Forests

19 pages, 4026 KB

Open AccessArticle

Structural Optimization of Sustainable Lightweight Hemp Shive-Fiber Panels

by Viktor Savov, Petar Antov, Viktoria Dudeva and Georgi Ivanov

Forests 2025, 16(10), 1541; https://doi.org/10.3390/f16101541 - 3 Oct 2025

This study investigates the structural optimization of lightweight three-layer panels made from industrial hemp shives (core) and hemp fibers (faces) as a sustainable alternative to wood-based materials in furniture manufacturing. Panels with target densities of 400–600 kg·m⁻³ and face-layer contents of 30%–50%were [...] Read more.

This study investigates the structural optimization of lightweight three-layer panels made from industrial hemp shives (core) and hemp fibers (faces) as a sustainable alternative to wood-based materials in furniture manufacturing. Panels with target densities of 400–600 kg·m⁻³ and face-layer contents of 30%–50%were produced and tested to European standards. The optimal configuration—600 kg·m⁻³ with ~37%–41% face layers—achieved a modulus of elasticity up to 3750 N·mm⁻² and a bending strength (MOR) up to 21.57 N·mm⁻². Across the design space, water absorption ranged from ~83% to 162%, and the minimum thickness swelling was ~29%, indicating that while the mechanical properties meet the requirements for P2 particleboards (EN 312) and in some cases approach MDF benchmarks for dry use, thickness swelling remains above the EN 622-5 limit (12%) and thus precludes MDF classification. These findings demonstrate the technical feasibility of hemp shive–fiber panels and underscore the need to balance density and face-layer ratio to avoid loss of core densification at excessive face contents. From a sustainability perspective, the use of rapidly renewable hemp and agricultural residues highlights the potential of these composites to support resource-efficient, low-carbon furniture production, while future work should target improved water resistance through binder and process modifications. Full article

(This article belongs to the Special Issue Advanced Research and Technology on Biomass Materials in Forestry)

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13 pages, 2022 KB

Open AccessArticle

Assessment of Standing and Felled Tree Measurements for Volume Estimation

by Maria Triantafyllidou, Elias Milios and Kyriaki Kitikidou

Forests 2025, 16(10), 1540; https://doi.org/10.3390/f16101540 - 3 Oct 2025

Abstract

Accurate stem-volume estimation supports inventory, valuation and carbon accounting, but Pressler’s single-section formula has never been tested in the highly productive European-beech forests of the Central Rhodope Mountains, Greece. We quantified the bias of Pressler estimates and developed size-specific correction factors. Sixty Fagus [...] Read more.

Accurate stem-volume estimation supports inventory, valuation and carbon accounting, but Pressler’s single-section formula has never been tested in the highly productive European-beech forests of the Central Rhodope Mountains, Greece. We quantified the bias of Pressler estimates and developed size-specific correction factors. Sixty Fagus sylvatica L. trees felled in 2023–2024 were measured destructively at 1-m intervals. Pressler standing volumes were compared with Smalian-plus-cone reference volumes (hereafter referred to as true volumes) and analysed with generalized additive models. Pressler underestimated true volume (mean bias = −0.088 m³; RMSE = 0.204 m³; MAPE = 21%). Under-estimation increased with diameter. A GAM with DBH and height explained 96.7% of the variance in true volume. We also fit a Random Forest as a complementary check. Multipliers of 1.30 (<25 cm DBH), 1.20 (25–45 cm), 1.30 (45–55 cm) and ≥1.35 (≥55 cm) cut residual error to ≤20% overall and <10% inside the well-sampled 35–45 cm class. A simple DBH-class correction table restores Pressler’s speed while meeting modern accuracy standards for inventory and carbon reporting. Full article

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

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27 pages, 2889 KB

Open AccessArticle

In Vitro Plantlet Regeneration and Accumulation of Ginkgolic Acid in Leaf Biomass of Ginkgo biloba L.

by Yumei Xie, Keyuan Zheng, Yuan Chen, Jianxu Li, Juan Guo, Jianguo Cao and Mulan Zhu

Forests 2025, 16(10), 1539; https://doi.org/10.3390/f16101539 - 3 Oct 2025

Abstract

This study established an efficient in vitro regeneration system using stem nodes from root collar suckers as explants. Subsequently, regenerated shoots were used to establish an in vitro medicinal production protocol that achieved ginkgolic acid production. The self-developed Ginkgo biloba medium (GBM), first [...] Read more.

