Forests

16 pages, 4967 KiB

Open AccessArticle

Genome-Wide Analysis of the MAPKKK Gene Family Under Abiotic Stresses in Moso Bamboo (Phyllostachys edulis)

by Feiyi Huang and Jiaxin Wang

Forests 2024, 15(11), 1883; https://doi.org/10.3390/f15111883 - 25 Oct 2024

Mitogen-activated protein kinase kinase kinases (MAPKKKs) are the upstream components of MAPK cascades and are involved in mediating stress responses and developmental processes. Although MAPKKK genes have been investigated in many plants, the identification and characterization of MAPKKKs in moso bamboo were [...] Read more.

Mitogen-activated protein kinase kinase kinases (MAPKKKs) are the upstream components of MAPK cascades and are involved in mediating stress responses and developmental processes. Although MAPKKK genes have been investigated in many plants, the identification and characterization of MAPKKKs in moso bamboo were still limited. Here, 134 MAPKKKs were identified as unevenly distributed on 23 chromosomes (except for chromosome 1) of moso bamboo and divided into three subfamilies by phylogenetic analysis. The gene structure and conserved motif of PeMAPKKKs were investigated. The expansions of PeMAPKKKs were driven by whole-genome duplication (WGD) or segmental duplication events. The duplicated gene pairs were under purifying selection based on the Ka/Ks ratios, suggesting they underwent functional conservation. Most PeMAPKKKs contained cis-elements related to development, hormones, and stress responses. Tissue expression patterns showed that PeMAPKKKs had multiple expression patterns. The qPCR analysis showed distinct expression patterns of PeMAPKKKs under drought, salt, and cold stress conditions. Taken together, this study provides a solid foundation for future functional characterizations of MAPKKKs and identifies candidate stress-responsive genes for further study in moso bamboo. Full article

(This article belongs to the Special Issue Genome-Wide Identification and Expression Analysis for the Genetic Improvement of Forest Plants)

13 pages, 6373 KiB

Open AccessArticle

Mapping Forest Parameters to Model the Mobility of Terrain Vehicles

by Tomáš Mikita, Marian Rybansky, Dominika Krausková, Filip Dohnal, Ondřej Vystavěl and Sabina Hollmannová

Forests 2024, 15(11), 1882; https://doi.org/10.3390/f15111882 - 25 Oct 2024

Abstract

This study aims to evaluate the feasibility of using non-contact data collection methods—specifically, UAV (unmanned aerial vehicle)-based and terrestrial laser scanning technologies—to assess forest stand passability, which is crucial for military operations. The research was conducted in a mixed forest stand in the [...] Read more.

This study aims to evaluate the feasibility of using non-contact data collection methods—specifically, UAV (unmanned aerial vehicle)-based and terrestrial laser scanning technologies—to assess forest stand passability, which is crucial for military operations. The research was conducted in a mixed forest stand in the Březina military training area, where the position of trees and their DBHs (Diameter Breast Heights) were recorded. The study compared the effectiveness of different methods, including UAV RGB imaging, UAV-LiDAR, and handheld mobile laser scanning (HMLS), in detecting tree positions and estimating DBH. The results indicate that HMLS data provided the highest number of detected trees and the most accurate positioning relative to the reference measurements. UAV-LiDAR showed better tree detection compared to UAV RGB imaging, though both aerial methods struggled with canopy penetration in densely structured forests. The study also found significant variability in DBH estimation, especially in complex forest stands, highlighting the challenges of accurate tree detection in diverse environments. The findings suggest that while current non-contact methods show promise, further refinement and integration of data sources are necessary to improve their applicability for assessing forest passability in military or rescue contexts. Full article

(This article belongs to the Special Issue Modeling of Vehicle Mobility in Forests and Rugged Terrain)

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19 pages, 6528 KiB

Open AccessArticle

Estimation of Tree Diameter at Breast Height from Aerial Photographs Using a Mask R-CNN and Bayesian Regression

by Kyeongnam Kwon, Seong-kyun Im, Sung Yong Kim, Ye-eun Lee and Chun Geun Kwon

Forests 2024, 15(11), 1881; https://doi.org/10.3390/f15111881 - 25 Oct 2024

Abstract

A probabilistic estimation model for forest biomass using unmanned aerial vehicle (UAV) photography was developed. We utilized a machine-learning-based object detection algorithm, a mask region-based convolutional neural network (Mask R-CNN), to detect trees in aerial photographs. Subsequently, Bayesian regression was used to calibrate [...] Read more.

A probabilistic estimation model for forest biomass using unmanned aerial vehicle (UAV) photography was developed. We utilized a machine-learning-based object detection algorithm, a mask region-based convolutional neural network (Mask R-CNN), to detect trees in aerial photographs. Subsequently, Bayesian regression was used to calibrate the model based on an allometric model using the estimated crown diameter (CD) obtained from aerial photographs and analyzed the diameter at breast height (DBH) data acquired through terrestrial laser scanning. The F1 score of the Mask R-CNN for individual tree detection was 0.927. Moreover, CD estimation using the Mask R-CNN was acceptable (rRMSE = 10.17%). Accordingly, the probabilistic DBH estimation model was successfully calibrated using Bayesian regression. A predictive distribution accurately predicted the validation data, with 98.6% and 56.7% of the data being within the 95% and 50% prediction intervals, respectively. Furthermore, the estimated uncertainty of the probabilistic model was more practical and reliable compared to traditional ordinary least squares (OLS). Our model can be applied to estimate forest biomass at the individual tree level. Particularly, the probabilistic approach of this study provides a benefit for risk assessments. Additionally, since the workflow is not interfered by the tree canopy, it can effectively estimate forest biomass in dense canopy conditions. Full article

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

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19 pages, 22283 KiB

Open AccessArticle

The Impact of Different Types of Trees on Annual Thermal Comfort in Hot Summer and Cold Winter Areas

by Xiao Chen, Zilong Li, Zhenyu Wang, Jiayu Li and Yihua Zhou

Forests 2024, 15(11), 1880; https://doi.org/10.3390/f15111880 - 25 Oct 2024

Abstract

Trees positively improve the annual thermal comfort of the built environment in tropical areas, where climate change is slight throughout the year. However, for areas with high changes in climate all year, the current studies have only explored the summer cooling performance of [...] Read more.

Trees positively improve the annual thermal comfort of the built environment in tropical areas, where climate change is slight throughout the year. However, for areas with high changes in climate all year, the current studies have only explored the summer cooling performance of trees without the impact of different types of trees on annual thermal comfort, especially in cold seasons. Therefore, to quantify the impacts and scientifically guide the optimization of green space layout in hot summer and cold winter areas, this study selected Changsha City as the study area and analyzed how the annual thermal comfort is affected by evergreen trees and deciduous trees, which are two common types of trees in hot summer and cold winter areas. The analytical results indicated that the difference in the effect of deciduous and evergreen trees on outdoor thermal comfort was insignificant in summer, where the difference in the monthly mean PET for the three summer months was slight, being 0.28 °C, 0.14 °C, and 0.29 °C, respectively. However, evergreen trees greatly exacerbated winter cold compared to deciduous trees, with a monthly mean PET decrease by nearly 1.0 °C and an hourly PET reduced by up to 3.57 °C. The difference is mainly attributed to the absorption and reflection of solar radiation by the tree canopy, as well as the cooling and humidifying effect of the tree leaf. In hot summer and cold winter areas, outdoor thermal comfort is still in the “comfortable” and “slightly warm” acceptable stage despite the warming effect of deciduous trees in the spring and autumn seasons. Planting evergreen trees is an inevitable thermal mitigation choice for tropical areas. However, for the areas with high annual climate change, such as hot summer and cold winter areas in China, a change in empirical tree planting patterns and selecting deciduous trees where appropriate will improve year-round outdoor thermal comfort. Full article

(This article belongs to the Section Urban Forestry)

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17 pages, 1262 KiB

Open AccessArticle

Analyzing the Impact of EU’s Legality Requirements Policies on Sustainable Timber and Sawnwood Trade—Focusing on Tropical Wood Trade

by Dong Hyun Kim, Byeong Il Ahn and Gyuhun Shim

Forests 2024, 15(11), 1879; https://doi.org/10.3390/f15111879 - 25 Oct 2024

Abstract

This study analyzes the impact of the EU′s policy to prohibit the import of illegally harvested timber on the trade of tropical timber and sawnwood. The analysis uses a difference-in-differences approach based on gravity models, with panel data from over 193 countries that [...] Read more.

