Forests

16 pages, 3447 KB

Open AccessArticle

Predicting the Dynamic Modulus of Elasticity of Logs at the Standing Tree Stage: A Site-Specific Approach to Streamline Log Trading

by Kiichi Harada, Yasutaka Nakata, Masahiko Nakazawa, Keisuke Kojiro and Keiko Nagashima

Forests 2025, 16(9), 1438; https://doi.org/10.3390/f16091438 - 9 Sep 2025

Abstract

As wooden buildings become larger and taller, wood properties such as the dynamic modulus of elasticity (

M O E_{d y n}

), a criterion for evaluating structural timber, are becoming increasingly important. However, the

M O E_{d y n}

of [...] Read more.

As wooden buildings become larger and taller, wood properties such as the dynamic modulus of elasticity (

M O E_{d y n}

), a criterion for evaluating structural timber, are becoming increasingly important. However, the

M O E_{d y n}

of logs is rarely considered in forestry management. In this study, standing trees that can produce logs with high

M O E_{d y n}

at the standing tree stage were identified to facilitate log sales decisions based on the

M O E_{d y n}

values. In the generalized linear mixed model-based prediction of log

M O E_{d y n}

, bucking position and site index were selected as random effects. Incorporating random effects improved the coefficient of determination to 0.651, and log

M O E_{d y n}

could be predicted using the site index class, which reflects site productivity. The results indicate that detailed site conditions conventionally used to assess forest productivity are also useful for predicting the

M O E_{d y n}

of logs before harvesting. Moreover, the

M O E_{d y n}

of logs estimated at the standing tree stage can inform decisions regarding appropriate sales destinations. Full article

(This article belongs to the Special Issue Recent Advances in Nondestructive Evaluation of Wood: In-Forest Wood Quality Assessments—2nd Edition)

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24 pages, 8487 KB

Open AccessArticle

Morphological and Morphometric Characterization of Lycopodiaceae Spores from the Białowieża Primeval Forest Ecosystem (NE Poland)

by Konrad Wilamowski, Monika Puchlik, Tomasz Pawłowicz and Tomasz Oszako

Forests 2025, 16(9), 1437; https://doi.org/10.3390/f16091437 - 9 Sep 2025

Abstract

Spores offer the most accessible diagnostic characters for the early-divergent Lycopodiaceae. We quantified eight morphometric traits—equivalent diameter, polar length, equatorial width, projected area, perimeter, and aspect ratio—in a balanced sample of 50 spores from each of six Central European taxa (Diphasiastrum alpinum [...] Read more.

Spores offer the most accessible diagnostic characters for the early-divergent Lycopodiaceae. We quantified eight morphometric traits—equivalent diameter, polar length, equatorial width, projected area, perimeter, and aspect ratio—in a balanced sample of 50 spores from each of six Central European taxa (Diphasiastrum alpinum, D. tristachyum, D. complanatum, Lycopodium annotinum, L. clavatum, and Huperzia selago) collected in the Białowieża Primeval Forest. Integrated light-microscope and scanning-electron-microscope imaging revealed three discrete wall-ornamentation syndromes (reticulate, verrucate, and granulose) that parallel the quantitative gradients. Principal component analysis showed that a single, collinear size axis accounts for 79% of variance, situating H. selago at the large-diameter extreme (mean:

37 μ m

) and the three Diphasiastrum species at the small-diameter pole (mean: 32–

33 μ m

). One-way ANOVA (

p < 10^{- 31}

) and PERMANOVA (

R^{2} = 0.52

) confirmed decisive interspecific separation that mirrors published molecular phylogenies, underscoring a strong phylogenetic signal in spore form. While trait baselines are taxonomically stable, moderate microhabitat-driven shifts indicate limited ecophenotypic plasticity. The resulting high-resolution benchmark refines palynological identification, enables rapid spore-based bioindication of demographic stress, and strengthens conservation monitoring in relic temperate forest ecosystems. Full article

(This article belongs to the Special Issue Pollen Monitoring of Forest Communities)

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12 pages, 3027 KB

Open AccessArticle

Exploring Paulownia as a Sustainable Alternative to Balsa in Plywood Manufacturing

by Marius Cătălin Barbu, Katharina Burešova, Eugenia Mariana Tudor and Thomas Sepperer

Forests 2025, 16(9), 1436; https://doi.org/10.3390/f16091436 - 9 Sep 2025

Abstract

As industries continue to prioritize sustainability and resource efficiency, Paulownia stands out as a sustainable candidate for replacing Balsa in engineered wood products, offering a lighter, cost-effective solution with the added benefit of reduced ecological impact. The aim of this research is to [...] Read more.

