarios addressed in this research, namely energy generation from bark-based biomass, extraction of bark, and use of extracted bark residues in the production of bark-based particleboard. Full article

In general, bark serves a protective role for trees and is genetically determined. The quantification of bark based on biometric characteristics is linked to studies on the distribution of forest species across the globe and vegetation fires. In Romania, on the other hand, the improvement of the wood traceability system requires an increase in the accuracy of the estimation of the biometric characteristics of bark and, implicitly, of the volume of wood under the bark. The aim of this study was to develop more precise models for predicting bark thickness along the stem of three key Romanian species, taking into account a comprehensive range of models and stem sections, including those with a diameter over bark smaller than 8 cm, which have been excluded in previous studies. The study is based on two datasets, one containing the national measurements of three commercially valuable forest species, i.e., Norway spruce (Picea abies (L.) Karst), European beech (Fagus sylvatica L.), and pedunculate oak (Quercus robur L.) from 12,186 trees, and a second dataset containing the measurements from 61 logs of the same species at a specific forest site. A set of seven double bark thickness (DBT) estimation models with stem diameter over bark (DOB), DOB and total tree height (H), DOB and relative height along the stem (h/H), and diameter over bark at breast height (DBH) and DOB as predictors were used. The DBT models were evaluated using the coefficient of determination (R²), mean absolute error (MAE), root mean squared error (RMSE), the Akaike information criterion (AIC), and the Bayesian information criterion (BIC). This led to the selection of two more accurate models, Model 2 (based on a third-degree polynomial) and Model 3 (based on a logarithmic function), with DOB as the predictor. Relative double bark thickness (RDBT) and proportion of bark area (PBA) were also estimated using a sixth-degree polynomial and relative height as a predictor variable after stratifying the data by DBH classes to reduce variability. The results of this study indicate that there is a need to complete the database, for all three forest species of commercial value in Romania especially for large trees with DBH greater than 60–70 cm. The models obtained for PBA are of great use to the industry and the economy, in particular in the context of the traceability of wood. This is due to the fact that PBA can be equated with the proportion of bark volume (PBV), which describes the variation in the proportion of bark in the volume of the wood assortments along the stem. For a given DBH, PBA and PBV demonstrate minimal variability in sections from the tree’s base to a relative height of 0.6; however, a pronounced increase is observed at crown level in sections above relative heights of 0.8. Full article

Insect infestation triggers multiple defense responses in plants, both locally at the infection site and systemically throughout the plant, including the production of feeding deterrents, toxins, defensive proteins, enzymes, and secondary metabolites. Our study aimed to compare the endogenous levels of antioxidative enzymes, photosynthetic pigments, phytohormones, total phenols, and flavonoids in bark-beetle-infested and uninfested trees. We evaluated the surviving trees in bark-beetle-infested stands, assessing both the condition and defense of uninfested and infested beech (Fagus sylvatica), pine (Pinus sylvestris), and fir (Abies alba) trees. Sampling was performed at six affected sites in the Czech Republic, targeting trees that were resilient to significant health deterioration caused by abiotic and biotic factors. The results showed different levels of most of the measured compounds in the three species. Among all the tested species, photosynthetic pigment levels showed the strongest association with infestation status, which was generally lower in the infested plants. For chlorophyll a, extremely significant reductions were observed from 123 ± 20.6 to 101 ± 17.9 μg/g dry weight (DW) in pine, from 231 ± 33.1 to 199 ± 22.2 μg/g DW in beech, and from 60 ± 5.66 to 51.3 ± 6.27 μg/g DW in fir. In contrast, enzymatic activities indicated only isolated instances of significant association, whereas antioxidative properties (total phenolic content, flavonoids, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging capacity) were not significantly associated with infestation status. There was a statistically significant increase in glutathione reductase activity in infested fir and pine trees. However, this difference was not statistically significant in beech. In contrast, a significant increase in superoxide dismutase activity was detected in infected beech trees. Phytohormones have emerged as the most diverse group of analyzed compounds. Cytokinins were the most distinct, with many of them being significantly increased in infested pines, whereas both beech and fir showed only one significant association. Additionally, derivatives of jasmonic acid also showed a distinct pattern of change associated with bark beetle infestation, with the levels of three out of the four analyzed jasmonates being significantly decreased in infested pines, whereas no effects were observed in beeches and firs. Notably, many phytohormones were significantly elevated in the infested pine, whereas both beech and fir exhibited only one significant association. Overall, the data showed that pines responded differently to bark beetles than to beeches or firs. The greatest changes in phytohormones were observed in pine, whereas the most significant changes in photosynthetic pigments were observed in beech and fir trees. Full article

