Forests

18 pages, 4531 KiB

Open AccessArticle

Does Forest Contemplation Provide Greater Psychological Benefits than Passive Exposure to the Urban Forest? A Pilot Study

by Emilia Janeczko, Małgorzata Woźnicka, Katarzyna Śmietańska, Anna Wiśniewska, Natalia Korcz and Agata Kobyłka

Forests 2024, 15(8), 1411; https://doi.org/10.3390/f15081411 (registering DOI) - 12 Aug 2024

Abstract

Human contact with the natural environment effectively counteracts negative symptoms of stress and has many positive psychological effects. For this reason, forests within city limits are increasingly seen as part of public health promotion. Being in an urban forest can take many forms, [...] Read more.

Human contact with the natural environment effectively counteracts negative symptoms of stress and has many positive psychological effects. For this reason, forests within city limits are increasingly seen as part of public health promotion. Being in an urban forest can take many forms, but there is still little known about whether being in a forest alone, without engaging one’s senses, is as effective for human renewal as an experience that involves greater, more conscious activation of the senses of sight, hearing, smell. A study measuring the effect of the forest (spring aspect) on human mental relaxation during passive exposure was conducted on a sample of 19 Polish young adults. The experiment consisted of two series. In the first, participants read an academic textbook in a tree stand for 20 min, while in the next session—conducted at the same location—they contemplated the landscape. Before the experiment and after each of the two series of tests, four psychological questionnaires were administered: the Profile of Mood State (POMS), Positive and Negative Affect Schedule (PANAS), the Restorative Outcome Scale (ROS) and the Subjective Vitality Scale (SVS). Analyses showed that being in a forest environment positively influenced the subjects’ mental relaxation, while the level of benefit from the activation of the senses, especially vision (looking at the forest) was significantly higher compared to the passive activity of reading a text. The research indicates that forest bathing is the best form of relaxation that can be obtained through contact with the forest. Full article

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

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21 pages, 13582 KiB

Open AccessArticle

Fabrication of Silica–Titanium Composite Film on Wood Surface and Optimization of Its Structure and Properties

by Zhigao Liu, Qianying Li, Si Cheng, Penglian Wei and Yunlin Fu

Forests 2024, 15(8), 1410; https://doi.org/10.3390/f15081410 (registering DOI) - 12 Aug 2024

Abstract

In this thesis, wood loaded with a silica–titanium (Si-Ti) composite film was prepared using the sol–gel method in order to achieve improved wood with high hydrophobicity and photocatalytic activity under visible light. The factors affecting the structure and properties of the composite film, [...] Read more.

In this thesis, wood loaded with a silica–titanium (Si-Ti) composite film was prepared using the sol–gel method in order to achieve improved wood with high hydrophobicity and photocatalytic activity under visible light. The factors affecting the structure and properties of the composite film, as well as the optimization process, were discussed. Infrared analysis revealed that the vibrational intensity of Si-O-Si, Ti-O-Ti, and Ti-O-Si telescopic vibration peaks increased with an increase in vinyltriethoxysilane (VETS). Additionally, the number of Ti-O-Ti telescopic vibration peaks also increased with an increase in VETS. Furthermore, the intensity of -NO₃, Si-O-Si, and Ti-O-Ti telescopic vibrational peaks was enhanced with a higher dosage of nitric acid. Conversely, the intensity of -OH telescopic vibrational peaks decreased with an increase in drying temperature. XRD analysis showed that nitric acid could promote the transformation of TiO₂ from amorphous to anatase, while SiO₂ would reduce the grain size of anatase TiO₂ and promote the growth of rutile TiO₂. Additionally, wood surfaces loaded with Si-Ti composite film changed from hydrophilic to hydrophobic, with significant differences observed between different levels of each factor. The photocatalytic activity of surface-loaded Si-Ti composite films on wood was most affected by the amount of nitric acid, which influenced crystallinity of TiO₂ and thus impacted the photocatalytic activity. Furthermore, changes in VTES dosage not only affected the crystalline phase of TiO₂ and the grain size of Si-Ti composite film but also influenced the crystallinity of TiO₂ through generating SiO₂. Finally, based on optimal preparation process (titanium–alcohol ratio of 1:5, titanium–silicon ratio of 1:0.2, titanium–acid ratio of 1:0.5, and drying temperature of 100 °C), wood surfaces loaded with Si-Ti composite film achieved a contact angle up to 125.9° and exhibited a decolorization rate for rhodamine B under UV light reaching 94% within 180 min. Full article

(This article belongs to the Special Issue Wood Anatomy and Evaluation of Wood Structures and Their Modifications—2nd Edition)

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32 pages, 49926 KiB

Open AccessArticle

What Are the Variation Patterns of Vegetation and Its Influencing Factors in China from 2000–2020 from the Partition Perspective?

by Bing Guo, Mei Xu, Rui Zhang, Wei Luo and Jicun Yang

Forests 2024, 15(8), 1409; https://doi.org/10.3390/f15081409 (registering DOI) - 11 Aug 2024

Abstract

China’s vegetation ecosystem has undergone profound changes, and there is an urgent need to explore the mechanisms behind vegetation changes in different ecological sub-regions and historical periods across China. Based on NDVI (normalized difference vegetation index) data, this study analyzed the spatial and [...] Read more.

