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Forests
Volume 14
Issue 5
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Forests, Volume 14, Issue 5 (May 2023) – 209 articles

Cover Story (view full-size image): One of the most important by-products generated in the forestry industry is the bark obtained during the debarking process. The bark of P. radiata D. Don is an interesting source of extracts, rich in condensed tannins, with potential uses in biopolymer and bioadhesive preparation. Conversely, E. globulus bark extracts are rich in hydrolyzable tannins with few applications. Nevertheless, the forest industry generates a high volume of these by-products, simultaneously. In this work, a suitable process for the joint valorization of both forest by-products at a large scale was developed. The possibility of obtaining extracts from equal mixtures of both barks with applicability in the formulation of formaldehyde-free bioadhesives for industrial particleboards was also demonstrated. View this paper
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16 pages, 3595 KiB  
Article
Effects of Acid Rain Stress on the Physiological and Biochemical Characteristics of Three Plant Species
by Yuxuan Zhang, Feng Yang, Yunqi Wang, Yonglin Zheng and Junlin Zhu
Forests 2023, 14(5), 1067; https://doi.org/10.3390/f14051067 - 22 May 2023
Cited by 2 | Viewed by 4919
Abstract
The physiological and biochemical indicators of plants reflect the plant’s adaptation to environmental changes and provide information for the planting and management of acid-resistant tree species. To analyze the responses of typical tree species to recent changes in acid rain conditions in Jinyun [...] Read more.
The physiological and biochemical indicators of plants reflect the plant’s adaptation to environmental changes and provide information for the planting and management of acid-resistant tree species. To analyze the responses of typical tree species to recent changes in acid rain conditions in Jinyun Mountain, Chongqing, we focused on three representative tree species in the Jinyun Mountain area of Chongqing: Pinus massoniana, Phyllostachys edulis, and Cinnamomum camphora. A mixed acid rain experiment with five gradients of natural rainfall (NR) and pH values of 7.0, 4.5, 3.5, and 2.5 was conducted in May 2021. The changes in physiological and biochemical indicators (net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, transpiration rate, light saturation point, light compensation point, apparent quantum efficiency, dark respiration rate, soluble sugar, starch, soluble protein, proline, malondialdehyde, and antioxidant enzyme activity) were determined. The results show the following: 1. Compared with other treatments, NR and slightly acidic rain increased the relative chlorophyll content in plant seedlings. 2. The synthesis of soluble sugars, starches, and soluble proteins was inhibited to different degrees in the three species under acid rain stress at pH ≤ 3.5. 3. The enzyme activity of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) initially increased and then decreased with an increase in acidity. 4. Acid rain treatments with pH ≤ 4.5 reduced the net photosynthetic rate (Pn) of plants; the higher the acidity, the lower the Pn. Conclusion: A comprehensive comparison of the indicators revealed that NR and mild acid rain enhanced the plant seedlings’ physiological and biochemical characteristics. A pH of 3.5 was the threshold where acid rain had an adverse effect on Pinus massoniana, Phyllostachys edulis, and Cinnamomum camphora. The high indicator values for NR indicate that these tree species have adapted to current conditions in the Jinyun Mountain area of Chongqing. This study provides new information for selecting tree species adapted to the acid rain environment in Jinyun Mountain, Chongqing. Full article
(This article belongs to the Special Issue Physiological and Molecular Adaptable Strategies to Abiotic Stress in Forest Trees)
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14 pages, 1575 KiB  
Article
Do Distance-Dependent Competition Indices Contribute to Improve Diameter and Total Height Tree Growth Prediction in Juvenile Cork Oak Plantations?
by Paulo Neves Firmino, Margarida Tomé and Joana Amaral Paulo
Forests 2023, 14(5), 1066; https://doi.org/10.3390/f14051066 - 22 May 2023
Cited by 2 | Viewed by 1756
Abstract
Competition indices may improve tree growth modelling in high-density stands, found often in new cork oak plantations. Distance-dependent competition indices have hardly been considered for juvenile cork oak plantations since existing models were developed for low-density mature stands. This study aims at inspecting [...] Read more.
Competition indices may improve tree growth modelling in high-density stands, found often in new cork oak plantations. Distance-dependent competition indices have hardly been considered for juvenile cork oak plantations since existing models were developed for low-density mature stands. This study aims at inspecting the potential of including distance-dependent competition indices into diameter at breast height (d) and total height (h) growth models for Quercus suber L., comparing several distance-dependent and distance-independent competition indices. Annual d and h growth were modelled with linear and non-linear growth functions, formulated as difference equations. Base models were initially fitted considering parameter estimates depending only on site index (S) and/or stand density (N). They were refitted, testing the significance of adding each competition index to the model parameters. Selected models included the best-performing distance-dependent or -independent competition indices as additional predictors. Best base d and h growth models showed a modelling efficiency (ef) of ef = 0.9833 and ef = 0.9900, respectively. Adding a distance-dependent competition index slightly improved growth models, to an ef = 0.9851 for d and ef = 0.9902 for h. Best distance-dependent competition indices slightly overperformed distance-independent ones in diameter growth models. Neither S nor N were included on best fitted models. If inter-tree competition is present in juvenile undebarked cork oak plantations, it does not yet strongly impact individual tree growth, which may diminish the importance of using, at this stage, more complex spatially explicit competition indices on predicting individual tree growth. Full article
(This article belongs to the Special Issue Spatial Distribution and Growth Dynamics of Tree Species)
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11 pages, 13241 KiB  
Editorial
Intrinsic Regulation of Diameter Growth in Woody Plants
by Rodney Arthur Savidge
Forests 2023, 14(5), 1065; https://doi.org/10.3390/f14051065 - 22 May 2023
Cited by 1 | Viewed by 1345
Abstract
The defining feature of each forest is the organism that humanity generically designates as ‘tree’ [...] Full article
(This article belongs to the Special Issue Intrinsic Regulation of Diameter Growth in Woody Plants)
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23 pages, 16419 KiB  
Article
Biomass Estimation of Urban Forests Using LiDAR and High-Resolution Aerial Imagery in Athens–Clarke County, GA
by Katrina Ariel Henn and Alicia Peduzzi
Forests 2023, 14(5), 1064; https://doi.org/10.3390/f14051064 - 22 May 2023
Cited by 4 | Viewed by 2031
Abstract
The benefits and services of urban forests are becoming increasingly well documented, with carbon storage being the main focus of attention. Recent efforts in urban remote sensing have incorporated additional data such as LiDAR data but have been limited to sections of an [...] Read more.
The benefits and services of urban forests are becoming increasingly well documented, with carbon storage being the main focus of attention. Recent efforts in urban remote sensing have incorporated additional data such as LiDAR data but have been limited to sections of an urban area or only certain species. Existing models are not generalizable to remaining unmeasured urban trees. To make a generalizable individual urban tree model, we used metrics from NAIP aerial imagery and NOAA and USGS LiDAR data for 2013 and 2019, and two crown-level urban tree biomass models were developed. We ran a LASSO regression, which selected the best variables for the biomass model, followed by a 10-fold cross-validation. The 2013 model had an adjusted R2 value of 0.85 and an RMSE of 1797 kg, whereas the 2019 model had an adjusted R2 value of 0.87 and an RMSE of 1444 kg. The 2019 model was then applied to the rest of the unsampled trees to estimate the total biomass and total carbon stored for all the trees in the county. Recommendations include changes to ground inventory techniques to adapt to the current methods and limitations of remote sensing biomass estimation. Full article
(This article belongs to the Special Issue Geospatial Monitoring of Urban Green Space)
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16 pages, 3333 KiB  
Article
A Parametric Optimized Method for Three-Dimensional Corner Joints in Wooden Furniture
by Xiutong Xu, Xianqing Xiong, Xinyi Yue and Mei Zhang
Forests 2023, 14(5), 1063; https://doi.org/10.3390/f14051063 - 22 May 2023
Cited by 12 | Viewed by 2775
Abstract
The three-dimensional corner joint is a type of joint in wooden furniture structures with complex parameter relationships and many constraints. Traditional furniture structure design requires repeated modifications of geometric models to determine parameter dimensions, which is inefficient and challenging and severely impacts the [...] Read more.
