Forests

17 pages, 2997 KB

Open AccessArticle

Genome-Wide Identification and Expression Analysis of the GRX Gene Family Reveals Its Potential Role in Floral Organ Development and Sex Differentiation in Litsea cubeba

by Siqi Wang, Yangdong Wang, Ming Gao, Yicun Chen and Yunxiao Zhao

Forests 2026, 17(1), 128; https://doi.org/10.3390/f17010128 - 16 Jan 2026

Abstract

As a class of glutathione-dependent oxidoreductases, glutaredoxins (GRXs) play a central role in maintaining cellular redox homeostasis, thereby influencing diverse biological processes including growth, development, and stress adaptation in plants. This study identified 36 GRX genes in Litsea cubeba through whole-genome analysis. Phylogenetic [...] Read more.

As a class of glutathione-dependent oxidoreductases, glutaredoxins (GRXs) play a central role in maintaining cellular redox homeostasis, thereby influencing diverse biological processes including growth, development, and stress adaptation in plants. This study identified 36 GRX genes in Litsea cubeba through whole-genome analysis. Phylogenetic classification placed them into four subfamilies (CC-, CGFS-, CPYC-type, and a species-specific SS branch), consistent with patterns in model plants like Arabidopsis thaliana and Oryza sativa, indicating evolutionary conservation of GRX core motifs. Genomic analyses including chromosomal location, collinearity, and gene structure revealed family evolution features. Expression profiling showed 11 LcGRX genes were flower-specific, with marked differential expression during stamen (M2) and pistil (F2) degeneration, supporting their roles in sexual dimorphism. Functional assays confirmed that floral highly expressed LcGRX12 directly interacts with TGA transcription factor LcTGA10, similar to its Arabidopsis homolog ROXY1. This study reveals the GRX-TGA module’s role in floral organ development in L. cubeba, offering insights into redox-mediated sex differentiation in Lauraceae and providing candidate genes for molecular breeding. Full article

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

15 pages, 1904 KB

Open AccessArticle

Stand Age and Litter Shape Myriapod Communities in a Forest Mosaic (Diplopoda, Chilopoda)

by Marea Grinvald and Ivan Hadrián Tuf

Forests 2026, 17(1), 127; https://doi.org/10.3390/f17010127 - 16 Jan 2026

Abstract

(1) Forest fragmentation and associated edge effects can strongly modify the diversity and distribution of soil invertebrates, yet their responses in temperate floodplain forests remain poorly understood. We investigated myriapod (centipede and millipede) assemblages in a fragmented forest mosaic in the protected landscape [...] Read more.

(1) Forest fragmentation and associated edge effects can strongly modify the diversity and distribution of soil invertebrates, yet their responses in temperate floodplain forests remain poorly understood. We investigated myriapod (centipede and millipede) assemblages in a fragmented forest mosaic in the protected landscape area Litovelské Pomoraví (Czech Republic), focusing on the role of stand age, ecotones and key microhabitat variables. (2) Myriapods were sampled continuously during two years using pitfall traps arranged along transects crossing four neighboring patches (clear-cut with seedlings, 10-year-old stand, 87-year-old and 127-year-old Querco–Ulmetum forests). Species diversity was quantified using the Shannon–Wiener index, and patterns were analyzed by t-tests, canonical correspondence analysis and generalized additive models. (3) We collected over six thousand individuals (10 centipede and 10 millipede species). Diversity peaked in old-growth stands and adjacent ecotones, and two of the three ecotones supported particularly high species abundances. Litter cover and thickness, stand age, and the structure of the herb and shrub layers were the most important predictors of species distributions. Dominant species (e.g., Glomeris tetrasticha Brandt, 1833, Lithobius mutabilis L. Koch, 1862, L. forficatus (Linnaeus, 1758)) showed contrasting habitat preferences, reflecting niche differentiation along microhabitat and stand-age gradients. (4) Our findings indicate that conserving a fine-grained mosaic of stand ages, together with structurally complex forest interiors and ecotones, is essential for maintaining myriapod diversity and the ecosystem functions they provide in Central European forests. Full article

(This article belongs to the Special Issue Distribution, Species Richness, and Diversity of Wildlife in Forests)

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18 pages, 1383 KB

Open AccessArticle

Development of Low-Power Forest Fire Water Bucket Liquid Level and Fire Situation Monitoring Device

by Xiongwei Lou, Shihong Chen, Linhao Sun, Xinyu Zheng, Siqi Huang, Chen Dong, Dashen Wu, Hao Liang and Guangyu Jiang

Forests 2026, 17(1), 126; https://doi.org/10.3390/f17010126 - 16 Jan 2026

Abstract

A portable and integrated monitoring device was developed to digitally assess both water levels and surrounding fire-related conditions in forest firefighting water buckets using multi-sensor fusion. The system integrates a hydrostatic liquid-level sensor with temperature–humidity and smoke sensors. Validation was performed through field-oriented [...] Read more.