This study established an efficient in vitro regeneration system using stem nodes from root collar suckers as explants. Subsequently, regenerated shoots were used to establish an in vitro medicinal production protocol that achieved ginkgolic acid production. The self-developed Ginkgo biloba medium (GBM), first reported in this study, was pivotal to system establishment. The plantlet propagation system showed that the bases of stem nodes dipped in GBM with 2 mg·L⁻¹ 6-benzyladenine (BA) and 0.2 mg·L⁻¹ 1-naphthaleneacetic acid (NAA) achieved near-complete axillary bud induction (99.56%). Adventitious shoot induction reached 82.22% (3.5 shoots/explant) using GBM with 0.2 mg·L⁻¹ BA, 0.02 mg·L⁻¹ kinetin (Kin) and 0.2 g·L⁻¹ proline (Pro). Maximum adventitious shoot elongation (92.22%, average 3.35 cm) was observed on GBM containing 0.1 mg·L⁻¹ zeatin (ZT) and 0.01 mg·L⁻¹ BA. After 3-week preculture with 15 mg·L⁻¹ phloroglucinol (PG), treatment with 0.6 mg·L⁻¹ indole-3-butyric acid (IBA) and 0.2% activated carbon (AC) yielded 96.67% rooting (6.19 roots/explant) and 85% acclimatization survival. For medicinal resource production, bud cluster induction at 94.44% (20.89 buds/explant) on GBM with 1 mg·L⁻¹ BA, 0.03 mg·L⁻¹ Kin, and 0.2 g·L⁻¹ Pro. Leaf organs in GBM with 0.3 mg·L⁻¹ BA, 0.01 mg·L⁻¹ Kin, 0.01 mg·L⁻¹ IBA, 0.3 g·L⁻¹ Pro, and 0.01 mg·L⁻¹ glutamine (Gln) accumulated 20.64 g fresh weight and 41.910 mg·g⁻¹ DW ginkgolic acids, representing a 4.93-fold increase over mother plants. This system enables large-scale Ginkgo biloba L. propagation and provides an in vitro strategy for producing medicinal compounds in endangered plants. Full article

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

13 pages, 2982 KB

Open AccessArticle

Simulation of the Radial Sawing Technique for Pedunculata Oak (Quercus robur L.) Logs

by Josip Ištvanić, Dario Pervan, Alan Antonović, Krunoslav Piljak, Murčo Obućina and Miljenko Klarić

Forests 2025, 16(10), 1538; https://doi.org/10.3390/f16101538 - 3 Oct 2025

Abstract

Using the RadSawSim simulator for radial sawing, a simulation of the radial sawing technique was used to saw Pedunculata oak (Quercus robur L.) logs. Simulation was implemented with a view to producing as many radially sawn boards as possible and took into [...] Read more.

Using the RadSawSim simulator for radial sawing, a simulation of the radial sawing technique was used to saw Pedunculata oak (Quercus robur L.) logs. Simulation was implemented with a view to producing as many radially sawn boards as possible and took into account the influences of increasing volume yield, lumber value yield, and log-value yield. The methods that were analyzed were live sawing and radial sawing of third sections, fourth sections, fifth sections, and sixth sections of the log. Live sawing achieved the best results of volume yield during simulation, which was followed by radial sawing into the third, fourth, fifth, and sixth sections. The difference in volume yield with live sawing compared to the radial-sawing method is very large for logs up to a diameter of 45 cm. It becomes smaller when the log diameter is greater than 45 cm. A comparison of the radial method shows that the share of radially sawn boards and lumber value yield increased when the number of log sections during sawing simulation increased. If log-value yield is assumed to be the main criterion, and given the conditions used in this simulation, there is no justified reason to saw logs using the radial technique when the diameter is less than 45 cm. The live sawing technique is more efficient for these diameters of logs, and, therefore, the radial sawing technique is more efficient for logs with a diameter greater than 45 cm. Full article

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

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16 pages, 1492 KB

Open AccessReview

Nature Deficit in the Context of Forests and Human Well-Being: A Systematic Review

by Natalia Korcz

Forests 2025, 16(10), 1537; https://doi.org/10.3390/f16101537 - 2 Oct 2025

Abstract

Modern societies are increasingly experiencing limited contact with nature, a phenomenon referred to as the “nature deficit.” The article presents a systematic review of the literature on this issue, with particular emphasis on the role of forests in mitigating its effects. The analysis, [...] Read more.

Modern societies are increasingly experiencing limited contact with nature, a phenomenon referred to as the “nature deficit.” The article presents a systematic review of the literature on this issue, with particular emphasis on the role of forests in mitigating its effects. The analysis, based on the Scopus and Web of Science databases, synthesizes the current state of knowledge on the consequences of nature deficit for physical, mental, and social health, while also highlighting the potential of forests as spaces supporting human well-being. The review process followed a systematic methodology, using precisely defined keyword combinations and multi-stage screening. From an initial pool of 88 publications, a critical selection process led to 11 articles that met the inclusion criteria and were analyzed in depth. The findings show that regular contact with nature reduces stress, anxiety, and ADHD symptoms, supports cognitive development, and im-proves concentration, creativity, and social skills. At the same time, there is a lack of consistent tools for clearly diagnosing nature deficit, and existing studies face significant methodological limitations (small samples, subjective measurements, lack of laboratory control). The article also identifies research gaps, particularly in the context of sustainable forest management, cultural differences, and the long-term health effects of exposure to nature. Full article