This study analyzes the impact of the EU′s policy to prohibit the import of illegally harvested timber on the trade of tropical timber and sawnwood. The analysis uses a difference-in-differences approach based on gravity models, with panel data from over 193 countries that trade tropical timber and sawnwood. The result of the analysis shows that the European Union Timber Regulation (EUTR) reduces the trade of illegally harvested timber. It further suggests that the EUTR caused a relatively larger reduction in tropical sawnwood (−0.21%) than that of tropical timber (0.07%). In addition, the Voluntary Partnership Agreement (VPA) appeared to cause a significant reduction in tropical sawnwood (−0.07~−0.05%), whereas tropical timber did not appear to have been significantly impacted. In particular, the reduction in timber exports in countries that have signed the VPA, which aims to encourage exports of legally produced timber, has significant implications for both the EU and timber exporters preparing for the VPA, as both parties strive to expand the VPA. The results of this study suggest that the EU needs to make additional efforts to address the decline in exports from countries that signed the VPA. Full article

(This article belongs to the Special Issue Impact of Global Economic Changes on the Wood-Based Industry)

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22 pages, 6819 KiB

Open AccessArticle

Deriving Vegetation Indices for 3D Canopy Chlorophyll Content Mapping Using Radiative Transfer Modelling

by Ahmed Elsherif, Magdalena Smigaj, Rachel Gaulton, Jean-Philippe Gastellu-Etchegorry and Alexander Shenkin

Forests 2024, 15(11), 1878; https://doi.org/10.3390/f15111878 - 25 Oct 2024

Abstract

Leaf chlorophyll content is a major indicator of plant health and productivity. Optical remote sensing estimation of chlorophyll limits its retrievals to two-dimensional (2D) estimates, not allowing examination of its distribution within the canopy, although it exhibits large variation across the vertical profile. [...] Read more.

Leaf chlorophyll content is a major indicator of plant health and productivity. Optical remote sensing estimation of chlorophyll limits its retrievals to two-dimensional (2D) estimates, not allowing examination of its distribution within the canopy, although it exhibits large variation across the vertical profile. Multispectral and hyperspectral Terrestrial Laser Scanning (TLS) instruments can produce three-dimensional (3D) chlorophyll estimates but are not widely available. Thus, in this study, 14 chlorophyll vegetation indices were developed using six wavelengths employed in commercial TLS instruments (532 nm, 670 nm, 808 nm, 785 nm, 1064 nm, and 1550 nm). For this, 200 simulations were carried out using the novel bidirectional mode in the Discrete Anisotropic Radiative Transfer (DART) model and a realistic forest stand. The results showed that the Green Normalized Difference Vegetation Index (GNDVI) of the 532 nm and either the 808 nm or the 785 nm wavelengths were highly correlated to the chlorophyll content (R² = 0.74). The Chlorophyll Index (CI) and Green Simple Ratio (GSR) of the same wavelengths also displayed good correlation (R² = 0.73). This study was a step towards canopy 3D chlorophyll retrieval using commercial TLS instruments, but methods to couple the data from the different instruments still need to be developed. Full article

(This article belongs to the Special Issue Growth Models for Forest Stand Development Dynamics)

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19 pages, 1209 KiB

Open AccessArticle

Farmers’ Socioeconomic Characteristics and Perception of Land Use Change Defining Optimal Agroforestry Practices in Khost Province, Afghanistan

by Mujib Rahman Ahmadzai, Mohd Hasmadi Ismail, Pakhriazad Hassan Zaki, Mohd. Maulana Magiman and Paiman Bawon

Forests 2024, 15(11), 1877; https://doi.org/10.3390/f15111877 - 25 Oct 2024

Abstract

Agroforestry practices evolve with the development of basic and advanced facilities, changes in natural and artificial factors of land, and land use trade-offs. This study aims to examine the farmers’ socioeconomic characteristics and perception of land use changes that define optimal agroforestry practices [...] Read more.

Agroforestry practices evolve with the development of basic and advanced facilities, changes in natural and artificial factors of land, and land use trade-offs. This study aims to examine the farmers’ socioeconomic characteristics and perception of land use changes that define optimal agroforestry practices in Khost Province, Afghanistan. Data were collected from 662 farmers and analyzed using univariate Analysis of Variance (ANOVA) and Multivariate Analysis of Variance (MANOVA). The results found that forest and vegetable products, including fruits, berries, herbs, mushrooms, wild animals, oils, wood, honey, okra, eggplant, carrot, cucumber, pine nuts, pepper, and timber, have different impacts in terms of satisfaction with basic and advanced facilities, knowledge of land use changes, satisfaction with natural and artificial resources of land, and barriers to and economic benefits of land use. The limitations of this study included an absence of exogenous factors in the model such as climate change, financial conditions, market fluctuations, regulatory system, the area in which this study is selected, research design, and current condition of endogenous factors. Overall, this study defined a set of optimal agroforestry practices (expressed as crops and products) based on the farmers’ perception of land use changes in Khost Province, Afghanistan. This study provided useful insights for policymakers and development practitioners to promote agroforestry practice adoption and improve the socioeconomic development of agroforestry-dependent communities. Future works could explore the implications of agroforestry practices on the socioeconomic development of other dependent communities in Afghanistan. Full article

(This article belongs to the Section Forest Economics, Policy, and Social Science)

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18 pages, 2367 KiB

Open AccessArticle

Soil Physicochemical Properties and Carbon Storage Reserve Distribution Characteristics of Plantation Restoration in a Coal Mining Area

by Ruidong Wang, Yanlong Han, Zhongju Meng, Yong Gao and Zhenliang Wu

Forests 2024, 15(11), 1876; https://doi.org/10.3390/f15111876 - 25 Oct 2024

Abstract

The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on [...] Read more.

The Bulianta Coal Mine is among the problematic coal mining areas in China that is still creating environmental damage, especially associated with soil destruction. Therefore, a scientific investigation was conducted to establish a scientific basis for evaluating the impact of planted forest on soil physical and chemical properties, as well as the ecological benefits following 15 years of vegetation restoration in the area. The soil physicochemical characteristics and distribution of organic carbon storage in the 0–80 cm layer soils of Pinus sylvestris forests, Prunus sibirica forests, and Hippophae rhamnoides forests restored after 5, 10, and 15 years were investigated. The immersion method was used to determine soil porosity and density followed by the determination of soil indicators, and a statistical ANOVA test was applied to examine the differential effects of different vegetation types and restoration years on soil properties. The results clearly demonstrated the following: (1) The recovery of vegetation was achieved after a period of 15 years, with the average bulk density of the 0–80 cm soil layer as follows: P. sylvestris forest (1.513 g·cm⁻³) > P. sibirica forest (1.272 g·cm⁻³) > H. rhamnoides forest (1.224 g·cm⁻³), and the differences among different forest types were statistically significant (p < 0.05). (2) In planted forests, soil nutrients were predominantly concentrated in the 0–20 cm layer, while soil carbon storage exhibited a decline with an increasing soil depth. (3) The soil carbon storage across the three forest types was as follows: P. sylvestris forest (45.42 t·hm⁻²) > P. sibirica forest (44.56 t·hm⁻²) > H. rhamnoides forest (41.87 t·hm⁻²). In summary, during the ecological vegetation restoration process in the Bulianta Core Mine, both P. sylvestris forest and P. sibirica forest exhibit superior carbon storage capacities compared to H. rhamnoides forest, as well as more effective soil improvement outcomes. Full article

(This article belongs to the Section Forest Soil)

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27 pages, 37085 KiB

Open AccessArticle

A Method for Classifying Wood-Boring Insects for Pest Control Based on Deep Learning Using Boring Vibration Signals with Environment Noise

by Juhu Li, Xuejing Zhao, Xue Li, Mengwei Ju and Feng Yang

Forests 2024, 15(11), 1875; https://doi.org/10.3390/f15111875 - 25 Oct 2024

Abstract

Wood-boring pests are difficult to monitor due to their concealed lifestyle. To effectively control these wood-boring pests, it is first necessary to efficiently and accurately detect their presence and identify their species, which requires addressing the limitations of traditional monitoring methods. This paper [...] Read more.