The three-dimensional corner joint is a type of joint in wooden furniture structures with complex parameter relationships and many constraints. Traditional furniture structure design requires repeated modifications of geometric models to determine parameter dimensions, which is inefficient and challenging and severely impacts the development of the digital design and manufacture process. Based on the ideal value range of mortise–tenon joints, this study derived a parametric optimized method of three-dimensional corner joints in wooden furniture and refined the theoretical value range of at least four main parameters: the width of the beneficial mortise (B2), the depth of the cede mortise (C1), the margin thickness from the cede tenon to the rail1 reference edge (bt1), and the margin thickness from the beneficial tenon to the rail2 reference edge (bt2). With case verification, the results show that in the axial direction of the cede tenon, the maxC1 decreased by 5.4 mm and the combination of B2,C1 reduced at least 23 kinds. In the cases of different post widths and the margin thickness from rail2’s reference edge to the post’s reference edge (Btm2), the value range and value quantity of bt2 were narrowed and decreased in various degrees. In the axial direction of the beneficial tenon, the value range and quantity of available values of the margin thickness from the cede tenon to the rail1 reference edge (bt1) decrease with decreasing margin thickness from the rail1 reference edge to the post reference edge (Btm1) when Btm1 is less than constant z. The parametric optimized method of three-dimensional corner joints in wooden furniture can effectively reduce the parameter dimensional value range, both theoretically and practically, and more refined value ranges can be obtained by setting more standard values. This method also provides ideas for the digital and standardized design of wooden furniture structures. Full article
(This article belongs to the Special Issue Wood Technology Standardization and Wood Products)
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22 pages, 4141 KiB  
Article
Emission of Volatile Organic Compounds from the Heat Treatment of Afrormosia and Newtonia Wood: Effects of Air and Palm Oil Heat Media
by Lionnel Frederique Bidzanga Bessala, Jingjing Gao, Zhengbin He, Zhenyu Wang and Songlin Yi
Forests 2023, 14(5), 1062; https://doi.org/10.3390/f14051062 - 22 May 2023
Cited by 2 | Viewed by 1790
Abstract
The objective of this work was to study the influence of palm oil on the VOCs emitted during the heat treatment of Afromosia (Pericopsis Elata Van Meeuwen) and Newtonia (Newtonia paucijuga Harms) wood by comparing to the VOCs emitted during the [...] Read more.
The objective of this work was to study the influence of palm oil on the VOCs emitted during the heat treatment of Afromosia (Pericopsis Elata Van Meeuwen) and Newtonia (Newtonia paucijuga Harms) wood by comparing to the VOCs emitted during the heat treatment under air. Two batches of Afrormosia and Newtonia wood samples were heated under air and palm oil at temperatures of 160 °C, 180 °C, and 200 °C for 2 h. Then, the VOCs were collected by Solid Phase Micro Extraction (SPME) and measured using a Gas Chromatograph and Mass Spectrometer (GC-MS). The results showed that the temperature, the wood species, and the treatment medium have a great influence on the categories and percentages of VOCs emitted. In the air heat treatment, ethers were the most emitted VOCs from Afrormosia and Newtonia when these woods were thermally treated at 160 °C. Newtonia treated under air at 180 °C emitted more esters, while Afrormosia continued to emit more ethers under the same conditions. Moreover, Afrormosia and Newtonia treated at 200 °C emitted more ketones and aldehydes, respectively. Regarding the heat treatment of Afrormosia and Newtonia wood under palm oil, a similarity of the VOCs emitted from Newtonia with those emitted from Afrormosia under the same conditions was observed. Furthermore, palm oil was the main factor conditioning the nature of the VOCs emitted during the heat treatment. In general, for the treatment of Afrormoshia wood with palm oil, the VOCs emitted, such as alcohols, alkanes, and ethers, decreased with the treatment temperature. Ethers and ketones increased with the processing temperature. At 160 °C and 180 °C, the percentage of aldehydes was highest, while, at 200 °C, the percentage of esters was highest. Similarly, for Newtonia treated under palm oil, adehydes, ethers, and alcohols were the most abundant VOCs emitted at 160 °C. However, their percentages decreased with the increase in the treatment temperature; on the contrary, esters and ketones were weakly emitted at 160 °C and became abundant with the increase in temperature. Additionally, the ethers formed during the heat treatment of Afrormosia and Newtonia wood treated under air carry acetyl groups, while those formed during the treatment of the said wood under palm oil carry hydroxyl groups. Full article
(This article belongs to the Section Wood Science and Forest Products)
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16 pages, 9295 KiB  
Article
Biomass Spatial Pattern and Driving Factors of Different Vegetation Types of Public Welfare Forests in Hunan Province
by Huiting Liu, Yue Fu, Jun Pan, Guangjun Wang and Kongfei Hu
Forests 2023, 14(5), 1061; https://doi.org/10.3390/f14051061 - 22 May 2023
Cited by 3 | Viewed by 1845
Abstract
An ecological public welfare forest is an important basis for the construction of national ecological security. This study took public welfare forests at the provincial level or above in Hunan Province as the research object. Based on the in situ monitoring data and [...] Read more.
An ecological public welfare forest is an important basis for the construction of national ecological security. This study took public welfare forests at the provincial level or above in Hunan Province as the research object. Based on the in situ monitoring data and remote sensing data, we constructed a random forest (RF) model for inversing the biomass of public welfare forests with different types. Then, based on the inversion results, we investigated the biomass spatial pattern. Combined with topographical and socio-economic factors, we constructed a geographically weighted regression (GWR) model to analyze the biomass driving factors of different vegetation types in public forests. The results showed the following: (1) The biomass of public welfare forests in Hunan Province presented a strip distribution pattern that gradually increases from the central to the southwest and northeast. The total biomass of public welfare forests in Hunan Province was 338.13 million tons, with an average biomass of 68.31 t·hm−2. In the different types of public welfare forests, the mean biomass of the types were as follows: shrub (4.65 t·hm−2) < broadleaf forest (59.27 t·hm−2) < conifer–broadleaf mixed forest (62.44 t·hm−2) < bamboo forest (71.33 t·hm−2) < coniferous forest (100.33 t·hm−2). (2) Topographic and socio-economic factors have a significant impact on the spatial pattern of biomass in public welfare forests. Slope had the greatest effect on coniferous forest, conifer–broadleaf mixed forest, and shrub forest, while POP had the greatest effect on broadleaf forest and bamboo forest. This study investigates the spatial patterns and driving factors of biomass in public welfare forests at the provincial level, filling the gap in forest biomass monitoring in public welfare forests in Hunan Province. It provides a new method to improve the accuracy of forest biomass estimation and data support for the sustainable management of public welfare forests. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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26 pages, 18811 KiB  
Article
MARC-Net: Terrain Classification in Parallel Network Architectures Containing Multiple Attention Mechanisms and Multi-Scale Residual Cascades
by Xiangsuo Fan, Xuyang Li, Chuan Yan, Jinlong Fan, Ling Yu, Nayi Wang and Lin Chen
Forests 2023, 14(5), 1060; https://doi.org/10.3390/f14051060 - 22 May 2023
Cited by 5 | Viewed by 1566
Abstract
To address the problem that traditional deep learning algorithms cannot fully utilize the correlation properties between spectral sequence information and the feature differences between different spectra, this paper proposes a parallel network architecture land-use classification based on a combined multi-head attention mechanism and [...] Read more.