A portable and integrated monitoring device was developed to digitally assess both water levels and surrounding fire-related conditions in forest firefighting water buckets using multi-sensor fusion. The system integrates a hydrostatic liquid-level sensor with temperature–humidity and smoke sensors. Validation was performed through field-oriented experiments conducted under semi-controlled conditions. Water-level measurements were collected over a three-month period under simulated forest conditions and benchmarked against conventional steel-ruler readings. Early-stage fire monitoring experiments were carried out using dry wood and leaf litter under varying wind speeds, wind directions, and representative extreme weather conditions. The device achieved a mean water-level bias of −0.60%, a root-mean-square error of 0.64%, and an overall accuracy of 99.36%. Fire monitoring reached a maximum detection distance of 7.30 m under calm conditions and extended to 16.50 m under strong downwind conditions, with performance decreasing toward crosswind directions. Stable operation was observed during periods of strong winds associated with typhoon events, as well as prolonged high-temperature exposure. The primary novelty of this work lies in the conceptualization of a Collaborative Forest Resource–Hazard Monitoring Architecture. Unlike traditional isolated sensors, our proposed framework utilizes a dual-domain decision-making model that simultaneously assesses water-bucket storage stability and micro-scale fire threats. By implementing a robust ‘sensing–logic–alert’ framework tailored for rugged environments, this study offers a new methodological reference for the intelligent management of forest firefighting resources. Full article

(This article belongs to the Special Issue Smart Forest Inventory, Management and Planning: Intelligent Technologies and Their Applications)

20 pages, 2313 KB

Open AccessArticle

Estimating Carbon Sequestration of Urban Street Trees Using UAV-Derived 3D Green Quantity and the Simpson Model

by Xiaoxiao Ma and Tianyi Liu

Forests 2026, 17(1), 125; https://doi.org/10.3390/f17010125 - 16 Jan 2026

Abstract

Accurately measuring the three-dimensional green quantity (3DGQ) of urban trees is crucial for quantifying carbon sequestration benefits (CSB) in high-density cities. In this study, 540 street trees across 18 species (30 per species) in Shanghai were analyzed to evaluate an Improved Simpson Model [...] Read more.

Accurately measuring the three-dimensional green quantity (3DGQ) of urban trees is crucial for quantifying carbon sequestration benefits (CSB) in high-density cities. In this study, 540 street trees across 18 species (30 per species) in Shanghai were analyzed to evaluate an Improved Simpson Model (ISM) for UAV-derived crown volume estimation against a traditional Approximate Geometry Model (AGM) and a LiDAR-based point cloud method (PCM). The ISM integrates UAV imagery, edge-based canopy profiling, and Simpson’s numerical integration to account for irregular crown shapes and internal leaf-stem gaps. Results show that ISM achieved consistently lower estimation errors than the benchmark methods. Overall, ISM’s 3DGQ estimates had a root mean square error (RMSE) of approximately 5.2 m³ and a mean absolute error (MAE) of about 4.1 m³, indicating a close match with PCM reference values. This represents a dramatic error reduction, on the order of 90%–95% improvement in RMSE, compared to the conventional AGM approach. Broadleaf species with dense, regular canopies (e.g., Cinnamomum camphora and Platanus × acerifolia) exhibited the highest accuracy, with ISM-predicted volumes deviating only ~1%–2% from field measurements. Even for species with more irregular or porous crowns, the ISM maintained robust performance, yielding smaller errors than AGM and nearly matching the LiDAR-based PCM “ground truth.” These findings demonstrate that the proposed ISM can provide highly accurate 3D crown volume and carbon sequestration estimates in complex urban environments, outperforming existing geometric models and offering a practical, efficient alternative to labor-intensive LiDAR surveys. Full article

(This article belongs to the Special Issue Optimizing Urban Green Space Ecosystem Services for Resilient and Sustainable Cities)

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17 pages, 2257 KB

Open AccessArticle

The Effect of Fuel Bed Edges on Fire Dynamics

by Luis Reis, Jorge Raposo, Hugo Raposo and André Rodrigues

Forests 2026, 17(1), 124; https://doi.org/10.3390/f17010124 - 16 Jan 2026

Abstract

Wildfires are among the most frequent and destructive natural hazards in Europe, particularly in Portugal. They have severe impacts on forests, ecosystems, human health, and infrastructure, leading to substantial socio-economic losses due to firefighting efforts and post-fire recovery costs. Moreover, wildfires cause numerous [...] Read more.

Wildfires are among the most frequent and destructive natural hazards in Europe, particularly in Portugal. They have severe impacts on forests, ecosystems, human health, and infrastructure, leading to substantial socio-economic losses due to firefighting efforts and post-fire recovery costs. Moreover, wildfires cause numerous casualties each year, highlighting the need for a deeper understanding of fire behaviour to support effective firefighting strategies and ensure the safety of both responders and communities. This study examines the influence of wind flow velocity variation on fire behaviour, both in the presence and absence of an edge wall in the fuel bed, aiming to replicate the characteristics of real wildfire fronts at a laboratory scale. Experimental tests were conducted at the Combustion Laboratory of the University of Coimbra using a shrub mixture, composed of Ulex europaeus, Baccharis trimera, and Caralluma adscendens, representing one of the most common fine fuels in Portuguese forested landscapes. This research provides novel insights by experimentally analyzing the combined effect of wind velocity variation and fuel bed edge presence on fire behaviour, paving the way for future comparisons with numerical simulations and real wildfire fronts. As expected, increasing wind velocity and the presence of fuel bed edges resulted in higher values of rate of spread, fireline intensity, and fire intensity. Full article

