Search Results (63)

Face milling with end-mill tools represents a solution for woodworking applications on small-scale or complex surfaces, but information regarding the surface quality per specific tool type, wood material, and processing parameters is still limited. Therefore, this study examined the surface quality of tangential oak and maple CNC face-milled with two end-mill tools—straight-edged and helical—for three values of stepover (5, 7, 9 mm) and two cutting depths (1 and 3 mm). The surface quality was analyzed with roughness parameters, roughness profiles, and stereomicroscopic images and was referenced to that of very smooth surfaces obtained by super finishing. The helical end mill caused significant fiber tearing in maple and disrupted vessel outlines, while prominent tool marks such as regular ridges across the grain were noticed in oak. The best surface roughness was obtained in the case of the straight-edged tool and minimum stepover and depth of cut, which came closest to the quality of the shaved surfaces. An increase in the cutting depth generally increased the core surface roughness and fuzziness, for both tools, and this trend increased with an increase in the stepover value. The species-dependent machining quality implies that the selection of tool geometry and process parameters must be tailored per species. Full article

Over the past years, we experienced more extreme weather conditions during the growing season, April till October, with prolonged droughts. Rain-fed production of high-quality forest trees was possible, but recent droughts proved to have an economic impact on the plant quality. Therefore, the hardy nursery sector demands irrigation thresholds and suitable tools including soil and plant sensors to schedule irrigation based on crop water demand. Two trials were conducted with Acer pseudoplatanus liners (1 + 0) grown in a sandy soil in 2022 and 2023 at Viaverda (Destelbergen, Belgium). A rain-fed treatment was compared with a sprinkler irrigation treatment in both trials. Irrigation doses were evaluated with a soil water balance model, which is based on reference crop evapotranspiration (ET₀), rainfall, and soil hydraulic properties. The soil water balance model was calibrated based on the measurements of soil sensors and soil samples. Simultaneously, stem water potential at solar noon, tree length, and growth were measured. The irrigation treatment had a positive effect on the stem water potential of Acer in both trials with a less negative value, ±0.7 MPa, compared to the rain-fed treatment. Irrigation increased growth with 28.4% in 2022 and 5.8% in 2023 compared to the rain-fed treatment, resulting in trees of higher commercial quality that could even be classified into a superior grading range in 2022. Full article

This study evaluates the potential of various hardwood combinations in plywood production in response to increasing wood demand and a changing roundwood supply in Central Europe. Six different combinations of nine-layer plywood were produced using 2 mm rotary-cut veneers from lime (Tilia spp.), Norway maple (Acer platanoides), European hornbeam (Carpinus betulus), Sycamore maple (Acer pseudoplatanus), mountain ash (Sorbus aucuparia), and European beech (Fagus sylvatica) with phenol–formaldehyde adhesive, and they were compared to silver birch (Betula pendula) plywood as a reference. The raw densities of the test panels varied between 0.85 and 1.04 times the reference density (795 kg m⁻³). Flexural strengths (the modulus of rupture, MOR) ranged from 68 N mm⁻² to 104 N mm⁻² for a parallel fibre orientation and 44 N mm⁻² to 61 N mm⁻² for a perpendicular fibre orientation of the top layers. The modulus of elasticity (MOE) ranged from 7160 N mm⁻² to 11,737 N mm⁻² for the parallel fibre orientation and from 4366 N mm⁻² to 5575 N mm⁻² for the perpendicular orientation. The tensile shear strength varied between 0.91 and 1.69 times the reference (1.49 N mm⁻²). The thickness swelling after 24 h was higher in all variants than the reference (6.4%), with factors between 1.39 and 1.64. A significant effect was observed when layers with a lower density were arranged on the outside and those with a higher density in the core, resulting in a more uniform density distribution across the cross-section after hot pressing. This created a levelling effect on mechanical and physical properties, especially the modulus of rupture (MOR) and the modulus of elasticity (MOE). Overall, the evaluated hardwood combinations demonstrated comparable properties to the birch reference and industrially produced birch plywood. Full article

