Search Results (120)

Forest fires are recurrent in Spain and affect tree species in different ways. Fire incidence in the main Spanish forest species, both native and alien, is estimated in this study based on actual fire occurrences. Indices of presence, burned area, fire extent, frequency, and recurrence were calculated for each species, and with them, fire incidence indices were obtained. Significant fire incidence was detected in Pinus canariensis, P. pinaster, Eucalyptus globulus, Quercus robur, Betula spp., Castanea sativa, Pinus radiata, and Quercus pyrenaica. Most of the species with the highest fire incidence are not located in the areas with the highest climatic hazard. There is limited correlation between flammability and fire extension, and this is not significant when considering fire incidence. The relationship between fire incidence and conifers is valid in absolute terms, but only partially in relative terms. Similarly, there is no general relationship between relative fire incidence and species with a natural or reforested origin. Some native hardwood species have unexpectedly high incidence, probably due to collateral damage caused by fires in nearby pine and eucalyptus stands. The fire incidence index of forest species is useful for forest management and for protecting species that are suffering severely from fire effects. Full article

Energy production is a global concern, encouraging the search for sustainable alternatives such as charcoal, a promising solid biofuel. This study evaluated the effects of temperature and carbonisation time on charcoal produced from Quercus wood. Carbonisation was carried out at 550 °C for 30 min, 700 °C for 30 min and under two progressive heating profiles: one starting at 550 °C for 30 min and increasing to 700 °C for a further 30 min, and another starting at 300 °C for 2 h and rising to 1000 °C for 10 min. Mass and volumetric yield, bulk density, proximate analysis, calorific value, energy yield and fuel ratio were determined. The results showed that carbonisation temperature affected charcoal properties. Mass and volumetric yields were highest at 550 °C (30.10% and 4.81 m³ t⁻¹) in Q. convallata and Q. urbanii. At higher temperatures, bulk density (0.56 g cm⁻³), fixed carbon (91.51%) and calorific value (32.82 MJ kg⁻¹) increased in Q. urbanii. Lower temperatures led to lower moisture levels (2.46%) and a higher energy yield (48.02%). Overall, temperatures above 700 °C improved energy properties, while those below 550 °C favoured higher yields. Species’ characteristics also influenced charcoal quality. These findings offer valuable insights into optimising the carbonisation of Quercus species and supporting the development of more efficient, sustainable charcoal production methods. Full article

In this paper, we present the results of field investigations on the suitability of three types of trunk traps (‘Commercial 1’, ‘Commercial 2’, and ‘Prototype’) for capturing spongy moth (Lymantria dispar) larvae in two areas with different climates and forest ecosystems. In areas of NE Slovenia, which were characterized by Pannonian climate and regular rainfall during the research period (2022–2024), the ‘Commercial 2’ trap was the most suitable for the capture of old larvae. In a forest with 20–30 m tall trees with the dominant species Quercus robur, Carpinus betulus, and Pinus sylvestris, it proved easy to set ‘Commercial 2’ on trunks and change their parts upon inspection for captures. ‘Commercial 1’ traps proved to be less suitable, since their bags quickly were filled with water during downpours and consequently fell out of the traps. ‘Prototype’ traps proved to be the most suitable in an area with a Mediterranean climate (Greece), where the trees (Quercus spp.) were smaller (3–4 m) and both younger and older larvae could more easily come into contact with the sticky surface of the inner part of the trap, of which longer-lasting effectiveness was possible in a drier climate. For the mass trapping of larvae in urban areas with a more humid climate, we therefore suggest the use of ‘Commercial 2’ traps, and in areas with a drier climate, the use of ‘Prototype’ traps. Full article

Acute oak decline (AOD) is a multifactorial disease that affects European oaks and represents a growing threat to forests. The disease results from a complex interaction between biotic and abiotic factors: the various environmental stresses, which vary depending on the area in question, and generally increased by climate change, predispose trees to attack by opportunistic pathogens. Among them, we focused on a bacterial consortium associated with AOD, consisting mainly of Brenneria goodwinii, Gibbsiella quercinecans, Rahnella victoriana, and Lonsdalea britannica, which produce degrading enzymes that contribute to phloem necrosis and the development of stem bleeds and bark cracks. However, the role of other pathogens, such as fungi, cannot be ruled out, but instead could be contributory. The potential involvement of xylophagous insects is also being studied, particularly Agrilus biguttatus, which, although, frequently associated with the disease, has not been conclusively demonstrated to act as an active vector of the bacteria. Currently, disease management requires integrated approaches, including monitoring and other forestry strategies to increase forest resilience. Given the phenomenon’s complexity and the risk of the future expansion of that bacterial consortium, further research is necessary to understand the dynamics and to develop effective containment strategies of AOD-associated bacteria. Full article

