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Forests, Volume 14, Issue 6 (June 2023) – 212 articles

Cover Story (view full-size image): This research aims to analyze the strengths, weaknesses, opportunities, and threats (SWOT) of economic instruments by extracting these aspects from the forest policy documents of the EU, Austria, and the Czech Republic using the qualitative content analysis method. It has been found that the EU channels its resources from economic instruments through various financing programs that make distribution more effective and align with the environmental objectives of the EU. Additionally, the SWOT analysis indicates that the economic instruments applied in the EU present significant differences in the application and management of forests and the performance of the financial instruments according to the national strategies and action plans used. View this paper
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19 pages, 2779 KiB  
Article
Extractable Compounds in a Birch Tree—Variations in Composition and Yield Potentials
by Philipp Janzen, Katrin Zimmer and Jörn Appelt
Forests 2023, 14(6), 1279; https://doi.org/10.3390/f14061279 - 20 Jun 2023
Viewed by 1396
Abstract
Extractives from silver birch (Betula pendula) can play an important role in the future bioeconomy by delivering the feedstock, for instance, for antioxidative applications. It is, therefore, inevitable to gain knowledge of the distribution of extractive content and composition in the [...] Read more.
Extractives from silver birch (Betula pendula) can play an important role in the future bioeconomy by delivering the feedstock, for instance, for antioxidative applications. It is, therefore, inevitable to gain knowledge of the distribution of extractive content and composition in the different tissues of the tree for estimating the potential volumes of valuable extractable compounds. This study examines the extractable compound distribution of different tree tissues such as outer and inner bark and wood, respectively, considering the original height of the stem and comparing the yields after Soxhlet and accelerated solvent extraction (ASE). Eleven parts of the model tree (seven stem discs and four branches) were separated into primary tissues and extracted with a ternary solvent system. The investigated extraction methods resulted in a comparable performance regarding yields and the composition of the extractives. The extractives were divided into single compounds such as betulin, lupeol, γ-sitosterol, and lupeone and substance groups such as carbohydrates, terpenes, aromatics, and other groups. The distribution of single substances and substance groups depends on the location and function of the examined tissues. Furthermore, the evidence for the correlation of a single substance’s location and original tree height is stronger for lupeol than for betulin. Primary betulin sources of the calculated betulin output are the outer bark of the stem and the branches. By using small branches, further potential for the extraction of betulin can be utilized. A model calculation of the betulin content in the current birch tree revealed a significant potential of 23 kg of betulin available as a valuable chemical resource after by-product utilization. Full article
(This article belongs to the Section Wood Science and Forest Products)
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24 pages, 18961 KiB  
Article
Study on the Ecology, Biology and Ethology of the Invasive Species Corythucha arcuata Say, 1832 (Heteroptera: Tingidae), a Danger to Quercus spp. in the Climatic Conditions of the City of Sibiu, Romania
by Cristina Stancă-Moise, George Moise, Mihaela Rotaru, Ghizela Vonica and Dorina Sanislau
Forests 2023, 14(6), 1278; https://doi.org/10.3390/f14061278 - 20 Jun 2023
Cited by 1 | Viewed by 3144
Abstract
This scientific paper examines the impact of climate change on the spread and survival of the invasive species Corythucha arcuata Say, 1832 (oak lace bug, or OLB) in Romania. The OLB is native to the Eastern USA and Canada, and in its native [...] Read more.
This scientific paper examines the impact of climate change on the spread and survival of the invasive species Corythucha arcuata Say, 1832 (oak lace bug, or OLB) in Romania. The OLB is native to the Eastern USA and Canada, and in its native habitat, it coexists with minimal impact to the preferred host plant species Quercus. However, in Europe, the OLB in high density causes early defoliation, slowing tree growth. As Quercus spp. is a keystone species, the impact of the OLB on European forests is significant. This paper aims to address several gaps in knowledge about the OLB by presenting findings from a study conducted by the Lucian Blaga University of Sibiu (ULBS) in Romania. The study identified the species’ chronology of spread, ecology, ethology and biology of the species, in addition to foliage classification to determine the extent of attack. The study found a direct link between the temperature and the speed of the generational lifecycle. The findings support the thesis that climate change is enabling the healthy, rapid density growth of OLB, which is a danger to the Quercus spp. Further research is needed in the area of the thermal tolerance of the OLB, and the research conducted by the ULBS represents the first documented research into the thermal constant of the insect. The paper concludes that further research must be in the direction to understand how and where these insects survive during winter to find future management measures and identify chemical or biological methods as solutions to eradicate and stop the expansion of the invasion of the OLB, and the potential consequences for the Quercus sp. Full article
(This article belongs to the Section Forest Ecology and Management)
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15 pages, 2697 KiB  
Article
Physiological and Gene Expression Response of Interspecific Hybrids of Fraxinus mandshurica × Fraxinus americana to MJ or SNP under Drought
by Yang Cao, Liming He, Fei Song, Chuanzhou Li, Qitian Ji, Jianfei Liu, Guangzhou Peng, Boyao Li, Fansuo Zeng and Yaguang Zhan
Forests 2023, 14(6), 1277; https://doi.org/10.3390/f14061277 - 20 Jun 2023
Viewed by 932
Abstract
Drought affects the growth and production of Fraxinus tree species, such as the precious woody plant Fraxinus mandshurica. Based on interspecific hybrid F1 combinations, D110 plants of F. mandshurica × F. americana with strong drought resistance were selected for this study. To further [...] Read more.
Drought affects the growth and production of Fraxinus tree species, such as the precious woody plant Fraxinus mandshurica. Based on interspecific hybrid F1 combinations, D110 plants of F. mandshurica × F. americana with strong drought resistance were selected for this study. To further reveal their heterosis mechanism under drought, in this study, an analysis was conducted pertaining to the physiological indexes and gene expression of related key gene changes in materials of 5 yr D110 seedlings and their female and male parental controls (D113 and 4–3) in response to drought, as well as to the addition of sodium nitrate (SNP, a donor of nitric oxide) and methyl jasmonate (MJ, a donor of jasmonate) signal molecules after drought. The results showed that under drought stress, hybrid D110 plants performed significantly better than their parents, especially compared to D113, in plant growth (the plant height growth was 29.48% higher), photosynthesis (the net photosynthetic rate was 38.4% higher), peroxidation (the increase in MDA content was 71.77% lower), defense enzyme activity (SOD and POD activities were 36.63% and 65.58% higher), hormone contents (ABA, IAA and GA were 33.9%~51.2% higher) and gene expression (the LHY and TOC1 rhythmic genes were 131.97%~165.81% higher). When an exogenous additive agent (SNP or MJ) was applied after drought, the negative effects of drought on growth were effectively alleviated (the tree height growth of D110 increased from 22.76% to 22.32% in comparison to drought conditions); meanwhile, the height growth of D110 plants was significantly higher than that of their parents. Further results of physiological indexes and the expression of related key gene changes in response to SNP or MJ also indicated that D110 plants can recover faster from drought than their parents after application of SNP or MJ. This article provides new ideas for revealing the heterosis mechanism of the drought resistance of interspecific F1 hybrids and supplies effective measures for improving drought resistance in F. mandshurica. Full article
(This article belongs to the Special Issue Advances in Tree Germplasm Innovation and High-Efficiency Propagation)
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10 pages, 1905 KiB  
Communication
Moisture Content of Fresh Scots Pine Wood in Areas near Damage Caused by Harvester Head Feed Rollers
by Karol Tomczak, Francesco Latterini, Natalia Smarul, Zygmunt Stanula, Tomasz Jelonek, Robert Kuźmiński, Piotr Łakomy and Arkadiusz Tomczak
Forests 2023, 14(6), 1276; https://doi.org/10.3390/f14061276 - 20 Jun 2023
Cited by 1 | Viewed by 910
Abstract
By damaging bark, mechanized harvesting deprives wood of its natural mechanical barrier. This study concerns the effect of this damage on the changes in moisture content that occur near the damaged areas of Scots pine (Pinus sylvestris L.). This study was carried [...] Read more.