To address the problem that traditional deep learning algorithms cannot fully utilize the correlation properties between spectral sequence information and the feature differences between different spectra, this paper proposes a parallel network architecture land-use classification based on a combined multi-head attention mechanism and multiscale residual cascade called MARC-Net. This parallel framework is firstly implemented by deeply mining the features generated by grouped spectral embedding for information among spectral features by adding a multi-head attention mechanism, which allows semantic features to have expressions from more subspaces while fully considering all spatial location interrelationships. Secondly, a multiscale residual cascade CNN (convolutional neural network) is designed to fully utilize the fused feature information at different scales, thereby improving the network’s ability to represent different levels of information. Lastly, the features obtained by the multi-head attention mechanism are fused with those obtained by the CNN, and the merged resultant features are downgraded through the fully connected layer to obtain the classification results and achieve pixel-level multispectral image classification. The findings show that the algorithm proposed in this paper has an aggregate precision of 97.22%, compared to that of the Vision Transformer (ViT) with 95.08%; its performance on the Sentinel-2 dataset shows a huge improvement. Moreover, this article mainly focuses on the change rate of forest land in the study area. The Forest land area was 125.1143 km2 in 2017, 105.6089 km2 in 2019, and 76.3699 km2 in 2021, with an increase of 15.59%, an decrease of 0.97%, and increase of 14.76% in 2017–2019, 2019–2021 and 2017–2021, respectively. Full article
(This article belongs to the Special Issue Remote Sensing Approaches to Mapping and Monitoring Forest Vegetation Conditions)
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16 pages, 3633 KiB  
Article
Natural Factors Play a Dominant Role in the Short-Distance Transmission of Pine Wilt Disease
by Yanqing Liu, Jixia Huang and Tong Yang
Forests 2023, 14(5), 1059; https://doi.org/10.3390/f14051059 - 21 May 2023
Cited by 2 | Viewed by 1512
Abstract
Pine wilt disease (PWD) is regarded as one of the most serious conifer diseases affecting pines worldwide. To date, an in-depth study of the driving mechanisms behind short-distance PWD spread is lacking. In this study, we collected PWD forest subcompartment data in Fushun, [...] Read more.
Pine wilt disease (PWD) is regarded as one of the most serious conifer diseases affecting pines worldwide. To date, an in-depth study of the driving mechanisms behind short-distance PWD spread is lacking. In this study, we collected PWD forest subcompartment data in Fushun, China, and analysed the effects of factors on the short-distance transmission of PWD; the analysed factors included the number of neighbouring PWD-infected forest subcompartments, the canopy density, the slope direction, and different traffic corridor types. The results suggested that the spatial spill-over effect of nearby PWD-infected subcompartments contributed the most to short-distance PWD transmission, with an impact of up to 78% on its propagation. The impact of the traffic corridor was 20%. With the help of a beetle vector, PWD can spread to nearby forest subcompartments, and this spatial PWD spill-over effect showed a linearly decaying trend as the distance to neighbouring subcompartments increased. Different traffic corridor types exhibited significant PWD transmission impact differences. County roadways and highways had great impacts, while others had relatively small impacts. For each additional 100 m of distance from a county roadway, highway, national, or provincial roadway, the PWD infection risks in forest subcompartments were reduced by 18%, 11%, 5%, and 3%, respectively. In this study, we quantified the influence of driving factors on the short-distance spread of PWD and provided a theoretical basis for the control of PWD transmission; the results obtained herein are critical for maintaining the ecological security of forests, promoting ecological forest management and stabilising forest carbon sinks. Full article
(This article belongs to the Section Forest Health)
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20 pages, 5661 KiB  
Article
Prediction of Potential Distribution Patterns of Three Larix Species on Qinghai-Tibet Plateau under Future Climate Scenarios
by Xiu An, Tousheng Huang, Huayong Zhang, Junjie Yue and Bingjian Zhao
Forests 2023, 14(5), 1058; https://doi.org/10.3390/f14051058 - 21 May 2023
Cited by 5 | Viewed by 2010
Abstract
How climate change affects the plants on the Qinghai-Tibet Plateau (QTP) has become a hot research topic in recent years. It was widely recognized that Larix. are sensitive to climate change, while the corresponding research of Larix. on the QTP has [...] Read more.
How climate change affects the plants on the Qinghai-Tibet Plateau (QTP) has become a hot research topic in recent years. It was widely recognized that Larix. are sensitive to climate change, while the corresponding research of Larix. on the QTP has been rare. Using the maximum entropy (MaxEnt) model, we predicted the potential distribution patterns of Larix potaninii Batalin, Larix griffithii and Larix speciosa on the QTP in this study under different future climate scenarios. The results demonstrated that the area of suitable habitat for Larix potaninii Batalin (Larix griffithii) presented a loss (gain) trend, while that for Larix speciosa remained unchanged on the whole. The centroids of their suitable habits all migrated to the high-altitude and high-latitude areas, suggesting the three species may take the same survival strategy in response to climate change. Annual Precipitation was the most significant environmental factor influencing the distribution pattern of Larix potaninii Batalin, while Temperature Annual Range was the most significant for Larix griffithii and Larix speciosa. The overlapping potential suitable area for the three Larix species was the maximum under the 2041–2060 SSP126 future climate scenarios and decreased with the increasing emission concentration, suggesting that the niches of these species may step towards separation. This study suggested the survival strategies of the Larix species in response to climate change and the findings may provide a reliable basis for conserving the endangered Larix species under different future climate scenarios. Full article
(This article belongs to the Section Forest Meteorology and Climate Change)
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17 pages, 4159 KiB  
Article
The Sensitivity Feature Analysis for Tree Species Based on Image Statistical Properties
by Xin Shi and Jiangming Kan
Forests 2023, 14(5), 1057; https://doi.org/10.3390/f14051057 - 21 May 2023
Cited by 1 | Viewed by 1197
Abstract
While the statistical properties of images are vital in forestry engineering, the usefulness of these properties in various forestry tasks may vary, and certain image properties might not be enough to adequately describe a particular tree species. To address this problem, we propose [...] Read more.
While the statistical properties of images are vital in forestry engineering, the usefulness of these properties in various forestry tasks may vary, and certain image properties might not be enough to adequately describe a particular tree species. To address this problem, we propose a novel method to comprehensively analyze the relationship between various image statistical properties and images of different tree species, and to determine the subset of features that best describe each individual tree species. In this study, we employed various image statistical properties to quantify images of five distinct tree species from diverse places. Multiple feature-filtering methods were used to find the feature subset with the greatest correlation with the tree species category variable. Support Vector Machines (SVM) were employed to determine the number of features with the greatest correlation with the tree species, and a grid search was used to optimize the model. For each type of tree species image, we obtained the important ranking of all features in this type of tree species, and the sensitive feature subset of various tree species according to the order of features was determined by adding them to the Deep Support Vector Data Description (Deep SVDD). Finally, the feasibility of using a sensitive subset of the tree species was confirmed. The experimental results revealed that by utilizing the filtering method in conjunction with SVM, a total of eight feature subsets with the highest correlation with tree species categories were identified. Additionally, the sensitive feature subsets of different tree species exhibited significant differences. Remarkably, employing the sensitive feature subset of each tree species resulted in F1-score higher than 0.7 for all tree species. These experimental results demonstrate that the sensitive feature subset of tree species based on image statistical properties can serve as a potential representation of a specific tree species, while features that are less strongly associated with tree species may be significant in related areas, such as forestry protection and other related fields. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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14 pages, 4384 KiB  
Article
Screen of Pinus massoniana for Resistance to Pinewood Nematode: In Vitro Propagation and Evaluation of Regenerated Microshoots
by Jia-Yi Guo, Zi-Hui Zhu, You-Mei Chen and Li-Hua Zhu
Forests 2023, 14(5), 1056; https://doi.org/10.3390/f14051056 - 21 May 2023
Viewed by 2133
Abstract
To accelerate breeding of Pinus massoniana Lamb. resistance to pine wilt disease (PWD), caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus, a protocol was established for the in vitro propagation of P. massoniana and the evaluation of resistance of regenerated microshoots from [...] Read more.
