Search Results (77)

Thermal modification applies to a technique for the enhancement of biological durability, stability, and appearance of wood. Much is known about its effects on the chemical and physical attributes of wood. However, there is a knowledge gap concerning the effects of heat treatment on surface coating performance of different wood species. The focus of this research is heat treatment regulation of 160 °C, 180 °C, and 200 °C for three commercially important wood species which are Populus (poplar), Quercus (oak), and Pinus (pine). These treatments were evaluated in relation to coating performance indicators adhesion, integrity, and visual stability during and after natural and artificial weathering. It was revealed that specific responses among species differences exist. Populus behaved differently and exhibited a steady loss in mass and volume. Quercus demonstrated gradual degradation alongside enhanced lignin stability. Pinus exhibited maintenance of volume and mass until 180 °C after which accelerated degradation was observed. Coating durability and adhesion exhibited dependence on thermal condition, wood species, porosity, surface chemistry and microstructural variations that occurred. The research results can be used to streamline finishing processes for thermally modified wood while underscoring the critical nature of precise treatment parameter adjustments guided by species-specific responses to ensure long-term stability. Full article

Climate models forecast warmer winter conditions, which could lead to an earlier spring xylem phenology in trees. Localized stem heat experiments mimic this situation and have shown that stem warming leads to an earlier cambial resumption in evergreen conifers. However, there are still few comprehensive studies comparing the responses to stem heating in coexisting conifers and hardwoods, particularly in drought-prone regions where temperatures are rising. We addressed this issue by comparing the responses (xylem phenology, wood anatomy, growth, and sapwood concentrations of non-structural carbohydrates—NSCs) of two pines (the Eurosiberian Pinus sylvestris L., and the Mediterranean Pinus pinaster Ait.) and a ring-porous oak (Quercus pyrenaica Willd.) to stem heating. We used the Vaganov-Shashkin growth model (VS model) to simulate growth phenology considering several emission scenarios and warming rates. Stem heating in winter advanced cambial phenology in P. pinaster and Q. pyrenaica and enhanced radial growth of the three species 1–2 years after the treatment, but reduced the transversal lumen area of earlywood conduits. P. sylvestris showed a rapid and high growth enhancement, whereas the oak responded with a 1-year delay. Heated P. pinaster and Q. pyrenaica trees showed lower sapwood starch concentrations than non-heated trees. These results partially agree with projections of the VS model, which forecasts earlier growth onset, particularly in P. pinaster, as climate warms. Climate-growth correlations show that growth may be enhanced by warm conditions in late winter but also reduced if this is followed by dry-warm growing seasons. Therefore, forecasted advancements of xylem onset in spring in response to warmer winters may not necessarily translate into enhanced growth if warming reduces the hydraulic conductivity and growing seasons become drier. Full article

Palaeoecological investigations connected with extensive pre-bog, stone walls, and field systems at Kilmore, Dingle peninsula, Ireland, are presented. The main pollen profile, KLM I, spans the last 4000 years. When the record opened, pine (Pinus sylvestris) was already a minor tree, oak (probably Quercus petraea) was the main tall-canopy tree, and birch and alder were dominant locally. Substantial farming is recorded between ca. 1530 and 600 BCE (Bronze Age) when the stone walls were likely constructed. From ca. 560 CE onwards, intensive farming was conducted for much of the time. A largely treeless landscape emerged in the late twelfth century CE. Fine-spatial reconstructions of landscape and vegetation dynamics, including the timing of blanket bog initiation, are made. Post-glacial change in the western Dingle peninsula, based on published Holocene lake profiles and drawing on the new information presented here, is discussed. Reported are (a) fossil spores of the filmy ferns Hymenophyllum tunbrigense, H. wilsonii, and Trichomanes speciosum; (b) the first fossil pollen record for Arbutus unedo (strawberry tree) in the Dingle peninsula (540 CE); and (c) the first published records for Fagopyrum fossil pollen in Ireland, indicating that buckwheat was grown at Kilmore in the late eighteenth/early nineteenth centuries. Full article