Wood-boring pests are difficult to monitor due to their concealed lifestyle. To effectively control these wood-boring pests, it is first necessary to efficiently and accurately detect their presence and identify their species, which requires addressing the limitations of traditional monitoring methods. This paper proposes a deep learning-based model called BorerNet, which incorporates an attention mechanism to accurately identify wood-boring pests using the limited vibration signals generated by feeding larvae. Acoustic sensors can be used to collect boring vibration signals from the larvae of the emerald ash borer (EAB), Agrilus planipennis Fairmaire, 1888 (Coleoptera: Buprestidae), and the small carpenter moth (SCM), Streltzoviella insularis Staudinger, 1892 (Lepidoptera: Cossidae). After preprocessing steps such as clipping and segmentation, Mel-frequency cepstral coefficients (MFCCs) are extracted as inputs for the BorerNet model, with noisy signals from real environments used as the test set. BorerNet learns from the input features and outputs identification results. The research findings demonstrate that BorerNet achieves an identification accuracy of 96.67% and exhibits strong robustness and generalization capabilities. Compared to traditional methods, this approach offers significant advantages in terms of automation, recognition efficiency, and cost-effectiveness. It enables the early detection and treatment of pest infestations and allows for the development of targeted control strategies for different pests. This introduces innovative technology into the field of tree health monitoring, enhancing the ability to detect wood-boring pests early and making a substantial contribution to forestry-related research and practical applications. Full article

(This article belongs to the Special Issue Forest Ecology and Resource Monitoring Based on Sensors, Signal and Image Processing)

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3 pages, 642 KiB

Open AccessEditorial

Wood Quality and Mechanical Properties

by André Luis Christoforo

Forests 2024, 15(11), 1874; https://doi.org/10.3390/f15111874 - 25 Oct 2024

Abstract

The recent Special Issue (SI) of Forests on “Wood Quality and Mechanical Properties” offers an in-depth exploration of the complex relationship between the quality of wood and its mechanical properties, in addition to describing innovations in the field [...] Full article

(This article belongs to the Special Issue Wood Quality and Mechanical Properties)

22 pages, 4658 KiB

Open AccessArticle

Development and Application of Microsatellite Markers for Genetic Diversity Assessment and Construction of a Core Collection of Myrciaria dubia (Kunth) McVaugh Germplasm from the Peruvian Amazon

by Juan C. Castro, Stalin J. Vasquez-Guizado, Bianca E. Vigil, Francisco Ascue, Naysha Rojas-Villa, Jae D. Paredes, Marianela Cobos, Carlos G. Castro, Daniel E. Motta, Pedro M. Adrianzén, Sixto A. Imán and J. Dylan Maddox

Forests 2024, 15(11), 1873; https://doi.org/10.3390/f15111873 - 25 Oct 2024

Abstract

The Amazonian shrub Myrciaria dubia (camu-camu) produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. This study aimed to develop and apply microsatellite markers to assess genetic diversity and [...] Read more.

The Amazonian shrub Myrciaria dubia (camu-camu) produces vitamin C-rich fruits of growing commercial interest. However, sustainable utilization requires assessment and protection of the genetic diversity of the available germplasm. This study aimed to develop and apply microsatellite markers to assess genetic diversity and construct a core collection of M. dubia germplasm from the Peruvian Amazon. Sixteen polymorphic microsatellite loci were developed using an enrichment approach. The evaluation of 336 genotypes from 43 accessions of the germplasm bank, originating from eight river basins, was conducted using these newly developed markers. Genetic diversity parameters, including observed and expected heterozygosity, were calculated. Analysis of molecular variance (AMOVA) was performed to assess the distribution of genetic variation within and among accessions and river basins. Bayesian clustering analysis was employed to infer population structure. A core collection was constructed to maximize allelic richness. High genetic diversity was observed, with heterozygosity values ranging from 0.468 to 0.644 (observed) and 0.684 to 0.817 (expected) at the river basin level. AMOVA indicated significant genetic variation within (73–86%) compared to among (14–27%) accessions and river basins. Bayesian clustering detected ten genetic clusters, with several degrees of admixture among river basins, except for the genetically homogeneous Putumayo River basin. A core collection comprising 84 plant genotypes (25% of the full collection) was established, representing 90.82% of the overall allelic diversity. These results have important implications for M. dubia conservation strategies and breeding programs, in demonstrating a need for genetic connectivity between populations but preserving unique genetic resources in isolated basins. These results validate the expected levels of diversity and population subdivision in a crop and stress the need to secure genetically diverse germplasms, underscoring the importance of thorough genetic characterization for ex situ germplasm management. Full article

(This article belongs to the Special Issue Biodiversity in Forests: Management, Monitoring for Conservation)

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24 pages, 5518 KiB

Open AccessReview

Integrating Forest Ecosystem Services into Health Strategies to Improve Human Well-Being

by Yuan Liu, Chengyuan Wang, Yuwen Liu, Tiantian Feng, Enheng Wang, Liwei Yang, Qian Niu and Xuegang Mao

Forests 2024, 15(11), 1872; https://doi.org/10.3390/f15111872 - 25 Oct 2024

Abstract

As the largest terrestrial ecosystem covering extensive expanses of the Earth’s surface, forests offer crucial health benefits to humans, both directly and indirectly. Presently, health services derived from forest resources have presented significant opportunities for enhancing human well-being. Nonetheless, the absence of a [...] Read more.

As the largest terrestrial ecosystem covering extensive expanses of the Earth’s surface, forests offer crucial health benefits to humans, both directly and indirectly. Presently, health services derived from forest resources have presented significant opportunities for enhancing human well-being. Nonetheless, the absence of a comprehensive understanding regarding the mechanisms by which forests impact human health jeopardizes the potential gains in health. Regrettably, there remains a dearth of scholarly work elucidating these pathways. This paper aims to furnish a thorough examination of how forests influence human health. We initiate by formulating a conceptual framework upon which we delineate the various pathways through which forests impact human health. These encompass the provisioning of resources, preventive services, and forest therapies. Concurrently, we outline the moderating influence of social, economic, and individual characteristics as mediators within this pathway. These characteristics are classified into two overarching dimensions: accessibility and behavioral choices, which notably affect marginalized demographics such as those with lower socioeconomic status, women, the elderly, individuals with disabilities, and children in developing nations. Consequently, we build upon these foundational insights to propose six strategies aimed at perpetuating the positive impact of forests on human health in the foreseeable future. In the future, the development of forest management policies, the assessment of long-term health benefits, social practices, and international cooperation must be considered holistically to attain the dual objective of sustainable forest management and the advancement of human well-being. Full article

(This article belongs to the Special Issue Social and Cultural Benefits of Forests Contributing to Human Health and Well-Being)

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23 pages, 14850 KiB

Open AccessArticle

Influence of Terrain on MODIS and GLASS Leaf Area Index (LAI) Products in Qinling Mountains Forests

by Jiaman Zheng, Mengyuan Wang, Mingyue Liang, Yuyang Gao, Mou Leong Tan, Mengyun Liu and Xiaoping Wang

Forests 2024, 15(11), 1871; https://doi.org/10.3390/f15111871 - 25 Oct 2024

Abstract

Leaf Area Index (LAI), as a pivotal parameter in characterizing the structural properties of vegetation ecosystems, holds significant importance in assessing the carbon sink function. Given the availability of multiple long-term LAI products, validating these LAI products with consideration of topographic factors is [...] Read more.