By damaging bark, mechanized harvesting deprives wood of its natural mechanical barrier. This study concerns the effect of this damage on the changes in moisture content that occur near the damaged areas of Scots pine (Pinus sylvestris L.). This study was carried out using 45 randomly selected 11 m long logged pine stems. Additionally, the effect of bark thickness on the depth of damage was measured. To determine the influence of the location of the damage and bark thickness on the wood moisture near the damaged region, wood samples were collected from two sections. The first was located one meter above the log’s base, while the second was located one meter from the end of the log. Two increment cores were taken by a Pressler borer in each section: one from the damaged wood zone and the second from the undamaged wood zone. The average bark thickness one meter from the base of the log was 11.2 mm, which decreased to 1.8 mm in the samples taken one meter from the top of the log. The average depths of the damage caused by feed roller spikes in the two sections were 3.9 and 3.8 mm, respectively, indicating that there was no significant effect of bark thickness on the depth of the damage. The wood samples collected near the damaged wood zone (DW) had about 13 percent lower moisture content than those taken from the undamaged zone (UDW). This difference was statistically significant. We observed greater mean moisture content closer to the top of the log for both the samples taken near the damaged zone and the samples taken from the undamaged zone. One meter from the base of the log, the moisture content difference between the DW and UDW was 9.8 percentage points, which was statistically insignificant. By contrast, significantly lower moisture content (−16%) was observed in the DW one meter from the top of the log. Full article
(This article belongs to the Section Wood Science and Forest Products)
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14 pages, 5085 KiB  
Article
Experimental Study of Surface Roughness of Pine Wood by High-Speed Milling
by Chunmei Yang, Yaqiang Ma, Tongbin Liu, Yucheng Ding and Wen Qu
Forests 2023, 14(6), 1275; https://doi.org/10.3390/f14061275 - 20 Jun 2023
Cited by 1 | Viewed by 1249
Abstract
The surface roughness of wood has a great influence on its performance and is a very important indicator in processing and manufacturing. In this paper, we use the central composite design experiment (CCD experiment) and artificial neural network (ANN) model to study the [...] Read more.
The surface roughness of wood has a great influence on its performance and is a very important indicator in processing and manufacturing. In this paper, we use the central composite design experiment (CCD experiment) and artificial neural network (ANN) model to study the changing pattern of surface roughness during the high-speed milling process of pine wood. In the CCD experiments, the spindle speed, feed speed, and depth of cut are used as the influencing factors, and the surface roughness is used as the index to analyze the variation law and fit the surface roughness parameter equation. By measuring the chip size in each group in the CCD experiment, the ANN model is used to predict the surface roughness under this machining parameter by measuring the chip size in each test group. The experimental results showed that the mean error of the surface roughness prediction values in the CCD experiment (12.2%) was larger than that of the ANN model (7.8%), and the mean squared error (MSE) of the ANN model was 0.025, the mean absolute percentage error(MAPE) was 0.01, and the coefficient of determination R2 was 0.95. Compared with the CCD experiment, the ANN model had a higher prediction accuracy. The results of this paper can provide some guidance for the prediction of surface roughness during wood processing. Full article
(This article belongs to the Special Issue New Development of Smart Forestry: Machine and Automation)
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21 pages, 6425 KiB  
Article
An Alternative Method for Estimation of Stand-Level Biomass for Three Conifer Species in Northeast China
by Shidong Xin, Muhammad Khurram Shahzad, Surya Bagus Mahardika, Weifang Wang and Lichun Jiang
Forests 2023, 14(6), 1274; https://doi.org/10.3390/f14061274 - 20 Jun 2023
Viewed by 873
Abstract
Accurate large-scale biomass prediction is crucial for assessing forest carbon storage and dynamics. It can also inform sustainable forest management practices and climate change mitigation efforts. However, stand-level biomass models are still scarce worldwide. Our study aims to introduce the generalized additive model [...] Read more.
Accurate large-scale biomass prediction is crucial for assessing forest carbon storage and dynamics. It can also inform sustainable forest management practices and climate change mitigation efforts. However, stand-level biomass models are still scarce worldwide. Our study aims to introduce the generalized additive model (GAM) as a convenient and efficient approach for forest biomass estimation. Data from 311 sample plots of three conifer species in northeastern China were used to evaluate the performance of the GAM model and compare it with traditional nonlinear seemingly unrelated regression (NSUR) models in predicting stand biomass, including total, aboveground, and component biomass. The results indicated that the goodness of fit of GAM was better than that of NSUR in two model systems. In the majority of cases, the scatter plots and prediction performance revealed that the stand total and component biomass models utilizing GAM outperformed those based on NSUR. Disregarding heteroscedasticity and requiring fewer statistical assumptions provide additional support for the replacement of NSUR-based models with GAM-based models. This study implies that the GAM approach has greater potential for developing a system of stand biomass models. Full article
(This article belongs to the Section Forest Ecology and Management)
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16 pages, 766 KiB  
Article
Development of Structural Criteria for the Certification and Designation of Recreational and Therapeutic Forests in Bavaria, Germany
by Gisela Immich and Eva Robl
Forests 2023, 14(6), 1273; https://doi.org/10.3390/f14061273 - 20 Jun 2023
Cited by 2 | Viewed by 1072
Abstract
Background: Based on the increasing evidence of forest on health, a research project assessed the structural certification criteria of recreational and therapeutic forests in 15 Bavarian pilot sites. The main project objectives were (1) to develop a certification standard for recreational and therapeutic [...] Read more.
Background: Based on the increasing evidence of forest on health, a research project assessed the structural certification criteria of recreational and therapeutic forests in 15 Bavarian pilot sites. The main project objectives were (1) to develop a certification standard for recreational and therapeutic forests and (2) to establish a certification and designation process. Methods: Relevant criteria were identified by a literature review. The findings, in conjunction with landscape planning principles, were used to develop a catalog of certification criteria, which was then tested and amended in field testing in the pilot sites. Results: The criteria catalog for recreational and therapeutic forests was structured into four sections: general requirements, forest-specific requirements, safety and infrastructure, and preventive and/or therapeutic interventions. At 13 pilot sites, 13 recreational forests and 3 therapeutic forests were designated, 47 professionals were trained, the designation process and a certification body were established, and the results were published in a manual (BayKK KuH). Conclusions: This newly developed Bavarian certification standard for recreational and therapeutic forests represents an innovative synthesis of science and empirical on-site experience. It enables interested parties to develop a recreational or therapeutic forest on the basis of transparently published standards in order to use the health-promoting effects of the forest in prevention and therapy. Full article
(This article belongs to the Special Issue Forest Bathing and Forests for Public Health)
18 pages, 3633 KiB  
Article
The Influence of Wild Ungulates on Forest Regeneration in an Alpine National Park
by Jeannine Fluri, Pia Anderwald, Fränzi Korner-Nievergelt, Sonja Wipf and Valentin Amrhein
Forests 2023, 14(6), 1272; https://doi.org/10.3390/f14061272 - 20 Jun 2023
Cited by 1 | Viewed by 1066
Abstract
The browsing of wild ungulates can have profound effects on the structure and composition of forests. In the Swiss National Park, the density of wild ungulates, including red deer (Cervus elaphus), ibex (Capra ibex), and chamois (Rupicapra rupicapra [...] Read more.
The browsing of wild ungulates can have profound effects on the structure and composition of forests. In the Swiss National Park, the density of wild ungulates, including red deer (Cervus elaphus), ibex (Capra ibex), and chamois (Rupicapra rupicapra), is exceptionally high due to strict protection and the absence of large predators. We examined count data of larch (Larix decidua), cembra pine (Pinus cembra), spruce (Picea abies), upright mountain pine (Pinus mugo subsp. uncinata), and mountain ash (Sorbus aucuparia) of four sampling years between 1991 and 2021, and modelled how topographic and location factors affected the probability of browsing on saplings of larch, cembra pine, and spruce. Despite the high density of wild ungulates, the number of saplings and young trees has increased over the past 30 years. The probability of browsing on saplings was highest for larch at a height of 10–40 cm and increased with increasing elevation. In our study area, open grasslands are mainly located above the tree line, which might explain the positive correlation between elevation and the probability of browsing. Further, the probability of browsing was related to exposition and slope, diversity of tree species, and disturbance by humans. It appears that in the investigated part of the Swiss National Park, the potential of the forest to regenerate has increased despite the high densities of wild ungulates. Full article
(This article belongs to the Section Forest Ecology and Management)
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14 pages, 2683 KiB  
Article
Studying the Genetic and the Epigenetic Diversity of the Endangered Species Juniperus drupacea Labill. towards Safeguarding Its Conservation in Greece
by Evangelia V. Avramidou, Evangelia Korakaki, Ermioni Malliarou and Stefanos Boutsios
Forests 2023, 14(6), 1271; https://doi.org/10.3390/f14061271 - 20 Jun 2023
Cited by 4 | Viewed by 902
Abstract
Juniperus drupacea Labill is a unique representative tree which, nowadays, has limited geographical range. In Greece, it exists only in the southeastern part of the Peloponnese, and it is labeled as endangered according to the IUCN in Europe. In the light of climatic [...] Read more.