(This article belongs to the Topic Biophilic Cities and Communities: Human-Environment Interaction and Sustainable Governance)

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22 pages, 32792 KB

Open AccessArticle

MRV-YOLO: A Multi-Channel Remote Sensing Object Detection Method for Identifying Reclaimed Vegetation in Hilly and Mountainous Mining Areas

by Xingmei Li, Hengkai Li, Jingjing Dai, Kunming Liu, Guanshi Wang, Shengdong Nie and Zhiyu Zhang

Forests 2025, 16(10), 1536; https://doi.org/10.3390/f16101536 - 2 Oct 2025

Abstract

Leaching mining of ion-adsorption rare earths degrades soil organic matter and hampers vegetation recovery. High-resolution UAV remote sensing enables large-scale monitoring of reclamation, yet vegetation detection accuracy is constrained by key challenges. Conventional three-channel detection struggles with terrain complexity, illumination variation, and shadow [...] Read more.

Leaching mining of ion-adsorption rare earths degrades soil organic matter and hampers vegetation recovery. High-resolution UAV remote sensing enables large-scale monitoring of reclamation, yet vegetation detection accuracy is constrained by key challenges. Conventional three-channel detection struggles with terrain complexity, illumination variation, and shadow effects. Fixed UAV altitude and missing topographic data further cause resolution inconsistencies, posing major challenges for accurate vegetation detection in reclaimed land. To enhance multi-spectral vegetation detection, the model input is expanded from the traditional three channels to six channels, enabling full utilization of multi-spectral information. Furthermore, the Channel Attention and Global Pooling SPPF (CAGP-SPPF) module is introduced for multi-scale feature extraction, integrating global pooling and channel attention to capture multi-channel semantic information. In addition, the C2f_DynamicConv module replaces conventional convolutions in the neck network to strengthen high-dimensional feature transmission and reduce information loss, thereby improving detection accuracy. On the self-constructed reclaimed vegetation dataset, MRV-YOLO outperformed YOLOv8, with mAP@0.5 and mAP@0.5:0.95 increasing by 4.6% and 10.8%, respectively. Compared with RT-DETR, YOLOv3, YOLOv5, YOLOv6, YOLOv7, yolov7-tiny, YOLOv8-AS, YOLOv10, and YOLOv11, mAP@0.5 improved by 6.8%, 9.7%, 5.3%, 6.5%, 6.4%, 8.9%, 4.6%, 2.1%, and 5.4%, respectively. The results demonstrate that multichannel inputs incorporating near-infrared and dual red-edge bands significantly enhance detection accuracy for reclaimed vegetation in rare earth mining areas, providing technical support for ecological restoration monitoring. Full article

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

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25 pages, 2657 KB

Open AccessArticle

Hydro-Functional Strategies of Sixteen Tree Species in a Mexican Karstic Seasonally Dry Tropical Forest

by Jorge Palomo-Kumul, Mirna Valdez-Hernández, Gerald A. Islebe, Edith Osorio-de-la-Rosa, Gabriela Cruz-Piñon, Francisco López-Huerta and Raúl Juárez-Aguirre

Forests 2025, 16(10), 1535; https://doi.org/10.3390/f16101535 - 1 Oct 2025

Abstract

Seasonally dry tropical forests (SDTFs) are shaped by strong climatic and edaphic constraints, including pronounced rainfall seasonality, extended dry periods, and shallow karst soils with limited water retention. Understanding how tree species respond to these pressures is crucial for predicting ecosystem resilience under [...] Read more.

Seasonally dry tropical forests (SDTFs) are shaped by strong climatic and edaphic constraints, including pronounced rainfall seasonality, extended dry periods, and shallow karst soils with limited water retention. Understanding how tree species respond to these pressures is crucial for predicting ecosystem resilience under climate change. In the Yucatán Peninsula, we characterized sixteen tree species along a spatial and seasonal precipitation gradient, quantifying wood density, predawn and midday water potential, saturated and relative water content, and specific leaf area. Across sites, diameter classes, and seasons, we measured ≈4 individuals per species (n = 319), ensuring replication despite natural heterogeneity. Using a principal component analysis (PCA) based on individual-level data collected during the dry season, we identified five functional groups spanning a continuum from conservative hard-wood species, with high hydraulic safety and access to deep water sources, to acquisitive light-wood species that rely on stem water storage and drought avoidance. Intermediate-density species diverged into subgroups that employed contrasting strategies such as anisohydric tolerance, high leaf area efficiency, or strict stomatal regulation to maintain performance during the dry season. Functional traits were strongly associated with precipitation regimes, with wood density emerging as a key predictor of water storage capacity and specific leaf area responding plastically to spatial and seasonal variability. These findings refine functional group classifications in heterogeneous karst landscapes and highlight the value of trait-based approaches for predicting drought resilience and informing restoration strategies under climate change. Full article

(This article belongs to the Special Issue Adaptive Physiology of Forest Plants: Mechanisms, Strategies, and Responses to Environmental Challenges)

19 pages, 6526 KB

Open AccessArticle

Population Structure and Genetic Diversity of Castanea sativa Mill. Genotypes in the Republic of Croatia

by Nevenka Ćelepirović, Sanja Novak Agbaba, Sanja Bogunović, Mladen Ivanković, Gaye Kandemir, Monika Karija Vlahović and Marija Gradečki-Poštenjak

Forests 2025, 16(10), 1534; https://doi.org/10.3390/f16101534 - 1 Oct 2025

Abstract

The European sweet chestnut (Castanea sativa Mill.) is an ecologically and culturally significant forest tree species in Croatia; however, its genetic diversity and population structure remain insufficiently characterized. This study aimed to evaluate the genetic diversity, structure, and connectivity of chestnut populations [...] Read more.