This study investigated, for the first time, the phenolic acid profile along with the in vitro antioxidant and acetylcholinesterase (AChE) inhibitory activities of leaves and fruits from five Romanian wild-grown Acer spp. (Sapindaceae): A. campestre L., A. monspessulanum L., A. platanoides L., A. pseudoplatanus L., and A. tataricum L. High-performance liquid chromatography coupled with ultraviolet and mass spectrometry (HPLC/UV/MS) was employed to identify and quantify key phenolic acids, including gallic, caffeic, protocatechuic, chlorogenic, and p-coumaric acids. Total phenolic content (TPC) ranged from 61.48 ± 3.76 to 512.8 ± 20.54 µg gallic acid equivalents (GAE)/mL. Antioxidant activities, assessed through 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays, demonstrated the strongest radical scavenging capacities for A. tataricum fruits, with half maximal inhibitory concentration (IC₅₀) values of 10.88 ± 3.39 µg/mL and 10.39 ± 2.86 µg/mL, respectively. The ferric-reducing antioxidant power (FRAP) assay revealed the highest reducing power for A. tataricum fruits (1158 ± 48.98 µmol Fe²⁺/L) and leaves (1119 ± 164.6 µmol Fe²⁺/L). AChE inhibition was only found in A. tataricum, with an IC₅₀ of 7.91 ± 7.50 mg/mL for leaves and 15.95 ± 8.52 mg/mL for fruits. These results highlight A. tataricum as a promising source of natural antioxidants and neuroprotective agents. Full article

Electron microscopy (EM) is a key tool for studying the microstructure of wood; however, observing uncoated samples poses a challenge due to surface charging. This study aims to identify the critical voltage that allows for the effective observation of uncoated wood samples without significant loading. As part of the experiment, samples of different wood species were tested, including Acacia (Robinia pseudoacacia L.), Oak (Quercus robur L.), Maple (Acer pseudoplatanus spp.), Ash (Fraxinus excelsior L.), Spruce (Picea abies (L.) Karst.), Thermowood (Thermal modifed Spruce), Garapa (Apuleia leiocarpa), Ipé (Handroanthus spp.), Merbau (Intsia bijuga), and Massaranduba (Manilkara spp.). Several methods were tested for surface preparation for SEM analysis, including the use of a circular saw, a hand milling machine, and a microtome. The results show that the optimal voltage for observing uncoated wood samples varied depending on the wood species. Regarding the selection of wood species and the results obtained, it was found that uncoated samples could be effectively observed. This finding suggests that practical observations can be accelerated and more cost-effective, as all wood species exhibited the required voltage range of 1 kV to 1.6 kV. Additionally, it was determined that using a secondary electron detector was optimal for such observations, as it provided a sufficiently strong signal even at relatively low voltages. Conversely, when using a backscattered electron detector, it was more beneficial to use coated samples to achieve a sufficient signal at higher voltages. This study brings new knowledge that will facilitate further research and applications of electron microscopy in the study of other wood species or wood-based materials. Full article

Air pollution, including particulate matter (PM), impacts public health in urban areas. Vegetation acts as a natural filter, removing environmental pollution by absorbing large quantities of toxic substances on the foliage. Ambient air pollution problems are real in Armenia’s cities. This article presents the results of a study based on field sampling in July 2022 undertaken in urban parks and streets in the Armenian cities of Yerevan, Gyumri, and Vanadzor. The three cities have different climates and geographic conditions. The main research goal was a comparative study of the accumulation of PM by urban greenery. The most widespread tree species were selected for the study in each city: in Yerevan, Platanus orientalis and Quercus robur; in Gyumri, Fraxinus excelsior and Tilia caucasica; and in Vanadzor, Aesculus hippocastanum and Acer pseudoplatanus. The ecological status of trees was assessed through visual observation. Tree species with high PM uptake potential were identified and selected for inclusion in urban greening systems (Platanus orientalis, Fraxinus excelsior, and Quercus robur in Yerevan; Tilia caucasica, Sorbus persica, Fraxinus excelsior, and Populus alba in Grumri; Acer pseudoplatanus, Fraxinus excelsior, Aesculus hippocastanum, and Thuja occidentalis in Vanadzor.). High PM accumulation was found on the leaves of tree species in all of the investigated cities, with the largest amount recorded in Yerevan. In these cities, PM levels were higher in street plantations than in parks. All studied tree species have a high potential for PM absorption, demonstrating strong phytofilter properties. Therefore, they can be effectively used in their typical climatic zones and included in street plantings, gardens, and parks. These results can help urban planners and policymakers make informed decisions about urban greening initiatives to improve air quality and overall wellbeing. Full article

Hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG) are protoxins produced by Sapindaceae plants, particularly Acer pseudoplatanus, and are responsible for causing atypical myopathy (AM) in equids. These protoxins metabolise into toxic compounds, such as methylenecyclopropylacetyl-CoA (MCPA-CoA), which alters energy metabolism and induces severe rhabdomyolysis. Currently, no specific treatment exists for this poisoning, in vitro models fail to reproduce HGA’s toxic effects on equine primary myoblasts, and mammalian models are impractical for large-scale drug screening. This study aimed to develop a zebrafish embryo model for screening therapeutic compounds against AM. Zebrafish embryos were exposed to various concentrations of HGA, MCPrG, and methylenecyclopropylacetate (MCPA) for 72 h. MCPrG did not induce toxicity, while HGA and MCPA showed median lethal concentration (LC50) values of 1.7 µM and 1 µM after 72 h, respectively. The highest levels of the conjugated metabolite MCPA–carnitine were detected 24 h after HGA exposure, and the acylcarnitines profile was highly increased 48 h post-exposure. Isovaleryl-/2- methylbutyrylcarnitine levels notably rose after 24 h, suggesting potential exposition biomarkers. Glycine and carnitine effectively reduced mortality, whereas riboflavin showed no protective effect. These findings suggest that the zebrafish embryo represents a valuable model for identifying therapeutic compounds for Sapindaceae poisoning. Full article

Fly ashes produced in huge amounts during coal combustion requires proper management. The purpose of this study was to determine the impact of fly ash from burning hard coal used in large doses (250, 500, 1000 and 2000 t ha⁻¹) on soil properties and vegetation of fresh mixed coniferous forest within 43 years from the ash application. The experiment was established in the Podzols in the forest habitat of Czułów, Katowice Forest district, Upper Silesia, Poland. Eight tree species were planted in ridges created by ploughing: Pinus sylvestris, P. nigra, Larix decidua, Betula pendula, Quercus robur, Q., Acer pseudoplatanus and Fagus sylvatica. The changes in soil morphology caused significant transformations in the physical and chemical properties of the soil such as soil texture, pH, macronutrients (P, K and Mg) content and C:N ratio. Increasing of ash doses changed the granulometric composition of the soil levels from loamy sand (250 t/ha⁻¹) to silt loam (2000 t ha⁻¹). Initially, the acidic Podzols were alkalized under the influence of the fly ash and then acidified, possibly due to the impact of accumulated litter layers, and the reaction of organic soil horizons changed from strongly acidic (250–1000 t ha⁻¹) to alkalis (2000 t/ha⁻¹). The macronutrients content increased in proportion to the fly ash dose, but the subsequent acidification resulted in a gradual decrease in the macronutrients share in the soil layers. The value of the C:N ratio grew after the ash application and then it gradually reduced, even by half. The transformations of soil horizons’ properties also increased the capacity of the soil sorption complex (CEC). All these processes led to a change in the trophic status of the habitat expressed by the soil habitat index (SIG) and the initial coniferous forest site can be classified as a mixed forest habitat even with the lowest ash dose used. The composition of plant communities developed forty years after the ash application was similar at the lower ash doses and the most frequent and abundant tree species were L. decidua, P. nigra and P. silvestris. B. pendula was previously co-dominant, but it was eliminated from the tree stands during the experiment. Planted trees characteristic of late stages of succession, such as Q. robur, Q. rubra, F. sylvatica and A. pseudoplatanus either did not survive or remained in very low quantities. The herb and moss layers developed in the process of spontaneous colonization, and together with the trees led to phytostabilisation of the bare substrates. After acidification of the topsoil horizons, the herb layers consisted mostly of coniferous, mixed, and deciduous forest species, and the most frequent or abundant were Lysimachia europea and Pteridium aquilinum. The moss layers were represented by coniferous forest flora. At the ash dose of 2000 t ha⁻¹, Tilia cordata settled in one of the seral stages of spontaneous succession and this species dominated in the community and formed a dense tree stand. After the soil acidification, a shift from calcicole to calcifuge plant strategy took place among species of the herbaceous layer. The transformations of plant communities’ composition occurred in relation to changes in the soil properties. Full article