To accelerate breeding of Pinus massoniana Lamb. resistance to pine wilt disease (PWD), caused by the pinewood nematode (PWN), Bursaphelenchus xylophilus, a protocol was established for the in vitro propagation of P. massoniana and the evaluation of resistance of regenerated microshoots from different clones to PWN. Axillary bud induction was achieved by culturing cotyledonary node explants from 3-week-old seedlings in Gupta and Durzan (DCR) medium that was supplemented with 4 mg L−1 6-benzyladenine (BA) and 0.2 mg L−1 α-naphthaleneacetic acid (NAA). Explants with induced buds were transferred to DCR medium without a plant growth regulator to facilitate elongation. Stem segments from elongated shoots were used as propagules for further shoot multiplication. Six-month-old regenerated shoots that met the requirements for a nematode resistance test were inoculated with aseptic PWN (500 PWNs/shoot). The wilting rate varied between clones from 20% to 100%, 18 days after inoculation. Except for Clone 227, which showed the highest resistance with a wilting rate of 0%, other clones showed wilting to various degrees 30 d after inoculation. The number of nematodes that were recovered from Clone 227 was significantly lower than from other clones. This study promotes the resistance breeding of P. massoniana to pine wilt disease and provides an effective method to study the host/pathogen interaction between PWN and P. massoniana. Full article
(This article belongs to the Special Issue Advance in Pine Wilt Disease)
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14 pages, 3184 KiB  
Article
Effect of Irradiation Process on Physical and Chemical Properties and Mildew Resistance of Bamboo
by Shengfeng Mao, Zhuchao Xu, Qiuyi Wang, Xin Han, Xinzhou Wang, Meiling Chen and Yanjun Li
Forests 2023, 14(5), 1055; https://doi.org/10.3390/f14051055 - 20 May 2023
Cited by 3 | Viewed by 1898
Abstract
With the scarcity of wood resources and calls for “substituting bamboo for wood” and “substituting bamboo for plastic”, bamboo has gained greater popularity for its abundant reserves and outstanding mechanical properties. However, Mildew is a common problem for bamboo, which can significantly reduce [...] Read more.
With the scarcity of wood resources and calls for “substituting bamboo for wood” and “substituting bamboo for plastic”, bamboo has gained greater popularity for its abundant reserves and outstanding mechanical properties. However, Mildew is a common problem for bamboo, which can significantly reduce the quality and service lives of bamboo products. In this work, a safe, eco-friendly, controllable and efficient method of gamma-ray irradiation was used to modify bamboo. The irradiation dose, moisture content (MC), and irradiation dose rate were adopted as factors of an orthogonal experiment. The results showed that the bamboo strips reached their best mechanical properties under the condition of irradiation at 150 KGy doses, moisture content of 40%, and irradiation dose rate of 44 KGy/H. In addition, the change in the chemical composition of bamboo and mildew resistance was also explored in this paper. The major chemical components (cellulose, hemicellulose and lignin), as well as starch, were degraded, and the bamboo strips exhibited excellent mildew resistance after gamma-ray irradiation. Full article
(This article belongs to the Section Wood Science and Forest Products)
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23 pages, 5549 KiB  
Article
MISF: A Method for Measurement of Standing Tree Size via Multi-Vision Image Segmentation and Coordinate Fusion
by Lufeng Mo, Lijuan Shi, Guoying Wang, Xiaomei Yi, Peng Wu and Xiaoping Wu
Forests 2023, 14(5), 1054; https://doi.org/10.3390/f14051054 - 20 May 2023
Cited by 2 | Viewed by 1656
Abstract
With the development of computer vision technology, its applications in forestry are steadily becoming wider. To address the problems of inconvenience in transporting unmanned aerial vehicles (UAVs), as well as the complex operation of large instruments for measurement, a new method based on [...] Read more.
With the development of computer vision technology, its applications in forestry are steadily becoming wider. To address the problems of inconvenience in transporting unmanned aerial vehicles (UAVs), as well as the complex operation of large instruments for measurement, a new method based on multi-vision image segmentation and coordinate fusion (MISF) is proposed in this paper for measuring the size of standing trees. In MISF, after images of a standing tree are captured using a camera from multiple angles, a semantic segmentation method based on deep learning is used to segment the main body of the standing tree and automatically detect the edge feature points. Next, the effects of visual field splicing and fusion are analyzed collaboratively using the correlations among images, so as to restore the three-dimensional spatial information of the feature points of the tree to be measured. Lastly, the size attributes of the standing tree, such as height, diameter at breast height (DBH), and crown width, are automatically measured. The urban environment measurement experiment showed that the relative errors of tree height, DBH, and crown width measured using the proposed method, i.e., MISF, were 1.89%, 2.42%, and 3.15%, respectively, representing a significant enhancement compared with binocular measurement. On the one hand, the experimental results exhibited a high degree of measurement accuracy; therefore, MISF can be used for the management inventory of typical forests. On the other hand, MISF cannot be used if a tree’s images cannot be acquired due to environmental or other reasons. Full article
(This article belongs to the Section Forest Inventory, Modeling and Remote Sensing)
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14 pages, 2041 KiB  
Article
Uncertainties of Climate Change on Suitable Habitat of Calligonum mongolicum Turcz. (Polygonaceae) in Desert Areas of Central Asia
by Guan Liu, Yanru Zhang, Qi Lu, Keli An, Yurong Li, Dongyang Xiong, Guoqing Li and Sheng Du
Forests 2023, 14(5), 1053; https://doi.org/10.3390/f14051053 - 20 May 2023
Cited by 1 | Viewed by 1790
Abstract
Understanding the climatically suitable habitat of species plays a vital role in the sustainable use and management of target species. Calligonum mongolicum Turcz., a native shrub species found in desert areas of Central Asia, is generally considered as one of the top four [...] Read more.
Understanding the climatically suitable habitat of species plays a vital role in the sustainable use and management of target species. Calligonum mongolicum Turcz., a native shrub species found in desert areas of Central Asia, is generally considered as one of the top four tree species for desertification control. However, previous works on suitable habitat simulation had focused mainly on either the national or specific geographical scales rather than entire biota scales, which have underestimated the climatic tolerance of the species. Furthermore, the uncertainty outcomes of climate change were largely ignored. With these questions, the arid regions of Central Asia were selected as our research background area. Occurrence data of C. mongolicum were obtained from various sources, such as the Global Biodiversity Information Facility, the Chinese Virtual Herbarium, and the iPlant website. The maximum entropy model (MaxEnt) was used to simulate the suitable habitat change dynamics under various climate change scenarios [5 general circulation models (GCMs) × 3 shared socioeconomic pathways (SSPs)]. The uncertainty of climate change induced by GCMs and SSPs were decomposed by the two-way ANOVA method. Our results show that hydrological-related variables are more important for the species’ habitat suitability than thermal-related variables. The climatic threshold for the core suitable habitat was 1–30 mm for precipitation of the coldest quarter, 14–401 mm for annual precipitation, −16.01–12.42 °C for mean temperature of the driest quarter, 9.48–32.63 °C for mean temperature of the wettest quarter, and −25.01–−9.77 °C for the minimum temperature of the coldest month. The size of suitable habitat was about 287.4 × 104 km2 under the current climate condition, located in China and Mongolia. Climate change has less impact on the total area size, but it has bigger impacts on the gain area and loss area sizes. The loss area is mainly located in the southeast boundaries, whereas the gain area is mainly located in Mongolia and the Qinghai-Tibet Plateau. The decomposition uncertainty of climate change indicates that GCMs could explain 14.5%, 66.4%, and 97.0% of total variation, respectively, and SSPs could explain 85.5%, 33.6%, and 3.0% of the total variation for gain, loss, and total habitat sizes, respectively. Our work clearly demonstrates that while C. mongolicum has great planting potential in Central Asia under various climate change scenarios, the sensitive areas possess large uncertainties requiring long-term climate monitoring for afforestation projects. Full article
(This article belongs to the Special Issue Indicators and Baselines of Afforestation and Reforestation)
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13 pages, 2133 KiB  
Article
Forest Land Expectation Value or Maximum Sustained Yield? Resolving A Long-Standing Paradox
by Craig Loehle
Forests 2023, 14(5), 1052; https://doi.org/10.3390/f14051052 - 19 May 2023
Cited by 2 | Viewed by 2879
Abstract
The Faustmann formula, equivalent to the land expectation value (LEV), yields the present value, starting with bare land, of an infinite series of future timber rotations for a stand. If this formula is used to find the rotation age that maximizes the present [...] Read more.