In 2023, branches of European beech (Fagus sylvatica L.) were placed on 24 different study sites within beech stands in the Czech Republic to study the distribution of the beech bark beetle (Taphrorychus bicolor Her.). After infestation, the branches were placed in emergence traps to capture adults of the offspring generation. In total, 2167 adults of T. bicolor were captured across the 24 study sites. The average capture (mean ± SE) was 90.3 ± 24.4 adults per site. Statistical analyses, including GLMM and GLM, were employed to assess the influence of elevation and stand age on the abundance of T. bicolor. The results indicate that the distribution of T. bicolor is mainly influenced by the elevation and age of the beech stand. The number of captured adults decreased with elevation and increased with stand age. Climatic region, volumes of beech, and volumes of felled beech wood from principal felling and thinning felling had no significant effect on the number of T. bicolor adults captured. We found that, overall, 73.37% of Czech beech stands (at elevations 300–650 m a.s.l.) are possibly threatened (either highly or slightly) by the large occurrence of T. bicolor, because they are present at elevations where T. bicolor is widespread. No outbreaks of T. bicolor have yet been reported in the Czech Republic, but with the increasing amount of beech planted, combined with global climate change, the possibility of outbreaks in the future cannot be excluded. Full article

The aim of this work was to determine the sorption capacity of the cationic dyes Basic Red 46 (BR46) and Basic Violet 10 (BV10) on the prepared sorbents: beech bark (BBe) and birch bark (BBi). Two fractions of bark were used in the research: fine (2–3 mm) and coarse (4–5 mm). The carried out tests made it possible to determine the influence of the pH value on the sorption efficiency, the sorption equilibrium time and the maximum sorption capacity of the two tested sorbents. The Langmuir model and the Freundlich model were used to describe the obtained experimental data. Beech and birch barks are effective sorbents for cationic dyes; however, the efficiency of dye sorption on both bark sorbents depends on the type of cationic dye. According to the obtained data, beech and birch bark sorbents showed higher sorption efficiency for Basic Red 46 than for Basic Violet 10. The pH correction was a necessary condition for sorption, and the sorption pH value for the cationic dyes Basic Red 46 and Basic Violet 10 was be determined individually for each dye. The most favourable pH value for the sorption of the BR46 dye on the beach and birch bark sorbents was pH = 6, while for the dye BV10, it was pH = 3. The sorption equilibrium time for Basic Red 46 was 300 min and for Basic Violet 10–240 min. The fine fraction of beech bark had the highest sorption capacity for both BR46 (128.45 mg/g dry matter) and BV10 (18.07 mg/g dry matter). Full article

The task of tree species classification through deep learning has been challenging for the forestry community, and the lack of standardized datasets has hindered further progress. Our work presents a solution in the form of a large bark image dataset called CentralBark, which enhances the deep learning-based tree species classification. Additionally, we have laid out an efficient and repeatable data collection protocol to assist future works in an organized manner. The dataset contains images of 25 central hardwood and Appalachian region tree species, with over 19,000 images of varying diameters, light, and moisture conditions. We tested 25 species: elm, oak, American basswood, American beech, American elm, American sycamore, bitternut hickory, black cherry, black locust, black oak, black walnut, eastern cottonwood, hackberry, honey locust, northern red oak, Ohio buckeye, Osage-orange, pignut hickory, sassafras, shagbark hickory silver maple, slippery elm, sugar maple, sweetgum, white ash, white oak, and yellow poplar. Our experiment involved testing three different models to assess the feasibility of species classification using unaltered and uncropped images during the species-classification training process. We achieved an overall accuracy of 83.21% using the EfficientNet-b3 model, which was the best of the three models (EfficientNet-b3, ResNet-50, and MobileNet-V3-small), and an average accuracy of 80.23%. Full article