(This article belongs to the Special Issue Forest Fire: Landscape Patterns, Risk Prediction and Fuels Management)

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16 pages, 7704 KB

Open AccessArticle

Impacts of Afforestation on Soil Organic Carbon Dynamics Along the Aridity Gradient in China

by Juxiao Lu, Su Wang, Yajing Dong, Yue Wang, Yafeng Jiang, Hailong Zhang, Wenwen Lv, Wangliang Ge, Ruihua Bai and Lei Deng

Forests 2026, 17(1), 123; https://doi.org/10.3390/f17010123 - 16 Jan 2026

Abstract

Afforestation is recognized as a highly effective strategy for enhancing ecosystem carbon sequestration. However, the changes and drivers of soil organic carbon (SOC) following afforestation are still debated due to climate differences. Clarifying these responses is critical for improving the effectiveness of afforestation-based [...] Read more.

Afforestation is recognized as a highly effective strategy for enhancing ecosystem carbon sequestration. However, the changes and drivers of soil organic carbon (SOC) following afforestation are still debated due to climate differences. Clarifying these responses is critical for improving the effectiveness of afforestation-based carbon sequestration strategies. In this study, we analyzed nine 20-year-old afforestation sites (coniferous and broad-leaved) along a Chinese climatic gradient to quantify SOC and its fractional changes following farmland-to-forest conversion, and to identify the dominant factors controlling SOC sequestration across climatic gradients and forest types. The results showed that afforestation enhanced SOC (5.1%–210.5%, p < 0.05) in humid and semi-humid regions, but showed no significant effect in semi-arid regions, and it even reduced SOC in arid regions (−19%–−53.8%). Across all climatic zones, mineral-associated organic carbon was the dominant contributor to SOC accumulation throughout the entire soil profile (0–60 cm). Climatic-scale analyses based on the aridity index determined that root and litter C/N ratios were the primary drivers of SOC sequestration in coniferous forests, whereas in broad-leaved forests, they were more strongly controlled by soil physicochemical properties, particularly total nitrogen, bulk density, and soil water content. This study identified that SOC responses to afforestation are strongly mediated by climate and forest type, which is helpful for managers to take targeted measures to increase soil carbon sequestration in forest management. Full article

(This article belongs to the Section Forest Soil)

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14 pages, 4372 KB

Open AccessArticle

A Multi-Scale Anatomical Wood Identification Approach Applied to Traditional Japanese Chord Instruments

by Flavio Ruffinatto, Simonetta Capetta, Aurora Canepari and Alan Crivellaro

Forests 2026, 17(1), 122; https://doi.org/10.3390/f17010122 - 15 Jan 2026

Abstract

Accurate wood identification is fundamental to any study, conservation, or restoration activity involving cultural heritage objects, including musical instruments. Here, we apply WoodScope, a structured, multi-scale and minimally invasive workflow for wood identification, to three traditional Japanese chord instruments, showing how a systematic [...] Read more.

Accurate wood identification is fundamental to any study, conservation, or restoration activity involving cultural heritage objects, including musical instruments. Here, we apply WoodScope, a structured, multi-scale and minimally invasive workflow for wood identification, to three traditional Japanese chord instruments, showing how a systematic sequence of visual, macroscopic, and microscopic observations maximizes diagnostic accuracy while safeguarding object integrity. The results show that out of 39 wooden parts analysed, 38 were identified non-invasively. In one case, targeted micro-sampling was performed, based on macroscopic observation, to obtain additional information. Overall, our results confirm that most instrument components can be reliably identified at the genus level or, when diagnostic characters are insufficient, to broader anatomical groups, without the need for destructive sampling. Our study demonstrates the efficacy of the WoodScope approach to optimise wood identification outcomes while preserving the object’s integrity and confining micro-targeted sampling to instances where microscopic anatomical characters are indispensable for reliable taxonomic identification and cannot be evaluated non-invasively. Full article

(This article belongs to the Special Issue Advances in Wood Anatomy: From Species Identification to Ecological and Technological Insights)

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13 pages, 1868 KB

Open AccessArticle

Stand Properties Relate to the Accuracy of Remote Sensing of Ips typographus L. Damage in Heterogeneous Managed Hemiboreal Forest Landscapes: A Case Study

by Agnis Šmits, Jordane Champion, Ilze Bargā, Linda Gulbe-Viļuma, Līva Legzdiņa, Elza Gricjus and Roberts Matisons

Forests 2026, 17(1), 121; https://doi.org/10.3390/f17010121 - 15 Jan 2026

Abstract

Under the intensifying water shortages in the vegetation season, early identification of Ips typographus L. damage is crucial for preventing wide outbreaks, which undermine the economic potential of commercial stands of Norway spruce (Picea abies Karst.) across Europe. For this purpose, remote [...] Read more.