Leaf Area Index (LAI), as a pivotal parameter in characterizing the structural properties of vegetation ecosystems, holds significant importance in assessing the carbon sink function. Given the availability of multiple long-term LAI products, validating these LAI products with consideration of topographic factors is a prerequisite for enhancing the quality of LAI products in mountainous areas. Therefore, this study aims to evaluate the performance of MODIS LAI and GLASS LAI products from 2001 to 2021 by comparing and validating them with ground-measured LAI data, focusing on the spatio-temporal and topographic aspects in the Qinling Mountains. The results show that the GLASS LAI product is a better choice for estimating LAI in the Qinling Mountains. The GLASS LAI product has better completeness and generally higher values compared to the MODIS LAI product. The time-series curve of the GLASS LAI product is more continuous and smoother than the MODIS LAI product. Both products, however, face challenges in quantifying LAI values of evergreen vegetation during winter. The MODIS and GLASS LAI products exhibit differences between sunny and shady slopes, with mean LAI values peaking on sunny slopes and reaching their lowest on shady slopes. When the slope ranges from 0 to 10°, the mean values of GLASS LAI product show a higher increasing trend compared to the MODIS LAI product. At elevations between 1450 and 2450 m, the mean LAI values of the GLASS LAI product are higher than the MODIS LAI product, primarily in the southern Qinling Mountains. Compared to ground-measured LAI data, the GLASS LAI product (R² = 0.33, RMSE = 1.62, MAE = 0.61) shows a stronger correlation and higher accuracy than the MODIS LAI product (R² = 0.24, RMSE = 1.61, MAE = 0.68). Full article

(This article belongs to the Special Issue Remote Sensing of Forest Biomass and Carbon Dynamics Using Multiple Sources and Technologies)

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17 pages, 3722 KiB

Open AccessArticle

Transcriptomic Profiling Analyses Revealed Candidate Genes Under Freezing Stress in Siberian Apricot (Prunus sibirica)

by Quangang Liu, Wenying Li, Xin Zhao, Hongrui Zhang, Jianhua Chen, Qingbai Liu, Tianlai Li and Shengjun Dong

Forests 2024, 15(11), 1870; https://doi.org/10.3390/f15111870 - 24 Oct 2024

Abstract

Siberian apricot (Prunus sibirica) is an important ecological and commercial woody plant that is negatively affected by spring frosts. However, the mechanisms that control gene expression in adaptation to freezing remain largely unknown. In this work, we investigated the physiological, molecular, [...] Read more.

Siberian apricot (Prunus sibirica) is an important ecological and commercial woody plant that is negatively affected by spring frosts. However, the mechanisms that control gene expression in adaptation to freezing remain largely unknown. In this work, we investigated the physiological, molecular, and phenotypic characteristics of pistils of two P. sibirica clones that differ in their ability to withstand freezing stress. A total of 14,717 unigenes categorized into 38 functional groups were identified. Additionally, the two P. sibirica clones included 3931 up-regulated and 2070 down-regulated differentially expressed genes (DEGs). Many DEGs are related to Ca²⁺ and MAPK signaling, carbohydrate biosynthesis and metabolism, plant hormone signal transduction, biosynthesis of amino acids, and photosynthesis. The metabolism of carbohydrates, amino acids, lipids, secondary metabolites, plant hormone signal transduction, and terpenoid metabolism were the transcriptome modifications most significantly altered by freezing stress. Real-time quantitative PCR (RT-qPCR) was used to verify the precision of the RNA-seq data. PsbHLH18, PsMYB4, PsMYB44, PsPOD1, and PsCDPK5 may play important roles in the freezing tolerance of the P. sibirica floral organ. This study provides a foundation for further studies on the complex mechanisms of freezing stress response in P. sibirica. Full article

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

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15 pages, 2617 KiB

Open AccessArticle

Pollarding May Relieve Drought Stress in Black Poplars

by J. Julio Camarero, Cristina Valeriano, José Antonio Sánchez-Sancho and Chabier de Jaime Loren

Forests 2024, 15(11), 1869; https://doi.org/10.3390/f15111869 - 24 Oct 2024

Abstract

Pollarding has historically been used in broadleaf tree species across European woodlands. However, despite pollarding enhances vigor growth in the short term, it is still unclear how long this effect lasts and whether it can alleviate drought stress in seasonally dry regions. We [...] Read more.

Pollarding has historically been used in broadleaf tree species across European woodlands. However, despite pollarding enhances vigor growth in the short term, it is still unclear how long this effect lasts and whether it can alleviate drought stress in seasonally dry regions. We compared the radial growth and wood δ¹³C (¹³C/¹²C), a proxy of intrinsic water-use efficiency (iWUE), of trees pollarded 10 and 20 years ago in two black poplar (Populus nigra L.) riparian stands located in North Eastern Spain and subjected to different ecohydrological conditions. We also assessed if pollarded trees showed different leaf phenology as compared with uncut trees of coexisting white poplar (Populus alba L.) trees. The relationships between growth, climate variables, drought severity and river flow were quantified. Pollarded and uncut trees showed a similar leaf phenology with a trend towards earlier leaf unfolding as springs become warmer. Pollarding increased growth rates by 54% (ratio between trees pollarded 10 and 20 years ago, respectively), but this enhancement was transitory and lasted ca. 10 years, whereas wood δ¹³C decreased −5%. The growth of black poplar increased in response to high precipitation in the previous winter, cool wet conditions, and a higher river flow in summer. Pollarding improves growth and relieves drought stress. Full article

(This article belongs to the Special Issue Water Use Efficiency and Hydraulic Traits of Forest Trees in Changing Environment)

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25 pages, 14333 KiB

Open AccessArticle

Soundscapes in Urban Green Spaces of a Megacity Across an Urban–Rural Gradient: A Case Study of Shanghai

by Lu Liu, Xiao Yang, Jingli Yan, Wenwen Zhang, Yunzheng Ke, Tong Zhang and Shan Yin

Forests 2024, 15(11), 1868; https://doi.org/10.3390/f15111868 - 24 Oct 2024

Abstract

Urban soundscapes are valuable indicators of urban biodiversity and ecosystem health. This study investigated the spatial and temporal characteristics of soundscapes in megacity green spaces and their relationship with the urban environment. An acoustic index was formulated and calculated using long-term data from [...] Read more.

Urban soundscapes are valuable indicators of urban biodiversity and ecosystem health. This study investigated the spatial and temporal characteristics of soundscapes in megacity green spaces and their relationship with the urban environment. An acoustic index was formulated and calculated using long-term data from Shanghai’s urban green spaces. The results show a significant increase in the acoustic index during spring and summer, peaking during these periods, while a decrease was observed from December to February, dominated by abiotic sounds. Diurnal variations indicate a rapid increase in the acoustic index at sunrise, reflecting heightened avian activity during the dawn chorus. Human interference in the urban center limited acoustic activity, whereas the outer suburbs, with their more natural environments, supported greater acoustic richness. Full article

(This article belongs to the Special Issue Soundscape in Urban Forests - 2nd Edition)

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23 pages, 4965 KiB

Open AccessArticle

Development of Polymorphic Index Model for Assessing Subtropical Secondary Natural Oak Forest Site Quality Under Complex Site and Climate Variables

by Lang Huang, Guangyu Zhu and Guoqi Chen

Forests 2024, 15(11), 1867; https://doi.org/10.3390/f15111867 - 24 Oct 2024

Abstract

Site and climate conditions are the key determinants controlling dominant height growth and forest productivity, both independently and interactively. Secondary natural oak forests are a typical forest type in China, especially in Hunan Province, but little is known about the site index of [...] Read more.