The quantity, quality, and accumulation rate of plant litter play a key role in forest floor flammability and, by extension, fire regimes. The varying foliage properties of different tree species also determine litter’s decomposition and its accumulation on the forest floor. The removal of litter by soil fauna, i.e., bioturbation, depends on both the dominant tree species and the successional stage of the forest stand. This research involved laboratory mesocosm experiments aiming to determine the effects of litter quality and earthworm activity on the flammability of the forest floor material at different successional ages. The mesocosms simulated the planting of four tree species (the broadleaf species Alnus glutinosa (L.) Gaertn. (Black alder) and Quercus robur L. (English oak) and the conifers Picea omorika (Pančić) Purk. (Serbian spruce) and Pinus nigra J.F. Arnold (Austrian pine)) at a reclamation site near Sokolov (NW Czechia). The mesocosms contained litter from these different tree species, placed directly on overburden soil (immature soil) or on well-developed Oe and A layers (mature soil), inoculated or not inoculated with earthworms, and incubated for 4 months. The surface material in the mesocosms was then subjected to simulated burn events, and the fire path and soil temperature changes were recorded. Burn testing showed that litter type (tree species) and soil maturity significantly influenced flammability. Pine had longer burning times and burning paths and higher post-burn temperatures than those of the other tree species. The immature soil with earthworms had significantly shorter burning times, whereas in the mature soil, earthworms had no effect. We conclude that earthworms have a significant, immediate effect on the litter flammability of immature soils. Full article

Case studies of climate adaptation approaches are needed to inform the broader use of these strategies across longleaf pine (Pinus palustris Mill.) ecosystems in the Southern US. To address this need, we evaluated overstory structure and tree regeneration in longleaf pine-hardwood stands, and a transition approach was implemented to intentionally facilitate change to encourage adaptive responses. Stand density reduction and species selection were prescribed to reduce tree vulnerability to drought stress. Turkey oaks (Quercus laevis W.) were also planted as a part of an assisted population migration strategy. After the treatments, Hurricane Michael impacted the study stands. The percent reduction in large overstory longleaf pines due to the hurricane was 6.3 ± 6.1% (grand mean ± standard deviation, which was derived from the stand means). At least one live planted turkey oak was present in 74 ± 26% of the planted clusters of turkey oaks that could be located six years after planting them. Our findings demonstrate the ability of transition stands to accommodate a large-scale disturbance event and maintain ecosystem functionality, the desired stand structure, and species composition. The relative success of forestry assisted migration plantings of turkey oaks may alleviate some concerns about the risk of maladaptation. Full article

Evaluating SOC lability is crucial for sustainable agriculture policies and environmental quality. This study assessed the impact of well-stocked forest cover on SOC pools and lability compared to shrubby soil. Geo-referenced soils under Red pine (Pinus brutia), Black pine (Pinus nigra), Cedar (Cedrus libani), Fir (Abies cilicia), Juniper (Juniperus excelsa), Oak (Quercus L.), Carob (Ceratonia siliqua), and degraded shrubs were collected from a depth of 0 to 30 cm in the Seyhan River Basin, Mediterranean Turkey. The analysis of soil organic carbon (SOC), soil AC (active carbon), and PC (passive carbon) were analyzed to understand soil carbon management across diverse vegetation types. Juniper forests have the highest SOC (27.98 g/kg) and PC (27.35 g/kg), followed by Cedar (SOC: 27.64 g/kg, PC: 27.05 g/kg) and Fir (SOC: 26.44 g/kg, PC: 25.85 g/kg). Shrubby areas have the lowest SOC (4.06 g/kg) and PC (3.61 g/kg). The Oak soil had the highest CLI (1.16), suggesting a relatively higher proportion of labile carbon than other forests. CPI indicates forests have a greater carbon storage capacity (1.09) compared to shrublands (0.18), with forests also having a higher CMI (0.83). The findings emphasize the critical role of forests, especially Juniper forests, in carbon sequestration and climate change mitigation within the Seyhan River Basin in Turkey. Full article