The European sweet chestnut (Castanea sativa Mill.) is an ecologically and culturally significant forest tree species in Croatia; however, its genetic diversity and population structure remain insufficiently characterized. This study aimed to evaluate the genetic diversity, structure, and connectivity of chestnut populations on Zrin Mountain, the country’s largest continuous chestnut area. Using seven nuclear SSR markers, we genotyped 153 individuals from three populations (PET, HRK, and BAC). All populations exhibited moderate genetic diversity (mean He = 0.571), with BAC showing the highest allelic richness and number of private alleles. AMOVA revealed that most genetic variance (67%) occurred among individuals, while population differentiation was low to moderate (FST = 0.064; PhiPT = 0.146), consistent with high inferred gene flow (Nm = 7.48). Both STRUCTURE and PCoA indicated that HRK was the most genetically distinct population, whereas PET and BAC were more similar. Overall, these findings demonstrate substantial gene flow and connectivity among Croatian chestnut populations, providing a foundation for sustainable management and conservation strategies in a broader European context. Full article

(This article belongs to the Special Issue Genetic Variation and Conservation of Forest Species)

17 pages, 3902 KB

Open AccessArticle

Whole-Genome Resequencing Provides Insights into the Genetic Structure and Evolution of Paulownia spp.

by Yang Zhao, Jie Qiao, Chaowei Yang, Baoping Wang, Yuanyuan Si, Siqin Liu, Xinliang Zhang and Yanzhi Feng

Forests 2025, 16(10), 1533; https://doi.org/10.3390/f16101533 - 1 Oct 2025

Abstract

Paulownia trees are grown globally for their robust timber, agroforestry, and effective carbon dioxide drawdown. China possesses rich Paulownia germplasm resources, offering favorable material for the genetic improvement. Understanding the taxonomy and phylogenetic relationships of Paulownia species is essential for the advancement of [...] Read more.

Paulownia trees are grown globally for their robust timber, agroforestry, and effective carbon dioxide drawdown. China possesses rich Paulownia germplasm resources, offering favorable material for the genetic improvement. Understanding the taxonomy and phylogenetic relationships of Paulownia species is essential for the advancement of germplasm innovation. In this study, we re-sequenced 67 typical accessions of 11 species within the Paulownia genus. A total of 16,163,790 high-quality single nucleotide polymorphisms (SNPs) were identified. Based on these markers, these accessions were classified into three groups: P. fortunei and P. lampropylla (Group I); P. tomentosa, P. fargesii, and P. kawakamii (Group II); and P. taiwaniana, P. jianshiensis, P. catalpifolia, P. elongata, P. ichangensis, and P. albiphloea (Group III). Using maximum likelihood estimation, population genetic structure analysis revealed that the 11 species originated from four different ancestral populations. The two predominant breeding species—P. fortunei and P. tomentosa—exhibit divergent origins: P. fortunei arose from hybridization between two ancestral species followed by complex admixture, whereas P. tomentosa retains a predominantly singular ancestral lineage, with traces of P. kawakamii. The genetic diversity (π) of P. tomentosa was 0.002588, which was considerably lower than that of P. fortune (0.004181) suggesting that P. tomentosa is subjected to a stronger breeding selection during the evolution than P. fortune. A total of 59 selected regions and 65 genes were identified by selective sweep analysis. These genes may be involved in biological processes such as morphological development and response to abiotic stress and hormonal activity regulation. These findings provide valuable references for further research on the genetic differentiation and adaptive evolutionary mechanisms of Paulownia species, laying a foundation for future germplasm innovation and variety improvement. Full article

(This article belongs to the Special Issue Tree Breeding: Genetic Diversity, Differentiation and Conservation)

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19 pages, 4726 KB

Open AccessArticle

Integrative ATAC-Seq and RNA-Seq Analysis Identifies a WD40 Repeat Protein, ObWPA, as a Significant Regulator of the Purple Coloration in Syringa oblata

by Liting Man, Lulu Zhang, Ying Mao, Senyan Zhang, Guiying Liu, Guanghua Ma, Haihong Wang, Wenjie Zhao, Shaofei Tong, Wenlu Yang and Jinmei Zhang

Forests 2025, 16(10), 1532; https://doi.org/10.3390/f16101532 - 30 Sep 2025

Abstract

Lilac (Syringa spp.) is a widely cultivated ornamental plant prized for its fragrant aroma and attractive flower colors. However, the molecular mechanisms governing its flower pigmentation remain poorly understood. In this study, we performed integrated transcriptomic and metabolomic analyses on purple ( [...] Read more.