The Faustmann formula, equivalent to the land expectation value (LEV), yields the present value, starting with bare land, of an infinite series of future timber rotations for a stand. If this formula is used to find the rotation age that maximizes the present value, a lower annual harvest will result when compared to a maximum sustained yield (MSY) regime for an ownership with many stands. However, the LEV is strongly preferred by economists. This is the LEV vs. rents paradox. Herein, this paper demonstrates that an infinite series of annual harvests for an ownership under an even flow regime, discounted to the present using any interest rate, will provide the same optimal rotation age as the time of the peak MAI for a single stand, though with different estimates for the profitability, depending on the interest rate. Thus, rotations producing the MSY and the maximum financial return are identical when analyzed at the ownership scale but are not the same when based on the analysis at the stand scale using the Faustmann formula (LEV). This is the solution to the paradox. The formulas for internal rate of return (IRR) and the land valuation for transaction purposes are also presented. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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15 pages, 7229 KiB  
Article
Complete Chloroplast Genome of Bamboo Species Pleioblastus ovatoauritus and Comparative Analysis of Pleioblastus from China and Japan
by Weihan Peng, Beibei Wang, Zhuolong Shen and Qirong Guo
Forests 2023, 14(5), 1051; https://doi.org/10.3390/f14051051 - 19 May 2023
Viewed by 2473
Abstract
Pleioblastus ovatoauritus T.H.Wen ex W.Y.Zhang is bamboo species published in 2018, originated from and existing in southeastern China. The chloroplast genome of Pl. ovatoauritus was obtained using a high-throughput sequencing platform. The chloroplast genome is up to 139,708 bp in length and displays [...] Read more.
Pleioblastus ovatoauritus T.H.Wen ex W.Y.Zhang is bamboo species published in 2018, originated from and existing in southeastern China. The chloroplast genome of Pl. ovatoauritus was obtained using a high-throughput sequencing platform. The chloroplast genome is up to 139,708 bp in length and displays a typical quadripartite structure with one large single-copy region, one small single-copy region, and two inverted repeat regions. There are 82 protein-coding genes, 8 rRNA genes, and 39 tRNA genes in the plastome genome. However, the interspecific relationship of Pleioblastus species originated from China and Japan has not been revealed explicitly. To understand their relationship, data from four Chinese species and four Japanese species were selected to investigate the distinctions between their genome structures, codon usage patterns, and SSR sites. We moved forward to examine the sequence divergence and polymorphic sites between the eight species. Phylogenetic trees were then plotted using the maximum likelihood method based on different parts of the sequences. Obvious difference found in the JLB boundary and a split in the phylograms contributed to our decision to split Pleioblastus species of China and Japan into different clades. Moreover, taxonomy using the subgenera concept in Flora Reipublicae Popularis Sinicae proved untenable. Nine SSR primers for Pleioblastus genus were then developed from cp genomes, aimed at facilitating identification and germplasm investigation. Full article
(This article belongs to the Topic Plant Chloroplast Genome and Evolution)
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14 pages, 8548 KiB  
Article
Tree Species Identification in Urban Environments Using TensorFlow Lite and a Transfer Learning Approach
by Diego Pacheco-Prado, Esteban Bravo-López and Luis Ángel Ruiz
Forests 2023, 14(5), 1050; https://doi.org/10.3390/f14051050 - 19 May 2023
Cited by 2 | Viewed by 2735
Abstract
Building and updating tree inventories is a challenging task for city administrators, requiring significant costs and the expertise of tree identification specialists. In Ecuador, only the Trees Inventory of Cuenca (TIC) contains this information, geolocated and integrated with the taxonomy, origin, leaf, and [...] Read more.
Building and updating tree inventories is a challenging task for city administrators, requiring significant costs and the expertise of tree identification specialists. In Ecuador, only the Trees Inventory of Cuenca (TIC) contains this information, geolocated and integrated with the taxonomy, origin, leaf, and crown structure, phenological problems, and tree images taken with smartphones of each tree. From this dataset, we selected the fourteen classes with the most information and used the images to train a model, using a Transfer Learning approach, that could be deployed on mobile devices. Our results showed that the model based on ResNet V2 101 performed best, achieving an accuracy of 0.83 and kappa of 0.81 using the TensorFlow Lite interpreter, performing better results using the original model, with an accuracy and kappa of 0.912 and 0.905, respectively. The classes with the best performance were Ramo de novia, Sauce, and Cepillo blanco, which had the highest values of Precision, Recall, and F1-Score. The classes Eucalipto, Capuli, and Urapan were the most difficult to classify. Our study provides a model that can be deployed on Android smartphones, being the beginning of future implementations. Full article
(This article belongs to the Special Issue Urban Forestry Measurements)
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17 pages, 8541 KiB  
Article
How Climate Change Impacts the Distribution of Lithocarpus hancei (Fagaceae), a Dominant Tree in East Asian Montane Cloud Forests
by Yongjingwen Yang, Lin Lin, Yunhong Tan and Min Deng
Forests 2023, 14(5), 1049; https://doi.org/10.3390/f14051049 - 18 May 2023
Cited by 1 | Viewed by 1957
Abstract
Subtropical montane moist evergreen broadleaf forests (MMEBFs) have a unique environmental envelope harboring a high percentage of endemic biota. This ecosystem is highly vulnerable, and little is known about its possible response to future climate change. In this study, we used Lithocarpus hancei [...] Read more.