Site and climate conditions are the key determinants controlling dominant height growth and forest productivity, both independently and interactively. Secondary natural oak forests are a typical forest type in China, especially in Hunan Province, but little is known about the site index of this forest under the complex site and climate variables in the subtropics. Based on survey data of dominant trees and site variables from 101 plots in Hunan oak natural secondary forests and climate data obtained using spatial interpolation, we used the random forest method, correlation analysis, and the analysis of variance to determine the main site and climate factors affecting oak forest dominant height and proposed a modeling method of an oak natural secondary forest site index based on the random effect of site–climate interaction type. Of the site variables, elevation affected stand dominant height the most, followed by slope direction and position. Winter precipitation and summer mean maximum temperature had the greatest impact on stand dominant height. To develop the modeling method, we created 10 popular base models but found low performance (R² ranged from 0.1731 to 0.2030). The optimal base model was Mitscherlich form M3 (R² = 0.1940) based on parameter significance tests. Since site and climate factors affect the site index curve, the dominant site and climate factors were combined into site types and climate types, respectively, and a nonlinear mixed-effects approach was used to simulate different site types, climate types, site–climate interaction types, and their combinations as random effects. Site–climate interaction type as a random factor enhanced model (M3.4) performance and prediction accuracy (R² from 0.1940 to 0.8220) compared to the optimum base model. After clustering the 62 site–climate interaction types into three, five, and eight groups using hierarchical clustering, a mixed-effects model with the random effects of eight groups improved model performance (R² = 0.8265) and applicability. The modeling method developed in this study could be used to assess a regional secondary natural oak forest site index under complex site and climate variables to evaluate the forest productivity. Full article

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

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17 pages, 8188 KiB

Open AccessArticle

Identification and Mapping of Eucalyptus Plantations in Remote Sensing Data Using CCDC Algorithm and Random Forest

by Miaohang Zhou, Xujun Han, Jinghan Wang, Xiangyu Ji, Yuefei Zhou and Meng Liu

Forests 2024, 15(11), 1866; https://doi.org/10.3390/f15111866 - 24 Oct 2024

Abstract

Eucalyptus plantations are one of the primary artificial forests in southern China, experiencing rapid expansion in recent years due to their significant socio-economic benefits. This expansion has raised concerns about the ecological environment, necessitating accurate mapping of eucalyptus plantations. In this study, the [...] Read more.

Eucalyptus plantations are one of the primary artificial forests in southern China, experiencing rapid expansion in recent years due to their significant socio-economic benefits. This expansion has raised concerns about the ecological environment, necessitating accurate mapping of eucalyptus plantations. In this study, the phenological characteristics of eucalyptus plantations were utilized as the primary classification basis. Long-term time series Landsat and Sentinel-2 data from 2000 to 2022 were rigorously preprocessed pixel by pixel using the Google Earth Engine (GEE) platform to obtain high-quality observation data. The Continuous Change Detection and Classification (CCDC) algorithm was employed to fit the multi-year observation data with harmonic curves, utilizing parameters such as normalized intercept, slope, phase, and amplitude of the fitted curves to characterize the phenological features of vegetation. A total of 127 phenological indices were generated using the Normalized Burn Ratio (NBR), Normalized Difference Fractional Index (NDFI), and six spectral bands, with the top 20 contributing indices selected as input variables for the random forest algorithm to obtain preliminary classification results. Subsequently, eucalyptus plantation rotation features and the Simple Non-Iterative Clustering (SNIC) superpixel segmentation algorithm were employed to filter the results, enhancing the accuracy of the identification results. The producer’s accuracy, user’s accuracy, and overall accuracy of the eucalyptus plantation map for the year 2020 were found to be 96.67%, 89.23%, and 95.83%, respectively, with a total area accuracy of 94.39%. Accurate mapping of eucalyptus plantations provides essential information and evidence for ecological environment protection and the formulation of carbon-neutral strategies. Full article

(This article belongs to the Special Issue Satellite Time Series Analysis for Forest Mapping and Change Detection)

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17 pages, 1597 KiB

Open AccessArticle

Transparent Coating Systems Applied on Spruce Wood and Their Colour Stability on Exposure to an Accelerated Ageing Process

by Jozef Kúdela, Richard Hrčka, Ján Svocák and Simona Molčanová

Forests 2024, 15(11), 1865; https://doi.org/10.3390/f15111865 - 24 Oct 2024

Abstract

The objective of this study was to investigate the colour stability of spruce wood surfaces treated with coating systems (CS) and exposed to accelerated ageing. The tested CSs were transparent and three-layered; the top layer was modified with ultraviolet (UV) absorbers, while the [...] Read more.

The objective of this study was to investigate the colour stability of spruce wood surfaces treated with coating systems (CS) and exposed to accelerated ageing. The tested CSs were transparent and three-layered; the top layer was modified with ultraviolet (UV) absorbers, while the base layer was modified with lignin stabiliser. Spruce wood surfaces treated with unmodified CSs were not colour-stable during the accelerated ageing process, with the surface exhibiting colour change after just 100 ageing hours. Adding specific UV absorbers into the top layer and lignin stabiliser into the base layer significantly improved the colour stability of the surface-treated wood. In all cases, however, the colour variation associated with ongoing ageing was significant. An additional study task was to determine whether the discolouration of surface-treated wood is caused by the discolouration of the wood substrate alone or also by the CS discolouration. Consequently, there was also the examination of discolouration of the individual coating materials or coating systems applied to glass slides. This testing proved that in the case of wood surface-treated with CS, without lignin stabiliser, the discolouration was the same as that of the substrate, and this was true throughout the whole ageing process. In the case of wood surface-treated with CS, but with lignin stabiliser, there were, in some cases, significant differences in discolouration between surface-treated wood and the wood substrate. These variations were especially evident during the initial 300 ageing hours. Full article

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

12 pages, 1949 KiB

Open AccessArticle

Response of Non-Structural Carbohydrates and Carbon, Nitrogen, and Phosphorus Stoichiometry in Pinus yunnanensis Seedlings to Drought Re-Watering

by Chengyao Liu, Junwen Wu, Jianyao Gu and Huaijiao Duan

Forests 2024, 15(11), 1864; https://doi.org/10.3390/f15111864 - 24 Oct 2024

Abstract

Pinus yunnanensis is an endemic tree species in southwest China that has high ecological and economic benefits. Nowadays, global climate change is remarkable, the frequency of drought is increasing day by day, the distribution of rainfall is unbalanced, and even the phenomenon of [...] Read more.

Pinus yunnanensis is an endemic tree species in southwest China that has high ecological and economic benefits. Nowadays, global climate change is remarkable, the frequency of drought is increasing day by day, the distribution of rainfall is unbalanced, and even the phenomenon of alternating drought and flood has appeared, which is unfavorable to the growth of P. yunnanensis. We set up four treatments, namely normal water (CK), light drought (LD), moderate drought (MD), and severe drought (SD), and water content was controlled by the weighing method. After continuous drought for 30 days, re-watering was performed for 7 days. The stoichiometric characteristics of non-structural carbohydrates (NSC), soluble sugars (SS), and starch (ST), as well as carbon (C), nitrogen (N), and phosphorus (P), in various organs of P. yunnanensis seedlings were measured. The results revealed significant effects of re-watering on NSC and its components in P. yunnanensis seedlings. The SS and NSC contents in the leaves of P. yunnanensis seedlings treated with SD were significantly higher than those of the control. The C content in the leaves and stems of P. yunnanensis seedlings recovered to the CK level after re-watering under different drought degrees. The contents of N in different organs and P in the fine roots of P. yunnanensis seedlings increased after re-watering with the LD, MD, and SD treatments, while the C/N ratio decreased. In summary, the recovery mechanism of P. yunnanensis seedlings to re-watering varied with the drought degree. The contents and ratios of NSC, C, N, and P in different organs of P. yunnanensis seedlings were significantly affected by re-watering. Combining the phenotypic plasticity index and PCA results, seedlings of P. yunnanensis adapted to drought re-watering by adjusting leaf NSC, leaf P, stem SS/ST, fine root ST, and fine root NSC. Full article

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

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19 pages, 58315 KiB

Open AccessArticle

The Distributional Range Changes of European Heterobasidion Under Future Climate Change

by Shen Shen, Xueli Zhang and Shengqi Jian

Forests 2024, 15(11), 1863; https://doi.org/10.3390/f15111863 - 24 Oct 2024

Abstract

Heterobasidion, a significant forest pathogen affecting coniferous forests in the Northern Hemisphere, can infect 27 species of coniferous trees, leading to widespread forest mortality. It has already caused considerable damage to both natural and plantation forests in Europe. As essential components of [...] Read more.