Under the intensifying water shortages in the vegetation season, early identification of Ips typographus L. damage is crucial for preventing wide outbreaks, which undermine the economic potential of commercial stands of Norway spruce (Picea abies Karst.) across Europe. For this purpose, remote sensing based on satellite images is considered one of the most efficient methods, particularly in homogenous and wide forested landscapes. However, under highly heterogeneous seminatural managed forest landscapes in lowland Central and Northern Europe, as illustrated by the eastern Baltic region and Latvia in particular, the efficiency of such an approach can lack the desired accuracy. Hence, the identification of smaller damage patches by I. typographus, which can act as a source of wider outbreaks, can be overlooked, and situational awareness can be further aggravated by infrastructure artefacts. In this study, the accuracy of satellite imaging for the identification of I. typographus damage was evaluated, focusing on the occurrence of false positives and particularly false negatives obtained from the comparison with UAV imaging. Across the studied landscapes, correct or partially correct identification of damage patches larger than 30 m² occurred in 73% of cases. Still, the satellite image analysis of the highly heterogeneous landscape resulted in quite a common occurrence of false negatives (up to one-third of cases), which were related to stand and patch properties. The high rate of false negatives, however, is crucial for the prevention of outbreaks, as the sources of outbreaks can be underestimated, burdening prompt and hence effective implication of countermeasures. Accordingly, elaborating an analysis of satellite images by incorporating stand inventory data could improve the efficiency of early detection systems, especially when coupled with UAV reconnaissance of heterogeneous landscapes, as in the eastern Baltic region. Full article

(This article belongs to the Special Issue Application of Remote Sensing and Geographic Information Systems for Natural Resource Management of Forest Ecosystems)

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13 pages, 2486 KB

Open AccessArticle

Influence of Density, Temperature, and Moisture Content on the Dielectric Properties of Pedunculate Oak (Quercus robur L.)

by Dario Pervan, Stjepan Pervan, Miljenko Klarić, Jure Žigon and Aleš Straže

Forests 2026, 17(1), 120; https://doi.org/10.3390/f17010120 - 15 Jan 2026

Abstract

This study examines the effects of temperature, relative humidity, moisture content, and density on the dielectric constant (ε′) and dielectric loss tangent (tan δ) of oak wood lamellae within a frequency range of 0.079 MHz to 25.1 MHz. The hypothesis tested was that [...] Read more.

This study examines the effects of temperature, relative humidity, moisture content, and density on the dielectric constant (ε′) and dielectric loss tangent (tan δ) of oak wood lamellae within a frequency range of 0.079 MHz to 25.1 MHz. The hypothesis tested was that increased temperature and moisture content enhance both dielectric polarization and loss, while density acts as a dominant structural determinant of dielectric behaviour. Oak lamellas were conditioned above saturated salt solutions at 20 °C and measured using an Agilent 4285A LCR meter according to ASTM D150-22. Multiple linear regression was used to demonstrate the statistically significant influence of temperature, relative humidity, moisture content, and density on the tested electrical properties of the lamellas. The results showed that the dielectric properties increase with higher sample density and higher air humidity. Temperature also had an influence, but it was significantly smaller, though still statistically significant (p < 0.05). Changes in dielectric properties were most pronounced at frequencies below 1 MHz, suggesting that dipolar and interfacial polarization are greater at lower frequencies. The findings in this paper provide a basis for optimizing the high frequency/dielectric heating process for heating before bending of oak and other similar hardwoods. Full article

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

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23 pages, 3941 KB

Open AccessArticle

How Environmental Perception and Place Governance Shape Equity in Urban Street Greening: An Empirical Study of Chicago

by Fan Li, Longhao Zhang, Fengliang Tang, Jiankun Liu, Yike Hu and Yuhang Kong

Forests 2026, 17(1), 119; https://doi.org/10.3390/f17010119 - 15 Jan 2026

Abstract

Urban street greening structure plays a crucial role in promoting environmental justice and enhancing residents’ daily well-being, yet existing studies have primarily focused on vegetation quantity while neglecting how perception and governance interact to shape fairness. This study develops an integrated analytical framework [...] Read more.

Urban street greening structure plays a crucial role in promoting environmental justice and enhancing residents’ daily well-being, yet existing studies have primarily focused on vegetation quantity while neglecting how perception and governance interact to shape fairness. This study develops an integrated analytical framework that combines deep learning, machine learning, and spatial analysis to examine the impact of perceptual experience and socio-economic indicators on the equity of greening structure distribution in urban streets, and to reveal the underlying mechanisms driving this equity. Using DeepLabV3+ semantic segmentation, perception indices derived from street-view imagery, and population-weighted Gini coefficients, the study quantifies both the structural and perceptual dimensions of greening equity. XGBoost regression, SHAP interpretation, and Partial Dependence Plot analysis were applied to reveal the influence mechanism of the “Matthew effect” of perception and the Site governance responsiveness on the fairness of the green structure. The results identify two key findings: (1) perception has a positive driving effect and a negative vicious cycle effect on the formation of fairness, where positive perceptions such as beauty and safety gradually enhance fairness, while negative perceptions such as depression and boredom rapidly intensify inequality; (2) Site management with environmental sensitivity and dynamic mutual feedback to a certain extent determines whether the fairness of urban green structure can persist under pressure, as diverse Tree–Bush–Grass configurations reflect coordinated management and lead to more balanced outcomes. Policy strategies should therefore emphasize perceptual monitoring, flexible maintenance systems, and transparent public participation to achieve resilient and equitable urban street greening structures. Full article