Subtropical montane moist evergreen broadleaf forests (MMEBFs) have a unique environmental envelope harboring a high percentage of endemic biota. This ecosystem is highly vulnerable, and little is known about its possible response to future climate change. In this study, we used Lithocarpus hancei (Fagaceae), a dominant tree in East Asian subtropical MMEBFs, as a proxy to investigate MMEBF distribution dynamics and key distribution restriction factors. In total, 607 L. hancei occurrence points were obtained after being gathered and filtered. The random forest model was selected as the best model. Eight environmental variables were selected to simulate the potential suitable areas of L. hancei under the Last Glacial Maximum (LGM), present, and future (2041–2060, 2061–2080, 2081–2100) climate change scenarios, including four shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, SSP5-8.5). Our results showed that precipitation of the warmest quarter, the precipitation of the driest month, the mean diurnal range, and temperature seasonality are the key factors affecting the spatial range of L. hancei with 11.2%, 10.9%, 8.1%, and 7.6% contributions, respectively. The current distribution of L. hancei is mainly within East and South China, with a scattered distribution in North Indo-China and the Southeast Himalayas. The highly suitable area only accounts for 9.7% of the total distribution area. The distribution area of the current suitability area is the smallest compared to that under LGM and future scenarios. In all the future climatic scenarios, the highly suitable areas of L. hancei would decrease or even disappear, whereas the medium- and low-suitability areas might increase with the centroid of the total suitable area northern. Its distribution in Central China, the Southern Himalayas, and Northern Indo-China will be lost in the future. Overall, our study predicted a prominent degradation of East Asian MMEBFs in the future. In situ and ex situ conservation on East Asian MMEBFs should be prioritized and enforced. Full article
(This article belongs to the Special Issue Forest Species Distribution, Diversity and Growth under Climate Change)
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18 pages, 4689 KiB  
Article
Legacy of Prior Management of Cropland after Afforestation with Populus x euroamericana (Dode) Guinier: Effects on Soil Respiration
by María Eugenia Priano, Félix Zorita and Carmen Trasar-Cepeda
Forests 2023, 14(5), 1048; https://doi.org/10.3390/f14051048 - 18 May 2023
Viewed by 1328
Abstract
Afforestation is a good strategy for climate change mitigation through increasing carbon stocks. This study determined changes in soil respiration (SR) brought about by the afforestation of high quality agricultural land in a temperate-humid region (Galicia, NW Spain), identified the variables that explain [...] Read more.
Afforestation is a good strategy for climate change mitigation through increasing carbon stocks. This study determined changes in soil respiration (SR) brought about by the afforestation of high quality agricultural land in a temperate-humid region (Galicia, NW Spain), identified the variables that explain the observed changes and determined the main factors regulating SR temporal variation. Paired plots of fertile soils (cropped vs. afforested plots) were established in two similar areas (Pontevea and Laraño) where afforestation with Populus x euroamericana (Dode) Guinier was carried out in the same year. Different management practices and crop rotations were used (maize–pasture, Laraño and maize–fallow, Pontevea). The SR was measured in situ with a CO2 static chamber every 15 days (every month in winter) for 16 months; soil temperature (Ts) and soil moisture content (W) were also measured. In both areas, significant differences (p < 0.05) in SR between paired plots were related to soil organic C content and SR was mainly influenced by Ts, except during the summer period where SR fluctuations were accompanied by W fluctuations. These findings show that growing pasture crops on high quality land can prevent the loss of soil N and C and probably improve the greenhouse gas balance in the system. Full article
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11 pages, 5740 KiB  
Article
The Influence of Processing Conditions on the Quality of Bent Solid Wood from European Oak
by Aleš Straže, Jure Žigon, Stjepan Pervan, Mislav Mikšik and Silvana Prekrat
Forests 2023, 14(5), 1047; https://doi.org/10.3390/f14051047 - 18 May 2023
Cited by 1 | Viewed by 1551
Abstract
Bending of solid wood from European oak is one of the most demanding technological processes due to its specific structural and physical properties and variability. We investigated the influence of wood moisture content (MC) and stiffness, determined by NDT, as well as previous [...] Read more.
Bending of solid wood from European oak is one of the most demanding technological processes due to its specific structural and physical properties and variability. We investigated the influence of wood moisture content (MC) and stiffness, determined by NDT, as well as previous drying methods on the bending ability of the wood. The best quality was obtained with bending specimens bent at a moisture content of at least 16% and quarter- or semi-quartersawn. The number of rejected specimens increased slightly when HF bending was used. Single-stage predrying of oak to a final MC of 8% resulted in a high rejection rate (>70%) regardless of drying technique. The acceptance rate was higher for less stiff specimens where the ratio of ultrasonic velocity in the straight (vS) and bent region (vB) was less than 0.5 (vB/vS). Full article
(This article belongs to the Special Issue Advanced Technologies in Physical and Mechanical Wood Modification)
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18 pages, 3675 KiB  
Article
Logging Affects Genetic Diversity Parameters in an Araucaria angustifolia Population: An Endangered Species in Southern Brazil
by Rafael H. Roque, Alexandre M. Sebbenn, David H. Boshier, Afonso F. Filho and Evandro V. Tambarussi
Forests 2023, 14(5), 1046; https://doi.org/10.3390/f14051046 - 18 May 2023
Cited by 1 | Viewed by 1732
Abstract
Araucaria angustifolia is an endangered species with more than 97% of its natural populations extinct. Logging of the species in the few remaining natural populations is highly restricted, though not readily accepted by farmers and logging companies. Consequently, political pressures have emerged for [...] Read more.
Araucaria angustifolia is an endangered species with more than 97% of its natural populations extinct. Logging of the species in the few remaining natural populations is highly restricted, though not readily accepted by farmers and logging companies. Consequently, political pressures have emerged for a return to logging of the species. Assessing the sustainability of such logging requires studies of a range of impacts on the remaining populations, including their genetic viability. We investigated the effect of selective logging on genetic diversity, intrapopulation spatial genetic structure (SGS), effective population size (Ne), and pollen and seed dispersal in three A. angustifolia permanent sample blocks established in a remnant of Araucaria Forest in Brazil. In these sample blocks, three logging intensities were applied (LI: 18.4, 31.4, and 32.3% of trees). Microsatellite analysis was performed for all adult and juvenile trees pre- and post-logging saplings. After selective logging, the greatest loss of alleles and the greatest decrease in Ne were observed from the highest LI. Logging increased SGS, while the distance and patterns of pollen and seed dispersal were different for both pre- and post-logging scenarios, with pollen dispersed over greater distances than seed. Pollen dispersal distance post-logging and seed dispersal distance pre- and post-logging decreased with the increased distance between parents. After logging, Ne reduced from 27.7 (LI = 31.4%) to 28.8 (LI = 18.4%) and 39.5% (LI = 32.3%), and some alleles were lost. Despite this, the loss of these alleles may be compensated for in subsequent generations, considering that logging resulted in changes such as an increase in the rate and distance of pollen immigration. Under the conditions evaluated in this study, selective logging of A. angustifolia is not adequate. To achieve truly sustainable forest logging, new rules that combine higher minimum DBH, lower logging intensity, and longer cutting cycles must be adopted. Furthermore, extensive genetic studies must be performed before logging any individual from a natural population. Full article
(This article belongs to the Special Issue Geographic Distribution of Quantitative Trait Variation and Genetic Variability in Natural Tree Species)
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31 pages, 13839 KiB  
Article
Identifying Cultural Ecosystem Services and Relevant Landscape Elements Provided by Urban Green Space throughout History from an Information Communication Perspective
by Wei Gao, Siyou Wang, Shaotao Chen, Shengjie Hu and Hui Li
Forests 2023, 14(5), 1045; https://doi.org/10.3390/f14051045 - 18 May 2023
Cited by 3 | Viewed by 2141
Abstract
Throughout the long history of urban expansion and development, some of the natural mountains, lakes, and rivers that were once located on the outskirts of a city have gradually been encircled within it and have become nature in the urban, i.e., they are [...] Read more.