Forest wood biomass is a key renewable resource for advancing energy transition and mitigating climate change. This review analyzes the physicochemical properties of forest biomass from major European tree species to assess their suitability for bioenergy applications. This study encompasses key parameters, such as moisture content, ash content, volatile matter, fixed carbon, elemental composition, bulk density, and energy content (HHV and LHV). This review analyzed data from 43 publications and extracted 140 records concerning the physicochemical properties of the most common European forest species used for bioenergy. The most commonly represented species were Quercus robur, Eucalyptus spp., and Fagus sylvatica. Moisture content, referring to fresh matter, ranged from 5% to 65%; ash content, referring to a dry basis, ranged from 0.2% to 3.5%; and higher heating value (HHV), referring to dry matter, ranged from 17 to 21 MJ kg⁻¹. This study highlights variability among species and underscores the importance of standardizing biomass characterization methods and the scarcity of data on bulk density and other key logistical parameters. These findings emphasize the need for consistent methodologies and species-specific selection strategies to optimize sustainability and efficiency in forest biomass utilization for bioenergy. Full article

Catastrophic wind events play important but poorly documented roles in shaping bottomland hardwood forest structure and composition. The objective of this study was to survey a forested wetland area in Illinois, USA, twenty years following a severe tornado (wind speeds ranging from 333–418 km/h). Part of the damaged area had a subsequent salvage logging operation, and we compared the stand structure and composition of these damaged areas to adjacent reference sites. Stem density, basal area, and diversity differed significantly but slightly among disturbance types (p < 0.05). The density of Quercus spp. decreased in regenerated stands, while the density of Fraxinus pennsylvanica and invasive non-native species cover increased (p < 0.05). Salvage logging further increased the density of key bottomland taxa: Salix spp., Taxodium distichum, and Nyssa aquatica, as well as early successional species such as Liriodendron tulipifera (p < 0.05). Productivity did not differ between wind-impacted areas that were logged and not logged (p > 0.05). Recognizing the need for caution when informing management with case studies, this study highlights the value of delaying the assessment of even extreme wind disturbance impacts in hardwood forest recovery until the contribution of crown regrowth of severely wind-damaged trees, along with post-disturbance origin regeneration, can be ascertained. Full article

The decline of perennial plant species, including oak, olive, and kiwifruit, is a phenomenon currently observed in many areas of the world. In this review, such species are chosen precisely because, despite the differences in their botany, native distribution, and current utilization, they are all affected by significant global or local declines. An analysis of the main common causes involved could be useful for a better understanding of the phenomenon. Quercus species are impacted by “Chronic Oak Decline” (COD), “Sudden Oak Decline” (SOD), and “Acute Oak Decline” (AOD). In Italy, olive groves are severely damaged by “Olive Quick Decline Syndrome”, whereas kiwifruit orchards are struck by “Kiwifruit Vine Decline Syndrome” (KVDS). Among the abiotic inciting stressors, drought, warmer temperatures, and waterlogging, all within a climate change scenario, are involved in all declines described herein as well as in plant dysbiosis. The involvement of some aggressive phytopathogens is another common feature of all these declines. Oomycetes contribute to COD, SOD, and KVDS; Xylella fastidiosa subsp. pauca and Botryosphaeriaceae affect olive, and some enterobacteria are involved in AOD, all representing decisive contributing factors. These declines are quite complex, and a comprehensive approach is required to dissect all the facets involved. A better understanding of altered host–microbial community relationships can lead to a more tailored approach to understanding and managing declines. Maintaining tree resilience in a warmer Earth remains a primary goal to achieve for preserving both natural ecosystems and profitable crops. Full article