China’s vegetation ecosystem has undergone profound changes, and there is an urgent need to explore the mechanisms behind vegetation changes in different ecological sub-regions and historical periods across China. Based on NDVI (normalized difference vegetation index) data, this study analyzed the spatial and temporal evolution patterns and driving mechanisms of six ecological sub-regions in China. The results showed that: (1) over the past 20 years, the vegetation coverage in mainland China showed a decreasing trend from east to west. (2) Over the past 20 years, the vegetation coverage of the six ecological sub-regions showed an increasing trend, with the highest increase in Central Southern China (0.0039) and the lowest increase in East China (0.002). (3) The gravity center of Northeast China showed a trend of migration to the northwest. The gravity center of North China, East China, and Central South China showed a trend of migration to the southwest, while that of Northwest and Southwest China showed a trend of migration to the southeast. (4) During the period from 2000 to 2020, vegetation cover levels showed an upward trend. (5) The lag time of vegetation types in different regions was different. (6) Precipitation was the dominant influencing factor in the evolution of vegetation in Northeast China, North China, Northwest China, and Southwest China. The dominant influencing factors of vegetation evolution in East China were land use and GDP (gross domestic product), while the dominant influencing factors of vegetation evolution in Central South China were precipitation and land use. Full article

(This article belongs to the Special Issue Monitoring Forest Change Dynamic with Remote Sensing)

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21 pages, 5648 KiB

Open AccessArticle

Photosynthesis and Latex Burst Characteristics in Different Varieties of Rubber Trees (Hevea brasiliensis) under Chilling Stress, Combing Bark Tensile Property and Chemical Component Analysis

by Linlin Cheng, Huichuan Jiang, Guishui Xie, Jikun Wang, Wentao Peng, Lijun Zhou and Feng An

Forests 2024, 15(8), 1408; https://doi.org/10.3390/f15081408 (registering DOI) - 11 Aug 2024

Abstract

Rubber trees (Hevea brasiliensis) serve as the primary source of natural rubber. Their native habitat is characterized by warm and humid conditions, so they are particularly sensitive to low temperatures. Under such stress, latex burst can cause severe damage to rubber [...] Read more.

Rubber trees (Hevea brasiliensis) serve as the primary source of natural rubber. Their native habitat is characterized by warm and humid conditions, so they are particularly sensitive to low temperatures. Under such stress, latex burst can cause severe damage to rubber trees, which is due to the uniqueness of their economically productive parts. In order to establish a correlation between young and mature rubber trees and provide a novel prospective for investigating the mechanisms of latex burst and chilling resistance in rubber trees, the chlorophyll contents, photosynthesis, and chlorophyll fluorescence parameters in four varieties of one-year-old rubber tree seedlings were analyzed under artificially simulated chilling stress. The latex burst characteristics were subsequently recorded. A comprehensive statistical analysis of the chilling-resistance rank was conducted using the membership function method and the combination weighting method. Meanwhile, chemical compositions and tensile properties of barks from two-year-old twigs of mature rubber trees were ascertained. A correlation analysis between chilling resistance, chemical compositions, and tensile properties was performed to identify any interrelationships among them. The results showed that the number and the total area of latex-burst positions in variety Reken628 seedlings were greater than those in other varieties, and the lowest number and total area of latex-burst positions were observed in variety RRIM600 and variety PR107, respectively. With the exception of variety GT1, nectar secretion was noted in all other varieties of rubber tree seedlings under chilling stress. The chilling resistance of the four varieties decreased in the following order: variety GT1 > variety RRIM600 > variety PR107 > variety Reken628. The chilling resistance was strongly (p < 0.001) negatively correlated with cellulose content and acid-insoluble lignin content, respectively. The total area of latex burst was significantly (p < 0.001) and positively correlated with holocellulose content and maximum load, respectively. Furthermore, this study also provides new insights into the mechanism of nectar secretion induced by low temperatures and its association with the chilling resistance of rubber trees. Full article

(This article belongs to the Special Issue Stress Resistance of Rubber Trees: From Genetics to Ecosystem, 2nd Edition)

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Changes in photosynthetic pigment contents in rubber tree leaves under chilling stress. (A) Chlorophyll a content. (B) Chlorophyll b content. (C) Total chlorophyll content. (D) Carotenoid content. The data represent the average of three replicates. Bars show standard errors. Different lowercase letters represent significant differences (Duncan’s test of one-way ANOVA, p < 0.05) among different varieties of rubber trees. Full article ">Figure 2
Effect of chilling stress on the chlorophyll fluorescence parameters of rubber tree leaves. (A) The maximum photochemical efficiency of PSII, Fv/Fm. (B) The actual photochemical yield of PSII, ΦPSII. Data are means ± SEs (n = 3). Different lowercase letters represent significant differences (Duncan’s test of one-way ANOVA, p < 0.05) among different rubber tree varieties. Full article ">Figure 3
Effect of chilling stress on gas exchange parameters. (A) Photosynthetic rate is denoted as Pn. (B) Stomatal conductance is denoted as Gs. (C) Intercellular CO2 concentration is denoted as Ci. (D) Transpiration rate is denoted as Tr. Different lowercase letters represent significant differences (Duncan’s test of one-way ANOVA, p < 0.05) among different rubber tree varieties. Full article ">Figure 4
Visual latex burst in different rubber tree seedlings. (A-1–A-3) Variety PR107 seedlings. (B-1–B-4) Variety RRIM600 seedlings. (C-1–C-4) Variety Reken628 seedlings. (D-1–D-3) Variety GT1 seedlings. Full article ">Figure 5
Stress–strain curves for barks of two-year-old twigs in different varieties. Different colors represent different stress–strain curves of different specimens, respectively. (A) Variety PR107. (B) Variety RRIM600. (C) Variety Reken628. (D) Variety GT1. Full article ">Figure 6
Correlation analysis between latex burst in seedlings exposed to chilling stress, bark tensile properties, and chemical components with the chilling resistance of different varieties of rubber trees. CR, chilling resistance; TALB, total area of latex burst; TLBP, total latex burst positions; BT, bark thickness; ML, maximum load; TS, tensile strength; DBP, displacement at break point; EBP, elongation at break point; YM, Young’s modulus; PC, pectin content; CC, cellulose content; AILC, acid-insoluble lignin content; HOC, holocellulose content. The larger the circle and the darker the color, the larger the correlation coefficient. Positive correlations are exhibited in red and negative correlations in blue. Significant differences are marked by asterisks, with the levels of significance indicated as follows: *** p < 0.001. Full article ">