(This article belongs to the Section Urban Forestry)

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24 pages, 2392 KB

Open AccessArticle

Genetic Diversity and Mating System Analysis in a Second-Generation Seed Orchard of Chamaecyparis hodginsii

by Ling Ye, Ziyi Wang, Weiyong Gong, Jiawang Zhang, Biaoqiang Zhang, Guobin Wang, Zhiyun Chen, Liming Zhu, Zezhong Lin, Zhaoliang Zheng, Shunde Su and Renhua Zheng

Forests 2026, 17(1), 118; https://doi.org/10.3390/f17010118 - 15 Jan 2026

Abstract

Plantations of the valuable Chinese timber species, Chamaecyparis hodginsii, established by planting, primarily rely on seed orchards for propagation. Therefore, effective management of the genetic composition of these orchards is essential to ensure a sustainable supply of high-quality seeds. However, the mating [...] Read more.

Plantations of the valuable Chinese timber species, Chamaecyparis hodginsii, established by planting, primarily rely on seed orchards for propagation. Therefore, effective management of the genetic composition of these orchards is essential to ensure a sustainable supply of high-quality seeds. However, the mating system and pollen dispersal mechanisms in its high-generation seed orchards remain unclear, limiting precise genetic management. To address this, we analyzed 30 parental clones and 75 of their open-pollinated progeny from a second-generation seed orchard using 15 polymorphic EST-SSR markers. Compared to reported natural populations of C. hodginsii, both parental and progeny populations maintained high genetic diversity (mean uHe = 0.438 and 0.449, respectively), with a significant excess of heterozygotes (mean Fis = −0.084 and −0.066, respectively). Population genetic structure analysis indicated weak genetic differentiation among the parental genetic groups (mean Fst = 0.012), which was further reduced in the progeny population (mean Fst = 0.003) due to open pollination, reflecting a trend toward genetic homogenization. The mating system was characterized exclusively by outcrossing (tm = 1.000). However, paternity analysis revealed highly skewed paternal contributions, a low effective number of pollen donors (Nep = 8.13), and contributions of S5, S11, and S17 as dominant pollen parents, with 17.33% external pollen flow. These findings elucidate the mechanisms underlying sustained genetic diversity despite unequal paternal contributions and provide a theoretical basis for optimizing parental configuration and pollen management. Full article

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

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14 pages, 5149 KB

Open AccessArticle

Comparative Metabolomics Reveals Enhanced TCA Cycle and Suppressed Secondary Metabolism as Metabolic Hallmarks of Embryogenic Calli in Picea mongolica

by Shengli Zhang, Jinling Dai, Linhu Xi, Yanqiu Yan, Jialu Cao and Yu’e Bai

Forests 2026, 17(1), 117; https://doi.org/10.3390/f17010117 - 15 Jan 2026

Abstract

Somatic embryogenesis (SE) plays a pivotal role in the propagation and genetic improvement of coniferous trees; however, its efficiency is frequently limited by the reduced embryogenic potential of callus cultures. Here, we investigated the metabolic determinants underlying this phenomenon in Picea mongolica by [...] Read more.

Somatic embryogenesis (SE) plays a pivotal role in the propagation and genetic improvement of coniferous trees; however, its efficiency is frequently limited by the reduced embryogenic potential of callus cultures. Here, we investigated the metabolic determinants underlying this phenomenon in Picea mongolica by conducting a comparative metabolomic analysis of embryogenic calli (EC) and non-embryogenic calli (NEC). We observed significant metabolic differences between EC and NEC using an integrated approach combining morphological observations and untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics. EC exhibited increased central carbon metabolism, characterized by enhanced citrate cycle (TCA) flux, with significantly increased levels of the key TCA intermediates, citric acid and L-malic acid—18.8- and 3.6-fold higher, respectively, than those in NEC. Conversely, NEC displayed a divergent metabolic state, characterized by the accumulation of various amino acids and the activation of secondary metabolic pathways, especially alkaloid biosynthesis. These results indicate that embryogenic competence in P. mongolica is supported by a distinct metabolic program that prioritizes energy generation and efficient carbon-nitrogen allocation for biosynthetic processes. Conversely, the non-embryogenic state arises from a shift in metabolic resources toward secondary metabolism. These findings provide key metabolic insights and a theoretical basis for enhancing conifer SE systems. Full article

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

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11 pages, 1772 KB

Open AccessArticle

Species and Functional Trait Determinants of Biochar Carbon Retention: Insights from Uniform Smoldering Experiments

by Jingyuan Wang

Forests 2026, 17(1), 116; https://doi.org/10.3390/f17010116 - 14 Jan 2026

Abstract

Understanding the influence of tree species and their intrinsic traits on biochar yield and carbon retention is essential for optimizing the conversion of biomass to biochar in carbon-negative systems. While it is well-established that pyrolysis temperature and broad feedstock categories significantly affect biochar [...] Read more.