Lilac (Syringa spp.) is a widely cultivated ornamental plant prized for its fragrant aroma and attractive flower colors. However, the molecular mechanisms governing its flower pigmentation remain poorly understood. In this study, we performed integrated transcriptomic and metabolomic analyses on purple (Syringa oblata) and white (Syringa oblata var. alba) lilacs at the P1 stage, the point of deepest pigmentation. Compared with W1, P1 has a total of 918 differentially expressed genes, including 614 up-regulated genes and 304 down-regulated genes. And S. oblata exhibited significant upregulation of key anthocyanin biosynthesis genes, including the rate-limiting enzyme gene ObDFR, ObF3’H and transcriptional regulators such as ObWPA, which encodes a WD40 repeat protein. This transcriptional activation was accompanied by a substantial accumulation of 27 anthocyanins, including Petunidin Chloride, Cyanidin Chloride, Delphinidin and so on, while the Petunidin-3-O-rutinoside, Petunidin-3-O-(6-O-p-coumaroyl)-glucoside and Malvidin-3-O-sambubioside-5-O-glucoside were only detected in S. oblata. Furthermore, ATAC-seq analysis revealed that, in comparison to white lilac, purple lilac exhibited 3522 and 805 genes with increased and decreased chromatin accessibility, respectively. Integrative analysis with the transcriptome identified 135 genes that were both more accessible and transcriptionally upregulated in purple lilac, including ObWPA, Ob0214386, and Ob0227194 which belong to WD40 members. Subsequent qRT-PCR validation confirmed ObWPA as the most significantly upregulated gene in purple lilac, a finding consistent with the specific chromatin accessibility detected in its promoter region. To validate its function, we knocked down ObWPA expression in purple lilac using Virus-Induced Gene Silencing (VIGS). This intervention resulted in a dramatic color shift from purple to white, concomitant with a significant decrease in key anthocyanin metabolites such as Cyanidin-3-(6-O-p-caffeoyl)-glucoside, Cyanidin Chloride, Pelargonidin, Cyanidin-3-O-rutinoside, Dihydrokaempferol, and Petunidin Chloride. Collectively, our findings demonstrate that ObWPA is an indispensable positive regulator of purple color formation in S. oblata. Full article

(This article belongs to the Special Issue Forest Tree Breeding: Genomics and Molecular Biology)

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15 pages, 1753 KB

Open AccessArticle

Photosynthetic Performance and Phytoremediation Potential of Narrow Crown Black-Cathay Poplar Under Combined Cadmium and Phenol Pollution

by Huimei Tian, Kaixin Zheng, Qiyun Lu, Siyuan Sun, Chuanrong Li and Huicheng Xie

Forests 2025, 16(10), 1531; https://doi.org/10.3390/f16101531 - 30 Sep 2025

Abstract

Heavy metal pollutants and organic contaminants often co-exist in the environment, posing significant ecological risks due to their combined toxicity. Phytoremediation, a plant-based biotechnology, offers a promising solution for pollutant removal. This study investigated the potential cadmium (Cd) removal capacity of Narrow Crown [...] Read more.

Heavy metal pollutants and organic contaminants often co-exist in the environment, posing significant ecological risks due to their combined toxicity. Phytoremediation, a plant-based biotechnology, offers a promising solution for pollutant removal. This study investigated the potential cadmium (Cd) removal capacity of Narrow Crown Black-Cathay poplar (Populus × canadensis Moench × Populus simonii Carr. f. fastigiata Schneid.) under combined Cd-phenol stress. The results showed that the combined stress synergistically inhibited the photosynthetic physiological characteristics, with an inhibition rate up to 54.0%, significantly higher than that under single stress (p < 0.05). Cd accumulation varied markedly among plant organs, following the order: root (ranging from 4000.2 to 9277.0 mg/kg) > stems (ranging from 96.0 to 383.6 mg/kg) > leaf (ranging from 10.3 to 40.1 mg/kg). Phenol enhanced Cd absorption and enrichment in the roots by up to 1.8 times but reduced its translocation to aboveground parts by 37.8–40.0%. Notably, at low Cd concentrations, the Cd removal efficiency under combined stress (26.0%) was substantially higher than under single Cd stress (6.6%). In contrast, biomass, tolerance index, and root–shoot ratio were slightly affected in all treatments (p > 0.05). These findings demonstrate that Narrow Crown Black-Cathay poplar is a suitable candidate for the short-term remediation of Cd in environments co-contaminated with cadmium and phenol. Full article

(This article belongs to the Special Issue Physiological Mechanisms of Plant Responses to Environmental Stress)

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15 pages, 1405 KB

Open AccessArticle

Acoustic Resonance Characteristics of Birch Wood Loudspeaker Enclosures: Analysis of Influence of Shape and Filling

by Petr Horák and Vlastimil Borůvka

Forests 2025, 16(10), 1530; https://doi.org/10.3390/f16101530 - 30 Sep 2025

Abstract

This study presents a comparative analysis of a “design” speaker cabinet shape and a conventional block enclosure, both having identical internal volumes. Both enclosures were built from birch wood, and for comparison, block-shaped baffles were also made from medium-density fiberboard (MDF). While the [...] Read more.