16 pages, 15433 KiB

Open AccessArticle

Identifying Even- and Uneven-Aged Forest Stands Using Low-Resolution Nationwide Lidar Data

by Anže Martin Pintar and Mitja Skudnik

Forests 2024, 15(8), 1407; https://doi.org/10.3390/f15081407 (registering DOI) - 11 Aug 2024

Abstract

In uneven-aged forests, trees of different diameters, heights, and ages are located in a small area, which is due to the felling of individual trees or groups of trees, as well as small-scale natural disturbances. In this article, we present an objective method [...] Read more.

In uneven-aged forests, trees of different diameters, heights, and ages are located in a small area, which is due to the felling of individual trees or groups of trees, as well as small-scale natural disturbances. In this article, we present an objective method for classifying forest stands into even- and uneven-aged stands based on freely available low-resolution (with an average recording density of 5 points/m²) national lidar data. The canopy closure, dominant height, and canopy height diversity from the canopy height model and the voxels derived from lidar data were used to classify the forest stands. Both approaches for determining forest structural diversity (canopy height diversity—CHD_CHM and CHD_V) yielded similar results, namely two clusters of even- and uneven-aged stands, although the differences in vertical diversity between even- and uneven-aged stands were greater when using CHM. The first analysis, using CHM for the CHD assessment, estimated the uneven-aged forest area as 49.3%, whereas the second analysis using voxels estimated it as 34.3%. We concluded that in areas with low laser scanner density, CHM analysis is a more appropriate method for assessing forest stand height heterogeneity. The advantage of detecting uneven-aged structures with voxels is that we were able to detect shade-tolerant species of varying age classes beneath a dense canopy of mature, dominant trees. The CHD_CHM values were estimated to be 1.83 and 1.86 for uneven-aged forests, whereas they were 1.57 and 1.58 for mature even-aged forests. The CHD_V values were estimated as 1.50 and 1.62 for uneven-aged forests, while they were 1.33 and 1.48 for mature even-aged forests. The classification of stands based on lidar data was validated with data from measurements on permanent sample plots. Statistically significantly lower average values of the homogeneity index and higher values of the Shannon–Wiener index from field measurements confirm the success of the classification of stands based on lidar data as uneven-aged forests. Full article

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

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17 pages, 2569 KiB

Open AccessArticle

Easement Reform and Employment Transfer of Forest Farmers: Evidence from China’s National Parks

by Qiang Liu, Xinyu Jin, Lanying Li and Qianqian Xu

Forests 2024, 15(8), 1406; https://doi.org/10.3390/f15081406 (registering DOI) - 11 Aug 2024

Abstract

The easement reform of collective forest land (ERCFL) is an important part of national park system construction, which plays an important role in promoting the employment transfer of forest farmers. On the basis of survey data from forest farmers in Qianjiangyuan–Baishanzu National Park [...] Read more.

The easement reform of collective forest land (ERCFL) is an important part of national park system construction, which plays an important role in promoting the employment transfer of forest farmers. On the basis of survey data from forest farmers in Qianjiangyuan–Baishanzu National Park in Zhejiang Province, this paper uses the propensity score matching-difference in differences model to empirically analyze the impact of ERCFL on the transfer employment behavior and employment quality of forest farmers to provide experience for promoting the employment transfer of forest farmers and improving the ERCFL in national parks. This research shows the following: (1) The ERCFL in national parks has significantly promoted the employment transfer and improved the employment quality of forest farmers. This effect remains significant when controlling for possible endogeneity issues. (2) Three mechanisms of the ERCFL affect forest farmers’ transfer of employment, namely improving non-agricultural employment skills, expanding the scope of non-agricultural employment, and increasing non-agricultural employment opportunities. (3) Significant gender, age, and education differences exist in terms of the impact of the ERCFL on the employment transfer of forest farmers. The impact on men, middle-aged and elderly groups, and low-education groups is more significant. Finally, this paper proposed forward countermeasures and suggestions to promote the employment transfer of forest farmers. Full article

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

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23 pages, 6757 KiB

Open AccessArticle

Function of the NAC1 Gene from Fraxinus mandshurica in Cold Resistance and Growth Promotion in Tobacco

by Yang Cao, Liming He, Shengdian Lu, Yuling Wang, Chenxi Zhang and Yaguang Zhan

Forests 2024, 15(8), 1405; https://doi.org/10.3390/f15081405 (registering DOI) - 10 Aug 2024

Abstract

To elucidate the function of the cold-resistance regulatory gene FmNAC1 from Fraxinus mandshurica Rupr., this study identified the role that overexpression of the FmNAC1 gene plays in tobacco growth and cold-stress regulation. The cloned FmNAC1 gene from F. mandshurica is 891 bp [...] Read more.