Juniperus drupacea Labill is a unique representative tree which, nowadays, has limited geographical range. In Greece, it exists only in the southeastern part of the Peloponnese, and it is labeled as endangered according to the IUCN in Europe. In the light of climatic changes, a conservation plan which will secure its adaptation and resilience is important. Knowledge of the genetic and the epigenetic diversity of J. drupacea in Greece can establish a pledge for sustainability. In this study, genetic diversity with amplified fragment length polymorphism (AFLP) markers and epigenetic diversity assessed with methylation-sensitive amplification polymorphism (MSAP) were used for eleven subpopulations of the species. Simultaneously, first assessment between midday water potential (Ψmd) and epigenetic diversity was calculated in order to determine drought response of the species. Results showed that genetic diversity was higher than epigenetic diversity and no subpopulation differentiation was observed. No significant correlations were found between geographic, epigenetic, and genetic diversity, indicating that the genetic diversity is uncoupled from epigenetic diversity. A significant negative correlation between epigenetic Shannon index and Ψmd was found. The holistic research of genetic and epigenetic diversity paves the way for an effective conservation plan for the species. Full article
(This article belongs to the Special Issue Genetic Variation and Phenotypic Plasticity in Trees)
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10 pages, 2155 KiB  
Article
A Rapid and Easy Way for National Forest Heights Retrieval in China Using ICESat-2/ATL08 in 2019
by Shijuan Gao, Jianjun Zhu and Haiqiang Fu
Forests 2023, 14(6), 1270; https://doi.org/10.3390/f14061270 - 20 Jun 2023
Cited by 2 | Viewed by 1152
Abstract
Continuous and extensive monitoring of forest height is essential for estimating forest above-ground biomass and predicting the ability of forests to absorb CO2. In particular, forest height at the national scale is an important indicator reflecting the national forestry economic construction, [...] Read more.
Continuous and extensive monitoring of forest height is essential for estimating forest above-ground biomass and predicting the ability of forests to absorb CO2. In particular, forest height at the national scale is an important indicator reflecting the national forestry economic construction, environmental governance, and ecological balance. However, the lack of inventory data restricts large-scale monitoring of forest height to some extent. Conducting manual surveys of forest height for large-scale areas would be labor-intensive and time-consuming. The successful launch of the new generation of spaceborne light detection and ranging (LiDAR) (The Ice, Cloud, and Land Elevation Satellite-2/the Advanced Topographic Laser Altimeter System, ICESat-2/ATLAS) has brought new opportunities for national-scale forestry resource surveys. This paper explores a method to survey national forest canopy height from the new generation of ICESat-2/ATLAS data. In view of the sparse sampling and little overlap between repeated spaceborne LiDAR data, a strategy for assessing the overall change of canopy height for large scales is provided. Some spatially continuous ancillary data were used to assist ICESat-2/ATLAS data to generate a wall-to-wall (spatially continuous) forest canopy height map in China by using the machine learning approach and then quantifying the analysis of forest canopy height in various provinces. The results show that there is a good correlation between the model forest height and the verification data, with a root mean squared error (RMSE) of 3.30 m and a coefficient of determination (R2) of 0.87. This indicates that the method for retrieving national forest canopy height is reliable. There are some limitations in areas with lower vegetation coverage or complex topography which need additional filtering or terrain correction to achieve higher accuracy in measuring forest canopy height. Our analysis suggests that ICESat-2/ATLAS data can achieve the retrieval of national forest height at an overall level, and it would be feasible to use ICESAT-2/ATLAS products to estimate forest canopy height change for large-scale areas. Full article
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19 pages, 2108 KiB  
Article
Construction of Core Collection and Phenotypic Evaluation of Toona sinensis
by Jianhua Dai, Yanru Fan, Shu Diao, Hengfu Yin, Xiaojiao Han and Jun Liu
Forests 2023, 14(6), 1269; https://doi.org/10.3390/f14061269 - 19 Jun 2023
Cited by 1 | Viewed by 1184
Abstract
Toona sinensis is an important “vegetable and timber” tree species that is widely distributed in eastern and southeastern Asia. An efficient mechanism for preserving and utilizing germplasm resources is crucial for speeding up the process of genetic improvement of T. sinensis. We [...] Read more.
Toona sinensis is an important “vegetable and timber” tree species that is widely distributed in eastern and southeastern Asia. An efficient mechanism for preserving and utilizing germplasm resources is crucial for speeding up the process of genetic improvement of T. sinensis. We collected a total of 1040 germplasm resources of T. sinensis from China, Britain, and New Zealand. Using a total of 27,040 markers, we analyzed the genetic diversity, genetic structure, and core collection of these resources. Additionally, a comprehensive evaluation method for phenotypes of T. sinensis was established by principal component analysis (PCA) and the technique for order preference by similarity to ideal solution (TOPSIS). Our analysis included three main results: Firstly, the breeding population, consisting of a total of 1040 individuals, contains a diverse genetic pool and can be divided into two genetic clusters. Secondly, the best core collection was obtained from the alternative population, consisting of a total of 208 individuals and comprising 20% of the breeding population. It was screened out based on Core Hunter 3 software with the average entry-to-nearest-entry (E-NE) algorithm. Finally, a comprehensive evaluation method was established based on eight selected agronomic traits of the core collection. This method allowed us to screen the best individual plants of the core collection, including N0237, N0972, and N0409. Overall, our research findings will enable better preservation and utilization of T. sinensis germplasm resources and result in faster improvement of T. sinensis varieties. Full article
(This article belongs to the Special Issue Molecular Markers in Forest Management and Tree Breeding)
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18 pages, 3191 KiB  
Article
Exogenous Carbon Addition Reduces Soil Organic Carbon: The Effects of Fungi on Soil Carbon Priming Exceed Those of Bacteria on Soil Carbon Sequestration
by Limin Zhang, Yang Wang, Jin Chen, Chengfu Zhang, Yang Cao, Guojun Cai and Lifei Yu
Forests 2023, 14(6), 1268; https://doi.org/10.3390/f14061268 - 19 Jun 2023
Cited by 1 | Viewed by 1329
Abstract
Soil organic carbon (SOC) forms the largest terrestrial organic carbon (C) pool, which is regulated by complex connections between exogenous C input, microbial activity, and SOC conversion. Few studies have examined the changes in natural abundance C due to microbial activity after exogenous [...] Read more.
Soil organic carbon (SOC) forms the largest terrestrial organic carbon (C) pool, which is regulated by complex connections between exogenous C input, microbial activity, and SOC conversion. Few studies have examined the changes in natural abundance C due to microbial activity after exogenous C inputs in karst lime soils in China. In this research, the 13C isotope tracer technique was employed to investigate the priming effect of SOC on typical lime soil (0~20 cm) of 13C_litter and 13C_calcium carbonate (CaCO3) through a mineralization incubation experiment. Samples were collected at 5, 10, 20, 40, 60, and 80 days of incubation and analyzed for SOC mineralization, SOC distribution across fractions (>250 μm, 53~250 μm, and <53 μm), and soil microbial diversity. A control consisting of no exogenous C addition was included. SOC mineralization and SOC priming were considerably higher (15.48% and 61.00%, respectively) after litter addition compared to CaCO3. The addition of either litter or CaCO3 reduced the total organic C (TOC) and macroaggregate (>250 μm) and microaggregate (53~250 μm) C fractions by 2150.13, 2229.06, and 1575.06 mg C kg−1 Cbulk on average and increased the mineral particulate C fraction (<53 μm) by 1653.98 mg C kg−1 Cbulk. As the incubation time extended, a significantly positive correlation was apparent between SOC priming and soil fungal diversity, as well as between the mineral particulate C fraction and soil bacterial diversity. The effect of soil fungal diversity on SOC priming (R = 0.40, p = 0.003) significantly exceeded that of bacterial diversity on SOC sequestration (R = 0.27, p = 0.02). Our results reveal that after adding litter or CaCO3, soil fungi stimulate SOC mineralization and decomposition and soil bacteria enhance SOC sequestration, with the effects of fungi being more pronounced. These findings can provide a theoretical basis for understanding C sequestration and emission reduction in karst lime soils. Full article
(This article belongs to the Section Forest Soil)
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20 pages, 16714 KiB  
Article
Constructing Coupling Model of Generalized B-Spline Curve and Crown (CMGBCC) to Explore the 3D Modeling of Chinese Fir Polymorphism
by Zeyu Cui, Huaiqing Zhang, Yang Liu, Jing Zhang, Tingdong Yang, Yuanqing Zuo and Kexin Lei
Forests 2023, 14(6), 1267; https://doi.org/10.3390/f14061267 - 19 Jun 2023
Viewed by 957
Abstract
Crown simulation based on basis spline (b-spline) interpolation is a compatible method to simulate tree polymorphism at present. However, there are two problems when it simulates the crown: the first problem is that the derivative value at the top point needs to be [...] Read more.