As industries continue to prioritize sustainability and resource efficiency, Paulownia stands out as a sustainable candidate for replacing Balsa in engineered wood products, offering a lighter, cost-effective solution with the added benefit of reduced ecological impact. The aim of this research is to manufacture 7 mm- and 15 mm-thick plywood from Paulownia tomentosa x elongata veneers (as an alternative for balsa veneers) using polyurethane (PUR) and melamine–urea–formaldehyde (MUF) adhesives, and to analyze their physical and mechanical properties. Panels with five and seven layers and thicknesses from 0.8 to 3 mm were tested for bulk density (247–385 kg/m³), thickness swelling (2.47%–5.34%), and water absorption (35%–68%) according to European standards. Mechanical properties assessed included three-point bending strength (MOR) parallel (22–35.8 N/mm²) and perpendicular to the fiber/grain (13.4–21.8 N/mm²), three-point modulus of elasticity (MOE) in longitudinal (2824–3799 N/mm²) and transverse directions (1183–1825 N/mm²), tensile shear strength (1.76–2.52 N/mm²), and screw withdrawal resistance (41.9–60.6 N/mm). Results indicate that Paulownia plywood has significant potential for lightweight construction due to its low density and favorable properties, with MUF adhesive showing superior performance in terms of density and panel properties. This positions Paulownia plywood as a strong contender in the ongoing evolution of lightweight construction materials. Full article

(This article belongs to the Special Issue Physical–Mechanical Characteristic Analysis of Wood and Wood-Based Composites)

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22 pages, 2809 KB

Open AccessArticle

Soil Quality Assessment for Sustainable Management: A Minimum Dataset for Long-Term Fertilization in Subtropical Plantations in South China

by Jiani Peng, Qinggong Mao, Senhao Wang, Sichen Mao, Baixin Zhang, Mianhai Zheng, Juan Huang, Jiangming Mo, Xiangping Tan and Wei Zhang

Forests 2025, 16(9), 1435; https://doi.org/10.3390/f16091435 - 9 Sep 2025

Abstract

Restoration plantations in subtropical regions, often established with fast-growing tree species such as Acacia auriculiformis A. Cunn. ex Benth and Eucalyptus urophylla S. T. Blake, are frequently developed on highly weathered soils characterized by phosphorus deficiency. To investigate strategies for mitigating nutrient imbalances [...] Read more.

Restoration plantations in subtropical regions, often established with fast-growing tree species such as Acacia auriculiformis A. Cunn. ex Benth and Eucalyptus urophylla S. T. Blake, are frequently developed on highly weathered soils characterized by phosphorus deficiency. To investigate strategies for mitigating nutrient imbalances in such ecosystems, a long-term (≥13 years) fertilization experiment was designed. The experiment involved three fertilization regimes: nitrogen fertilizer alone (N), phosphorus fertilizer alone (P), and a combination of nitrogen and phosphorus (NP) fertilizers. The objective of this study was to investigate the effects of long-term fertilization practices on soil quality in subtropical plantations using a soil quality index (SQI). Consequently, all conventional soil physical, chemical, and biological indicators associated with the SQI responses to long-term fertilization treatments were systematically evaluated, and a principal component analysis (PCA) was conducted, along with a literature review, to develop a minimum dataset (MDS) for calculating the SQI. Three physical indicators (silt, clay, and soil water content), three chemical indicators (soil organic carbon, inorganic nitrogen, and total phosphorus), and two biological indicators (microbial biomass carbon and phosphodiesterase enzyme activity) were finally chosen for the MDS from a total dataset (TDS) of eighteen soil indicators. This study shows that the MDS provided a strong representation of the TDS data (R² = 0.81), and the SQI was positively correlated with litter mass (R² = 0.37). An analysis of individual soil indicators in the MDS revealed that phosphorus addition through fertilization (P and NP treatments) significantly enhanced the soil phosphorus pool (64–101%) in the subtropical plantation ecosystem. Long-term fertilization did not significantly change the soil quality, as measured using the SQI, in either the Acacia auriculiformis (p = 0.25) or Eucalyptus urophylla (p = 0.45) plantation, and no significant differences were observed between the two plantation types. These findings suggest that the MDS can serve as a quantitative and effective tool for long-term soil quality monitoring during the process of forest sustainable management. Full article

(This article belongs to the Section Forest Soil)

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23 pages, 2967 KB

Open AccessArticle

Genetic Diversity and Risk of Non-Adaptedness in Natural North Moroccan and Planted South Spanish Atlas Cedar

by Belén Méndez-Cea, Isabel García-García, David Manso-Martínez, Juan Carlos Linares, Francisco Javier Gallego and Jose Luis Horreo

Forests 2025, 16(9), 1434; https://doi.org/10.3390/f16091434 - 8 Sep 2025

Abstract

The Atlas cedar Cedrus atlantica is a relict and endemic conifer from Morocco and Algeria, although plantations may be found in several locations aside from its natural range. Recurrent droughts have been widely related to Atlas cedar dieback, growth decline, and mortality, but [...] Read more.