The rapid environmental changes associated with climate change increase the need for adaptation strategies in forest management based on profound knowledge about tree species, particularly in the context of assisted migration. For research purposes, selected native and non-native tree species were planted in Brandenburg, Germany more than 120 years ago. Today, these sites provide an opportunity to gather insights about their performance and growth-response throughout the past century. We analyzed the height growth increment of 18 tree species on 1765 long-term experimental plots, the earliest of which have been monitored since 1878. We additionally investigated the stand-level volume increments on 60 unmanaged plots for two of these species. Our results show increasing trends in forest stand growth for Scots pine (Pinus sylvestris L.) and Sessile oak (Quercus petraea (Matt.) Liebl.). However, long-term height increment showed positive, negative, and indifferent growth trends in reaction to changing environmental conditions. Remarkably, 16 out of 18 species showed a growth decline between the years 2000 and 2020, likely attributable to increasing frequencies of single and consecutive drought events. We found non-native species to perform comparably to native tree species. Forest management should reconsider the role of native and non-native species in climate-adapted forests. We recommend focusing on provenance and local site adaptability in assisted migration efforts and argue that maintenance of long-term experiments can provide us with valuable insights on species performance in the near future. Full article

An important issue in container nurseries is the production of seedlings of appropriate quality. These seedlings must meet specific biometric parameters and possess traits that ensure their suitability for later use in forest cultivation. One such traitis the ease of pulling the seedling out of the container cell, characterized by the pulling resistance. This resistance depends on many factors, including theseedling parameters, substrate, and container. In this work, a prototype measuring station was used to record seedling pull-out resistance as a function of their vertical displacement. Tests were conducted on 30 seedlings of each species: pine, beech, and oak. These were grown in polystyrene containers with cell volumes of 150 cm³ for pine (Pinus sylvestris L.) and 300 cm³ for beech (Fagus sylvatica L.) and oak (Quercus robur L.). Significant differences were observed in seedling extraction resistance between species, as well as between resistances associated with containers of different cell volumes. The maximum pull-out resistance of pine seedlingswas the lowest at 12.4 ± 8.58 N, followed by 22.5 ± 1.87 N for beech, and 33.5 ± 18.08 N for oak (extraction speed of 2.5 cm·s⁻¹).Similarly, the total energy required to extract pine seedlings was 0.358 ± 0.196 J, compared to 0.502 ± 0.316 J for beech and 1.479 ± 0.774 J for oak. The pattern of pull-out resistance regardingvertical displacement was consistent across all species. A correlation was found between the maximum pull-out resistance and the total energy required to extract the seedlings, along with biometric parameters such as root collar diameter, shoot height, dry mass of seedling parts, root volume, the extent of root ball overgrowth, and the volumetric density of the substrate within the cell.These relationships should be considered when designing devices for the automatic extraction of seedlings from polystyrene containers. Full article

Maritime forests are coastal ecosystems that stabilize coastlines, recharge aquifers, and provide protection against storm surges. The range of these forests has been decreasing due to threats such as urban expansion, clearing for agriculture, climate change, and an influx of native but competitive loblolly pine (Pinus taeda L.) from pine plantations. To restore maritime forests, southern live oak (Quercus virginiana Mill.) should be established as the dominant canopy species; however, knowledge of how to grow live oak in a restoration setting is limited. We planted southern live oak seedlings into a clearcut experimental site that was formerly a loblolly pine plantation. Our goal was to test how planting density (1, 2, or 3 m), mulch, and fertilization at planting impacted the initial growth of seedlings over the course of four growing seasons. The application of fertilizer had an initial positive effect on seedling diameter (36%) after the first growing season. The application of mulch increased seedling height in years 2 through 4 (25.6% to 22.7%), diameter in years 3 and 4 (20.9% to 19.3%), and crown width in year four (8.5%). Planting density had no consistent effect over the first four years. These results demonstrate the potential benefits of incorporating fertilizer and mulch into restoration prescriptions to promote seedling field establishment. Planting density should continue to be monitored through canopy closure for potential effects of plant facilitation. Integrating silvicultural treatments such as planting density, soil amendments, and vegetation control may inform cost-effective management recommendations for maritime forest restoration. Full article