To elucidate the function of the cold-resistance regulatory gene FmNAC1 from Fraxinus mandshurica Rupr., this study identified the role that overexpression of the FmNAC1 gene plays in tobacco growth and cold-stress regulation. The cloned FmNAC1 gene from F. mandshurica is 891 bp in length and encodes 296 amino acids. Our subcellular localization analysis confirmed that FmNAC1 is primarily located in the nucleus and functions as a transcription factor. FmNAC1 is responsive to cold and NaCl stress, as well as to the induction of IAA, GA, and ABA hormone signals. To further elucidate its function in cold resistance, four transgenic tobacco lines expressing FmNAC1 (FmNAC1-OE) were generated through tissue culture after the Agrobacterium-mediated transformation of wild-type (WT) Nicotiana tabacum L.. These FmNAC1-OE plants exhibited accelerated growth after transplantation. When exposed to low-temperature conditions at −5 °C for 24 h, the rates of wilting and yellowing of the FmNAC1-OE plants were significantly lower than those of the WT tobacco plants. Additionally, the membrane integrity, osmotic regulation, and reactive oxygen species (ROS)-scavenging abilities of the FmNAC1-OE tobacco lines were better than those of the WT plants, indicating the potential of the FmNAC1 gene to improve plant cold resistance. The gene expression results further revealed that the FmNAC1 transcription factor exhibits regulatory interactions with growth-related genes such as IAA and AUX1; cold-resistance-related genes such as ICE, DREB, and CBF1; and genes involved in the clearance of reactive oxygen species (ROS), such as CAT and SOD. All of this evidence shows that the FmNAC1 transcription factor from F. mandshurica plays a key role in contributing to the enhancement of growth, cold resistance, and ROS clearance in transgenic tobacco plants. Full article

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

16 pages, 3386 KiB

Open AccessArticle

Effects of Tree Leaf Color on Human Physical and Mental Recovery from a Looking-Up Perspective

by Yuheng You, Saixin Cao, Nian Li, Bingyang Lv, Kai Li, Ping Zhang, Yilin Zhang, Jun Cai and Xi Li

Forests 2024, 15(8), 1404; https://doi.org/10.3390/f15081404 (registering DOI) - 10 Aug 2024

Abstract

Numerous studies have demonstrated the benefits of understory spaces and plants on human well-being, but most spatial research has focused on a horizontal perspective. Additionally, there is a lack of research on the effects of plant color on human recovery, especially with respect [...] Read more.

Numerous studies have demonstrated the benefits of understory spaces and plants on human well-being, but most spatial research has focused on a horizontal perspective. Additionally, there is a lack of research on the effects of plant color on human recovery, especially with respect to color proportions. This study classifies the leaf colors of trees in autumn, which are observed from a looking-up perspective, into green, red, and yellow. On this basis, we created monochromatic, two-color, and three-color groups with varying color proportions to assess their recovery effects and preferences. A total of 30 participants participated in this experiment, and their physiological, psychological, and preference-related indicators were evaluated. The results revealed that the following. (1) The two-color groups had the greatest reduction effect on systolic blood pressure. Monochromatic groups were most effective at reducing diastolic blood pressure. The three-color groups had the greatest effect on lowering the pulse rate. (2) EEG responses varied by color type. (3) The three-color groups had the best recovery effects on the psychological measures. (4) The three-color groups were most favored by participants, with a red–yellow–green ratio of 0.2/0.4/0.4 being the most preferred. These findings demonstrate the differing recovery potentials of various leaf color proportions from a looking-up perspective. This study can provide valuable references for the planning and design of urban forest parks, supplementing the theoretical foundation and research framework for evaluating and creating environments that meet people’s restorative needs. Full article

(This article belongs to the Special Issue Forests and Human Health: Effects on Acute and Chronic Illness, and Public Health)

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Leaf colors and corresponding color proportions from an upward view. Full article ">Figure 2
Experimental procedure diagram. Full article ">Figure 3
Changes in PANAS scores before and after participants viewed the three color types. PA: positive affect; NA: negative affect. N = 30; ** p < 0.01. Full article ">Figure 4
Changes in blood pressure and pulse before and after participants viewed the three color. types. n = 30; mean ± SD; ** p < 0.01, *** p < 0.001; verified via paired t-tests. Full article ">Figure 5
Changes in theta, delta, high beta, low beta, high alpha, low alpha, middle gamma, and low-gamma data of participants viewing the three color types. n = 30; ** p < 0.01, *** p < 0.001. G1: single-color group, G2: two-color group, G3: three-color group. Full article ">Figure 6
Changes in the theta/H-beta, theta/L-beta, H-beta/H-alpha, and L-beta/L-alpha data of. participants viewing the three color types. n = 30; * p < 0.05, ** p < 0.01, *** p < 0.001. G1: single-color group, G2: two-color group, G3: three-color group. Full article ">

20 pages, 12372 KiB

Open AccessArticle

Influence of Anatomical Spatial Architecture of Pinus devoniana on Pressure Gradients Inferred from Coupling Three-Dimensional CT Imaging and Numerical Flow Simulations

by Juan Gabriel Rivera-Ramos, José Cruz de León, Dante Arteaga, Raúl Espinoza-Herrera, Erica Arreola García, Manuel Arroyo-Albiter and Luis Olmos

Forests 2024, 15(8), 1403; https://doi.org/10.3390/f15081403 (registering DOI) - 10 Aug 2024

Abstract

Conifer forests in Michoacán are facing climate change. Pinus devoniana Lindley, with natural distribution in the state, has shown certain adaptability, and knowing the influence of anatomy in the flow system is essential to delimit how it contributes to safety margins and water [...] Read more.