The Atlas cedar Cedrus atlantica is a relict and endemic conifer from Morocco and Algeria, although plantations may be found in several locations aside from its natural range. Recurrent droughts have been widely related to Atlas cedar dieback, growth decline, and mortality, but the genetic basis of potential adaptive capacity is unknown. We used the double digest restriction-site associated DNA sequencing technique (ddRAD-seq) to describe the genetic structure and variability of Atlas cedar along an aridity gradient in Morocco. Furthermore, we investigated the potential genetic origin of three Spanish plantations, also along an aridity gradient. The obtained single nucleotide polymorphisms (SNPs) were used to perform genotype–environment associations (GEAs) to define SNPs related to bioclimatic variables of temperature and precipitation. The vulnerability of this species to environmental variations was also estimated by its risk of non-adaptedness (RONA). Population structure showed a divergence between the Moroccan natural stands and some of the Spanish plantations, with each Moroccan nucleus being genetically distinct. The genetic variability was significantly lower in plantations than in natural populations. The drier Spanish plantations (easternmost) were genetically very similar to the driest Moroccan population (southernmost), suggesting that as its origin. A total of 41 loci under selection were obtained with the Moroccan dataset. In relation to temperature and precipitation variables, isothermality showed the highest number of associated loci (10) in GEA studies, and genotype–phenotype associations (GPAs) showed one locus associated with the Specific Leaf Area. RONA value was higher in the southernmost High Atlas population, where rising temperature was the main driver of expected genetic offset by allele frequency changes under the worst emissions scenario. In contrast, Spanish plantations would need smaller genetic changes to cope with the expected climate change. Likely gene flow from southern to northern areas suggests a latitudinal heading, where Spanish plantations might operate as an assisted migration. Moreover, one locus showed a northern/southern pattern in saplings but not in adults, suggesting a potential latitudinal pattern of selection. Our results are discussed on the basis of their management and conservation. Full article

(This article belongs to the Special Issue Forest Dieback, Tree Mortality Risks and Post-disturbance Resilience to Environmental Changes)

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16 pages, 1557 KB

Open AccessArticle

Analysis of Volatile Organic Compounds in Cinnamomum camphora Leaves by Direct Thermal Desorption–Gas Chromatography/Mass Spectrometry (DTD-GC/MS)

by Guangrong Li, Fang Cai, Jiayang Hu, Ying’ao Hu and Yixun Wang

Forests 2025, 16(9), 1433; https://doi.org/10.3390/f16091433 - 8 Sep 2025

Abstract

This study established a novel detection method for volatile organic compounds in forest therapy tree species based on direct thermal desorption technology. The optimized parameters included 20 mg sample loading, 110 °C desorption temperature, 30 min desorption time, and 1:30 split ratio. The [...] Read more.

This study established a novel detection method for volatile organic compounds in forest therapy tree species based on direct thermal desorption technology. The optimized parameters included 20 mg sample loading, 110 °C desorption temperature, 30 min desorption time, and 1:30 split ratio. The optimal loading was 5–65 mg to balance the separation resolution and detection sensitivity. Desorption temperature significantly affected component detection: terpenoids accounted for the highest proportion (82.0%) at 90 °C; alkanes surged to 53.3% at 150 °C; acids (19.0%) and esters (19.4%) became dominant; and ascorbyl dipalmitate (17.3%) exceeded linalool (14.6%) at 180 °C. Chemotype analysis revealed that camphor-type leaves were dominated by camphor (72.8%) while linalool-type leaves by linalool (54.3%). Compared with steam distillation, DTD increased the camphor/linalool extraction efficiency while eliminating solvent contamination. Relative to dynamic headspace sampling, DTD mitigated the environmental interference and reduced the pretreatment time. The study confirmed that 110 °C is the optimal temperature for maximized characterization of terpenoids (63.3%), providing technical support for selecting high-terpenoid-emitting trees in forest therapy and evaluating the therapeutic efficacy. It also reveals the linkages between leaf volatiles and stand-level air composition and promotes the development of dynamic forest VOC databases. Full article

(This article belongs to the Section Forest Ecophysiology and Biology)

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27 pages, 11860 KB

Open AccessArticle

The Analysis of the Spatial Distribution Characteristics and Influencing Factors of SOC in a Coastal Tamarix Chinensis Forest—The Case of China’s Changyi National Marine Ecological Special Protection Area

by Ruiting Liu, Jin Wang, Feiyong Chen, Xiuqin Sun, Xiaoxiang Cheng, Keqin Liu, Lin Wang, Geng Xu, Yufeng Du and Jingtao Xu

Forests 2025, 16(9), 1432; https://doi.org/10.3390/f16091432 - 7 Sep 2025

Abstract

This study investigates the spatial distribution characteristics and influencing factors of soil organic carbon (SOC) in the Tamarix chinensis forest ecosystem in Changyi National Marine Ecological Special Reserve, China. Five sampling routes and 32 sampling points were established; 293 soil samples were collected [...] Read more.

This study investigates the spatial distribution characteristics and influencing factors of soil organic carbon (SOC) in the Tamarix chinensis forest ecosystem in Changyi National Marine Ecological Special Reserve, China. Five sampling routes and 32 sampling points were established; 293 soil samples were collected every 10 cm from the surface downwards. GIS spatial analysis techniques were employed to analyze the overall, horizontal, and vertical distribution characteristics of SOC within the 0–100 cm depth range. The results show that SOC content in the reserve ranges from 1.0 to 10.0 gC/kg, with an average of 2.5–8.2 gC/kg. High-SOC zones are in the southwest, where human disturbance is minimal and vegetation is dense, whereas low-SOC areas are in the west, and the north suffers from frequent tides and salinization. Horizontally, the surface SOC (0–10 cm) increased from 2.30 gC/kg in the east to 9.15 gC/kg in the western tidal flat. Vertically, six profile types were identified; the fluctuating type dominated (74.07%). Eight ecological zones were delineated based on land cover and function: the Tamarix core area exhibited surface aggregation with a depth-wise decline; the ecological restoration zone showed a mid-depth peak; and the moisture-proof dam zone displayed a “shallow-rise–deep-drop” pattern. Storm surges, moisture-proof dams, ecological zoning, and restoration projects were key drivers of SOC distribution. Full article