Soil infiltration properties (SIPs) are important components of forest hydrological responses; however, few studies have investigated the mechanisms through which soil physical properties affect SIPs. In this study, two SIPs, the initial infiltration rate (IIR) and saturated hydraulic conductivity (Ks), were quantified at five soil depths (0–10, 10–20, 20–30, 30–40, and 40–50 cm) in three forest stands (pine (Pinus taeda), oak (Quercus acutissima), and bamboo (Phyllostachys edulis) forests). We constructed a structural equation model (SEM) to analyze the main physical properties affecting the SIPs and their influence pathways, and the results show that the IIR and Ks values for the whole soil profile decreased as follows: pine forest > oak forest > bamboo forest. Soil total porosity (STP), soil field capacity (SFC), capillary water holding capacity (CMC), saturated water capacity (SWC), and initial soil water content (ISWC) were positively correlated with the SIPs, while soil bulk density (SBD) was negatively correlated with the SIPs. The SEM indicated that the main positive driver of soil infiltration was STP, while the sand content and SBD reduced soil infiltration. Soil texture indirectly affected SBD by mediating STP, and SBD indirectly affected the SIPs through SWC. These results provide data that support the simulation of subsurface hydrological responses in forests and have significant implications for forest management. Full article

The Chinese pine (Pinus tabuliformis) community on the ridge is one of the most important zonal forest communities on the southern slope of the mid-Qinling Mountains. This study aimed to investigate the driving factors of Chinese pine population distribution in the ridge habitats and its adaptability characteristics. Population age structure and the relationship between regeneration dynamics and environmental factors were investigated in 32 plots in the Huoditang Forest region. The results showed that the niche of Chinese pine was wide but overlapped greatly with that of Quercus aliena var. acutiserrat, an oak species. The population in the ridge habitats exhibited an expansion trend, while that inhabiting slope habitats was declining. Seedling density in ridge habitats was much higher than that of the understory in the slope habitats. Still, the seedling growth rate in both ridge and understory habitats was much lower than that characteristic of gap habitats. Seedling density positively correlated with understory solar conditions, while growth positively correlated with soil fertility, indicating that environmental factors significantly influence the regeneration process. Thus, light conditions and intrinsic biological traits of Pinus tabuliformis influence its distribution. In ridge habitats, sufficient light conditions promote Pinus tabuliformis regeneration and recruitment of larger classes, but poor soil conditions also limit its growth. Full article

While many tree species occur across the Coastal Plain of the southeastern United States, longleaf pine (Pinus palustris C. Lawson) savannas and woodlands once dominated this region. To quantify longleaf pine’s past primacy and trends in the Coastal Plain, we combined seven studies consisting of 255,000 trees from land surveys, conducted between 1810 and 1860 with other descriptions of historical forests, including change to the present day. Our synthesis found support that Pinus palustris predominantly constituted 77% of historical Coastal Plain trees and upland oaks (Quercus) contributed another 8%. While Pinus still dominates these forests today (58% of all trees), most are now either planted loblolly (Pinus taeda L.) or slash (Pinus elliottii Engelm.) pines. Water oak (Quercus nigra L.), live oak (Quercus virginiana Mill.), sweetgum (Liquidambar styraciflua L.), and red maple (Acer rubrum L.) have increased their proportions compared to historical surveys; both longleaf pine and upland oaks have declined to ≤5% of all trees. Our work also supports previous estimates that longleaf pine originally dominated over 25–30 million ha of Coastal Plain forests. As late as the early 1900s, longleaf pine may still have covered 20 million ha, but declined to 7.1 million ha by 1935 and dropped to 4.9 million ha by 1955. Longleaf pine’s regression continued into the mid-1990s, reaching a low of about 1.3 million ha; since then, restoration efforts have produced a modest recovery to 2.3 million ha. Two centuries of overcutting, land clearing, turpentining for chemicals, fire exclusion followed by forest densification by fire-sensitive species, and other silvicultural influences, including widespread loblolly and slash pine plantations, have greatly diminished the Coastal Plain’s once extensive open longleaf pine forests. Full article