Crown simulation based on basis spline (b-spline) interpolation is a compatible method to simulate tree polymorphism at present. However, there are two problems when it simulates the crown: the first problem is that the derivative value at the top point needs to be given manually, and the second is that the type of value point needs to be collected equidistantly. To solve the above problems and realize convenient and accurate tree polymorphism simulation, this study took Chinese fir as the study object, set the crown morphological feature as the model value point, and constructed a coupling model of generalized B-spline curve and crown (CMGBCC) as the constraint condition of the crown shape to simulate the polymorphism in the process of a tree three-dimensional (3D) model. The position and size of the distribution on the 3D model of the branches were constrained by the curve, and the 3D modeling of a Chinese fir polymorphism was constructed. According to the collection of Chinese fir-type value points in the sample plot, the study realized the detailed types of value points’ precise simulation for three polymorphisms of the Chinese fir crown, including natural pruning, crown displacement, and crown shape difference. At the same time, the different withered existence states of the branches were considered preliminarily. Compared to the 3D model with the field survey data, indicating that constructed models could simulate the difference in tree crown morphology precisely, the branch models were separated by convenience to simulate the process of Chinese fir growth. In the process of construction, CMGBCC did not need to add the derivative value in a manual way and could collect the type of value points according to the characteristics of the crown morphological changes completely. Compared to the results of the crown curve constructed, which were based on generalized B-spline (GB-spline) interpolation and b-spline interpolation, it showed that the number of crown value points collected by the GB-spline interpolation method decreased by 18% on average. The precision of the crown shape constraint was improved by 7.63% compared to b-spline interpolation. The 3D modeling of tree polymorphism was combined with the relationship between tree morphology and environment. At the same time, it was convenient to simulate the behavior of forest management measures, such as pruning. Full article
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26 pages, 4538 KiB  
Article
A Study on the Soundscape Preferences of the Elderly in the Urban Forest Parks of Underdeveloped Cities in China
by Lei Luo, Qi Zhang, Yingming Mao, Yanyan Peng, Tao Wang and Jian Xu
Forests 2023, 14(6), 1266; https://doi.org/10.3390/f14061266 - 19 Jun 2023
Cited by 3 | Viewed by 1421
Abstract
Against the backdrop of the global aging trend, the proportion of the elderly population is severely increasing in the urban areas of underdeveloped regions. Despite evidence that urban forest parks are effective at enhancing the physical and mental well-being of the elderly, little [...] Read more.
Against the backdrop of the global aging trend, the proportion of the elderly population is severely increasing in the urban areas of underdeveloped regions. Despite evidence that urban forest parks are effective at enhancing the physical and mental well-being of the elderly, little has been done to investigate the connection between urban forest parks and the elderly in underdeveloped regions, and landscape studies in particular are lacking. This study attempted to address this gap, using a subjective evaluation method in which 725 elderly respondents were engaged in a questionnaire survey on their soundscape preferences in the urban forest parks of an underdeveloped city in China. The results revealed the elderly people’s preferences for soundscapes, and a further analysis demonstrated the relationships between these preferences and landscape features. The effects of personal traits and living situations on soundscape preferences were determined by analyzing the impacts of living conditions, occupation, and education on soundscape preferences. By building a model with regression coefficients, the most powerful factors influencing soundscape choice were investigated. It was found that (1) the types of sound sources preferred by the elderly, in descending order, were natural sound, livestock sound, bird song, musical sound, other sounds. (2) The differences among education, occupation, and age all affected the participants’ soundscape preferences, i.e., the mean values of the soundscape preferences among older adults varied with education, occupation, and age. The mean value of soundscape preference was higher among older adults who had received higher education, were government officials and business managers, and belonged to higher age groups. (3) Among the various factors influencing the soundscape preference of the elderly, the most influential factors were the length of time spent in the waterfront environment, the time spent in the forest park, and the importance of road signs. (4) The preference for soundscapes was strongly connected with happiness in life. (5) Wearing a mask significantly reduced soundscape perception scores under epidemic conditions, while vaccinated individuals were more tolerant of various noises. Recommendations for landscape design to improve the soundscape perception of elderly people are accordingly provided. Full article
(This article belongs to the Special Issue Landsenses in Green Spaces)
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16 pages, 5276 KiB  
Article
Tree Species Classification Using Optimized Features Derived from Light Detection and Ranging Point Clouds Based on Fractal Geometry and Quantitative Structure Model
by Zhenyang Hui, Zhaochen Cai, Peng Xu, Yuanping Xia and Penggen Cheng
Forests 2023, 14(6), 1265; https://doi.org/10.3390/f14061265 - 19 Jun 2023
Cited by 2 | Viewed by 1029
Abstract
Tree species classification is a ubiquitous task in the forest inventory field. Only directly measured feature vectors have been applied to most existing methods that use LiDAR technology for tree species classification. As a result, it is difficult to obtain a satisfactory tree [...] Read more.
Tree species classification is a ubiquitous task in the forest inventory field. Only directly measured feature vectors have been applied to most existing methods that use LiDAR technology for tree species classification. As a result, it is difficult to obtain a satisfactory tree species classification performance. To solve this challenge, the authors of this paper developed two new kinds of feature vectors, including fractal geometry-based feature vectors and quantitative structural model (QSM)-based feature vectors. In terms of fractal geometry, both two fractal parameters were extracted as feature vectors for reflecting how tree architecture is distributed in three-dimensional space. In terms of QSM, the ratio of length change and the ratio of radius change of different branches were extracted as feature vectors. To reduce the feature vector dimensionality and explore valuable feature vectors, feature vector dimension reduction was conducted using the classification and regression tree (CART). Five hundred and sixty-eight individual trees with five tree species were selected for evaluating the performance of the developed feature vectors. The experimental results indicate that the tree species of Fagus sylvatica achieved the highest overall accuracy, which is 98.06%, while Quercus petraea obtained the lowest overall accuracy, which is 96.65%. Four other classical supervised learning methods were adopted for comparison. The comparison result indicates that the proposed method outperformed the other four supervised learning methods no matter which accuracy indicator was adopted. In comparison with the relevant method, the eight feature vectors developed in this paper also performed much better. This indicates that the fractal geometry-based feature vectors and QSM-based feature vectors developed in this paper can effectively improve the performance of tree species classification. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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15 pages, 3453 KiB  
Article
Nitrogen Addition Alleviates Cadmium Toxicity in Eleocarpus glabripetalus Seedlings
by Meihua Liu, Mengjiao Shi, Haili Gao, Yu Zheng and Lita Yi
Forests 2023, 14(6), 1264; https://doi.org/10.3390/f14061264 - 19 Jun 2023
Viewed by 812
Abstract
Cadmium (Cd) accumulation in soil is a serious form of heavy metal pollution affecting environmental safety and human health. In order to clarify the tolerance mechanisms to Cd-contaminated soils under N deposition, changes in plant growth, root architecture and physiological characteristics of Eleocarpus [...] Read more.