(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)

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13 pages, 3168 KB

Open AccessArticle

Production and Storage of Male-Sterile Somatic Embryos of Sugi (Japanese Cedar, Cryptomeria japonica) at Temperatures Above Freezing

by Tsuyoshi E. Maruyama, Momi Tsuruta, Saneyoshi Ueno and Yoshinari Moriguchi

Forests 2025, 16(9), 1431; https://doi.org/10.3390/f16091431 - 7 Sep 2025

Abstract

Sugi-pollinosis poses a significant socioeconomic and public health concern in Japanese society. Consequently, the use of male-sterile plants (pollen-free plants or PFPs) is anticipated in reforestation efforts. In this context, we developed an improved, simplified method for efficiently propagating sugi PFPs. In the [...] Read more.

Sugi-pollinosis poses a significant socioeconomic and public health concern in Japanese society. Consequently, the use of male-sterile plants (pollen-free plants or PFPs) is anticipated in reforestation efforts. In this context, we developed an improved, simplified method for efficiently propagating sugi PFPs. In the present study, we compared the efficiency of different embryogenic cell lines (ECLs) in producing somatic embryos and examined how effectively these embryos germinate and convert into plantlets. We also evaluated the germination potential of somatic embryos stored for various durations at temperatures above freezing and room temperature. The production efficiency of somatic embryos ranged from 129.6 to 504.1 per plate, with an average of 349.8 across the ECLs tested. The overall average germination and conversion rates of somatic embryos were found to be 93.9% and 92.4%, respectively. Furthermore, although differences were observed among the evaluated genotypes, our five-year study demonstrated that sugi somatic embryos could be stored at 25 °C, 15 °C, or 5 °C for 6, 12, or 24 months, respectively, without a notable decline in germination capacity. The developed method enhances flexibility in plant production scheduling and facilitates the optimal timing for transferring somatic seedlings to the field. Full article

(This article belongs to the Section Genetics and Molecular Biology)

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23 pages, 7451 KB

Open AccessArticle

Comparing Machine Learning and Statistical Models for Remote Sensing-Based Forest Aboveground Biomass Estimations

by Shashika Himandi Gardeye Lamahewage, Chandi Witharana, Rachel Riemann, Robert Fahey and Thomas Worthley

Forests 2025, 16(9), 1430; https://doi.org/10.3390/f16091430 - 7 Sep 2025

Abstract

Understanding the distribution of forest aboveground biomass (AGB) is pivotal for carbon monitoring. Field-based inventorying is time-consuming and costly for large-area AGB estimations. The integration of multimodal remote sensing (RS) observations with single-year, field-based forest inventory analysis (FIA) data has the potential to [...] Read more.

Understanding the distribution of forest aboveground biomass (AGB) is pivotal for carbon monitoring. Field-based inventorying is time-consuming and costly for large-area AGB estimations. The integration of multimodal remote sensing (RS) observations with single-year, field-based forest inventory analysis (FIA) data has the potential to improve the efficiency of large-scale AGB modeling and carbon monitoring initiatives. Our main objective was to systematically compare the AGB prediction accuracies of machine learning algorithms (e.g., random forest (RF) and support vector machine (SVM)) with those of conventional statistical methods (e.g., multiple linear regression (MLR)) using multimodal RS variables as predictors. We implemented a method combining AGB estimates of actual FIA subplot locations with airborne LiDAR, National Agriculture Imagery Program (NAIP) aerial imagery, and Sentinel-2 satellite images for model training, validation, and testing. The hyperparameter-tuned RF model produced a root mean square error (RMSE) of 27.19 Mgha⁻¹ and an R² of 0.41, which outperformed the evaluation metrics of SVM and MLR models. Among the 28 most important explanatory variables used to build the best RF model, 68% of variables were derived from the LiDAR height data. The hyperparameter-tuned linear SVM model exhibited an R² of 0.10 and an RMSE of 32.17 Mgha⁻¹. Additionally, we developed an MLR using eight explanatory variables, which yielded an RMSE of 22.59 Mgha⁻¹ and an R² of 0.22. The linear ensemble model, which was developed using the predictions of all three models, yielded an R² of 0.79. Our results suggested that more field data are required to better generalize the ensemble model. Overall, our findings highlight the importance of variable selection methods, the hyperparameter tuning of ML algorithms, and the integration of multimodal RS data in improving large-area AGB prediction models. Full article

(This article belongs to the Special Issue Forest Inventory: The Monitoring of Biomass and Carbon Stocks)

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18 pages, 1649 KB

Open AccessArticle

Experimental Approaches to Improve Yerba Mate Tissue Culture Using Nanoparticles

by Bruna Zanatta Pereira, Regina Caetano Quisen, Juliana Degenhardt and Ivar Wendling

Forests 2025, 16(9), 1429; https://doi.org/10.3390/f16091429 - 6 Sep 2025

Abstract

Ilex paraguariensis (yerba mate), a culturally and economically important South American species, faces significant challenges in vitro, including contamination, phenolic oxidation, and low regeneration rates. Nanoparticles have recently emerged as promising tools to overcome such limitations. This study evaluated silver (AgNPs) and chitosan [...] Read more.