Forest aboveground biomass (AGB, Mg/ha) measurement is one of the key indicators for carbon storage evaluation. Remote sensing techniques have been widely employed to predict forest AGB. However, little attention has been paid to the implications involved in the preprocessing of satellite data. In this work, considering the areas of low forest AGB in our survey plots, we explored the implications of employing atmospheric correction and speckle filtering with Sentinel-1 (S1) synthetic aperture radar (SAR) and Sentinel-2 (S2) to predict forest AGB using multiple linear regression (MLR) and extreme gradient boosting (XGBoost). In the present study, the types of plots examined included oaks (Quercus spp.), Chinese firs (Cunninghamia lanceolata), and Masson pines (Pinus massoniana), and all of the plots were investigated. Specifically, the feature variables related to S1 (dual polarization and texture measures) and S2 (spectral bands) were modeled individually, and 16 feature sets, including different combinations of S1 and S2 based on different preprocessing measures, were established using MLR and XGBoost. The results show that speckle filtering and atmospheric correction marginally influenced the capacity of the S2 spectral bands, the SAR dual-polarization backscatter, and the SAR-based textural measures in predicting the AGB in our survey plots. The associations between the speckle-filtered and unfiltered SAR images and the S2 Top-of-Atmosphere and Bottom-of-Atmosphere products were considerably strong. Additionally, the texture models generally showed better performances than the raw SAR data. Ultimately, the groups that only encompassed the S2 spectral bands were the best-performing groups among the 16 feature sets, while the groups that included only S1-based data generally performed the worst. Full article

The dependence of longleaf pine (Pinus palustris) ecosystems on fire is well-understood, and the anthropogenic alteration of fire cycles within its natural range has contributed to its decline. This has been increasingly exacerbated in areas of urban interfaces, wherein the use of prescribed fire can be problematic. The purpose of this study—the University of West Florida Campus Ecosystem Study—was to examine the effects of fire exclusion on longleaf pine in the unique urban interface of a university campus. This was an interconnected series of investigations on the main campus and three associated natural areas that comprised remnant longleaf stands following the cessation of widespread longleaf pine harvesting—120 years ago. This period of chronic fire exclusion allowed for a distinct shift in the stand structure and composition. The open, savanna-like structure of fire-maintained longleaf stands has transitioned into closed-canopy forests with the increased prevalence of southern evergreen oaks (especially live oak—Quercus virginiana) and Magnolia spp., resulting in the complete absence of longleaf regeneration. Fire exclusion also appeared to decrease soil fertility. The significant variation in the mean age of longleaf pine stems on the main campus; natural areas suggest that these natural areas were likely under separate ownership with contrasting land-use history prior to its purchase by the State of Florida for campus construction in 1963. Full article

Wood is a sustainable renewable material that is widely used in the building sector. Due to recent trends in green initiatives in European and other countries, wood waste is becoming more popular for sound absorption and insulation because of its renewability. Recycled wood material granulated charcoal is an effective acoustic treatment. In this study, we investigated the sound absorption coefficients of raw wood and granulated charcoal species: birch (Betula pendula), pine (Pinus sylvestris), and oak (Quercus robur). The impedance tube method was used to characterize the sound absorption properties of the granulated charcoal. The maximum bulk densities of the materials investigated were 567 kg/m³ for birch (B. pendula) wood and 247 kg/m³ for granulated charcoal. The airflow resistivity of wood and granulated charcoal was found using the static airflow method according to the standard. The grain size distribution of charcoal was also determined, with the highest percentage (25–29%) of the birch and pine grain distribution of charcoal species having a size of 400 µm and 30.7% of the oak a size of 1 mm. All species had the lowest grain size value, i.e., 900 µm (1–4%). The sound absorption of granulated charcoal does not depend on the carbonization temperature at 400, 500, or 600 °C. Granular charcoal of 25 mm has a better sound absorption thickness coefficient for birch at 600 °C (0.57 at 315 Hz) compared to wood of the same thickness. The effectiveness of absorption for wood and granular charcoal depends on the type of wood (birch > pine > oak), grain size, airflow resistivity, and bulk density. Full article