Conifer forests in Michoacán are facing climate change. Pinus devoniana Lindley, with natural distribution in the state, has shown certain adaptability, and knowing the influence of anatomy in the flow system is essential to delimit how it contributes to safety margins and water efficiency. For this, the pressure gradients in the cell lumens and their ramifications were analyzed by numerical simulations of flow throughout the real microstructure. Xylem were evaluated in radial, tangential and longitudinal directions. With the skeletonization of lumens and their constrictions, a branching system of interconnection between tracheids, ray cells, intercellular chambers, extensions, and blind pits were identified. In the simulation, the branched system bypasses the longitudinal fluid passage through the pores in membranes of pairs of pits to redirect it through the direct path branching, contributing to safety margins and water efficiency. Thus, resilience at low pressures because of the lower pressure drop in the extensions. The interface between the branching system and the cell lumens are sites of higher pressure gradient, more conducive to water-vapor formation or air leakage in the face of the lowest pressure system. The flow lines move along easy paths, regardless of the simulated flow direction. Deposits in the cell extensions were shown to be attached to the S3 layer of the cell wall, leaving the center of the duct free to flow. It is concluded that the spatial architecture of the xylem anatomy of Pinus dvoniana is a factor in the resilience at low pressures due to high water stress of the species. Full article

(This article belongs to the Special Issue Wood Anatomy and Evaluation of Wood Structures and Their Modifications—2nd Edition)

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13 pages, 5416 KiB

Open AccessArticle

Tree-Ring Chronologies from the Upper Treeline in the Russian Altai Mountains Reveal Strong and Stable Summer Temperature Signals

by Alexander V. Kirdyanov, Alberto Arzac, Alina A. Kirdyanova, Tito Arosio, Dmitriy V. Ovchinnikov, Dmitry A. Ganyushkin, Paul N. Katjutin, Vladimir S. Myglan, Andrey N. Nazarov, Igor Y. Slyusarenko, Tatiana Bebchuk and Ulf Büntgen

Forests 2024, 15(8), 1402; https://doi.org/10.3390/f15081402 (registering DOI) - 10 Aug 2024

Abstract

Radial tree growth at high-elevation and high-latitude sites is predominantly controlled by changes in summer temperature. This relationship is, however, expected to weaken under projected global warming, which questions the reliability of tree-ring chronologies for climate reconstructions. Here, we examined the growth–climate response [...] Read more.

Radial tree growth at high-elevation and high-latitude sites is predominantly controlled by changes in summer temperature. This relationship is, however, expected to weaken under projected global warming, which questions the reliability of tree-ring chronologies for climate reconstructions. Here, we examined the growth–climate response patterns of five tree-ring width (TRW) and maximum latewood density (MXD) chronologies of larch (Larix sibirica) from upper-treeline ecotones in the Altai Mountains, which is a key region for developing millennial-long dendroclimatic records in inner Eurasia. The TRW and MXD chronologies exhibited significant year-to-year coherency within and between the two parameters (p < 0.001). While TRW is mostly influenced by temperature changes during the first half of the growing season from June to July (r = 0.66), MXD is most strongly correlated with May–August temperatures (r = 0.73). All seasonal temperature signals are statistically significant at the 99% confidence level, temporally stable back to 1940 CE, the period with reliable instrumental measurements, and spatially representative for a vast area of inner Eurasia between northeastern Kazakhstan in the west, northern Mongolia in the east, southern Russia in the north and northwestern China in the south. Our findings demonstrate the paleoclimatic potential of TRW and especially MXD chronologies and reject any sign of the ´divergence problem´ at these high-elevation, mid-latitude larch sites. Full article

(This article belongs to the Special Issue Response of Tree Rings to Climate Change and Climate Extremes)

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Location of the tree-ring sampling sites (light-green circles) and the meteorological station (light-blue square). Full article ">Figure 2
Summer (red) and annual mean (blue) temperatures (a) and precipitation (b) recorded at the high-elevation Kara-Tyurek meteorological station near the tree sites. Lines indicate statistically significant (p < 0.05) trends over time since 1984. Full article ">Figure 3
Regional tree-ring width (TRW) (a) and maximum latewood density (MXD) (b) chronologies with local index chronologies shown in light color. The chronologies were smoothed with a 30-year cubic spline. Full article ">Figure 4
Correlation coefficients between standard tree-ring width (a) and maximum latewood density (b) local and regional chronologies and monthly temperature means from the previous year September–September of ring formation and seasonal temperature means for June–July (JJ), summer (JJA), and from May to August (MJJA). Grey horizontal lines indicate the significance level p < 0.05. Full article ">Figure 5
Twenty-five-year window running correlations between the regional tree-ring width (a) and maximum latewood density (b) index chronologies and seasonal temperature means of June–July (JJ), summer (JJA), and May–August (MJJA). Grey horizontal lines indicate the significance level p < 0.05. Full article ">Figure 6
Tree-ring width (TRW) scaled against June–July (JJ) temperature means (a) and maximum latewood density (MXD) versus May–August (MJJA) temperature means (b). The chronologies were smoothed with a 30-year cubic spline. Full article ">Figure 7
Correlation fields of tree-ring width (TRW) (a) and maximum latewood density (MXD) (b) regional chronologies against gridded June–July (JJ) and May–August (MJJA) averaged temperature means (TS4.07, [<a href="#B49-forests-15-01402" class="html-bibr">49</a>]) for the period of 1940–2014. Black rectangles indicate the study region. Built with KNMI Climate Explorer (<a href="https://climexp.knmi.nl/start.cgi" target="_blank">https://climexp.knmi.nl/start.cgi</a>, last accessed on 25 June 2024). Full article ">

19 pages, 5194 KiB

Open AccessArticle

Effect of Polyethylene Glycol with Different Molecular Weights on the Properties of Mytilaria laosensis Timber

by Linhan He, Xiaoling Liu, Yin Kuang, Liuliu Wang, Songwu Chen, Yufen Luo and Yao Chen

Forests 2024, 15(8), 1401; https://doi.org/10.3390/f15081401 (registering DOI) - 10 Aug 2024

Abstract

Mytilaria laosensis, a common fast-growing tree species in southern China, boasts excellent growth speed and attractive color and texture. However, due to its short growth cycle and high proportion of juvenile wood, it typically exhibits poor dimensional stability and low strength, which [...] Read more.