Ilex paraguariensis (yerba mate), a culturally and economically important South American species, faces significant challenges in vitro, including contamination, phenolic oxidation, and low regeneration rates. Nanoparticles have recently emerged as promising tools to overcome such limitations. This study evaluated silver (AgNPs) and chitosan nanoparticles (ChNPs) in eight experiments using nodal, leaf, and internodal explants. Surface disinfection with 1% colloidal silver solution 20 ppm significantly reduced contamination (17.2% and 15%) while maintaining viability (62.1%). However, supplementation of culture media with AgNPs (4–75 mg·L⁻¹) or ChNPs (5–120 mg·L⁻¹) did not improve nodal segment responses. In leaf explants, 4 mg·L⁻¹ AgNPs proved most effective, reducing contamination and markedly decreasing callus oxidation from 63.3% to 10.0%. Callogenesis was enhanced when AgNPs were combined with growth regulators, with the highest induction at 6 mg·L⁻¹ AgNPs + zeatin (38.1%) and 4 mg·L⁻¹ AgNPs + BAP (42.9%). Conversely, in internodal segments, AgNPs combined with BAP completely inhibiting callus formation. The resulting calli exhibited compact and friable morphologies but no signs of somatic embryogenesis. Overall, the effectiveness of AgNPs depends on their formulation, explant type, and interaction with cytokinins. Optimization of nanoparticle formulation and hormonal balance remains essential to maximize efficacy while minimizing toxicity. Full article

(This article belongs to the Special Issue Somatic Embryogenesis and Organogenesis on Tree Species: 2nd Edition)

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28 pages, 8299 KB

Open AccessEssay

Properties of Oak Veneer Dyed with Supercritical CO₂ and Vacuum-Pressurized Assisted Natural Dyes

by Yue Liu, Yiqing Qi, Yining Chen, Ziwen Zhou, Chanchan Cao, Qiao Zu and Jianlin Han

Forests 2025, 16(9), 1428; https://doi.org/10.3390/f16091428 - 6 Sep 2025

Abstract

This study investigated the sustainable dyeing process of two natural dyes, Phellodendron Bark and camphor fruit, on oak veneer. The oak was pretreated with SC-CO₂ and dyed using three methods, namely conventional water bath, SC-CO₂, and vacuum pressurization, and the [...] Read more.

This study investigated the sustainable dyeing process of two natural dyes, Phellodendron Bark and camphor fruit, on oak veneer. The oak was pretreated with SC-CO₂ and dyed using three methods, namely conventional water bath, SC-CO₂, and vacuum pressurization, and the dyeing rate, color difference, washing fastness, and sunlight fastness were compared horizontally. BET test showed that the specific surface area of the oak was increased by 38%, the pore volume was increased by 46%, and the permeability of the oak was significantly improved after SC-CO₂ pretreatment. The results of the three dyeing methods in dyeing show that vacuum-pressurized dyeing has the best effect, with a dyeing rate up to 27.64%, and an increase of 4.63%; the wood-washing color difference with SC-CO₂-assisted Phellodendron Bark dyeing is only 3.15; the camphor berries’ actual air pressurized wood dyeing increased the sunlight fastness by 49%; SC-CO₂-assisted Phellodendron Bark dyeing resulted in the highest crystallinity of 62.34%. This study compared the dyeing effects of different natural dyes under SC-CO₂ pretreatment and different dyeing methods to solve the poor effect and low color fastness that natural dyes exhibit on wood, hoping to expand the application of wood in green, sustainable, functional materials. Full article

(This article belongs to the Section Wood Science and Forest Products)

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22 pages, 4401 KB

Open AccessArticle

Forest Carbon Storage and Economic Valuation in Qilian Mountain National Park: Integrating Multi-Source Data and GARCH-M(1,1)-Driven Dynamic Carbon Pricing

by Weibao Sun, Yafang Gao, Xuemei Yang and Yalong Zhang

Forests 2025, 16(9), 1427; https://doi.org/10.3390/f16091427 - 6 Sep 2025

Abstract

Qilian Mountain National Park, an important forest ecosystem in northwest China, plays a crucial role in achieving the national “dual carbon” goals and advancing sustainable forest management. This study focuses on the systematic assessment of forest carbon storage and its market economic value, [...] Read more.

Qilian Mountain National Park, an important forest ecosystem in northwest China, plays a crucial role in achieving the national “dual carbon” goals and advancing sustainable forest management. This study focuses on the systematic assessment of forest carbon storage and its market economic value, employing multi-source data fusion and the GARCH-M(1,1) model to integrate forest carbon storage data from 2000 to 2020 with historical trading records from the EU and Chinese carbon markets (2017–2025). The study utilizes three dynamic carbon pricing scenarios—low, medium, and high—to assess the carbon storage capacity and economic value of the park’s forest ecosystems. Results show that forest carbon storage increased by approximately 4.0 × 10⁷ tons, with an average annual growth rate of 0.27%. Under the high carbon pricing scenario in 2025, the forest carbon sink value in the EU market reaches CNY 518.2 billion, approximately 12.5 times that of the Chinese market, highlighting the differences in market maturity and volatility persistence. Through Monte Carlo simulations and dynamic pricing analysis, this research reveals the substantial market potential of Qilian Mountain’s forest carbon sinks, providing data-driven support for regional carbon trading optimization, ecological compensation mechanisms, and sustainable forest management, while contributing to the global carbon trading system and international cooperation in forest-based climate mitigation. Full article