Molded plywood is used for furniture components such as seats, backrests, or integral seat shells, and it must be durable and harmless to health. Molded plywood is made with urea-formaldehyde (UF) adhesives; therefore, the issue of the fillers used in them is important. The potential of using ground beech (Fagus sylvatica L.) bark as an eco-friendly additive in UF adhesives for molded plywood manufacturing was investigated in this work. Wheat flour was used as a reference filler. The beech bark (BB) level as a filler was 10%, a value verified under laboratory conditions. Nine-layer flat and molded plywood were produced under industrial conditions from beech veneers bonded with a UF adhesive mixture. The mechanical (bending strength and bonding quality) and physical (swelling and absorbency values after 2 and 24 h) properties of the industrially fabricated molded plywood were evaluated and compared with the European standard requirements (EN 310 and EN 314-2). The mechanical properties of the molded plywood with the addition of BB in the adhesive mixture were acceptable and met these standards’ requirements. The positive effect of BB in the UF adhesive mixture on a reduction in formaldehyde emissions from the molded plywood was also confirmed. BB, considered to be wood-processing industry waste or a by-product, has significant potential to be used as a filler in UF resins for molded plywood production, providing an environmentally friendly, inexpensive solution for the industrial valorization of bark as a bio-based formaldehyde scavenger. Full article

Terrestrial laser scanning (TLS) technology characterizes standing trees with millimetric precision. An important step to accurately quantify tree volume and above-ground biomass using TLS point clouds is the discrimination between timber and leaf components. This study evaluates the performance of machine learning (ML)-derived models aimed at discriminating timber and leaf TLS point clouds, focusing on eight Mediterranean tree species datasets. The results show the best accuracies for random forests, gradient boosting machine, stacked ensemble model, and deep learning models with an average F1 score equal to 0.92. The top-performing ML-derived models showed well-balanced average precision and recall rates, ranging from 0.86 to 0.91 and 0.92 to 0.96 for precision and recall, respectively. Our findings show that Italian maple, European beech, hazel, and small-leaf lime tree species have more accurate F1 scores, with the best average F1 score of 0.96. The factors influencing the timber–leaf discrimination include phenotypic factors, such as bark surface (i.e., roughness and smoothness), technical issues (i.e., noise points and misclassification of points), and secondary factors (i.e., bark defects, lianas, and microhabitats). The top-performing ML-derived models report a time computation ranging from 8 to 37 s for processing 2 million points. Future studies are encouraged to calibrate, configure, and validate the potential of top-performing ML-derived models on other tree species and at the plot level. Full article

The composition of the substrate is one of the most critical factors influencing the quality as well as the nutritional value and bioactive content of mushrooms. Therefore, the effects of various substrates, such as barley and oat straw (BOS), beech wood shavings (BWS), coffee residue (CR), rice bark (RB) and wheat straw (WS, control substrate), on the biochemical properties (lipid, protein, polysaccharide, glucan, ash, and mineral content, fatty acids and tocopherols composition), total phenolic compounds and antioxidant activity of Pleurotus mushrooms, P. ostreatus (strains AMRL 144, 150) and P. eryngii (strains AMRL 166, 173-6), cultivated in ‘bag-logs’, was examined. Proximate analysis of A. bisporus and A. subrufescens grown on two different composts (C/N ratios of 10 and 13) was conducted, too. The whole carposomes, pilei and stipes were analyzed. Results showed that BOS, RB, BWS and CR improved the antioxidant activity of Pleurotus species and their nutritional characteristics. Both pilei and stipes were rich in polysaccharides (27.51–67.37 and 22.46–39.08%, w/w, for Pleurotus and Agaricus spp., respectively), lipids (0.74–8.70 and 5.80–9.92%, w/w), proteins (6.52–37.04 and 25.40–44.26, w/w, for Pleurotus and Agaricus spp., respectively) and total phenolic compounds (10.41–70.67 and 7.85–16.89 mg gallic acid equivalent/g for Pleurotus and Agaricus spp., respectively), while they contained important quantities of unsaturated FAs of nutritional and medicinal importance. Pilei were richer in proteins, total phenolic compounds and enhanced antioxidant activity and reducing power than stipes, whereas stipes were richer in IPSs and glucans compared to the corresponding pilei. Thus, mushroom cultivation could upgrade rejected agro-industrial residues and wastes to new uses as substrates for the production of mushrooms with specific nutritional and medicinal attributes. Full article