Mytilaria laosensis, a common fast-growing tree species in southern China, boasts excellent growth speed and attractive color and texture. However, due to its short growth cycle and high proportion of juvenile wood, it typically exhibits poor dimensional stability and low strength, which significantly limits its practical applications. This study uses vacuum impregnation to modify M. laosensis wood with polyethylene glycol (PEG), focusing on the effects and mechanisms of PEG with different molecular weights on wood properties. The results indicate that PEG enters the wood cell walls through capillary action and diffusion, forming hydrogen bonds with the free hydroxyl groups on cellulose and hemicellulose, which keeps the cell walls swollen and enhances dimensional stability. Post modification, the dimensional stability of M. laosensis wood improved, with an anti-swelling efficiency ranging from 61.43% to 71.22%, showing an initial increase followed by a decrease with increasing PEG molecular weight. The optimal PEG molecular weight for anti-swelling efficiency was 1500 Da, achieving 71.22%. The flexural modulus of elasticity and flexural strength of the treated wood also first decreased and then increased with increasing PEG molecular weight. Among them, the PEG1000-treated material showed the best performance, with the flexural modulus of elasticity increased by about 29% and the flexural strength increased by about 5% compared to untreated wood. Additionally, PEG, having a higher pyrolysis temperature than wood, raised the initial pyrolysis temperature and maximum pyrolysis rate temperature of M. laosensis wood, thus improving its thermal stability. These findings provide scientific evidence and technical support for the efficient utilization and industrialization of M. laosensis wood, promoting its widespread application and industrial development. Full article

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

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22 pages, 2067 KiB

Open AccessArticle

Does Out-Migration Really Affect Forestry Ecological Security? An Empirical Case Study Based on Heilongjiang Province, China

by Jiaqi Liu and Yukun Cao

Forests 2024, 15(8), 1400; https://doi.org/10.3390/f15081400 (registering DOI) - 10 Aug 2024

Abstract

In the new era, coordinating the relationship between population flow and forestry ecological security has become an important challenge. In this study, we take Heilongjiang Province in China as an example, and through the combination of macro data and micro in-depth interviews, we [...] Read more.

In the new era, coordinating the relationship between population flow and forestry ecological security has become an important challenge. In this study, we take Heilongjiang Province in China as an example, and through the combination of macro data and micro in-depth interviews, we explore whether population mobility really affects the intrinsic mechanism of forestry ecological security from the perspective of population exodus from forest areas. Based on the DPSIR model, we constructed a forestry ecological security evaluation index system, used the TOPSIS multi-objective decision analysis method to quantify the forestry ecological security status from 2000 to 2022, and utilized the impulse response function of the VAR model to explore the dynamic response relationship between population outflow and forestry ecological security. The results of this study show that, firstly, the comprehensive index of forestry ecological security level in Heilongjiang Province exhibits a fluctuating upward trend from 2000 to 2022. Second, forestry ecological security has a lagged effect on population outflow, and population outflow has almost no effect on forestry ecological security at present. Third, while the population outflow of Luobei County reduces the interference of human activities on the natural environment, it also brings about the pressures of insufficient forestry ecological resource management and forestry personnel. The Dongfanghong Forestry Bureau has effectively improved the efficiency of ecological construction and ecological security through the introduction of digitalized and intelligent equipment, which has effectively compensated for the negative impact of population outflow on the reduction in ecological management personnel. These findings will help realize the coordinated development of population, economy and society, and ecology. Full article

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

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4 pages, 627 KiB

Open AccessEditorial

Updates on Longleaf Pine Ecology, Restoration, and Management

by Xiongwen Chen and Qinfeng Guo

Forests 2024, 15(8), 1399; https://doi.org/10.3390/f15081399 (registering DOI) - 10 Aug 2024

Abstract

Longleaf pine (Pinus palustris L [...] Full article

(This article belongs to the Special Issue Longleaf Pine Ecology, Restoration, and Management)

12 pages, 2111 KiB

Open AccessArticle

Cut-to-Length Harvesting Prediction Tool: Machine Learning Model Based on Harvest and Weather Features

by Rodrigo Oliveira Almeida, Richardson Barbosa Gomes da Silva and Danilo Simões

Forests 2024, 15(8), 1398; https://doi.org/10.3390/f15081398 (registering DOI) - 10 Aug 2024

Abstract

Weather is a significant factor influencing forest health, productivity, and the carbon cycle. However, our understanding of these effects is limited for many regions and ecosystems. Assessing the impact of weather variability on harvester productivity from plantation forests may assist in forest planning [...] Read more.

Weather is a significant factor influencing forest health, productivity, and the carbon cycle. However, our understanding of these effects is limited for many regions and ecosystems. Assessing the impact of weather variability on harvester productivity from plantation forests may assist in forest planning through the use of data modeling. We investigated whether weather data combined with timber harvesting attributes could be used to create a high-performance model that could accurately predict harvester productivity in Eucalyptus plantations using machine learning. Furthermore, we aimed to provide an online application to assist forest managers in applying the model. For the modeling, we considered 15 weather and timber harvesting attributes. We considered productivity as the target attribute. We subjected the database to 24 common algorithms in default mode and compared them according to error metrics and accuracy. From the timber harvesting features combined with weather features, the Catboost model can predict the productivity of harvesters in a tuned mode, with a coefficient of determination of 0.70. The use of weather data combined with timber harvesting attributes in the model is an accurate approach for predicting harvester productivity in Eucalyptus plantations, allowing for the creation of an online, free application to assist forest managers. Full article

(This article belongs to the Special Issue New Development of Smart Forestry: Machine and Automation)

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18 pages, 5114 KiB

Open AccessArticle

Comparison of Radial Ply and Cross Ply Tire in Terms of Achieved Rolling Resistance and Soil Compaction in a Soil Test Channel

by Milan Helexa, Jozef Krilek, Ján Kováč, Tomáš Kuvik, Vladimír Mancel, Rudolf Abrahám and Radoslav Majdan

Forests 2024, 15(8), 1397; https://doi.org/10.3390/f15081397 (registering DOI) - 10 Aug 2024

Abstract

Many literature sources state that radial ply tires achieve lower rolling resistance values than cross ply tires. From a certain point of view, radial ply tires are gentler on the ground than cross ply tires. The effort was therefore to experimentally verify this [...] Read more.