Cadmium (Cd) accumulation in soil is a serious form of heavy metal pollution affecting environmental safety and human health. In order to clarify the tolerance mechanisms to Cd-contaminated soils under N deposition, changes in plant growth, root architecture and physiological characteristics of Eleocarpus glabripetalus seedlings under combined nitrogen (N) and cadmium (Cd) treatments were determined in this study. The results indicated that Cd-induced negative effects inhibited the growth of E. glabripetalus seedlings through increased underground biomass allocation, and affected transpiration and respiratory processes, resulting in a decreased soluble sugars concentration in leaves and non-structural carbohydrates (NSC) in the roots. Root systems might play a major role in Cd absorption. Cd stress restricted the growth of fine roots (<0.5 mm), and affected the uptake of N and P. N addition alleviated the Cd-induced negative effect on plant growth through improving the root system, increasing starch and NSC contents in the roots and increasing total biomass. These findings have important implications for understanding the underlying tolerance mechanisms of Cd pollution under N deposition in arbor species. Full article
(This article belongs to the Special Issue Effects of Abiotic Stress on Tree Physiology and Ecology)
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20 pages, 1898 KiB  
Article
Morphological Crown Attributes Contributing to Differential Height and Diameter Growth among Families in a Coastal Douglas-Fir Progeny Test: Crown Structural Evidence for Crop Ideotypes
by Sukhyun Joo, Douglas A. Maguire, J. Bradley St. Clair, Terrance Z. Ye and Keith J. S. Jayawickrama
Forests 2023, 14(6), 1263; https://doi.org/10.3390/f14061263 - 19 Jun 2023
Viewed by 986
Abstract
Theoretical tree crop ideotypes have long and narrow live crowns with a high total leaf area. This crown form allows more efficient exploitation of site resources, in part by physically occupying less growing space per unit leaf area and by packing a greater [...] Read more.
Theoretical tree crop ideotypes have long and narrow live crowns with a high total leaf area. This crown form allows more efficient exploitation of site resources, in part by physically occupying less growing space per unit leaf area and by packing a greater number of trees into a given area. Genetic selection for crop ideotypes has been proposed as a strategy for maximizing productivity per unit area in stands managed under intensive silviculture. The primary objective of this study was to test the relationship between the relative growth performance of different families in a Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.] Franco) progeny test and morphological crown attributes that conform to a theoretical crop ideotype. The overarching goal was to identify attributes conferring superior height and diameter growth on families and to facilitate the incorporation of these attributes and associated growth mechanisms into hybrid growth models for intensively managed plantations. Crown structural attributes were measured on destructively sampled trees and averaged for the entire crown and each third of live crown length among families. Multivariate analysis revealed that crown attributes averaged over the entire crown performed best for identifying families with different height and diameter growth, followed successively by the bottom, middle, and top crown third. Trees with relatively short branch lengths and steep branch angles tended to have higher total leaf area per unit crown length (TLACL), and this structural attribute showed a strong positive correlation with cumulative diameter growth. The ratio of crown width to crown length (CWL) was moderately and negatively correlated with cumulative height growth. The families displaying the most rapid diameter growth in this progeny test conformed to a theoretical crop ideotype, while those with the most rapid height growth displayed crown attributes with a less obvious relationship to the crop ideotype concept. TLACL implied one possible mechanism driving genetic gain in Douglas-fir families, given its high heritability and strongly positive correlation with growth performance. Incorporating TLACL as an explanatory variable in diameter growth models could at least partly represent different genetic levels. TLACL is less strongly correlated with height growth rate, so incorporating CWL may better represent genetic effects on height growth models. Full article
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17 pages, 3873 KiB  
Article
Identification of ApbHLH1 as a Partner Interacting with ApMYB1 to Promote Anthocyanin Biosynthesis during Autumnal Leaf Coloration in Acer palmatum
by Long Chen, Sujing Sun, Gengcheng Qiu and Jiading Yang
Forests 2023, 14(6), 1262; https://doi.org/10.3390/f14061262 - 19 Jun 2023
Viewed by 904
Abstract
Anthocyanin biosynthesis determines the leaf color of Acer palmatum as a widely-planted landscape tree. Previously, ApMYB1 has been characterized as a positive regulator of anthocyanin biosynthesis. To further elucidate the mechanism of leaf coloration, the present study identified a basic helix-loop-helix (bHLH) transcription [...] Read more.
Anthocyanin biosynthesis determines the leaf color of Acer palmatum as a widely-planted landscape tree. Previously, ApMYB1 has been characterized as a positive regulator of anthocyanin biosynthesis. To further elucidate the mechanism of leaf coloration, the present study identified a basic helix-loop-helix (bHLH) transcription factor (ApbHLH1) through the phylogenetic analysis of 156 putative bHLH proteins in Acer palmatum and eight reference bHLHs which were known to be involved in the anthocyanin biosynthesis of selected plants. Protein structure comparison showed that ApbHLH1 has a conserved bHLH domain, and its N-terminal contains an MYB-interacting region. The expression of ApbHLH1 in leaves was found to not be correlated with anthocyanin contents either in green, semi-red leaves or during leaf autumnal senescence when anthocyanin content increased. ApbHLH1 expression in detached leaves was induced by exogenous senescence-promoting chemicals, including H2O2, SA, MeJA, ACC and ABA, with certain durations. In particular, either high light or low temperature induced ApbHLH1 expression significantly, and combination of high light and low temperatures seemed more effective in inducing ApbHLH1 expression. Luciferase complementation imaging assays confirmed the physical interaction between ApbHLH1 and ApMYB1, which could be abolished by either the truncating MYB-interacting region of ApbHLH1 or the deleting bHLH interacting domain of ApMYB1. The transient expression of ApbHLH1 could not induce anthocyanin production, while the co-expression of ApbHLH1 and ApMYB1 resulted in a higher accumulation of anthocyanins compared to the expression of ApMYB1 alone in tobacco leaves. Collectively, our results revealed that ApbHLH1 participated in leaf coloration through binding with ApMYB1 and enhancing the ApMYB1 function of promoting anthocyanin biosynthesis during leaf autumnal reddening in Acer palmatum. ApbHLH1 could have the potential for breeding color-leafed plants through co-transformation with ApMYB1. Full article
(This article belongs to the Special Issue Genomics of Growth Traits and Stress Acclimation in Forest Trees)
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15 pages, 4168 KiB  
Article
Spatial–Temporal Distribution Pattern of Ormosia hosiei in Sichuan under Different Climate Scenarios
by Chunping Xie, Lin Chen, Meng Li, Dawei Liu and Chi-Yung Jim
Forests 2023, 14(6), 1261; https://doi.org/10.3390/f14061261 - 19 Jun 2023
Viewed by 940
Abstract
Ormosia hosiei is an endemic plant in China listed as a national grade II key protected wild plant with important scientific, economic, and cultural values. This study was designed to predict the potential suitable distribution areas for O. hosiei under current and future [...] Read more.
Ormosia hosiei is an endemic plant in China listed as a national grade II key protected wild plant with important scientific, economic, and cultural values. This study was designed to predict the potential suitable distribution areas for O. hosiei under current and future climate change and to provide a reference to enhance the species’ conservation and utilization. Based on the actual geographical locations of O. hosiei in Sichuan, we applied two species distribution models (BIOCLIM and DOMAIN) to predict its current and future potential suitable areas and future change patterns. We also analyzed the major climatic variables limiting its geographical distribution with principal component analysis. The results indicated that O. hosiei was mainly distributed in the eastern region of Sichuan and concentrated in the middle subtropical climate zone at relatively low elevations. The principal component analysis identified two critical factors representing temperature and moisture. The temperature was the most critical factor limiting O. hosiei distribution in Sichuan, especially the effect of extreme low temperatures. Both models’ simulation results of potential suitable areas under the current climate scenario showed that the excellent suitable habitat was consistent with the current actual distribution, remaining in the eastern region of Sichuan. Under the future climate scenario with doubled CO2 concentration (2100), both models predicted a sharp decrease in the areas of excellent and very high suitable habitats. The findings can inform strategies and guidelines for O. hosiei research, conservation, nursery production, and cultivation in Sichuan. Full article
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20 pages, 8758 KiB  
Article
Assessing the Global Pest Risk of Aeolesthes sarta with Regards to the Host Specie Populus alba under Climate Change Scenarios
by Umer Hayat, Sumeet Kour, Muhammad Akram, Juan Shi and Rinto Wiarta
Forests 2023, 14(6), 1260; https://doi.org/10.3390/f14061260 - 19 Jun 2023
Cited by 1 | Viewed by 1217
Abstract
Aeolesthes sarta or Trirachys sarta is a polyphagous long-horned beetle that has caused severe damage to the Populus alba forests/plantations in its regions of origin. Climate change could accelerate the introduction and spread of invasive pest species, potentially causing ecological damage and economic [...] Read more.