Heterobasidion, a significant forest pathogen affecting coniferous forests in the Northern Hemisphere, can infect 27 species of coniferous trees, leading to widespread forest mortality. It has already caused considerable damage to both natural and plantation forests in Europe. As essential components of the global ecosystem, forests are increasingly affected by ongoing environmental changes. The ability to accurately predict and effectively respond to pathogen outbreaks across different habitats is becoming increasingly critical. This study employs an optimized MaxEnt model in conjunction with six Global Climate Models (GCMs) to simulate and predict the potentially suitable distributions and changes of three Heterobasidion species in Europe (Heterobasidion abietinum, Heterobasidion annosum sensu stricto, Heterobasidion parviporum) under current conditions and four future climate scenarios (SSP126, SSP245, SSP370, and SSP585) for the period 2081–2100. The objective of this analysis is to assess the potential effects of climate change on the distribution of Heterobasidion species. The results indicate that the distributions of the three Heterobasidion species are influenced by factors such as temperature and precipitation. By 2081–2100, under most climate scenarios, except for the SSP585 scenario, the distribution areas of the three Heterobasidion species show an expansion trend. Notably, Heterobasidion abietinum showed the most significant expansion of its suitable habitat, while the expansion of low-suitability areas for Heterobasidion parviporum and Heterobasidion annosum sensu stricto was more pronounced. Heterobasidion abietinum is projected to shift southward due to factors such as precipitation, while Heterobasidion parviporum and Heterobasidion annosum sensu stricto are expected to migrate northward, influenced by factors such as temperature and host tree species. Full article

(This article belongs to the Section Forest Health)

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13 pages, 3335 KiB

Open AccessArticle

Effects of Woodland Conversion to Tea Plantations and Tea Planting Age on Soil Organic Carbon Accrual in Subtropical China

by Shun Zou, Chumin Huang, Tu Feng, Yang Chen, Xiaolong Bai, Wangjun Li and Bin He

Forests 2024, 15(11), 1862; https://doi.org/10.3390/f15111862 - 24 Oct 2024

Abstract

Tea (Camellia sinensis (L.) Kuntze) plantations have been rapidly expanding in recent years in developing countries, but there is a lack of knowledge about the effects of woodland conversion to tea plantations and tea plantation aging on soil organic carbon (SOC) accumulation [...] Read more.

Tea (Camellia sinensis (L.) Kuntze) plantations have been rapidly expanding in recent years in developing countries, but there is a lack of knowledge about the effects of woodland conversion to tea plantations and tea plantation aging on soil organic carbon (SOC) accumulation in subtropical regions, which may be a critical issue for accurately estimating the regional C balance in tea planting areas. Thus, in this study, we selected four tea plantations with ages ranging from 5 to 23 years, along with an adjacent mature pine forest (PF, more than 60 years of age), to investigate the effects of woodland conversion to tea plantations and stand age on SOC. Lignin phenols and amino sugars were used to distinguish the contributions of plant-derived C and microbial-derived C to SOC. The results showed that when PF is converted to a tea plantation, 54.12% of the SOC content in the topsoil is lost, with reductions of 84.77% in plant-derived C and 10.23% in microbial-derived C; however, there is a slight increase in microbial-derived C in the deep-layer soil. The tea planting age only has a negative effect on microbial-derived C in the topsoil. Additionally, the plant aboveground biomass, ratio of carbon to nitrogen, total nitrogen concentration, and clay–silt content are key environmental variables influencing SOC accrual, explaining 59.8% of the total variance. SOC and plant-derived C are thus implicated in the quick response to decreasing plant inputs with land conversion and do not accumulate with increasing tea plantation age under the current tea plantation management practices. Generally, more attention should be focused on SOC loss with woodland conversion to tea plantations at the regional scale, and more effective practices can be applied to enhance SOC accrual in subtropical tea plantations. Full article

(This article belongs to the Section Forest Soil)

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24 pages, 20172 KiB

Open AccessArticle

Estimation of Forest Above-Ground Biomass in the Study Area of Greater Khingan Ecological Station with Integration of Airborne LiDAR, Landsat 8 OLI, and Hyperspectral Remote Sensing Data

by Lu Wang, Yilin Ju, Yongjie Ji, Armando Marino, Wangfei Zhang and Qian Jing

Forests 2024, 15(11), 1861; https://doi.org/10.3390/f15111861 - 24 Oct 2024

Abstract

Accurate estimation of forest above-ground biomass (AGB) is significant for understanding changes in global carbon storage and addressing climate change. This study focuses on 53 samples of natural forests at the Greater Khingan Ecological Station, exploring the potential of integrating Canopy Height Model [...] Read more.

Accurate estimation of forest above-ground biomass (AGB) is significant for understanding changes in global carbon storage and addressing climate change. This study focuses on 53 samples of natural forests at the Greater Khingan Ecological Station, exploring the potential of integrating Canopy Height Model (CHM) with multi-source remote sensing (RS) data—airborne LiDAR, Landsat 8 OLI, and hyperspectral data to estimate forest AGB. Firstly, RS features with strong horizontal and vertical correlation with the forests AGB are optimized by a partial least squares algorithm (PLSR). Then, multivariate linear stepwise regression (MLSR) and K-nearest neighbor with fast iterative features selection (KNN-FIFS) are applied to estimate forest AGB using seven different data combinations. Finally, the leave-one-out cross-validation method is selected for the validation of the estimation results. The results are as follows: (1) When forest AGB is estimated using a single data source, the inversion results of using LiDAR are better, with R² = 0.76 and RMSE = 21.78 Mg/ha. (2) The estimation accuracy of two models showed obvious improvement after using fused CHM into RS information. The MLSR model showed the best performance, with R² increased by 0.41 and RMSE decreased to 14.15 Mg/ha. (3) The estimation results based on the KNN-FIFS model using the combined data of LiDAR, CHM + Landsat 8 OLI, and CHM + Hyperspectral imaging were the best in this study, with R² = 0.85 and RMSE = 18.17 Mg/ha. The results of the study show that fusing CHM into multi-spectral data and hyperspectral data can improve the estimation accuracy a lot; the forest AGB estimation accuracies of the multi-source RS data are better than the single data source. This study provides an effective method for estimating forest AGB using multi-source data integrated with CHM to improve estimation accuracy. Full article

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

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23 pages, 5405 KiB

Open AccessArticle

CPH-Fmnet: An Optimized Deep Learning Model for Multi-View Stereo and Parameter Extraction in Complex Forest Scenes

by Lingnan Dai, Zhao Chen, Xiaoli Zhang, Dianchang Wang and Lishuo Huo

Forests 2024, 15(11), 1860; https://doi.org/10.3390/f15111860 - 23 Oct 2024

Abstract

The three-dimensional reconstruction of forests is crucial in remote sensing technology, ecological monitoring, and forestry management, as it yields precise forest structure and tree parameters, providing essential data support for forest resource management, evaluation, and sustainable development. Nevertheless, forest 3D reconstruction now encounters [...] Read more.