Throughout the long history of urban expansion and development, some of the natural mountains, lakes, and rivers that were once located on the outskirts of a city have gradually been encircled within it and have become nature in the urban, i.e., they are now in the heart of the city. These are not only green infrastructure for contemporary cities; they have also accumulated a rich cultural heritage and are closely related to the physical health and subjective well-being of city dwellers. The objectives of this study were: (1) to identify the no-material services that the public perceives from UGSs throughout history that contribute to subjective well-being; (2) to analyze which landscape elements are associated with the provision of such services and then to clarify the value of UGSs throughout history and provide a theoretical basis for urban managers. We returned to the original concept of cultural services (information services) to understand how UGSs throughout history, as information sources, have provided subjective well-being to specific groups of people. And we build a classification system for information services based on this understanding. Based on existing research methods on cultural services, we found that collecting information carriers such as texts, images, and interview transcripts is a more effective way to identifying the intangible services provided by a landscape than monetary methods. From understanding of the information communication process, we attempted to integrate the supply and demand indicators of information services. We validated the feasibility of the method of information service identification using Yuexiu Hill in Guangzhou, which has a construction history of 2000 years, as an example. Through the word frequency statistics of 1063 ancient poems (a type of information carrier), elements of the historical landscape of Yuexiu Hill and the information services provided in the past were identified. After that, semantic networks were constructed to analyze the association between elements and services. The results of this study show that information service identification is an effective method of analyzing the effect of the promotion of UGSs throughout history on the subjective well-being of the public. The provision of information services depends on the accumulation and dissemination of environmental information; both natural and cultural elements, especially symbolic elements, play an important role in this process. Full article
(This article belongs to the Special Issue Strategic Planning of Urban Green Space in Large Spatiotemporal Scales)
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11 pages, 4748 KiB  
Article
Simulated Nitric Acid Rain Aggravated the C and P Limits of Forest Soil Microorganisms
by Meijia Zhou, Jinlong Wang, Haibo Hu, Jianyu Chen, Ziyi Zhu, Yuchen Heng and Yuanyuan Feng
Forests 2023, 14(5), 1044; https://doi.org/10.3390/f14051044 - 18 May 2023
Cited by 4 | Viewed by 1627
Abstract
With the comprehensive emissions of fossil fuel combustion and transportation waste gas, the concentrations of nitrogen oxides (NOX) in the environmental atmosphere increase significantly, leading to nitric acid rain (NAR) pollution. However, the effects of NAR on soil enzyme activities and [...] Read more.
With the comprehensive emissions of fossil fuel combustion and transportation waste gas, the concentrations of nitrogen oxides (NOX) in the environmental atmosphere increase significantly, leading to nitric acid rain (NAR) pollution. However, the effects of NAR on soil enzyme activities and soil microbial metabolism are unclear. In this study, the Quercus acutissima Carruth. forest in the Yangtze River Delta of China was selected as the experimental subject, and was exposed to the simulated spraying of NAR with pH values of 2.5, 3.5, and 4.5 to study the response of the forest soil enzyme activities and soil microbial metabolism to NAR. The results showed that compared to the non-NAR treatment, the activities of β-1,4-glucosidase (BG), L-leucine aminopeptidase (LAP), and β-1,4-N-acetylglucosidase (NAG) decreased by 56.48%–42.24%, 44.57%–38.20%, and 56.13%–48.11% under the AR2.5 and AR3.5 treatments, respectively. Moreover, there was no significant change in the Vector Length (VL) under different gradients of NAR. The Vector Angle (VA) increased with the decrease of the pH value and reached the maximum value with the AR2.5 treatment, indicating that the strong acid type NAR had a greater phosphorus-limiting effect on the soil microorganisms. The RDA analysis results showed that the dissolved organic carbon (DOC) was a significant factor affecting the soil enzyme activity and stoichiometric ratio, with interpretation rates of 40.2%. In conclusion, we believe that in the restoration of acidified soil, attention should be paid to the regulation of soil pH, reducing scour. Full article
(This article belongs to the Section Forest Soil)
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19 pages, 4870 KiB  
Article
Assessing the Likelihood of Failure Due to Stem Decay Using Different Assessment Techniques
by Ari Okun, Nicholas J. Brazee, James R. Clark, Michael J. Cunningham-Minnick, Daniel C. Burcham and Brian Kane
Forests 2023, 14(5), 1043; https://doi.org/10.3390/f14051043 - 18 May 2023
Cited by 4 | Viewed by 2128
Abstract
Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that: (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) sophisticated tools can reliably [...] Read more.
Arborists commonly investigate the extent of stem decay to assess the likelihood of stem failure when conducting tree risk assessments. Studies have shown that: (i) arborists can sometimes judge the extent of internal decay based on external signs; (ii) sophisticated tools can reliably illustrate the extent of internal decay; and (iii) assessing components of tree risk can be highly subjective. We recruited 18 experienced tree risk assessors who held the International Society of Arboriculture’s Tree Risk Assessment Qualification (TRAQ) to assess the likelihood of stem failure due to decay after each of five consecutive assessments on 30 individuals of 2 genera. The five assessment techniques, in stepwise order, were: (1) observing visually, (2) sounding the trunk with a mallet, (3) viewing a scaled diagram of the cross-section that revealed sound and decayed wood ascertained from resistance drilling, (4) viewing sonic and electrical resistance tomograms, and (5) consulting with a peer. For each technique, the assessors assigned two or more likelihood of failure ratings (LoFRs) for at least 83% of trees, which were proportionally greatest after the assessors viewed the tomograms; the proportions did not differ among the other four assessment techniques. Covariates that influenced the distribution of the LoFRs included percent of the cross-section that was decayed, and assessors’ experience using resistance drilling devices and tomography in regular practice. Practitioners should be aware that disagreement on the likelihood of tree failure exists even among experienced arborists. Full article
(This article belongs to the Special Issue Prediction and Management of Urban Forest Storm Damage)
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20 pages, 5043 KiB  
Article
Leaf Angle as a Criterion for Optimizing Irrigation in Forest Nurseries: Impacts on Physiological Seedling Quality and Performance after Planting in Pots
by Richardson Barbosa Gomes da Silva, Danilo Simões, Ivar Wendling, Débora Zanoni do Prado, Maria Márcia Pereira Sartori, Angelo Albano da Silva Bertholdi and Magali Ribeiro da Silva
Forests 2023, 14(5), 1042; https://doi.org/10.3390/f14051042 - 18 May 2023
Viewed by 1666
Abstract
Seedling species with different architectures, e.g., mean leaf angles, are often subjected to the same irrigation management in forest nurseries, resulting in wasted water and fertilizer and reduced seedling quality. We aimed to evaluate whether irrigation volumes applied to tree seedling species with [...] Read more.
Seedling species with different architectures, e.g., mean leaf angles, are often subjected to the same irrigation management in forest nurseries, resulting in wasted water and fertilizer and reduced seedling quality. We aimed to evaluate whether irrigation volumes applied to tree seedling species with different leaf angles affect the physiological quality in forest nurseries and, consequently, performance after potting. We submitted nine seedling species with different mean leaf angles to four daily water regimes (8, 10, 12, and 14 mm). In the nursery, the following physiological attributes were considered to assess seedling quality: leaf water potential, daily transpiration rate, SPAD value, chlorophyll a and b, anthocyanins, carotenoids, and total nutrient content. After potting, we evaluated height and stem diameter over 120 days. Leaf angle can be used as a criterion for optimizing irrigation in forest nurseries, avoiding water and fertilizer wastage, and increasing physiological seedling quality. Leaf angle measurements combined with concurrent assessments of leaf traits are helpful in further understanding the effects of leaf angle variation and water regime on seedling quality. For positive leaf angles, an irrigation volume of 8 mm is sufficient to increase physiological seedling quality. Conversely, seedlings with negative leaf angles show the opposite response, requiring the largest irrigation volume (14 mm) to increase physiological seedling quality, except when the mean leaf area is small and concentrated in the upper half of the stem, which facilitates the access of irrigation water to the substrate and thus satisfies seedling water requirements. For all species, up to 120 days after planting in pots, the effect of the irrigation volume that provides greater growth and physiological quality at the end of the nursery phase is not overcome by other irrigation volumes applied. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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13 pages, 3065 KiB  
Article
Trees Adjust the Shape of Branch Unions to Increase Their Load-Bearing Capacity
by Steffen Rust
Forests 2023, 14(5), 1041; https://doi.org/10.3390/f14051041 - 18 May 2023
Viewed by 3774
Abstract
The likelihood of branch union failure often needs to be assessed in tree risk assessment. Most of the guidance used in practice is based on the shape of these forks, specifically the shape (“U” or “V”), the angle between the branches, the presence [...] Read more.