Aeolesthes sarta or Trirachys sarta is a polyphagous long-horned beetle that has caused severe damage to the Populus alba forests/plantations in its regions of origin. Climate change could accelerate the introduction and spread of invasive pest species, potentially causing ecological damage and economic losses. Furthermore, globalization and increased trade can inadvertently transport pests across borders into regions where they do not already occur. Hence, it is crucial to identify areas where the climate is most suitable for the establishment of A. sarta’s and which areas of the world are suitable for the growth of P. alba under climate change scenarios. This study employed the CLIMEX model to estimate the potential global distribution of A. sarta and its correlation with its dominant host, P. alba, under current climatic conditions and potential future scenarios, namely the A1B and A2 climate change scenarios (CCSs). Under current climatic conditions, the model indicates that the establishment of a climatically suitable habitat for A. sarta extends beyond its current known range. The model estimated that, under the world’s current climatic conditions, 41.06% of the world can provide suitable areas (EI > 0) for the survival of A. sarta. For P. alba, under the current climatic conditions, suitable regions for the growth of P. alba are present in all continents (excluding Antarctica); under the world’s current climatic conditions, 53.52% of the world can provide suitable areas for the growth of P. alba (EI > 0). Climate change will significantly alter the number of suitable habitats for A. sarta development and P. alba growth globally. In future climatic conditions, the number areas capable of supplying suitable habitats (EI > 0) for A. sarta will slightly decrease to 40.14% (under A1B and A2 CCSs), while, for P. alba, the number areas capable of supplying suitable habitats will also marginally decrease to 50.39% (under A1B scenario), and this figure is estimated to drop to 48.41% (under A2 scenario) by the end century (2100). Asia, Europe, North America, South America, and Oceania have a high percentage of highly suitable areas for A. sarta development and P. alba growth under current climatic conditions; however, according to estimates of future climatic conditions, by the end century, only Asia, Europe, North America, and Oceania will have a high percentage of highly suitable areas for A. sarta development and P. alba growth. The range of highly suitable habitats is likely to increase in the northern hemisphere; however, this range is expected to shrink with regards to the southern hemisphere. The range contraction was higher under the A2 climate change scenario due to a higher warming trend than in the A1B scenario. Due to climate change, the range of A. sarta development shifted, as did the P. alba growth range, which, thanks to the suitable environmental conditions for the growth of P. alba, makes all those regions vulnerable to the introduction and development of A. sarta. Strict monitoring, prevention, and control measures at borders, airports, and seaports before the trade of P. alba and other suitable host species wood (logs/billets) are highly recommended to prevent the spread of A. sarta and ensure biodiversity security. It is expected that the A. sarta and P. alba climate models presented here will be useful for management purposes since both can be adapted to guide decisions about imparting resources to regions where the threat of pest invasion remains and away from regions where climate suitability is predicted to decrease in the future. Full article
(This article belongs to the Topic Plant Invasion)
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11 pages, 5202 KiB  
Article
Identification of Eight Pterocarpus Species and Two Dalbergia Species Using Visible/Near-Infrared (Vis/NIR) Hyperspectral Imaging (HSI)
by Xiaoming Xue, Zhenan Chen, Haoqi Wu, Handong Gao, Jiajie Nie and Xinyang Li
Forests 2023, 14(6), 1259; https://doi.org/10.3390/f14061259 - 17 Jun 2023
Cited by 1 | Viewed by 1232
Abstract
Pterocarpus santalinus is considered among the finest luxury woods in the world and has potential commercial and medicinal value. Due to its rich hue and high price, Pterocarpus santalinus has often been substituted and mislabeled with other woods of lower economic value. To [...] Read more.
Pterocarpus santalinus is considered among the finest luxury woods in the world and has potential commercial and medicinal value. Due to its rich hue and high price, Pterocarpus santalinus has often been substituted and mislabeled with other woods of lower economic value. To maintain the order of the timber market and the interests of consumers, it is necessary to establish a fast and reliable method for Pterocarpus species identification. In this study, wood samples of Pterocarpus santalinus and nine other wood samples commonly used for counterfeiting were analyzed by visible light/near-infrared (Vis/NIR) hyperspectral imaging (HSI). The spectral data were preprocessed with different algorithms. Principal component analysis (PCA) was applied in different spectral ranges: 400~2500 nm, 400~800 nm, and 800~2500 nm. Partial least squares discriminant analysis (PLS-DA) and square support vector machine (SVM) modeling methods were performed for effective discrimination. The best classification model was SVM combined with a normalization preprocessing method in whole spectral range (400~2500 nm), with prediction accuracy higher than 99.8%. The results suggest that the use of Vis/NIR-HSI in combination with chemometric approaches can be used as an effective tool for the discrimination of Pterocarpus santalinus. Full article
(This article belongs to the Special Issue Recent Advances in Wood Identification, Evaluation and Modification)
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14 pages, 2863 KiB  
Article
Strategy Trade-Off of Predominant Stress Tolerance Relative to Competition and Reproduction Associated with Plant Functional Traits under Karst Forests
by Xiaorun Hu, Yuejun He, Lu Gao, Muhammad Umer, Yun Guo, Qiyu Tan, Liling Kang, Zhengyuan Fang, Kaiping Shen and Tingting Xia
Forests 2023, 14(6), 1258; https://doi.org/10.3390/f14061258 - 17 Jun 2023
Cited by 4 | Viewed by 1319
Abstract
The Grime (1974) CSR framework posits that ecological strategies of competition, stress tolerance and ruderal reflect plants’ adaptability to their survival environments. Karst forests are crucial for terrestrial ecosystem functions. However, how karst forests regulate plant functional traits in ecological strategy to adapt [...] Read more.
The Grime (1974) CSR framework posits that ecological strategies of competition, stress tolerance and ruderal reflect plants’ adaptability to their survival environments. Karst forests are crucial for terrestrial ecosystem functions. However, how karst forests regulate plant functional traits in ecological strategy to adapt to infertile habitats remains unclear. Therefore, we surveyed fifty-three karst forest plots and measured plant functional traits involving the plan diameter at breast height (DBH), height, leaf area (LA), specific leaf area (SLA), leaf dry matter content (LDMC), leaf carbon (LC) and nitrogen (LN) and phosphorus (LP) with the leaf water content (LWC). We calculated CSR components on the individual and community levels introduced by community-weighted means (CWM) using the ‘StrateFy’ calculator. Principal component analysis (PCA) and Mantel’s test were used to investigate trait correlations with CSR components. Our results showed that stress tolerance (S) contributed an average 65.88% and 63.63% in individuals and communities, respectively, followed by competition (C) at 25.82% and 29.63%, and the least, ruderal (R), at 8.30% and 6.74%. Different plant functional traits exhibited different variations, coupled with significant correlations between CSR components and PC1 scores (except for CWM− LA, SLA and LDMC). Component S increased with the increase in CWM− LC and C:N ratio, and decreased with the increase in CWM− DBH, Height, LWC, LN, and N:P ratio, while it was the opposite for C and R, highlighting strategic trade-offs associated with plant functional traits. Mantel’s test revealed varied key trait combinations for each strategy. In conclusion, the predominant stress tolerance strategy relative to competition and ruderal is a result of trade-offs regulating karst forests, in association with plant functional traits. The disentangled CSR strategies provide insights into theoretically understanding functional maintenance for infertile forest ecosystems as an evolutional regulation mechanism. Full article
(This article belongs to the Section Forest Ecology and Management)
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8 pages, 2646 KiB  
Communication
A New Species of Ampelovirus Detected in Persea lingue (Ruiz & Pav.) Nees ex Kopp, a Common Tree of the Threatened Chilean Sclerophyll Forest
by Alan Zamorano, Camila Gamboa, Colombina Camilla, Francisca Beltrán, Carlos Magni, Suraj Vaswani, Eduardo Martínez-Herrera and Nicola Fiore
Forests 2023, 14(6), 1257; https://doi.org/10.3390/f14061257 - 16 Jun 2023
Viewed by 971
Abstract
Biotic and abiotic stress seriously affects the development of plants, leading to the death of a significant number of plants in natural landscapes. Over the last twelve years, the central zone of Chile has been under an intensive drought, affecting the species inhabiting [...] Read more.