(This article belongs to the Section Forest Ecology and Management)

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16 pages, 768 KB

Open AccessArticle

Beyond the Experience: How Lifestyle, Motivation, and Physical Condition Shape Forest Traveler Satisfaction

by Xi Wang, Jie Zheng, Zihao Han and Chenyu Zhao

Forests 2025, 16(9), 1426; https://doi.org/10.3390/f16091426 - 5 Sep 2025

Abstract

Forest tourism visitation in U.S. national forests has grown by approximately 8 percent over the past decade (from 2014 to 2022) from 147 million to 158.7 million visits per year, indicating a clear upward trajectory in demand for nature-based leisure experiences, yet the [...] Read more.

Forest tourism visitation in U.S. national forests has grown by approximately 8 percent over the past decade (from 2014 to 2022) from 147 million to 158.7 million visits per year, indicating a clear upward trajectory in demand for nature-based leisure experiences, yet the determinants of traveler satisfaction in this context remain insufficiently understood. Existing studies have primarily emphasized destination attributes, overlooking the interplay between psychological motivations, lifestyle orientations, and physical conditions. This omission is critical because it limits a holistic understanding of forest traveler’s experiences, which prevents us from fully capturing how internal dispositions, everyday life contexts, and well-being concerns interact with destination attributes to shape satisfaction. Therefore, the purpose of this study is to explore how motivation, lifestyle, and physical condition jointly shape satisfaction in forest tourism, drawing on Push–Pull Theory and environmental psychology. A dataset of 10,792 TripAdvisor reviews of U.S. national forests was analyzed using LIWC 2022 for psycholinguistic feature extraction and Ordered Logit Regression for hypothesis testing. Results show that positive emotional tone, leisure-oriented language, health references, and reward motivation significantly enhance satisfaction, while negative tone, illness, and work-related language reduce it. Curiosity and risk motivations were non-significant, and allure exerted only a marginal effect. These findings extend the Push–Pull framework by incorporating lifestyle and physical condition as moderating variables and validate emotional tone in user-generated content as a proxy for subjective evaluations. The study refines motivation theory by revealing context-specific effects of motivational dimensions. The results offer actionable insights for destination managers, service providers, marketers, and policymakers aiming to enhance forest travel experiences and promote sustainable tourism development. Full article

(This article belongs to the Special Issue The Sustainable Use of Forests in Tourism and Recreation)

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17 pages, 3655 KB

Open AccessArticle

Genome-Wide Identification of the PRP Gene Family Members of the Dove Tree (Davidia involucrata Baill.)

by Yanling Fan, Xiyi Zhang, Yanxian Luo, Jie Niu, Jia Li and Meng Li

Forests 2025, 16(9), 1425; https://doi.org/10.3390/f16091425 - 5 Sep 2025

Abstract

The large, white paired bract is a unique trait, as well as the most intriguing feature of the dove tree (Davidia involucrata). However, the mechanisms underlying bract development remain unclear. Our previous comparative transcriptome analysis concerning Davidia bracts at different developmental [...] Read more.

The large, white paired bract is a unique trait, as well as the most intriguing feature of the dove tree (Davidia involucrata). However, the mechanisms underlying bract development remain unclear. Our previous comparative transcriptome analysis concerning Davidia bracts at different developmental stages has identified a number of bract-specific genes. Among these, the genes encoding PRPs (proline-rich proteins) show dramatic expression variation, indicating the participation of this gene family in bract development. In this study, we screened the whole Davidia genome and identified twelve Davidia PRP (DiPRP) genes, showing obvious expression variation during bract development, with some upregulated up to 100-fold at the fast-developing stage. These PRP genes are evenly distributed on seven Davidia chromosomes. The cis-element composition of the promoter regions of the DiPRPs demonstrates that these genes might be controlled by phytohormones (especially ABA, GA, and MeJA), light, and the circadian clock, which is consistent with the environmental cues during Davidia bract development. Synteny analysis indicated that the PRP genes from the Davidia genome have higher collinearity with naturally bracted plants, such as Antirhonum majus and Bougainvillea glabra, but lower collinearity with non-bracted species. Our results suggest that high expression of certain PRP genes, specifically in bracts, might be critical for leaf metamorphosis. Full article

(This article belongs to the Special Issue Latest Progress in Research on Forest Tree Genomics)

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16 pages, 2211 KB

Open AccessArticle

Optimizing Season-Specific MET for Thermal Comfort Under Open and Closed Urban Forest Canopies

by Doyun Song, Sieon Kim, Minseo Park, Choyun Kim, Chorong Song, Bum-Jin Park, Dawou Joung and Geonwoo Kim

Forests 2025, 16(9), 1424; https://doi.org/10.3390/f16091424 - 5 Sep 2025

Abstract

Urban heat island conditions increase heat exposure and constrain safe outdoor activities. Urban forests can mitigate thermal loads; however, stand morphology can produce divergent microclimates. We aimed to quantify how stand type (open vs. closed), season (spring, summer, fall), and activity intensity (MET [...] Read more.