Stabilising the natural colour of wood species exposed to light in indoor conditions is a challenge that could be better addressed based on a deeper understanding of the occurring phenomena and influencing factors. This paper investigates comparatively the light-induced colour changes for three hardwood species, namely, European maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.) and European walnut (Juglans regia L.), as well as the influence of finishing with three types of clear, colourless waterborne lacquers: acrylic-polyurethane (F1), acrylic (F2) and polyurethane (F3) on their colour stability. Colour measurements in the CIELab system in conjunction with an artificial accelerated ageing test under the action of UV-VIS radiation, simulating natural light passing through window glass, and two types of test samples were employed to highlight the influence and contributions of the wood substrate and of the coating films to the global colour modifications. Coating films applied on 1 mm clear glass slides were employed as a sort of “detachable” finish for this purpose. Direct exposure to UV-VIS light caused visible colour changes for both uncoated and coated wood surfaces, the values of the calculated colour differences (ΔE) after a 72 h exposure being dependant on both the wood species and the coating material. Excepting two situations for walnut, statistically significantly higher colour differences were obtained for the uncoated samples: maple (9.36 units), ash (8.39 units), walnut (6.20 units), compared to the coated ones: maple (4.92–5.71 units), ash (2.25–3.94 units), walnut (4.74–7.70 units). The wood substrates underlying the coating films were found to bring the maximum contribution to the overall colour changes in the clear coated surfaces, while the coating films employed in this research demonstrated a fairly good colour stability to UV-VIS light exposure, with maximum colour changes (∆E) up to only 1.30 units. Overall, the wood species and the type of coating were found as influencing factors in interaction with the light-induced colour changes in wood surfaces in indoor conditions. Full article

The purpose of the study was to analyze the influence of the quality class and the orthotropy of wood upon the sound absorption coefficient, the reflection and the impedance ratio of two species widely used for stringed musical instruments, namely spruce (Picea abies L. Karst) and maple (Acer pseudoplatanus L.). An impedance tube for the frequency range 100–6400 Hz was used in these experimental determinations. Knowing the influence of porosity and tortuosity on the acoustic absorption, these properties were also determined, as well as the sound reduction coefficient and the maximum values of the acoustic absorption coefficients in relation to frequency. The main results highlighted the differences between the anatomical quality class of the wood within each species, but also concerning the sound direction relative to the three main sections of wood, as an orthotropic material. The article highlights the acoustic performance parameters related to the frequency of the wooden material and its relationship to density, porosity and quality class. The results represent useful information for musical instruments manufacturers and more. Full article

With the current increases in environmental stress, understanding species-specific responses to multiple stress agents is needed. This science is especially important for managing ecosystems that are already confronted with considerable pollution. In this study, responses to ozone (O3, ambient daily course values + 20 ppb) and mixed metal contamination in soils (MC, cadmium/copper/lead/zinc = 25/1100/2500/1600 mg kg⁻¹), separately and in combination, were evaluated for three plant species (Picea abies, Acer pseudoplatanus, Tanacetum vulgare) with different life forms and ecological strategies. The two treatments elicited similar stress reactions, as shown by leaf functional traits, gas exchange, tannin, and nutrient markers, irrespective of the plant species and life form, whereas the reactions to the treatments differed in magnitude. Visible and microscopic injuries at the organ or cell level appeared along the penetration route of ozone and metal contamination. At the whole plant level, the MC treatment caused more severe injuries than the O3 treatment and few interactions were observed between the two stress factors. Picea trees, with a slow-return strategy, showed the highest stress tolerance in apparent relation to an enhancement of conservative traits and an exclusion of stress agents. The ruderal and more acquisitive Tanacetum forbs translocated large amounts of contaminants above ground, which may be of concern in a phytostabilisation context. The deciduous Acer trees—also with an acquisitive strategy—were most sensitive to both stress factors. Hence, species with slow-return strategies may be of particular interest for managing metal-polluted sites in the current context of multiple stressors and for safely confining soil contaminants below ground. Full article