Understanding the influence of tree species and their intrinsic traits on biochar yield and carbon retention is essential for optimizing the conversion of biomass to biochar in carbon-negative systems. While it is well-established that pyrolysis temperature and broad feedstock categories significantly affect biochar properties, the extent of species-level variation within woody biomass under standardized pyrolysis conditions remains insufficiently quantified. Here, we synthesized biochar from seven common subtropical tree species at 600 °C under oxygen-limited smoldering conditions and quantified three key indices: biochar yield (Y), carbon recovery efficiency (ηC), and carbon enrichment factor (EC). We further examined the relationships of these indices with feedstock characteristics (initial carbon content, wood density) and functional group identity (conifer vs. broadleaf). Analysis of variance revealed significant interspecific differences in ηC but weaker effects on Y, indicating that species identity primarily governs carbon retention rather than total mass yield. Broadleaf species (Liquidambar formosana, Castanea mollissima) exhibited consistently higher ηC and EC than conifers (Pinus massoniana, P. elliottii), reflecting higher lignin content and wood density that favor aromatic char formation. Principal component and cluster analyses clearly separated coniferous and broadleaf taxa, accounting for over 80% of total variance in carbon-related traits. Regression models showed that feedstock carbon content, biochar carbon content, and wood density together explained 15.5% of the variance in ηC, with feedstock carbon content exerting a significant negative effect, whereas wood density correlated positively with carbon retention. These findings demonstrate that tree species and their functional traits jointly determine carbon fixation efficiency during smoldering. High initial carbon content alone does not guarantee enhanced carbon recovery; instead, wood density and lignin-derived structural stability dominate retention outcomes. Our results underscore the need for trait-based feedstock selection to improve biochar quality and carbon sequestration potential, and provide a mechanistic framework linking species identity, functional traits, and carbon stabilization in biochar production. Full article

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

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19 pages, 1947 KB

Open AccessArticle

Challenges and Weaknesses of Myanmar Forest Certification Sector

by May Zun Phyo, Thant Sin Aung and Xiaodong Liu

Forests 2026, 17(1), 115; https://doi.org/10.3390/f17010115 - 14 Jan 2026

Abstract

Forest certification in developing countries faces significant challenges due to weak institutions, limited market incentives, and complex trade conditions. This study investigates the status and key constraints of the Myanmar forest certification sector through a survey of 180 stakeholders from government organizations, NGOs, [...] Read more.

Forest certification in developing countries faces significant challenges due to weak institutions, limited market incentives, and complex trade conditions. This study investigates the status and key constraints of the Myanmar forest certification sector through a survey of 180 stakeholders from government organizations, NGOs, INGOs, third-party certification bodies, and private plantation owners, complemented by quantitative analysis and qualitative interviews. The results indicate a moderate level of familiarity with the Myanmar forest certification standard and high awareness of the Myanmar Forest Certification Committee; however, progress remains slow due to limited transparency, poor institutional coordination, financial and technical constraints, and insufficient stakeholder involvement. Non-compliances issues identified during pilot audits were primarily related to incomplete documentation, unclear land tenure, and weaknesses in environmental assessment. Geopolitical factors continue to limit Myanmar’s participation in certified timber markets and weaken efforts to improve traceability. Experiences from Indonesia, Malaysia, and Vietnam highlight that developing credible national certification systems requires time, clear legal frameworks, and strong cooperation among stakeholders. Strengthening institutional capacity, improving transparency, and aligning national standards with international forest governance frameworks are essential for Myanmar to build trust, achieve sustainable forest management, and regain market access. Full article

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

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26 pages, 5542 KB

Open AccessArticle

Diversity, Growth Parameters, and Ecosystem Services of Urban Trees Under Climate-Change Conditions: A Case Study of Topčider Park

by Nevenka Galečić, Djurdja Petrov, Dejan Skočajić, Jelena Čukanović, Radenka Kolarov, Sara Đorđević and Mirjana Ocokoljić

Forests 2026, 17(1), 114; https://doi.org/10.3390/f17010114 - 14 Jan 2026

Abstract

Urban tree planting is widely promoted for its benefits, but the long-term condition of trees is poorly documented, especially as changing and often incompatible conditions, intensified by climate change, affect their ability to deliver those benefits. A case study in Topčider Park (since [...] Read more.