The relative influence of climate and Indigenous cultural burning on past forest composition in southern New England, US, remains debated. Employing varied analyses, this study compared data on Indigenous settlements from over 5000 years before present (YBP) with relative tree abundances estimated from pollen and land survey records. Results suggested that fire-tolerant vegetation, mainly oak (Quercus spp.), was more abundant near Indigenous settlements from 4955 to 205 YBP (i.e., 86–91% fire-tolerant trees), and significantly (p < 0.05) higher from 3205 to 205 YBP; fire-tolerant vegetation was less abundant away from settlements, where it also experienced greater fluctuations. Correlative models showed that warmer temperatures and distance to Indigenous settlement, which are both indicators of fire, were important predictors in the 17th–18th centuries of fire-tolerant tree abundance; soil variables were less important and their relationships with vegetation were unclear. A marked increase in oak abundance occurred above 8 °C mean annual temperature and within 16 km of major Indigenous settlements. Pyrophilic vegetation was most correlated with distance to Indigenous villages in areas with 7–9 °C mean annual temperature, typical of higher latitudes and elevations that usually supported northern hardwoods. Widespread burning in warmer areas potentially weakened relationships between distance and pyrophilic abundance. Indigenous land use imprinted upon warmer areas conducive to burning created patterns in fire-tolerant vegetation in southern New England, plausibly affecting most low-elevation areas. Results imply that restoration of fire-dependent species and of barrens, savannas, and woodlands of oak in southern New England benefit from cultural burning. Full article

Wood, a vital material for both modern and heritage objects, is particularly susceptible to degradation caused by water due to its hydrophilic nature and porous structure. Therefore, developing sustainable strategies to protect wood is of significant importance. This study aims to produce a highly hydrophobic coating for the protection of wood following a straightforward procedure and using materials that are compatible with wood. First, nano/sub-microlignin (NL) is isolated and produced from beech wood through a one-step tailored organosolv process. Next, NL is incorporated into Sivo 121, a water-borne and solvent-free silane system recommended by the manufacturer for protecting wood surfaces. Composite coatings containing various concentrations of NL and Sivo 121 are applied to chestnut (Castanea spp.) and oak (Quercus spp.). The impact of NL concentration on the contact angles of water drops (CAs) and colour changes (ΔE) of the treated wood specimens is investigated. The coating with 4% w/w NL demonstrates enhanced hydrophobicity (CA = 145°) and has a negligible effect on the colour of pristine oak (ΔE < 3). The wetting properties of coated oak are not affected after 100 tape peeling cycles. However, the coating exhibits poorer performance on chestnut, i.e., CA = 135°, which declines after 80 peeling cycles, and ΔE > 5. The drop pH does not have any noticeable effect on CA. The latter remains stable even after prolonged exposure of coated oak and chestnut samples to artificial UV radiation and outdoor environmental conditions. Finally, the composite coating offers good and comparable protection for both wood species in the biological durability soil burial test Full article

Oaks are characterized by high plasticity and intense interspecific gene flow due to natural hybridization. This generates a wide phenotypic spectrum, which creates taxonomic confusion within the genus. We compared the acorn traits across a temperature gradient in two types of Mediterranean Quercus (Quercus faginea Lam. and Q. pyrenaica Willd.) and their hybrids. Genetic groups were identified using amplified fragment length polymorphism (AFLPs) analysis. Acorns sampled from each of the three genetic groups were used for comparative purposes by means of 15 morphological characteristics. Eight of the traits showed discriminant value among the three groups. The acorn height tended to decrease with decreasing temperatures across the gradient, whereas the acorn width exhibited the opposite response. However, fruit traits allowed discrimination between the three groups, and the differences were consistent in the different zones. Both the number of acorns produced and the individual acorn size were larger for Q. pyrenaica. Hybrids showed intermediate traits between both parent species. Traditionally, the persistence of parental species in the absence of reproductive barriers has been explained by the lower fitness of the hybrids. Our results, however, do not reveal the presence of transgressive characteristics in the hybrids that could justify a lower competitive capacity. Full article

Macrofungi are a group of fungi with important ecological functions and economic value in forest ecosystems. In this study, the species diversity and community composition of macrofungi in different areas, vegetation types, and elevation gradients from the Lingshan Natural Scenic Area and Xiaolongmen National Forest Park of the Dongling Mountains, Western Beijing were investigated. A total of 1379 specimens were collected. All specimens were identified by morphological and molecular methods, resulting in the identification of 311 species belonging to two phyla, four classes, 18 orders, 74 families, and 147 genera. The alpha diversity analysis indicated that the alpha diversity was significantly different among different vegetation types. The Betula spp. and Populus davidiana of the Lingshan Natural Scenic Area, and Quercus liaotungensis of Xiaolongmen National Forest Park had higher macrofungal alpha diversity. The difference in alpha diversity between the two areas was not significant. The principal coordinate analysis indicated a significant difference in macrofungal community composition among different vegetation types. The fungal community composition of the two areas was also significantly different. The fungal species richness and unique species tended to increase and then decrease with increasing elevation. The species composition of neighboring elevation gradients was more similar. The macrofungal species richness and the number of unique species were not significantly affected by elevation gradient. The vegetation types with higher fungal alpha diversity in the Dongling Mountains were Betula spp., Populus davidiana, and Quercus liaotungensis, and there were abundant fungal species in deciduous broad-leaved mixed forests. Macrofungal diversity and community composition was significantly affected by vegetation type. To better protect the macrofungi, the protection of these four vegetation types in the Dongling Mountains should be strengthened in the future. Full article