Biotic and abiotic stress seriously affects the development of plants, leading to the death of a significant number of plants in natural landscapes. Over the last twelve years, the central zone of Chile has been under an intensive drought, affecting the species inhabiting the Chilean Mediterranean forest, which is classified as a biological hotspot. In this context, our group started a small survey to monitor the presence of intracellular pathogens that may be infecting the plants, increasing the damage caused by the water deprivation. Several plants of one species, Persea lingue, showed symptoms of interveinal yellowing and leaf curling. RNA-seq analyses of one of these samples showed the presence of a long contig with high coverage only in symptomatic plants. Phylogenetic analysis and the molecular features indicated that it was a new species of the Ampelovirus genus. RT-PCR analyses determined the presence of the virus only in symptomatic plants of the same natural preserve. Full article
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22 pages, 12327 KiB  
Article
Comparative Transcriptome Analysis between Embryogenic and Non-Embryogenic Callus of Davidia involucrata
by Gaoman Linghu, Zhaoyou Yu, Meng Li, Anqi Wang and Yongxiang Kang
Forests 2023, 14(6), 1256; https://doi.org/10.3390/f14061256 - 16 Jun 2023
Cited by 1 | Viewed by 1208
Abstract
Davidia involucrata Baill. (D. involucrata), a rare and endangered wild plant, is native to China and is globally recognized as an ornamental tree species. However, D. involucrata exhibits inherent biological characteristics that contribute to its low reproductive efficiency. To address this [...] Read more.
Davidia involucrata Baill. (D. involucrata), a rare and endangered wild plant, is native to China and is globally recognized as an ornamental tree species. However, D. involucrata exhibits inherent biological characteristics that contribute to its low reproductive efficiency. To address this challenge, somatic embryogenesis, a biotechnological method, offers numerous advantages, including enhanced reproductive efficiency, a large reproductive coefficient, and a complete structural composition. Consequently, somatic embryogenesis holds significant value in the propagation and genetic improvement of this particular tree species. In a previous study, we utilized immature zygotic embryos of D. involucrata as explants and induced somatic embryogenesis from embryogenic callus, thereby establishing a rapid propagation and plant regeneration scheme. In this study, we utilized Illumina RNA sequencing to compare the transcriptomes of the embryogenic callus (EC) and non-embryogenic callus (NEC) of D. involucrata. The analysis revealed 131,109 unigenes assembled from EC and NEC, and 12,806 differentially expressed genes (DEGs) were identified. To verify the authenticity of the transcriptome sequencing results, qRT-PCR was performed and 16 DEGs were screened, with the stable reference gene UBQ being selected. Our analysis focused on genes related to plant growth regulators and somatic embryogenesis, such as the Aux, IAA, ARF, GH3, AHP, ARR, CYCD, BBM, WUS, GRF, SERK, and WOX gene families. We found that certain genes in these families were significantly upregulated in EC induction compared to NEC, indicating that they play crucial roles in D. involucrata cell proliferation, differentiation, and cell totipotency. These results offer new insights into the role of these gene families in EC, and may guide efforts to improve the somatic embryo induction, culture conditions, and genetic transformation efficiency of D. involucrata. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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28 pages, 5441 KiB  
Article
The Role of Vegetation on Urban Atmosphere of Three European Cities. Part 2: Evaluation of Vegetation Impact on Air Pollutant Concentrations and Depositions
by Mihaela Mircea, Rafael Borge, Sandro Finardi, Gino Briganti, Felicita Russo, David de la Paz, Massimo D’Isidoro, Giuseppe Cremona, Maria Gabriella Villani, Andrea Cappelletti, Mario Adani, Ilaria D’Elia, Antonio Piersanti, Beatrice Sorrentino, Ettore Petralia, Juan Manuel de Andrés, Adolfo Narros, Camillo Silibello, Nicola Pepe, Rossella Prandi and Giuseppe Carlinoadd Show full author list remove Hide full author list
Forests 2023, 14(6), 1255; https://doi.org/10.3390/f14061255 - 16 Jun 2023
Cited by 2 | Viewed by 1164
Abstract
This is the first study that quantifies explicitly the impact of present vegetation on concentrations and depositions, considering simultaneously its effects on meteorology, biogenic emissions, dispersion, and dry deposition in three European cities: Bologna, Milan, and Madrid. The behaviour of three pollutants (O [...] Read more.
This is the first study that quantifies explicitly the impact of present vegetation on concentrations and depositions, considering simultaneously its effects on meteorology, biogenic emissions, dispersion, and dry deposition in three European cities: Bologna, Milan, and Madrid. The behaviour of three pollutants (O3, NO2, and PM10) was investigated considering two different scenarios, with the actual vegetation (VEG) and without it (NOVEG) for two months, representative of summer and winter seasons: July and January. The evaluation is based on simulations performed with two state-of-the-art atmospheric modelling systems (AMS) that use similar but not identical descriptions of physical and chemical atmospheric processes: AMS-MINNI for the two Italian cities and WRF-CMAQ for the Spanish city. The choice of using two AMS and applying one of them in two cities has been made to ensure the robustness of the results needed for their further generalization. The analysis of the spatial distribution of the vegetation effects on air concentrations and depositions shows that they are highly variable from one grid cell to another in the city area, with positive/negative effects or high/low effects in adjacent cells being observed for the three pollutants investigated in all cities. According to the pollutant, on a monthly basis, the highest differences in concentrations (VEG-NOVEG) produced by vegetation were estimated in July for O3 (−7.40 μg/m3 in Madrid and +2.67 μg/m3 in Milan) and NO2 (−3.01 μg/m3 in Milan and +7.17 μg/m3 in Madrid) and in January for PM10 (−3.14 μg/m3 in Milan +2.01 μg/m3 in Madrid). Thus, in some parts of the cities, the presence of vegetation had produced an increase in pollutant concentrations despite its efficient removal action that ranges from ca. 17% for O3 in Bologna (January) to ca. 77% for NO2 in Madrid (July). Full article
(This article belongs to the Section Urban Forestry)
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16 pages, 5933 KiB  
Article
Urban Forest Recreation and Its Possible Role throughout the COVID-19 Pandemic
by Dastan Bamwesigye, Jitka Fialova, Petr Kupec, Evans Yeboah, Jan Łukaszkiewicz, Beata Fortuna-Antoszkiewicz and Jakub Botwina
Forests 2023, 14(6), 1254; https://doi.org/10.3390/f14061254 - 16 Jun 2023
Cited by 1 | Viewed by 1212
Abstract
Urban forests provide benefits in terms of the environment and society. Many people living in urban areas could profit from the recreational services provided by urban forests to alleviate the physical and psychological stresses caused by closure restrictions during the COVID-19 epidemic. However, [...] Read more.
Urban forests provide benefits in terms of the environment and society. Many people living in urban areas could profit from the recreational services provided by urban forests to alleviate the physical and psychological stresses caused by closure restrictions during the COVID-19 epidemic. However, limited research has been conducted on the role of forest recreation during the COVID-19 lockdown to support future policy decisions regarding such dramatic circumstances. The study aims to investigate the frequency of visitors in the reference Training Forest Enterprise Masaryk Forest Křtiny in Brno, Czech Republic, and to verify if the lockdown led to its intensified use, under the context of weather conditions. Data were collected using a Pyro Box Compact reader and TRAFx Infrared Trail Counter. Regression analysis was performed to determine whether individual weather factors significantly influenced the intensity of forest visitations before and during COVID-19. The number of visits in 2021 during the strict lockdown and post-lockdown periods was significantly higher during spring and autumn than in 2016 and 2017, respectively. The frequency pattern of forest users visibly changed in 2021, and the total number of visits was much higher, even though 2021 had worse weather than the reference years before the pandemic. The results show the recreational use and importance of the forest, especially during the pandemic. This work is a continuation of our previous research with regard to this area, which indicated the importance of forest recreational services for the well-being and health of city dwellers. Full article
(This article belongs to the Special Issue Forest Ecosystem Services and Landscape Design - Series II)
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15 pages, 2938 KiB  
Article
Decomposition and Nutrient Release from Larix olgensis Stumps and Coarse Roots in Northeast China 33-Year Chronosequence Study
by Xiuli Men, Yang Yue, Xiuwei Wang and Xiangwei Chen
Forests 2023, 14(6), 1253; https://doi.org/10.3390/f14061253 - 16 Jun 2023
Cited by 1 | Viewed by 971
Abstract
Stumps and coarse roots form an important C pool and nutrient pool in a Larix olgensis (Larix olgensis Henry) plantation ecosystem, and their decomposition processes would affect nutrient cycling dynamics of the overall Larix olgensis plantation. We studied the decomposition and release of [...] Read more.