The likelihood of branch union failure often needs to be assessed in tree risk assessment. Most of the guidance used in practice is based on the shape of these forks, specifically the shape (“U” or “V”), the angle between the branches, the presence of lateral bulges, and the aspect ratio of the branches. This study extends previous studies with a novel approach to the biomechanical analysis of fork shape and contributes results from destructive tests on two important European tree species, using comparatively large trees. Surprisingly, many samples deviated from the expected pattern of constant or decreasing cross-sectional area from the trunk beyond the fork. The results show three mechanisms that counteract the potential weakening at a bifurcation, two of which have not been documented before: an increase in section modulus from the stem base to where the stems part, an increase in section modulus caused by lateral bulging, and an increase in section modulus in the branches caused by an adjusted shape. Neither the shape of the forks nor the amount of included bark had a significant impact on their strength. Like several previous studies, the results of this study caution against the use of simple rules to assess the likelihood of branch union failure. The increasing availability of “digital twins” of urban trees may help us to use these results to assess the shape of branch unions in a quantitative way. Full article
(This article belongs to the Special Issue Tree Stability and Tree Risk Analysis)
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10 pages, 2392 KiB  
Article
Treatability Changes of Radiata Pine Heartwood Induced by White-Rot Fungus Trametes versicolor
by Xuan Fang, Yixin Xiong, Jiaxin Li and Xingxia Ma
Forests 2023, 14(5), 1040; https://doi.org/10.3390/f14051040 - 18 May 2023
Cited by 3 | Viewed by 1395
Abstract
Desired retention and depth into wood are necessary for wood preservatives to provide long-term durability. In general, heartwood of wood is difficult to treat, and bioincising was investigated as a potential technique to improve the treatability of refractory wood and heartwood. In order [...] Read more.
Desired retention and depth into wood are necessary for wood preservatives to provide long-term durability. In general, heartwood of wood is difficult to treat, and bioincising was investigated as a potential technique to improve the treatability of refractory wood and heartwood. In order to study the effects of bioincising treatment with white-rot fungus Trametes versicolor on the pore structure and treatability of radiata pine heartwood, this research conducted tests of mass loss, microscopic structures, pore structure parameters, uptake, and penetration of preservative of radiata pine heartwood specimens incubated by T. versicolor for 4, 8, and 12 weeks. The results showed that the optimal inoculation time of T. versicolor bioincising on radiata pine heartwood was 4 to 8 weeks. At this time, the retention of injected preservatives increased by 5.01%–17.73%, the penetration depth of preservatives increased significantly, and the corresponding mass loss was 3.04%–6.45%. The results of microstructure and pore structure showed that T. versicolor entered the adjacent tracheids via apertures, with less impact on the cell wall, mainly degrading pit membranes and ray parenchyma cells early in the inoculation of radiata pine heartwood. As the structures impeding fluid flow were connected, the porosity of the wood and the range of the main pore size distribution increased significantly, thus increasing the treatability of radiata pine heartwood. Full article
(This article belongs to the Special Issue Wood Treatments and Modification Technologies)
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14 pages, 7992 KiB  
Article
Power Compensation Strategy and Experiment of Large Seedling Tree Planter Based on Energy Storage Flywheel
by Binhai Zhu, Jiuqing Liu, Chunmei Yang, Wen Qu and Peng Ding
Forests 2023, 14(5), 1039; https://doi.org/10.3390/f14051039 - 18 May 2023
Cited by 2 | Viewed by 1592
Abstract
The intermittent hole-digging tree-planting machine shows a periodic short-time peak load law in planting operation, and the operation process is “idling” for small loads most of the time, leading to large torque fluctuations in the transmission system, unscientific power matching, and high energy [...] Read more.
The intermittent hole-digging tree-planting machine shows a periodic short-time peak load law in planting operation, and the operation process is “idling” for small loads most of the time, leading to large torque fluctuations in the transmission system, unscientific power matching, and high energy consumption. To solve the above problems, this article proposes to use a series of energy-saving flywheels in the transmission system of the tree planting machine. On the premise of obtaining holes that meet the target young tree planting requirements, the optimal power compensation strategy for the flywheel system of the tree planting machine is studied to reduce torque fluctuations in the power transmission system, use smaller power drive units, and save energy. Firstly, the nonlinear multi-body dynamics simulation model of soil cutting by the hole-digging component is established. The boundary and contact conditions are set to simulate the power consumption of the hole-digging component at three rotating speeds. Based on the simulation results, the flywheel power compensation strategy is discussed, and the torque fluctuation of the flywheel balance system is analyzed. The results showed that the higher the speed, the greater the power consumption. The power value suddenly increased from 17.82 kW (1.28 s) to 27.93 kW (1.43 s) when the speed was 220 r/min. Then, the power value rapidly decreased, and the power consumption presented a short-term peak feature. The transmission system’s maximum input power is determined as 17.82 kW according to the various simulated power consumption characteristics. The part exceeding the power consumption is compensated by the energy storage flywheel. The total compensation energy was 2382.5 J. After the flywheel system was involved, the maximum output power of the tractor power output shaft decreased by 36.2%, and the peak torque decreased from 445.7 N·m to 285.1 N·m. The power consumption obtained from the field test and simulation was similar, but the energy required to overcome peak load was jointly provided by the flywheel and the engine. The actual input power of the power output shaft during the energy release period of the flywheel system was 18.51 kW when the rotating speed of the hole-digging component was 220 r/min, and the relative error with the simulation value was 2.43%. The measured actual speed reduction of the flywheel system was 8.9%. After installing an energy storage flywheel in the transmission system of the tree planting machine, the output power of the power unit can be stabilized. Tree planting machines can be equipped with smaller power units, which can reduce energy consumption and exhaust emissions. Full article
(This article belongs to the Special Issue New Development of Smart Forestry: Machine and Automation)
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10 pages, 2115 KiB  
Brief Report
Energy Expenditure Estimation for Forestry Workers Moving on Flat and Inclined Ground
by Masayuki Okuda, Yutaka Kawamoto, Hiroyuki Tado, Yoshimasa Fujita and Yuta Inomata
Forests 2023, 14(5), 1038; https://doi.org/10.3390/f14051038 - 17 May 2023
Cited by 3 | Viewed by 1750
Abstract
Forestry workers endure highly physical workloads. Japanese forestry workers experience additional up-and-down movements due to geographical features. Fatigue is a common cause of injury. This pilot study aimed to determine an appropriate method for estimating energy expenditure while moving across inclined ground to [...] Read more.
Forestry workers endure highly physical workloads. Japanese forestry workers experience additional up-and-down movements due to geographical features. Fatigue is a common cause of injury. This pilot study aimed to determine an appropriate method for estimating energy expenditure while moving across inclined ground to simulate a Japanese forest. Six participants wore a portable indirect calorimeter (V˙O2), heart rate (HR) monitor (17 g), accelerometer (20 g; vector magnitude; VM), and a global navigation satellite system (GNSS) device. They walked shouldering 20 kg of weight on flat, 15°- and 30°-slopes. The time course of HR was similar to that of V˙O2, but that of VM and the vertical movement varied from that of V˙O2. GNSS cannot correctly detect vertical movements. The HR index (HRI), indicating the ratio of activity HR to resting HR, was significantly correlated with the metabolic equivalent of the task (MET) calculated from V˙O2 (r = 0.932, p < 0.0001), which fit the previously proposed formula for METs (METs = HRI × 6 − 5). However, VM was not correlated with VM (r = 0.354, p = 0.150). We can use HRI to measure the workload of Japanese forestry workers with a small burden in the field. Full article
(This article belongs to the Section Forest Operations and Engineering)
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