This study presents a comparative analysis of a “design” speaker cabinet shape and a conventional block enclosure, both having identical internal volumes. Both enclosures were built from birch wood, and for comparison, block-shaped baffles were also made from medium-density fiberboard (MDF). While the designer’s new shape was handcrafted using a lathe, a cube baffle was made using a CNC machine. The block-shaped sound box was made as a representative of the classic shape that occurs most often in the world of music. For this reason, it is offered as an ideal reference sample of the enclosure for comparison with the new design proposal, which was produced based on the shape predispositions and the interest of potential customers. The loudspeaker systems were then subjected to anechoic chamber testing using the exponential sine sweep (ESS) technique to assess and compare their resonance characteristics. The box-shaped enclosure showed a smoother course of the frequency response, but the differences are not significant. A potential improvement in acoustic performance was offered by an acoustic dampening material that was incorporated into each enclosure, and the measurement was repeated. The drop shape from solid birch benefits most from filling, with an 8 dB reduction in low-end boom and 2 dB smoothing, resulting in more controlled bass. The cuboid of solid birch is quite stable even without filling, but filling still improves deep bass by ~3 dB and smooths mid-bass by ~2 dB. For comparison, the cuboid made of MDF shows the largest improvement with filling, with a 10 dB reduction in sub-bass peaks and 4 dB smoothing in dips. With the acoustic filling, the frequency curves are even more smoothed, and it can be said that the damping material can eliminate some of the imperfections of the enclosures. Full article

(This article belongs to the Special Issue Properties and Uses of Value-Added Wood-Based Products and Composites)

20 pages, 3300 KB

Open AccessArticle

Development of an Integrated Forestry Survey Device for Tree Height and DBH

by Ao Xu, Xianfang Zheng, Kejie Zhao, Shaobin Zhang, Linhao Sun and Luming Fang

Forests 2025, 16(10), 1529; https://doi.org/10.3390/f16101529 - 30 Sep 2025

Abstract

Tree diameter at breast height (DBH) and tree height are important quantitative attributes in forestry surveys. They serve as essential data for calculating forest stock, growth, and carbon sequestration, and are of significant research value for forest health assessments and other research outcomes. [...] Read more.

Tree diameter at breast height (DBH) and tree height are important quantitative attributes in forestry surveys. They serve as essential data for calculating forest stock, growth, and carbon sequestration, and are of significant research value for forest health assessments and other research outcomes. To improve the efficiency of forest resource inventories and to reduce labor costs, a forestry survey device integrating multiple sensors has been developed. Based on the principles of laser ranging and the tunnel magnetoresistance effect, this device integrates both the DBH and tree height measurements. Compared to traditional measurement methods, it boasts a compact size, low cost, and high measurement accuracy. Experimental applications have shown that the average root mean square error (RMSE) of tree height measurements ranges from 31 to 55 cm, while the DBH measurement accuracy reaches 98%, We acknowledge that, although this accuracy meets the requirements for general forestry surveys, it still falls short of the accuracy required for high-precision forest resource surveys (<20 cm), which points to a direction for future improvement. Full article

(This article belongs to the Special Issue Forest Resources Inventory, Monitoring, and Assessment)

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11 pages, 1615 KB

Open AccessArticle

Comparative Analysis of Wettability of Hybrid and Indigenous Poplar Strands

by Ahmed Altaher Omer Ahmed, Csilla Mária Csiha, Tibor Alpár and László Bejó

Forests 2025, 16(10), 1528; https://doi.org/10.3390/f16101528 - 30 Sep 2025

Abstract

The increasing demand for sustainable raw materials in engineered wood production has prompted the evaluation of alternative raw materials. In this context, indigenous black poplar (Populus nigra) was analyzed as a potential alternative, by testing its wettability, characterized by contact angle, [...] Read more.