The three-dimensional reconstruction of forests is crucial in remote sensing technology, ecological monitoring, and forestry management, as it yields precise forest structure and tree parameters, providing essential data support for forest resource management, evaluation, and sustainable development. Nevertheless, forest 3D reconstruction now encounters obstacles including higher equipment costs, reduced data collection efficiency, and complex data processing. This work introduces a unique deep learning model, CPH-Fmnet, designed to enhance the accuracy and efficiency of 3D reconstruction in intricate forest environments. CPH-Fmnet enhances the FPN Encoder-Decoder Architecture by meticulously incorporating the Channel Attention Mechanism (CA), Path Aggregation Module (PA), and High-Level Feature Selection Module (HFS), alongside the integration of the pre-trained Vision Transformer (ViT), thereby significantly improving the model’s global feature extraction and local detail reconstruction abilities. We selected three representative sample plots in Haidian District, Beijing, China, as the study area and took forest stand sequence photos with an iPhone for the research. Comparative experiments with the conventional SfM + MVS and MVSFormer models, along with comprehensive parameter extraction and ablation studies, substantiated the enhanced efficacy of the proposed CPH-Fmnet model in addressing difficult circumstances such as intricate occlusions, poorly textured areas, and variations in lighting. The test results show that the model does better on a number of evaluation criteria. It has an RMSE of 1.353, an MAE of only 5.1%, an r value of 1.190, and a forest reconstruction rate of 100%, all of which are better than current methods. Furthermore, the model produced a more compact and precise 3D point cloud while accurately determining the properties of the forest trees. The findings indicate that CPH-Fmnet offers an innovative approach for forest resource management and ecological monitoring, characterized by cheap cost, high accuracy, and high efficiency. Full article

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

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22 pages, 5931 KiB

Open AccessArticle

Thermal Comfort Simulation-Based Forest Management Scenarios for Forest Healing

by Doyun Song, Sujin Park, Yeonhee Lee and Geonwoo Kim

Forests 2024, 15(11), 1859; https://doi.org/10.3390/f15111859 - 23 Oct 2024

Abstract

Background and objectives: Forest environments provide various healing benefits for humans and have been widely studied. Nevertheless, the field of forest management for forest healing remains relatively understudied. The purpose of this study is to utilize thermal environmental simulation to derive forest management [...] Read more.

Background and objectives: Forest environments provide various healing benefits for humans and have been widely studied. Nevertheless, the field of forest management for forest healing remains relatively understudied. The purpose of this study is to utilize thermal environmental simulation to derive forest management scenarios that are optimized for forest healing. Methods: This study focused on the Seogwipo Experimental Forest on Jeju Island, Korea. Three-dimensional forest models were generated based on field surveys. Thermal environment simulations were conducted using Grasshopper with the Ladybug and Honeybee plug-ins, and the thermal comfort levels of six forest management scenarios were evaluated using the Universal Thermal Climate Index (UTCI). Results: The simulation results showed that, among all the scenarios, only scenario (c), “10% thinning in the buffer zone”, led to an improvement in thermal comfort. Additionally, the study identified discrepancies in thermal comfort between different forest management scenarios. Conclusions: In the management of forests for healing forestry purposes, the distinction of forest zones by use and the application of different forest management scenarios have thermal comfort implications. Thus, the methodology could be employed in forest management for forest healing purposes. Full article

(This article belongs to the Special Issue Advances and Future Prospects in Science-Based Forest Therapy)

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19 pages, 16218 KiB

Open AccessArticle

Research on Non-Destructive Testing of Log Knot Resistance Based on Improved Inverse-Distance-Weighted Interpolation Algorithm

by Fenglu Liu, Wenhao Chen, Qinhui Wang and Jiawei Xiao

Forests 2024, 15(11), 1858; https://doi.org/10.3390/f15111858 - 23 Oct 2024

Abstract

The objective of this paper is to propose a non-destructive resistance detection imaging algorithm for log knots based on improved inverse-distance-weighted interpolation algorithm, i.e., the eccentric circle-based inverse-distance-weighted (ECIDW) method, to predict the size, shape, and position of internal knots of logs; evaluate [...] Read more.

The objective of this paper is to propose a non-destructive resistance detection imaging algorithm for log knots based on improved inverse-distance-weighted interpolation algorithm, i.e., the eccentric circle-based inverse-distance-weighted (ECIDW) method, to predict the size, shape, and position of internal knots of logs; evaluate its precision and accuracy; and both lay a theoretical foundation and provide a scientific basis for predicting and assessing knots in standing trees. Six sample logs with natural knots were selected for this study. Resistance measurements were performed on the log cross-sections using a digital bridge, and resistance tomography was conducted using the improved ECIDW algorithm, which combines the azimuth search method with the eccentric circle search method. The results indicated that both the conventional inverse-distance-weighted (IDW) algorithm and the ECIDW algorithm accurately predicted the positions of the knots. However, neither algorithm was able to predict the shape of the knots with high precision, leading to some discrepancies between the predicted and actual knot shapes. The relative error (

D t_{1}

) between the knot areas measured by the IDW algorithm and the actual knot areas ranged from 18.97% to 88.34%. The relative error (

D t_{2}

) for the knot areas predicted by the ECIDW algorithm ranged from 1.82% to 74.16%. The average prediction accuracy for the knot areas using the IDW algorithm was 51.58%, compared to 72.90% using the ECIDW algorithm. This indicates that the ECIDW algorithm has higher accuracy in predicting knot areas compared to the conventional IDW algorithm. The ECIDW algorithm proposed in this paper provides a more reasonable and accurate prediction and evaluation of knots inside logs. Compared to the conventional IDW algorithm, the ECIDW algorithm demonstrates greater precision and accuracy in predicting the shape and size of knots. While the resistance method shows significant potential for predicting internal knots in logs and standing trees, further improvements to the algorithm were needed to enhance the imaging effects and the precision and accuracy of knot area and shape predictions. 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, 19262 KiB

Open AccessArticle

Study on the Driving Factors of the Spatiotemporal Pattern in Forest Lightning Fires and 3D Fire Simulation Based on Cellular Automata

by Maolin Li, Yingda Wu, Yilin Liu, Yu Zhang and Qiang Yu

Forests 2024, 15(11), 1857; https://doi.org/10.3390/f15111857 - 23 Oct 2024

Abstract

Lightning-induced forest fires frequently inflict substantial damage on forest ecosystems, with the Daxing’anling region in northern China recognized as a high-incidence region for such phenomena. To elucidate the occurrence patterns of forest fires caused by lightning and to prevent such fires, this study [...] Read more.

Lightning-induced forest fires frequently inflict substantial damage on forest ecosystems, with the Daxing’anling region in northern China recognized as a high-incidence region for such phenomena. To elucidate the occurrence patterns of forest fires caused by lightning and to prevent such fires, this study employs a multifaceted approach, including statistical analysis, kernel density estimation, and spatial autocorrelation analysis, to conduct a comprehensive examination of the spatiotemporal distribution patterns of lightning-induced forest fires in the Greater Khingan Mountains region from 2016–2020. Additionally, the geographical detector method is utilized to assess the explanatory power of three main factors: climate, topography, and fuel characteristics associated with these fires, encompassing both univariate and interaction detections. Furthermore, a mixed-methods approach is adopted, integrating the Zhengfei Wang model with a three-dimensional cellular automaton to simulate the spread of lightning-induced forest fire events, which is further validated through rigorous quantitative verification. The principal findings are as follows: (1) Spatiotemporal Distribution of Lightning-Induced Forest Fires: Interannual variability reveals pronounced fluctuations in the incidence of lightning-induced forest fires. The monthly concentration of incidents is most significant in May, July, and August, demonstrating an upward trajectory. In terms of temporal distribution, fire occurrences are predominantly concentrated between 1:00 PM and 5:00 PM, conforming to a normal distribution pattern. Spatially, higher incidences of fires are observed in the western and northwestern regions, while the eastern and southeastern areas exhibit reduced rates. At the township level, significant spatial autocorrelation indicates that Xing’an Town represents a prominent hotspot (p = 0.001), whereas Oupu Town is identified as a significant cold spot (p = 0.05). (2) Determinants of the Spatiotemporal Distribution of Lightning-Induced Forest Fires: The spatiotemporal distribution of lightning-induced forest fires is influenced by a multitude of factors. Univariate analysis reveals that the explanatory power of these factors varies significantly, with climatic factors exerting the most substantial influence, followed by topographic and fuel characteristics. Interaction factor analysis indicates that the interactive effects of climatic variables are notably more pronounced than those of fuel and topographical factors. (3) Three-Dimensional Cellular Automaton Fire Simulation Based on the Zhengfei Wang Model: This investigation integrates the fire spread principles from the Zhengfei Wang model into a three-dimensional cellular automaton framework to simulate the dynamic behavior of lightning-induced forest fires. Through quantitative validation against empirical fire events, the model demonstrates an accuracy rate of 83.54% in forecasting the affected fire zones. Full article