Equine atypical myopathy is caused by hypoglycin A (HGA) and methylenecyclopropylglycine (MCPrG), the known protoxins of sycamore maple (Acer pseudoplatanus). Various tissues from five atypical myopathy cases were analyzed but only HGA was found. Whether deamination of MCPrG has already occurred in the intestine as the first stage of metabolization has not been investigated. Activation of the protoxins to methylenecyclopropylacetyl (MCPA)-CoA and methylenecyclopropylformyl (MCPF)-CoA, respectively, occurred mainly in the skeletal muscles, as evidenced by very high concentrations of MCPA-carnitine and MCPF-carnitine in this tissue. Inhibition of the acyl-CoA dehydrogenases of short- and medium-chain as well as branched-chain fatty acids by the toxins led to a strong increase in the corresponding acylcarnitines, again preferentially in skeletal muscles. An accumulation of the long-chain acylcarnitines beyond the level of the control samples could not be detected in the tissues. As a high amount of HGA was always found unmetabolized in the organs, we speculate that targeting the interruption of further metabolization might be a way to stop the progression of intoxication. Inhibition of the mitochondrial branched-chain amino acid aminotransferase, i.e., the first enzyme responsible for the activation of sycamore maple protoxins, could be a therapeutic approach. Full article

Senile trees in historic church gardens have natural, aesthetic, historical, and cultural value. Cutting them down too hastily annihilates the achievements of entire generations. We should try to preserve the greenery surrounding historic churches and integrate it into a clear compositional arrangement with the sacral architecture. The primary purpose of the paper was to describe the process of inventorying 200-year-old trees and to present the revalorization project for the garden around the historic Orthodox church in Horostyta, located in the Lublin Voivodeship, in southeastern Poland. The church complex consists of a wooden 18th-century building, bell tower, garden, and cemetery. Within the church garden’s boundaries, there are 15 trees, with two predominant species: Acer pseudoplatanus L. and Tilia cordata Mill. These trees are of varying ages and health conditions. We used acoustic tomography to perform tree health diagnostics. Three trees, for which the initial visual assessment was disturbing, were examined thanks to detailed tomography tests. Then, through a project adapting the church garden to the health conditions of the ancient trees, they were separated from users by flowerbeds and no small architectural objects were placed around them. The presented development concept forms a compromise between tradition and the modern user’s needs. In 2007, a general renovation of the temple building was completed. Currently, the presented project for the church garden is being implemented. Full article

Over the last few decades, globalization and global trade have increased the risk of the vehiculation of invasive organisms, which has had multiple negative effects, both economic and ecological. Through this study, we aimed to produce a report on the first record of the invasive scale insect Pulvinaria hydrangeae (Stein. 1946) in Brașov County in central Romania. It was found on two native tree species: sycamore (Acer pseudoplatanus) and linden (Tilia cordata). In this paper, we (i) highlight the list of possible hosts, (ii) provide a general outlook on infestations and (iii) review the control options for this particular pest. Because early detection and quick reporting are the most important actions in the successful management of invasive species, in general, we also provide a synthetic morphological description of the adult female specimens and ovisacs. Due to natural occurrence, our findings highlight the potential risks posed by the infestation of this insect to native tree species belonging to the Acer and Tilia genera. Because of the temperate climate in Romania and the fact that females are wingless, the new infestations will probably be made through the vehiculation of infested plants, rather than through natural spreading. However, because of global warming, the chances of this species surviving during the winter are likely to increase, making northern expansion of the cottony hydrangea scale feasible. Full article

Browsing by ungulates can affect the development of a forest stand due to selective browsing and shifts in the growth ranking between tree species. Assessing browsing impact in an objective way is difficult in patchily distributed beech forests. In systematically arranged plots near Kirchberg, Switzerland, the height increment of the two saplings nearest to the plot center (k-tree method) was measured for each height class and tree species, and the within-tree browsing intensity and damage frequency were assessed. In total, 21 tree species were found. Browsing was particularly frequent in climate-adapted species. Winter browsing was more frequent than summer browsing, which was also true for deciduous species, and it significantly reduced height growth. Former damage along the main stem further reduced upgrowth. Browsing shifted the height increment ratio in favor of Fagus sylvatica. Many winter-browsed saplings of Abies alba, Fagus sylvatica, Acer pseudoplatanus, Fraxinus excelsior and Prunus avium had no new leader shoot by the end of the next growing season, i.e., browsing had a long-lasting impact. For estimating browsing impact, it is thus important to assess delays in the response after browsing. Foresters could easily apply the k-tree method in autumn for effective assessments of browsing impact. Full article