Many literature sources state that radial ply tires achieve lower rolling resistance values than cross ply tires. From a certain point of view, radial ply tires are gentler on the ground than cross ply tires. The effort was therefore to experimentally verify this statement for two radial ply and cross ply tires similar in shape and size. The work deals with the diagnostics of rolling resistance levels achieved by radial ply and cross ply tires on selected forest soil under the laboratory conditions of a soil test channel. BKT 210/95 R16 Agrimax RT 855 and Özka 7.50-16 8PR KNK 50 were chosen as radial ply and cross ply tires, respectively, and had approximately the same dimensions. The soil in the soil test channel can be characterized as a loamy sand with an average moisture content of 30% and an initial bulk density of 1445.07 kg·m⁻³. Another monitored parameter was the diagnostics of changes in soil density caused by tire movement in order to assess the degree of soil compaction. From the results of the work, it follows that there is no statistically significant difference between radial ply and cross ply tires in terms of the achieved levels of rolling resistance on the soil. The observed tires also caused intense compaction of the soil in the soil test channel, especially at higher tire pressures and higher vertical loads. The analysis of the results also shows that changes in tire pressure in both tires cause more energy loss and soil compaction than changes in the vertical load. Full article

(This article belongs to the Special Issue Forest Machinery and Mechanization—2nd Edition)

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16 pages, 4885 KiB

Open AccessArticle

Germplasm Resource Status and Seed Adaptability of Nypa fruticans Wurmb, an Endangered Species in China

by Mengwen Zhang, Cairong Zhong, Xiaobo Lv, Zanshan Fang, Cheng Cheng and Jiewei Hao

Forests 2024, 15(8), 1396; https://doi.org/10.3390/f15081396 (registering DOI) - 10 Aug 2024

Abstract

Nypa fruticans, commonly known as the Nipa palm, belongs to the true mangrove plants of the Arecaceae family. In China, it is naturally distributed only on Hainan Island and designated as a second-class National Key Protected Wild Plants List. Field research and [...] Read more.

Nypa fruticans, commonly known as the Nipa palm, belongs to the true mangrove plants of the Arecaceae family. In China, it is naturally distributed only on Hainan Island and designated as a second-class National Key Protected Wild Plants List. Field research and indoor simulation experiments were systematically employed to study the resource status of N. fruticans and the adaptation of seed germination to environmental factors. The results showed that: (1) Four natural populations of N. fruticans, approximately 9319 trees within a total area of 3.96 hm², were distributed in Haikou, Wenchang, Qionghai, and Wanning on Hainan Island. Only the Wanning population was developed in small patches, while other populations were scattered sporadically. (2) A total of 23 mangrove species belonged to 19 genera in 13 families, which were recorded in all study sites, of which 18 were true mangroves and 5 were semi-mangrove species. The vertical structures of 4 N. fruticans communities exhibited the consistent pattern, characterized by distinct layers including the tree, shrub, and herb layers. However, notable differences in species composition and dominant species were observed among the layers of each community. (3) The population dynamics of N. fruticans in Haikou, Qionghai, and Wanning were declining, while the population in Wenchang was growing. (4) Seed germination of N. fruticans was not resistant to strong light and required some shade treatment with an optimal light intensity of 60%. The suitable salinity range for seed germination was 0‰ to 10‰. With the increase of salinity, the germination rate and seedling rate showed an increasing and then decreasing trend with maximum values of 63.3% and 50.0% at 5‰, which showed the sensitivity of seed germination to salinity, with low salinity promoting germination whereas high salinity inhibiting germination. Around 8 h/d of flooding time was most suitable for the seed germination, and 10 h/d was a critical flooding time. This study provides a theoretical basis for population recovery, resource utilization, and other further research of N. fruticans. Full article

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

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Figure 1
Geographic distribution and resource status of N. fruticans. Full article ">Figure 2
Age structure of the N. fruticans population. Full article ">Figure 3
The effect of light intensity on germination parameters of N. fruticans seeds. (A) initial germination time (IGT), duration of germination (DG), initial emergence time (IET) and duration of emergence (DE); (B) germination percentage (GP) and emergence percentage (EP); (C) plant height (PH); (D) leaf number (LN). Different letters indicate significant differences (p < 0.05). Full article ">Figure 4
The effect of salinity on germination parameters of N. fruticans seeds. (A) initial germination time (IGT), duration of germination (DG), initial emergence time (IET) and duration of emergence (DE); (B) germination percentage (GP) and emergence percentage (EP); (C) plant height (PH); (D) leaf number (LN). Different letters indicate significant differences (p < 0.05). Full article ">Figure 5
The effect of flooding time on germination parameters of N. fruticans seeds. (A) initial germination time (IGT), duration of germination (DG), initial emergence time (IET) and duration of emergence (DE); (B) germination percentage (GP) and emergence percentage (EP); (C) plant height (PH); (D) leaf number (LN). Different letters indicate significant differences (p < 0.05). Full article ">

23 pages, 13195 KiB

Open AccessArticle

Association of Carbon Pool with Vegetation Composition along the Elevation Gradients in Subtropical Forests in Pakistan

by Inam Khan, Umer Hayat, Gao Lushuang, Faiza Khan, He Xinyi and Wu Shufan

Forests 2024, 15(8), 1395; https://doi.org/10.3390/f15081395 (registering DOI) - 10 Aug 2024

Abstract

As the most important way to mitigate climate change, forest carbon storage has been the subject of extensive research. A comprehensive study was carried out to investigate the influence of elevation gradients and diameter classes on the forest growth, composition, diversity, and carbon [...] Read more.