(This article belongs to the Special Issue Forest Fires Prediction and Detection—2nd Edition)

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25 pages, 2897 KiB

Open AccessArticle

Comparison of Nature Tourism in Two Hungarian Forest-Dominated Areas—Results of Visitor Surveys

by Alexandra Ferencz-Havel, Dénes Saláta, György Orosz, Gergely Halász and Eszter Tormáné Kovács

Forests 2024, 15(11), 1856; https://doi.org/10.3390/f15111856 - 23 Oct 2024

Abstract

Recreation and nature-based tourism targeting forests are important cultural services provided by forests, and are also considered non-productive social functions of forests. Many factors influence the demand for forest recreation and tourism that are worth exploring for each forest area. The main aim [...] Read more.

Recreation and nature-based tourism targeting forests are important cultural services provided by forests, and are also considered non-productive social functions of forests. Many factors influence the demand for forest recreation and tourism that are worth exploring for each forest area. The main aim of our study was to compare the results of visitor surveys related to two mountainous forested areas (Börzsöny and Cserhát) that are both located near to the capital city of Budapest but have different characteristics regarding the forests, accessibility, and the level of tourism infrastructure and services. The questionnaires focused on the characteristics of the visits, perceptions of visitors regarding the values of the areas, and the development needs besides the characteristics of the respondents. In addition to basic statistics, Chi² and Fisher’s exact tests were used to detect the differences between the two sites. Despite the different characteristics of the study areas, the main results were quite similar at both sites. Most respondents came from Budapest or within a 60 km distance of the sites by car with family and friends, mainly for hiking and nature walks, and spent less than a day in the areas. The state of forests was perceived as good in both areas. Landscape and fresh air were the most attracting factors for visiting both sites. There was a demand for more guided tours, and regarding tourism infrastructure development needs, benches and toilets ranked high at both sites. However, there were also some slight differences between the sites. For example, Börzsöny was visited more frequently, and railway and bicycle were more often used to access this site. Pleasant climate, easy access and fresh air were more important reasons to visit Börzsöny, and it was more associated with wilderness. In Cserhát, low prices and cultural values seemed more important reasons to visit; Hollókő as a world heritage site was highlighted, and more nature-related and other tourism development needs were mentioned regarding this site. These differences were probably due to the different characteristics of the forests (more mosaic forests in Cserhát), the level of the public transportation network, tourist infrastructure and services (higher in Börzsöny), and cultural heritage (more important in Cserhát). Based on our results, Cserhát needs more development in tourism infrastructure and services, while in Börzsöny, the development of a visitor management plan would be useful to harmonize the different uses of the forest. Full article

(This article belongs to the Section Urban Forestry)

14 pages, 1538 KiB

Open AccessArticle

Effect of Sodium Selenite Foliar Treatment on the Nutritional Quality of Cyclocarya paliurus (Batalin) Iljinsk

by Xiaoling Chen, Yulan Dong, Zijue Wang, Qinghui Xia, Xingxing Dong, Shaopeng Zhang and Shuiyuan Cheng

Forests 2024, 15(11), 1855; https://doi.org/10.3390/f15111855 - 23 Oct 2024

Abstract

Cyclocarya paliurus (Batalin) Iljinskaja is a rare, endemic tree species in China. The leaves of C. paliurus contain a high concentration of biologically active compounds, and they are often used to make herbal tea. Exogenous selenium (Se) enrichment can promote the levels of [...] Read more.

Cyclocarya paliurus (Batalin) Iljinskaja is a rare, endemic tree species in China. The leaves of C. paliurus contain a high concentration of biologically active compounds, and they are often used to make herbal tea. Exogenous selenium (Se) enrichment can promote the levels of active ingredients in C. paliurus. To explore the effects of exogenous Se enrichment, this study applied different concentrations of sodium selenite solution on the leaves (0, 40, 80, 120, 160, and 300 mg/L) and measured the changes in Se, secondary metabolites, soluble sugar, soluble protein, starch, and trace elements in the leaves at different treatment times. The results showed that with the increase in the concentration of sodium selenite spray, the selenium content in the leaves of C. paliurus gradually increased, and high selenium concentrations could cause seedling burning to the leaf surface (>160 mg/kg). When the selenium treatment concentration was 80 mg/kg, the selenium content reached the maximum value of the selenium-rich tea standard (4 mg/kg). The content of polyphenols and most elements reached their maxima under the treatment of 40 mg/L Na₂SeO₃, except for Mg and Mn, which peaked at 300 mg/L. The content of soluble sugars (38.1 mg/g) and starch reached their maxima under relatively high selenium treatment concentrations, whereas soluble protein (10.63 mg/g) exhibited its maximum value in the control group. The optimal harvest time was mainly concentrated in the 10–20 day treatment period. The objective of this research is to investigate the effects of exogenous selenium application on the nutritional quality of C. paliurus leaves. The findings will provide guidance for the effective cultivation of selenium-enriched Poria cocos as a medicinal and health-promoting product. Full article

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

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10 pages, 2838 KiB

Open AccessArticle

Robinia pseudoacacia Quickly Adjusts Its Water Uptake After Rainfall in Seasonally Dry Regions

by Zhewei Hu, Caiyi Zhao, Wenbing Ji, Rongrong Ying, Xiaoyu Zhang and Shu Jin

Forests 2024, 15(11), 1854; https://doi.org/10.3390/f15111854 - 23 Oct 2024

Abstract

Precipitation is a key factor affecting plant growth and development in seasonally arid regions. However, most of the traditional hydrological methods mainly select typically sunny days for sampling, and the immediate water absorption strategy of plants during and after rainfall is still unclear. [...] Read more.

Precipitation is a key factor affecting plant growth and development in seasonally arid regions. However, most of the traditional hydrological methods mainly select typically sunny days for sampling, and the immediate water absorption strategy of plants during and after rainfall is still unclear. This study used stable hydrogen and oxygen isotope technology to study the soil moisture absorption rates of Robinia pseudoacacia and the soil moisture content at different soil layers at different sampling times (0, 6, 12, 18 and 24 h) after rainfall. The results showed that the moisture content of the shallow soil layer decreased, while that of the deep soil layer increased over time after rainfall. R. pseudoacacia mainly utilized water from the 0–20 and 20–40 cm soil layers at 6 h after rainfall, which accounted for 36.52% and 22.25% of the rainfall, respectively. At 24 h, the 40–60, 60–80 and 80–100 cm soil layers contributed 25.25%, 18.44% and 24.45% of the water content, respectively. The shallow soil layer retained more rainfall within 6 h after rain fell, and the water retention ratio of the medium–shallow soil layer (0–60 cm) increased to 48.4%, retaining more water at 14–20 h. At 12 h, the medium–shallow soil layer (0–60 cm), runoff and groundwater constituted 37.1%, 14.4% and 15.7% of the precipitation, respectively, and rainfall retained in the deep soil layer (60–100 cm) accounted for 32.8%. In summary, R. pseudoacacia tends to use a large amount of shallow soil water in seasonally arid regions when precipitation supplements the surface soil moisture content and it utilizes deep soil water when the rainfall infiltrates and recharges the deep soil layer. Since R. pseudoacacia is sensitive to precipitation, it can quickly adjust its water absorption depth range during the short-term rainfall period to absorb as much precipitation as possible. Full article

(This article belongs to the Special Issue Advances in Forest Carbon, Water Use and Growth Under Climate Change)

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Forests, Volume 15, Issue 11 (November 2024) – 45 articles

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