Urban heat island conditions increase heat exposure and constrain safe outdoor activities. Urban forests can mitigate thermal loads; however, stand morphology can produce divergent microclimates. We aimed to quantify how stand type (open vs. closed), season (spring, summer, fall), and activity intensity (MET 1.0–6.0) jointly modulate thermal comfort and to identify season-specific optimal MET levels in an urban forest in Daejeon, Republic of Korea. We combined site-specific 3D canopy modeling with hourly Predicted Mean Vote (PMV) simulations driven by AMOS tower data (2023–2024). Comfort was defined as |PMV| ≤ 0.5. Analyses included seasonal means, Cliff’s delta, and generalized estimating equation logistic models to estimate the SITE × SEASON × MET interactions and predict comfort probabilities. Across most seasons and MET levels, C1 was more comfortable than C2. However, at MET 1.0 in summer, the pattern was reversed, which may reflect the canopy shading and associated decreases in mean radiant temperature (MRT) of C2. Comfort peaked at MET 2.0–3.0 and declined sharply at ≥4.5 MET. The three-way SITE × SEASON × MET interaction was significant (p < 0.001). The season-specific optimal MET values under our boundary conditions were 3.0 (spring), 2.0–2.5 (summer), and 3.0 (fall). These simulation-based PMV-centered findings represent model-informed tendencies. Nevertheless, they support actionable guidance: prioritize high-closure stands for low-intensity summer use, leverage open stands for low-to-moderate activities in spring and fall, and avoid high-intensity programs during warm periods. These results inform the programming and design of urban-forest healing and recreation by matching stand type and activity intensity to season to maximize comfortable hours. Full article

(This article belongs to the Special Issue Forest and Human Well-Being)

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25 pages, 8260 KB

Open AccessArticle

A Novel Approach for Inverting Forest Fuel Moisture Content Utilizing Multi-Source Remote Sensing and Deep Learning

by Wenjun Wang, Cui Zhou, Junxiang Zhang, Yuanzong Li, Zhenyu Chen and Yongfeng Luo

Forests 2025, 16(9), 1423; https://doi.org/10.3390/f16091423 - 5 Sep 2025

Abstract

Fuel Moisture Content (FMC) is a critical indicator for assessing forest fire risk and formulating early warning strategies, as its spatiotemporal dynamics directly influence the accuracy of fire danger rating. To improve the accuracy of forest FMC estimation, this study proposes an innovative [...] Read more.

Fuel Moisture Content (FMC) is a critical indicator for assessing forest fire risk and formulating early warning strategies, as its spatiotemporal dynamics directly influence the accuracy of fire danger rating. To improve the accuracy of forest FMC estimation, this study proposes an innovative deep learning method integrating multi-source remote sensing data. By combining the global feature extraction capability of the Transformer architecture with the local temporal modeling advantages of Gated Recurrent Units (GRU) (referred to as the Transformer-GRU model), a high-precision FMC estimation framework is established. The study focuses on forested areas in California, USA, utilizing ground-measured FMC data alongside multi-source remote sensing datasets from MODIS, Sentinel-1, and Sentinel-2. A systematic comparison was conducted among Transformer-GRU model, standalone Transformer models, single GRU models, and two classical machine learning models (Random Forest, RF, and Support Vector Regression, SVR). Additionally, forward feature selection was employed to evaluate the performance of different models and feature combinations. The results demonstrate that (1) All models effectively utilize the derived features from multi-source remote sensing data, confirming the significant enhancement of multi-source data fusion for forest FMC estimation; (2) The Transformer-GRU model outperforms other models in capturing the nonlinear relationship between FMC and remote sensing data, achieving superior estimation accuracy (R² = 0.79, MAE = 8.70%, RMSE = 11.44%, rRMSE = 12.60%); (3) The spatiotemporal distribution patterns of forest FMC in California generated by the Transformer-GRU model align well with regional geographic characteristics and climatic variability, while exhibiting a strong relationship with historical wildfire occurrences. The proposed Transformer-GRU model provides a novel approach for high-precision FMC estimation, offering reliable technical support for dynamic forest fire risk early warning and resource management. Full article

(This article belongs to the Section Natural Hazards and Risk Management)

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18 pages, 1538 KB

Open AccessArticle

The Hygroscopicity and Strength Properties of Thermally Modified Gigantochloa scortechinii Bamboo from Peninsular Malaysia

by Zahidah Zafhian, Adlin Sabrina Muhammad Roseley, Sabiha Salim, Sik Huei Shing and Zairul Amin Rabidin

Forests 2025, 16(9), 1422; https://doi.org/10.3390/f16091422 - 5 Sep 2025

Abstract

Bamboo is a lignocellulosic material characterized by its high hygroscopicity, which refers to the ability of material to absorb and retain moisture from the surrounding environment. This attribute could adversely affect its dimensional stability and resistance against deterioration agents. Thus, a study was [...] Read more.