The increasing demand for sustainable raw materials in engineered wood production has prompted the evaluation of alternative raw materials. In this context, indigenous black poplar (Populus nigra) was analyzed as a potential alternative, by testing its wettability, characterized by contact angle, determined by the sessile drop method, to predict its adhesion when used as strands for OSB and LSL production. Surface tension was tested on strands with a wide range of surface roughnesses. The results show minor but statistically significant difference in favor of black poplar, which has somewhat lower contact angle values (62.01°) than hybrid poplar (64.71°), based on 300 measurements each. The absorption of the liquid into the strands, evaluated on a smaller sample, follows a logarithmic relation with time. These results also show a slightly faster decrease in contact angle in case of indigenous poplar, compared to hybrid poplar. The results indicate that the adhesion of indigenous poplar strands does not present extra challenges, compared to the currently more frequent hybrid poplar strands. Full article

(This article belongs to the Special Issue Transforming Wood into Smart Materials: Innovations in Processing and Application)

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4 pages, 548 KB

Open AccessEditorial

Recent Advances in Forest Ecosystem Services and Landscape Design

by Radu-Daniel Pintilii

Forests 2025, 16(10), 1527; https://doi.org/10.3390/f16101527 - 30 Sep 2025

Abstract

In a world of constant change, ecosystem services are becoming increasingly important to support the rapid demographic growth of recent decades [...] Full article

(This article belongs to the Special Issue Forest Ecosystem Services and Landscape Design)

21 pages, 5327 KB

Open AccessArticle

Long-Term Changes in the Structural and Functional Composition of Spruce Forests in the Center of the East European Plain

by Tatiana Chernenkova, Nadezhda Belyaeva, Alexander Maslov, Anastasia Titovets, Alexander Novikov, Ivan Kotlov, Maria Arkhipova and Mikhail Popchenko

Forests 2025, 16(10), 1526; https://doi.org/10.3390/f16101526 - 29 Sep 2025

Abstract

Norway spruce (Picea abies (L.) H. Karst.) is a primary forest-forming species in the European part of Russia, both in terms of its distribution and economic importance. A number of studies indicate that one of the reasons for the disturbance of spruce [...] Read more.

Norway spruce (Picea abies (L.) H. Karst.) is a primary forest-forming species in the European part of Russia, both in terms of its distribution and economic importance. A number of studies indicate that one of the reasons for the disturbance of spruce forests is linked to rising temperatures, particularly the detrimental effects of extreme droughts. The aim of our research is to identify changes in the structural and functional organization of mature spruce forests at the center of the East European Plain. The study was conducted in intact spruce forests using resurveyed vegetation relevés within the Smolensk–Moscow Upland, with relevés repeated after 40 years (in 1985 and 2025). Changes in structural and functional parameters of spruce communities were analyzed. The results showed that significant disturbances of the tree layer led to changes in the vegetation of subordinate layers, as well as the successional dynamics of spruce forests. It was found that following the collapse of old-growth spruce stands, two types of secondary succession developed: (1) with the renewal of spruce and (2) with active development of shrubs (hazel and rowan) and undergrowth of broadleaved species. It was also demonstrated that the typological diversity of the studied communities changed over 40 years not only due to the loss of the tree layer and the formation of new “non-forest” types but also because several mixed spruce-broadleaved communities transitioned into broadleaved ones, and pine–spruce communities of boreal origin shifted to nemoral types. An analysis of the complete species composition of spruce forests based on Ellenberg’s scales scoring revealed changes in habitat conditions over the 40-year period. A noticeable trend was an increase in the proportion of thermophilic and alkaliphilic species, indicating a shift toward a nemoral vegetation spectrum. It is expected that under the current forest management regime, the next 40 to 60 years will see a decline in the proportion of spruce within mixed stands, potentially culminating in the complete collapse of monospecific spruce forests in the center of the East European Plain. Full article

(This article belongs to the Special Issue Features of Forest Stand Structure Under Changing Conditions)

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34 pages, 2421 KB

Open AccessReview

Carbon Price Forecasting for Forest Carbon Markets: Current State and Future Directions

by Dimitra C. Lazaridou, Christina-Ioanna Papadopoulou, Christos Staboulis, Asterios Theofilou and Konstantinos Theofilou

Forests 2025, 16(10), 1525; https://doi.org/10.3390/f16101525 - 29 Sep 2025

Abstract

Accurate forecasting of carbon credit prices is increasingly vital for the effective functioning of forest carbon markets, which play a growing role in global climate mitigation strategies. Against this backdrop, the present study conducts a systematic literature review to evaluate the state of [...] Read more.

Accurate forecasting of carbon credit prices is increasingly vital for the effective functioning of forest carbon markets, which play a growing role in global climate mitigation strategies. Against this backdrop, the present study conducts a systematic literature review to evaluate the state of carbon price forecasting methodologies, with particular emphasis on their applicability to forest-based carbon credits. The review highlights the predominance of machine learning (ML) and hybrid modeling approaches, which demonstrate enhanced predictive capabilities relative to conventional econometric techniques, particularly in capturing nonlinear dynamics and integrating heterogeneous data sources. However, their predictive power is limited by data scarcity, market opacity, and regulatory volatility. These issues are particularly severe in voluntary forest credit markets. The review identifies a critical research gap. Few studies explicitly model the behavior of forest credit prices. The findings suggest that future research should prioritize the development of policy-sensitive, scenario-based models that incorporate ecological, economic, and regulatory dimensions. While the majority of studies concentrate on compliance carbon markets, the methodological insights and forecasting approaches reviewed are highly relevant for the evolving forest carbon sector, nature-based mitigation strategies, and climate solutions. It also offers guidance for creating more transparent and robust forecasting tools in the forest carbon sector. Full article