Urban tree planting is widely promoted for its benefits, but the long-term condition of trees is poorly documented, especially as changing and often incompatible conditions, intensified by climate change, affect their ability to deliver those benefits. A case study in Topčider Park (since 1836) was conducted during 2025 through the evaluation of diversity, growth parameters, ornamental value, vitality, and total fresh biomass and the identification of tree taxa with high carbon-sequestration potential in Belgrade (Serbia). The data were statistically processed using descriptive statistics, the Shannon diversity and the Pielou evenness index, PCA, Spearman rank and Chi-square tests. The results indicated a wide distribution and high homogeneity of taxa, greater stability within Angiospermae and moderate stability within Gymnospermae, with PCA showing no correlations between growth parameters, vitality, and ornamental value, confirming the close proximity of all taxa. At the taxon level, London plane, English oak, Ginkgo and Bald cypress stood out in growth parameters, while the assessment of total fresh biomass for all 51 taxa highlighted London plane, Scots pine and Bald cypress as particularly productive and adaptive. Carbon sequestration and CO₂ reduction varied with total fresh biomass. The study offers evidence-based recommendations for selecting urban tree taxa to enhance ecosystem services and support climate-adaptation efforts in urban planning. Full article

(This article belongs to the Special Issue Urban Trees Under Climate Change: Growth, Environmental Benefits and Potentials)

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20 pages, 22964 KB

Open AccessArticle

Overexpression of the PtrCLE1A Gene Enhances Drought Tolerance in Poplar

by Zheng Li, Feng-Xin Chen, Yu-Qi Liu, Xianli Tang, Meng-Bo Huang, Ming-Ming Li, Chao Liu, Hou-Ling Wang and Xinli Xia

Forests 2026, 17(1), 113; https://doi.org/10.3390/f17010113 - 14 Jan 2026

Abstract

Signaling mediated by CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptides and their receptors is essential for plants to adapt to abiotic stress. To address the global issue of drought-induced growth inhibition and mortality in poplar (Populus spp.), this study investigated the function of the [...] Read more.

Signaling mediated by CLAVATA3/EMBRYO SURROUNDING REGION-RELATED (CLE) peptides and their receptors is essential for plants to adapt to abiotic stress. To address the global issue of drought-induced growth inhibition and mortality in poplar (Populus spp.), this study investigated the function of the PtrCLE1A gene from Populus trichocarpa Torr. et Gray in drought tolerance regulation. We employed gene cloning, expression vector construction, and genetic transformation of poplar, combined with bioinformatics analysis, subcellular localization, phenotypic observation, physiological index measurement, and gene expression analysis. The results demonstrated that both PtrCLE1A and PtrCLE1B encode pre-propeptides containing a signal peptide, with an identical mature peptide sequence (RLSPGGPDPRHH), and their putative receptors are PtrCLV1/2. Furthermore, the PtrCLE1A pre-propeptide was localized around the plasma membrane in tobacco (Nicotiana benthamiana Domin) mesophyll cells, consistent with its predicted function. PtrCLE1A and PtrCLE1B are primarily expressed in the roots and xylem of P. trichocarpa. Additionally, only the PtrCLE1A promoter contained drought-responsive cis-elements, and its expression was induced by drought stress in root, xylem, and leaf tissues of P. trichocarpa. Overexpression of the PtrCLE1A gene in Populus tomentosa Carrière (triploid) significantly increased adventitious root length under osmotic stress. Overexpression lines exhibited 22.00% to 22.92% longer adventitious roots than EV lines at 50/100 mM mannitol, and 65.12% to 73.17% longer at 150 mM mannitol. The OE lines also exhibited higher photosynthetic capacity and instantaneous water use efficiency (iWUE), along with reduced membrane damage under drought conditions, indicating enhanced drought resistance. This study provides new genetic resources and a theoretical foundation for molecular breeding of drought-tolerant poplar. Full article

(This article belongs to the Special Issue Abiotic and Biotic Stress Responses in Trees Species—2nd Edition)

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29 pages, 16634 KB

Open AccessReview

Computer Vision, Machine Learning, and Deep Learning for Wood and Timber Products: A Scopus-Based Bibliometric and Systematic Mapping Review (1983–2026, Early Access)

by Gianmarco Goycochea Casas, Zool Hilmi Ismail and Helio Garcia Leite

Forests 2026, 17(1), 112; https://doi.org/10.3390/f17010112 - 14 Jan 2026

Abstract

This systematic mapping review and bibliometric analysis examines Scopus-indexed research on computer vision, image processing, and deep learning applied to wood and timber materials and products. A rule-based Scopus search (TITLE-ABS-KEY, 9 December 2025), combining wood and timber terms with imaging and computer [...] Read more.

This systematic mapping review and bibliometric analysis examines Scopus-indexed research on computer vision, image processing, and deep learning applied to wood and timber materials and products. A rule-based Scopus search (TITLE-ABS-KEY, 9 December 2025), combining wood and timber terms with imaging and computer vision terminology, followed by duplicate removal and structured exclusions, retained 1019 papers (1983–2026, early access) covering surface inspection, internal imaging, species identification, processing operations (log-yard/sawmill/panels), automation, dimensional metrology, and image-based property/structure characterization. The papers were classified into nine application categories and three methodological classes using improved rule-based classification with weighted scoring and exclusion rules. Paper output continues to accelerate, with 63.7% of papers published since 2016; Wood Surface Quality Control dominates (48.3%), followed by 3D and Internal Wood Imaging (13.6%), Wood Microstructure and Characterization (10.1%), and Wood Species and Origin Identification (10.6%). Methodologically, classical computer vision prevails (73.6%). Deep learning accounts for 26.4% of the corpus overall and 48.8% of papers from 2023–2026 (early access), while classical computer vision remains prevalent (70.1%) across most categories; the dataset totals 11,961 citations (mean: 11.74 per paper). Validation on 97 papers showed 80.41% accuracy for methodological classification and 70.1% for application categories. We quantitatively map method evolution across the nine categories, introducing a tailored taxonomy and tracking the shift from classical vision to deep learning at the category level. The remaining gaps include dimensional measurement automation, warp detection, sawing optimization, and benchmark datasets, with future directions emphasizing Vision Transformers, multi-modal sensing, edge computing, and explainable AI for certification. Full article