Bamboo is a lignocellulosic material characterized by its high hygroscopicity, which refers to the ability of material to absorb and retain moisture from the surrounding environment. This attribute could adversely affect its dimensional stability and resistance against deterioration agents. Thus, a study was conducted to investigate the effect of thermal modification on the hygroscopic, mechanical, and chemical properties of three-year-old Gigantochloa scortechinii, a native and highly exploited bamboo species in Malaysia. Overall, heat treatment effectively reduced the equilibrium moisture content and improved the dimensional stability of bamboo, with samples treated at 210 °C exhibited the most significant moisture resistance of up to 95.6% anti-swelling efficiency (ASE). The heat-treated bamboo exhibited an improvement in modulus of elasticity (MOE) at intermediate temperatures (170–190 °C) whereas modulus of rupture (MOR) declined at 210 °C. Chemical analysis indicated that a significant reduction in hemicellulose content and a relative increase in α-cellulose and lignin contributed to the improved moisture resistance of heat-treated bamboo. The results demonstrate the viability of heat treatment in producing quality thermally modified bamboo as an alternative raw material for construction materials and furniture manufacturing, thereby contributing to the development of Malaysia’s bamboo industry. Full article

(This article belongs to the Special Issue Advancements in Bamboo and Rattan: Insights into Molecular Biology, Physiology, Ecology, and Applications)

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15 pages, 6302 KB

Open AccessArticle

The Application of Structural Adhesives in Glulam Beams: A Comparative Study

by Leonor da Cunha Mastela, Pedro Gutemberg de Alcântara Segundinho, Fabricio Gomes Gonçalves, Clara Gaspar Fossi de Souza, Francisco Antônio Rocco Lahr, Daniela Minini, Michel Picanço Oliveira, Maria Alice Romanha Belumat and Caroline Palacio de Araujo

Forests 2025, 16(9), 1421; https://doi.org/10.3390/f16091421 - 5 Sep 2025

Abstract

This study aimed to evaluate the adhesion behavior of wood from an E. urophylla × E. grandis clone using the application of melamine–urea–formaldehyde (MUF), resorcinol–formaldehyde (RF), and polyurethane (PUR) adhesives in test samples obtained from 12 glulam beams. Adhesives were characterized by their [...] Read more.

This study aimed to evaluate the adhesion behavior of wood from an E. urophylla × E. grandis clone using the application of melamine–urea–formaldehyde (MUF), resorcinol–formaldehyde (RF), and polyurethane (PUR) adhesives in test samples obtained from 12 glulam beams. Adhesives were characterized by their pH, viscosity, density, and solid content. The wood–adhesive interface was assessed through the shear strength, percentage of wood failure, delamination, and photomicrograph analysis. A microdensitometer with X-rays and a resistograph were used to determine the material density and drilling resistance of the elements. Adhesive pH values ranged from 6.35 to 9.05. MUF exhibited the highest viscosity (1169 cP), while the adhesive density varied between 1.29 and 1.67 g cm⁻³. No statistically significant difference in results was obtained for the shear strength in dry conditions. The MUF adhesive showed a lower percentage of wood failure compared to PUR and RF. In the delamination test, the wood beams glued with RF yielded the best results. Photomicrographs revealed the adhesive’s penetration into the wood’s anatomical structure. Densitometry and resistograph profiles accurately represented the beam balancing configuration. The adhesives PUR, RF, and MUF demonstrated suitability for producing glulam beams with the Eucalyptus clone wood evaluated in this study. Full article

(This article belongs to the Special Issue Characterization and Numerical Simulation of Solid Wood and Engineered Wood Products)

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20 pages, 1026 KB

Open AccessArticle

Use of Cupressus lusitanica for Afforestation in a Mediterranean Climate: Biomass Production and Wood Quality

by José Lousada, André Sandim and Maria Emília Silva

Forests 2025, 16(9), 1420; https://doi.org/10.3390/f16091420 - 4 Sep 2025

Abstract

The selection of tree species for afforestation in Mediterranean environments involves challenges related to adaptability, impact on soil properties, and overall environmental quality. Cupressus lusitanica has been recognized for its rapid growth, environmental resilience, and versatile applications, positioning it as a promising candidate [...] Read more.

The selection of tree species for afforestation in Mediterranean environments involves challenges related to adaptability, impact on soil properties, and overall environmental quality. Cupressus lusitanica has been recognized for its rapid growth, environmental resilience, and versatile applications, positioning it as a promising candidate for these regions. Although it has been used for afforestation in Northeast Portugal since the 1990s, no comprehensive studies have evaluated its performance under local conditions. To address this knowledge gap, this study assessed a 14-year-old C. lusitanica stand in Northeast Portugal. The wood’s anatomical, physical, chemical, and mechanical properties, as well as biomass production, were evaluated. The species showed superior radial growth and adaptability compared with other species under similar environmental conditions. Despite exhibiting lower fiber length (1.6 mm) and basic wood density (404 kg/m³), shrinkage values fell within the typical range for softwoods. Nevertheless, a marked tendency for warping was observed. The extractive content was relatively high (5.1%), with the ethanol-soluble fraction being predominant (3.6%). Mechanical tests revealed low values for both Modulus of Elasticity (MOE) (3592.5–3617.1 MPa) and Modulus of Rupture (MOR) (57.7–68.9 MPa), with both properties significantly influenced by knot presence. Given the results obtained, the species C. lusitanica, despite its low wood density and potential limitations in use, exhibits remarkable growth and adaptability, which confer a high potential for biomass production and carbon sequestration, as well as potential applications of its wood in reconstituted panels and fiber- or particle-based boards. Full article

(This article belongs to the Section Wood Science and Forest Products)

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