The American beech (Fagus grandifolia Ehrh.) has been impacted by the beech bark disease (BBD) complex throughout the northeastern United States for over 100 years, but the disease has been present in the Great Lakes region only for around 20 years, requiring acknowledgement of the evolving context surrounding F. grandifolia. This disease threatens to remove a foundational tree species which is especially important ecologically for wildlife habitat and mast, and as a climax successional species. We review advances in propagation techniques of F. grandifolia with the goal of addressing their use in the rehabilitative restoration of forests affected by BBD. Natural regeneration and artificial methods of propagation are addressed, along with how they may be applied for mitigation. Silvicultural interventions are discussed that may be necessary to protect and release resistant seedlings to promote persistence. An existing framework is used to explore context necessary for decision making in restoration. Nucleated seed orchards of resistant trees may currently be the most effective and practical method for introduction of BBD-resistant F. grandifolia into affected northern hardwood forests. Full article

Beech leaf disease (BLD) is an emerging forest infestation affecting beech trees (Fagus spp.) in the midwestern and northeastern United States and southeastern Canada. BLD is attributed to the newly recognized nematode Litylenchus crenatae subsp. mccannii. First described in Lake County, Ohio, BLD leads to the disfigurement of leaves, canopy loss, and eventual tree mortality. Canopy loss limits photosynthetic capacity, likely impacting tree allocation to belowground carbon storage. Ectomycorrhizal fungi are root symbionts, which rely on the photosynthesis of autotrophs for nutrition and growth. Because BLD limits tree photosynthetic capacity, ECM fungi may receive less carbohydrates when associating with severely affected trees compared with trees without BLD symptoms. We sampled root fragments from cultivated F. grandifolia sourced from two provenances (Michigan and Maine) at two timepoints (fall 2020 and spring 2021) to test whether BLD symptom severity alters colonization by ectomycorrhizal fungi and fungal community composition. The studied trees are part of a long-term beech bark disease resistance plantation at the Holden Arboretum. We sampled from replicates across three levels of BLD symptom severity and compared fungal colonization via visual scoring of ectomycorrhizal root tip abundance. Effects of BLD on fungal communities were determined through high-throughput sequencing. We found that ectomycorrhizal root tip abundance was significantly reduced on the roots of individuals of the poor canopy condition resulting from BLD, but only in the fall 2020 collection. We found significantly more ectomycorrhizal root tips from root fragments collected in fall 2020 than in spring 2021, suggesting a seasonal effect. Community composition of ectomycorrhizal fungi was not impacted by tree condition but did vary between provenances. We found significant species level responses of ectomycorrhizal fungi between levels of both provenance and tree condition. Of the taxa analyzed, two zOTUs had significantly lower abundance in high-symptomatology trees compared with low-symptomatology trees. These results provide the first indication of a belowground effect of BLD on ectomycorrhizal fungi and contribute further evidence to the role of these root symbionts in studies of tree disease and forest pathology. Full article

Pests (e.g., insects, pathogens) affect forest communities through complex interactions with plants, other animals, and the environment. While the effects of exotic (non-native) pests on trees received broad attention and were extensively studied, fewer studies addressed the ecosystem-level consequences of these effects. Related studies so far mostly only targeted a very few dominant pests (e.g., hemlock woolly adelgid—HWA, beech bark disease—BBD, and spongy moth—SM) and were limited to aspects of the complex situation such as (1) pests’ direct physical disturbance to forest ecosystems, (2) altered geochemical elements of soils, water, and air (e.g., excretion), and (3) feedback effects from the alteration of ecosystems on plants, native insects, and present and future pest invasions. New studies also show that, in general, planted forests appear to be more prone to exotic pest invasions and thus suffer greater impacts than natural forests. Integrated studies are critically needed in the future to address (1) direct/indirect interactions of pests with ecosystem elements, (2) both short- and long-term effects, and (3) feedback effects. We discuss the implications of the new findings and corresponding management strategies. Full article