(This article belongs to the Special Issue Forest Management Planning and Decision Support)

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Graphical abstract

20 pages, 3679 KB

Open AccessArticle

Effects of Afforestation on Soil Organic Carbon and Nitrogen Stocks in the Long Term in Semi-Arid Regions of Türkiye

by Murat Sarginci and Adem Seçilmiş

Forests 2025, 16(10), 1524; https://doi.org/10.3390/f16101524 - 28 Sep 2025

Abstract

The black pine (Pinus nigra Arn.) is among the most preferred tree species for afforestation in Türkiye. This study aims to examine the effects of afforestation carried out in 1968, 1973, 1985, 1996, and 2002 on soil properties, especially soil organic carbon [...] Read more.

The black pine (Pinus nigra Arn.) is among the most preferred tree species for afforestation in Türkiye. This study aims to examine the effects of afforestation carried out in 1968, 1973, 1985, 1996, and 2002 on soil properties, especially soil organic carbon (SOC) and nitrogen (N) in a semi-arid region of Türkiye. Soil texture, electrical conductivity (EC), reaction (pH), Cation Exchange Capacity (CEC), lime (CaCO₃) concentration, N, and inorganic-organic C contents were determined for each afforestation site. Although afforestation significantly increases SOC and TN stocks, the stand’s age did not affect the dynamics of the SOC stocks. But early stages of afforestation increased N stocks by more than 500%–600% compared to older ones. Our results show that afforestation combined with soil preparation increases the SOC and N contents, and soil tilling without plantation accelerates this process in the initial stages of afforestation. Rather than planting only one tree species, a plantation that mixes broadleaves and conifers with other annual and perennial plants may be more suitable for long-term C sequestration and the use of assisted natural succession in the revegetation of degraded arid and semi-arid regions as an alternative to large-scale afforestation should be paid more attention in the future. Full article

(This article belongs to the Special Issue Afforestation of Degraded Lands)

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30 pages, 2577 KB

Open AccessArticle

Indigenous Knowledge and Sustainable Management of Forest Resources in a Socio-Cultural Upheaval of the Okapi Wildlife Reserve Landscape in the Democratic Republic of the Congo

by Lucie Mugherwa Kasoki, Pyrus Flavien Ebouel Essouman, Charles Mumbere Musavandalo, Franck Robéan Wamba, Isaac Diansambu Makanua, Timothée Besisa Nguba, Krossy Mavakala, Jean-Pierre Mate Mweru, Samuel Christian Tsakem, Michel Babale, Francis Lelo Nzuzi and Baudouin Michel

Forests 2025, 16(10), 1523; https://doi.org/10.3390/f16101523 - 28 Sep 2025

Abstract

The Okapi Wildlife Reserve (OWR) in northeastern Democratic Republic of the Congo represents both a biodiversity hotspot and the ancestral homeland of the Indigenous Mbuti and Efe peoples, whose livelihoods and knowledge systems are closely tied to forest resources. This study investigates how [...] Read more.

The Okapi Wildlife Reserve (OWR) in northeastern Democratic Republic of the Congo represents both a biodiversity hotspot and the ancestral homeland of the Indigenous Mbuti and Efe peoples, whose livelihoods and knowledge systems are closely tied to forest resources. This study investigates how Indigenous knowledge and practices contribute to sustainable resource management under conditions of rapid socio-cultural transformation. A mixed-methods approach was applied, combining socio-demographic surveys (n = 80), focus group discussions, floristic inventories, and statistical analyses (ANOVA, logistic regressions, chi-square, MCA). Results show that hunting, fishing, gathering, and honey harvesting remain central livelihood activities, governed by customary taboos and restrictions that act as de facto ecological regulations. Agriculture, recently introduced through intercultural exchange with neighboring Bantu populations, complements rather than replaces traditional practices and demonstrates emerging agroecological hybridization. Nevertheless, evidence of biodiversity decline (including local disappearance of species such as Dioscorea spp.), erosion of intergenerational knowledge transmission, and increased reliance on monetary income indicate vulnerabilities. Multiple Correspondence Analysis revealed a highly structured socio-ecological gradient (98.5% variance explained; Cronbach’s α = 0.977), indicating that perceptions of environmental change are strongly coupled with demographic identity and livelihood strategies. Floristic inventories confirmed significant differences in species abundance across camps (ANOVA, p < 0.001), highlighting site-specific pressures and the protective effect of persistent customary norms. The findings underscore the resilience and adaptability of Indigenous Peoples but also their exposure to ecological and cultural disruptions. We conclude that formal recognition of Indigenous institutions and integration of their knowledge systems into co-management frameworks are essential to strengthen ecological resilience, secure Indigenous rights, and align conservation policies with global biodiversity and climate agendas. Full article

(This article belongs to the Special Issue Forest Ecosystem Services and Sustainable Management)

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