(This article belongs to the Special Issue Innovations in Timber Engineering)

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12 pages, 1340 KB

Open AccessArticle

Impervious Surfaces Do Not Impact Urban Tree Crown Growth

by Peter Cybula, Patricia R. Torquato, Amy Hahs and Stefan K. Arndt

Forests 2026, 17(1), 111; https://doi.org/10.3390/f17010111 - 14 Jan 2026

Abstract

Tree canopies in urban areas have many important ecosystem functions, and councils have targets to increase urban tree canopy area, which has proved challenging. Urban centres have large areas of impervious surfaces, and there is a perception that impervious surfaces are harmful for [...] Read more.

Tree canopies in urban areas have many important ecosystem functions, and councils have targets to increase urban tree canopy area, which has proved challenging. Urban centres have large areas of impervious surfaces, and there is a perception that impervious surfaces are harmful for urban tree growth as water cannot penetrate the soil in which trees are growing. We investigated tree crown growth of young trees of eight common urban tree species in a suburb of Melbourne, Australia, that either grew in streets that were impacted by impervious surfaces or in parks. Four tree species had shown sensitivity to rainfall by lower crown growth in a low-rainfall suburb before, while the other four species had similar crown growth in high- and low-rainfall suburbs. We identified 40 trees per species and location (street vs. park) that were planted between 2009 and 2011 and measured their tree crown area in 2014 and again in 2018 using remote-sensed images. Trees that grew in streets that were impacted by impervious surfaces had larger crowns in 2014 than trees in parks, but both showed similar crown growth rates of 2.3 m² yr⁻¹ in the four-year period. Only one species (Eucalyptus sideroxylon A.Cunn ex Woolls) had a statistically significant greater relative crown growth rate in parks compared to streets. There was no statistically significant difference in the relative or absolute crown growth rates in tree species that have shown a previous sensitivity to rainfall compared to those that were insensitive to rainfall. Our data indicate that impervious surfaces had no detrimental impact on tree crown growth. It is possible that trees grown in streets have sufficient water resources and may benefit from the lack of competition for water, whereas trees in parks must compete for water resources with other plants. Full article

(This article belongs to the Special Issue Growing the Urban Forest: Building Our Understanding)

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15 pages, 7992 KB

Open AccessArticle

Impact of Introduced Spatholobus suberectus and Dalbergia balansae on Soil N Accumulation and P Depletion in Chinese Fir Plantations

by Qiwu Sun, Chai Lin, Lingyu Hou, Yuhong Dong, Shumeng Wei, Xiangrong Liu and Qian Wang

Forests 2026, 17(1), 110; https://doi.org/10.3390/f17010110 - 13 Jan 2026

Abstract

The introduction of understory vegetation can increase species diversity and potential productivity in forest ecosystems, which is considered a viable solution to the global problem of declining soil quality caused by deteriorating climatic conditions and human activities. The forest management model that achieves [...] Read more.

The introduction of understory vegetation can increase species diversity and potential productivity in forest ecosystems, which is considered a viable solution to the global problem of declining soil quality caused by deteriorating climatic conditions and human activities. The forest management model that achieves economic and ecological benefits by introducing legumes is widely used. However, there have been rare studies on the effects of introducing legumes under Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations on soil nutrient content and microbial diversity. In this study, we investigated the soil chemical properties, microbial diversity, and enzymatic activities in Chinese fir plantations introduced with Spatholobus suberectus (SRS), Dalbergia balansae (DRS), both species (BS), and in a monoculture plantation (CK). As indicated by the results, soil pH, total phosphorus (TP), available phosphorus (AP), available potassium (AK), urease activities, and the ratios of C:P and N:P decreased in SRS, DRS, and BS treatments, whereas soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), phosphatase, and sucrase activities increased. The decrease in soil pH and the effects of Chytridiomycota and Glomeromycota elevated phosphatase activity. Accordingly, the mineralization rate of soil phosphorus increased. This increase enhanced phosphorus availability and the risk of loss, resulting in the depletion of soil phosphorus and the inhibition of urease activity. The findings of this study reveal that the introduction of legumes effectively improves the soil microbial community and nitrogen accumulation in Chinese fir plantations while resulting in phosphorus depletion, highlighting the need for balanced nutrient management. Full article

(This article belongs to the Section Forest Soil)

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