Wood, in the form of cladding or furniture, is often placed in close proximity to heat radiant sources. This research focused on samples, which are Norway spruce (Picea abies L.), Red spruce (Picea rubens Sarg.), cherry (Prunus avium), and oak (Quercus spp.). The aim of this paper was to observe the effect of the distance of the selected wood samples from the radiant heat source on the process of thermal degradation of wood. Additionally, this research aimed to identify significant effects of wood species and sample distance on this process. A hot-plate device, an electric plate heated according to a temperature–time curve, was used as the initiating source. Samples were placed directly on the plate, as well as at two different distances from the plate (12 and 32 mm). During the experiment, the temperature history on the heat-exposed side of the sample, its mass loss, and the formation of a charred layer were monitored. Additionally, the progression of thermal degradation and related effects (smell, smoldering, and charring layer) were visually observed. The highest level of degradation was observed in the spruce sample placed directly on the plate, which started to smolder after 540 s of exposure to radiant heat at 291.2 °C. 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

Qualitative and quantitative differences in the chemical composition between bee pollen originated from Castanea sativa (Türkiye and Slovenia), Salix spp. (Türkiye and Slovenia), and Quercus spp. (Türkiye) and androecia of Castanea sativa, Salix alba, and Quercus pubescens (apetalous trees) were evaluated for the first time by new high-performance thin-layer chromatography (HPTLC) and ultra-performance liquid chromatography (UPLC) methods using marker compounds. N¹,N⁵,N¹⁰-tricaffeoylspermidine was isolated, and its structure was elucidated by nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS). It was the main and the marker compound common to bee pollen (≈3–41 mg/g) and androecia (≈3–6 mg/g) samples. To the best of our knowledge, this is the first report of the identification of N¹,N⁵,N¹⁰-tricaffeoylspermidine in bee pollen originated from Salix spp. and androecia of C. sativa, S. alba, and Q. pubescens. The botanical origins of bee pollen were determined via phytochemical profiling using HPTLC-image analyses showing that bee pollen from the same botanical source had almost identical profiles regardless of collection location, geographical differences, and the bee race. In vitro tests and HPTLC-effect-directed analyses (EDAs) were performed to assess antioxidant and xanthine oxidase (XO) inhibitory activities of bee pollen, androecia, and N¹,N⁵,N¹⁰-tricaffeoylspermidine. HPTLC-EDA combined with image analyses was used for comparing the activities of bee pollen, androecia, N¹,N⁵,N¹⁰-tricaffeoylspermidine, and also other marker compounds (quercetin, myricitrin, hyperoside, quercitrin, isoquercitrin, and rutin). The remarkable bioactivity of N¹,N⁵,N¹⁰-tricaffeoylspermidine was for the first time evaluated by HPTLC-EDA and in vitro tests. This is the first study performing HPTLC-XO inhibitory activity analyses on the HPTLC NH₂ F_254S plates. Further bioactivity studies on botanically and chemically well-characterized bee pollen samples are needed to aid in the use of bee pollen-containing supplements in the prevention and treatment of diseases. Full article

Land use and land cover (LULC) studies, particularly those focused on mapping forest species using Sentinel-2 (S2A) data, face challenges in delineating and identifying areas of heterogeneous forest components with spectral similarity at the canopy level. In this context, the main objective of this study was to compare and analyze the feasibility of two classification algorithms, K-Nearest Neighbor (KNN) and Random Forest (RF), with S2A data for mapping forest cover in the southern regions of Portugal, using tools with a free, open-source, accessible, and easy-to-use interface. Sentinel-2A data from summer 2019 provided 26 independent variables at 10 m spatial resolution for the analysis. Nine object-based LULC categories were distinguished, including five forest species (Quercus suber, Quercus rotundifolia, Eucalyptus spp., Pinus pinaster, and Pinus pinea), and four non-forest classes. Orfeo ToolBox (OTB) proved to be a reliable and powerful tool for the classification process. The best results were achieved using the RF algorithm in all regions, where it reached the highest accuracy values in Alentejo Central region (OA = 92.16% and K = 0.91). The use of open-source tools has enabled high-resolution mapping of forest species in the Mediterranean, democratizing access to research and monitoring. Full article