Stumps and coarse roots form an important C pool and nutrient pool in a Larix olgensis (Larix olgensis Henry) plantation ecosystem, and their decomposition processes would affect nutrient cycling dynamics of the overall Larix olgensis plantation. We studied the decomposition and release of nutrients from stumps and coarse roots that were cleared 0, 6, 16, 26 and 33 years ago in Northeast China. The stumps and coarse roots were divided into stump discs (SD), stump knots (SK), coarse roots (>10 cm in diameter) (CR1), medium-coarse roots (5–10 cm in diameter) (CR2) and fine-coarse roots (2–5 cm in diameter) (CR3). During the entire 33-year study period, SK, CR1, CR2 and CR3 lost 87.37%, 96.24%, 75.76% and 91.98% of their initial mass, respectively. The average annual decomposition rate (k) was 0.068 for SD, 0.052 for SK, 0.092 for CR1, 0.068 for CR2 and 0.066 for CR3. After 33 years of decomposition, CR3 lost 5% of its initial C, CR2 lost 2%, and SK accumulated 1%, indicating slow C release. The N residues in SK, CR1, CR2 and CR3 were 186%, 109%, 158% and 170%, respectively. Coarse roots released P significantly faster than SD and SK, with 13% of the initial P released in CR1. SD and SK release cellulose, hemicellulose and lignin faster than coarse roots. The results show that Larix olgensis stumps and coarse roots could contribute to soil fertility recovery and serve as a long-term nutrient reservoir for forest vegetation. Full article
(This article belongs to the Section Forest Soil)
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17 pages, 5068 KiB  
Article
Research on the Estimation of Chinese Fir Stand Volume Based on UAV-LiDAR Technology
by Shuhan Yu, Xiangyu Chen, Xiang Huang, Yichen Chen, Zhongyang Hu, Jian Liu and Kunyong Yu
Forests 2023, 14(6), 1252; https://doi.org/10.3390/f14061252 - 15 Jun 2023
Cited by 2 | Viewed by 983
Abstract
Chinese fir (Cunninghamia lanceolata) is the main fast-growing timber species in China, and studies of its stand volume are important for evaluating the effectiveness of forest management. However, it is difficult to accurately estimate stand volume from the perspective of a [...] Read more.
Chinese fir (Cunninghamia lanceolata) is the main fast-growing timber species in China, and studies of its stand volume are important for evaluating the effectiveness of forest management. However, it is difficult to accurately estimate stand volume from the perspective of a single tree due to the mutual concealment among Chinese fir trees. Therefore, in this study, we propose a method for identifying different forms of Chinese fir. The specific idea is to realize the accurate identification of a single Chinese fir tree, two Chinese fir trees, and three Chinese fir trees, and construct their respective stand volume estimation models to obtain an estimate of the forest stand volume. The key results are as follows: (1) the overall accuracy of recognition of different forms of Chinese fir is 79%, and the construction of different forms of Chinese fir units is beneficial for identifying forest trees; (2) a multiunit volume equation for different forms of Chinese fir is constructed; (3) based on predictions obtained with the constructed stand volume model, the difference between the estimated stand volume and the measured stand volume is small, and the average accuracy reaches 89.19%; and (4) compared to traditional volume estimation methods based on individual tree scale, the research method in this study shows a significant improvement (about 9.96%) in overall accuracy. In summary, this method can weaken the influence of erroneous individual tree segmentation on the accuracy of stand volume estimation, and can greatly reduce the working time of single tree segmentation to achieve the fast and accurate estimation of fir plantation stand volume. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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24 pages, 71380 KiB  
Article
Assessing the Sustainability of NTFP-Based Community Enterprises: A Viable Business Model for Indonesian Rural Forested Areas
by Jun Harbi, Yukun Cao, Noril Milantara and Ade Brian Mustafa
Forests 2023, 14(6), 1251; https://doi.org/10.3390/f14061251 - 15 Jun 2023
Cited by 3 | Viewed by 1761
Abstract
Indonesia’s vast forested areas have the potential to serve as a crucial source of livelihood for local communities. However, the current contributions of these forests to community livelihoods are significantly underutilized in comparison to their potential. This study evaluates the financial performance and [...] Read more.
Indonesia’s vast forested areas have the potential to serve as a crucial source of livelihood for local communities. However, the current contributions of these forests to community livelihoods are significantly underutilized in comparison to their potential. This study evaluates the financial performance and sustainability of community forest-based businesses operating around the forest management area of the Lakitan-Bukit Cogong forest management unit (LBC FMU). Data were collected through semi-structured and in-depth interviews with the key informants through purposive sampling. Financial viability analysis and a qualitative approach were used to assess the feasibility of the businesses. The findings revealed that all businesses show positive values for all financial indicators. From profit estimation and value-added distribution, all products are shown to be feasible. Concerning the value and supply chain, the rubber-processing industry has a remarkable flow. Moreover, small forest enterprises (SFEs) highlight natural capital optimization through multitudinous derivatives of products that could support a substantial regenerative economy, including citronella essential oil, native honeybees, rubber-based product, biochar, skewers, and liquid smoke. In addition, the multidimensional scaling and rapid appraisal for forest (MDS-RAPForest) approach generates a result based on multiple dimensions (ecology, economics, social and human resources, and institutional and administrative dimensions) showing that overall, SFEs are categorized as sufficient/quite sustainable. Furthermore, mainstreaming adaptable forest-based enterprises, jurisdiction approaches, and cross-production system strategies are also discussed. Our findings suggest that sustainable NTFP-based activities within a community context can be facilitated through interconnected market systems, appropriate price regulations, and support from stakeholders and legal frameworks. Full article
(This article belongs to the Special Issue Non-timber Forest Products: Beyond the Wood)
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16 pages, 8652 KiB  
Article
A Composite Whole-Biomass Tannin–Sucrose–Soy Protein Wood Adhesive with High Performance
by Guoming Xiao, Jiankun Liang, Zhigang Wu, Hong Lei, Feiyan Gong, Wen Gu, Yuan Tu and De Li
Forests 2023, 14(6), 1250; https://doi.org/10.3390/f14061250 - 15 Jun 2023
Cited by 4 | Viewed by 1260
Abstract
Whole-biomass adhesives are the research hotspot of wood adhesives andcan improve the competitiveness of adhesives. The tannin–sucrose adhesive studied by our research group shows good bonding performance, but poor bonding stability induced by low viscosity. In this study, the tannin–sucrose adhesive was modified [...] Read more.
Whole-biomass adhesives are the research hotspot of wood adhesives andcan improve the competitiveness of adhesives. The tannin–sucrose adhesive studied by our research group shows good bonding performance, but poor bonding stability induced by low viscosity. In this study, the tannin–sucrose adhesive was modified by isolated soybean protein (SPI), the effect of the SPI substitution ratio for tannin on the properties of the tannin–sucrose–SPI composite adhesive was investigated, and the bonding mechanism was explored using Fourier-transform infrared spectroscopy (FT-IR), thermogravimetry (TG), X-ray diffraction (XRD), and gas chromatography–mass spectroscopy (GC–MS). The results showed that: (1) when the SPI substitution ratio was above 40%, the viscosity of the composite adhesive increased significantly, which effectively avoided adhesive leakage. (2) The tannin–sucrose–SPI composite adhesive displayed high bonding performance and water resistance. (3) The FTIR and GC–MS results revealed that the curing mechanism of the tannin–sucrose–SPI adhesive was very complicated, but it was certain that the conversion of sucrose into furan compounds, especially 5-hydroxymethylfurfural (5-HMF), was the core of the cross-linking reaction of the adhesive when elevating temperature. (4) The macromolecules and high reactivity of SPI compensated for the shortage of high temperature required for the conversion of sucrose into furanic cross-linkers so that the tannin–sucrose–SPI adhesive experienced an efficient curing reaction at a low temperature, and the reaction degree and thermal stability of the curing product increased. Full article
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