As the most important way to mitigate climate change, forest carbon storage has been the subject of extensive research. A comprehensive study was carried out to investigate the influence of elevation gradients and diameter classes on the forest growth, composition, diversity, and carbon pools of the Bagh Drush Khel Forest area. Research revealed that elevation gradients significantly influenced the composition, diversity, and carbon pools in forests. At lower elevations, Eucalyptus camaldulensis was the dominant species, with Olea ferruginea as a co-dominant species, whereas at higher elevations, Pinus roxburghii was the dominant species with Quercus incana as a co-dominant species. Regeneration was higher at higher elevations with the maximum number of saplings and seedlings of P. roxburghii. Species diversity association with elevation was negative (R² = −0.44; p < 0.05—Shannon Index). Soil organic carbon (SOC association with elevation was non-significant while positive with DBH classes (R² = 0.37; p < 0.05). Overall, carbon pool association with elevation and diameter at breast height (DBH) were negative (R² = −0.73; p < 0.05) and (R² = −0.45; p < 0.05). Litter biomass correlated positively with elevation (R² = 0.25; p < 0.05) and DBH (R² = 0.11; p < 0.05), while deadwood biomass correlated negatively with elevation gradients (R² = −0.25; p < 0.05), and no effect was observed for DBH classes. The highest carbon stock (845.89 t C/ha) was calculated at low elevations, which decreased to (516.27 t C/ha) at high elevations. The overall carbon stock calculated was (2016.41 t C/ha) respectively. A total of six tree species were found at the study site. Future research is essential for forest health monitoring and understanding fine-scale impacts. This study offers a methodological framework for similar investigations in unexplored yet potentially significant forest regions worldwide. Full article

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

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18 pages, 2726 KiB

Open AccessArticle

Wood Quality of Pendulate Oak on Post-Agricultural Land: A Case Study Based on Physico-Mechanical and Anatomical Properties

by Karol Tomczak, Przemysław Mania, Jan Cukor, Zdeněk Vacek, Magdalena Komorowicz and Arkadiusz Tomczak

Forests 2024, 15(8), 1394; https://doi.org/10.3390/f15081394 (registering DOI) - 9 Aug 2024

Abstract

Oak is one of the most economically important hardwood tree species in Europe, and its prevalence will increase due to progressing global climate change, according to predictive models. With the increasing demand for timber and with the need for a balance between carbon [...] Read more.

Oak is one of the most economically important hardwood tree species in Europe, and its prevalence will increase due to progressing global climate change, according to predictive models. With the increasing demand for timber and with the need for a balance between carbon emissions and sequestration, it is essential to address the afforestation of agricultural land. Therefore, this research aimed to investigate the physico-mechanical properties and anatomical structure of pendulate oak (Quercus robur L.) wood—specifically focusing on the trunk’s cross-section—in post-agricultural areas compared with the forest land in the western part of Poland. Wood density, bending strength, modulus of elasticity, and other parameters were analyzed from 1626 wood samples. The analysis of physico-mechanical properties reveals that, historically, agricultural land use has an almost negligible impact on wood quality. Despite significant differences in small vessel diameter and fiber length favoring trees from post-agricultural land, the physico-mechanical properties remain consistent. Large vessel measurements show comparable diameter and length in both land types. These findings suggest that post-agricultural land can serve as an effective alternative for high-quality pendulate oak wood production for industrial purposes. However, wood from post-agricultural land may exhibit a decrease in modulus of rupture by over 30% and potentially lower density above the trunk’s halfway point. This observation hints at the fact that oak trees in post-agricultural areas could be cultivated in shorter rotation periods compared to forest land. Full article

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

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17 pages, 9132 KiB

Open AccessArticle

Enhancing Deep Line Segment Detection and Performance Evaluation for Wood: A Deep Learning Approach with Experiment-Based, Domain-Specific Implementations

by Jing Luo, Yufan Guo, Zhen Liu, Qicheng Hu, Md Ahatasamul Hoque and Asif Ahmed

Forests 2024, 15(8), 1393; https://doi.org/10.3390/f15081393 (registering DOI) - 9 Aug 2024

Abstract

In recent decades, wood structures have gained significant attention for their ecological benefits and architectural versatility. The performance of wood, a popular construction material, often depends on the integrity of its connections. This study focuses on bolted glulam timber connections, which are strong [...] Read more.

In recent decades, wood structures have gained significant attention for their ecological benefits and architectural versatility. The performance of wood, a popular construction material, often depends on the integrity of its connections. This study focuses on bolted glulam timber connections, which are strong but prone to cracks that pose structural health challenges. Traditional crack evaluation methods are manual, time-consuming, and error-prone. To address these issues, this research proposes a two-stage performance evaluation method. In the first stage, an innovative approach called ‘Enhanced Deep Line Segment Detection’ (Deep LSD), a non-supervised machine learning technique, is used for crack detection without relying on large, annotated datasets, thus enhancing efficiency and adaptability. In the second stage, cyclic loading assays simulate varying damage stages to collect data and establish a correlation between crack states and connection damage. The Park and Ang damage model is employed within this framework to assess the extent of damage. The efficacy of enhanced deep LSD is confirmed by comparing detected crack areas with ground truth measurements, yielding a high R-squared value of 0.98 and a minimal error margin of 1.41. Additionally, a damage index based on the Chinese standard (GB/T 24335-2009) is used to classify damage across different connection groups, ensuring robustness and alignment with established practices. Full article

(This article belongs to the Special Issue Measurement and Improvement of Wood Mechanical and Chemical Properties)

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