Forests

16 pages, 2589 KiB

Open AccessArticle

Comparison of Hydraulic and Aeration Properties of Peat Substrates Used to Produce Containerized White Spruce Seedlings (1+0) in Forest Nurseries

by Simon Boudreault, Jean Caron, Mohammed S. Lamhamedi and Steeve Pepin

Forests 2023, 14(4), 858; https://doi.org/10.3390/f14040858 - 21 Apr 2023

Cited by 1 | Viewed by 1185

Abstract

The physical properties of peat substrates from eight tree nurseries were characterized to determine bulk density, air-filled porosity, saturated hydraulic conductivity, pore effectiveness, relative gas diffusivity and chemical properties. There were significant variations among nurseries both in growth of white spruce [Picea [...] Read more.

The physical properties of peat substrates from eight tree nurseries were characterized to determine bulk density, air-filled porosity, saturated hydraulic conductivity, pore effectiveness, relative gas diffusivity and chemical properties. There were significant variations among nurseries both in growth of white spruce [Picea glauca (Moench) Voss] seedlings (1+0) and substrate properties. Shoot dry mass and root collar diameter were negatively correlated with air-filled porosity and saturated hydraulic conductivity, whereas root dry mass was positively correlated with bulk density. Seedling growth increased with increasing substrate bulk density up to ~0.11 g cm⁻³, above which value conditions may become limiting to plant performance. Our results suggest that there was no growth limitation due to restricted aeration (D_s D₀⁻¹ > 0.005 m² s⁻¹ m⁻² s for all substrates except one) and that over-aeration reduced seedling growth under dry irrigation management. Full article

(This article belongs to the Special Issue Production in Forest Nurseries and Field Performance of Seedlings)

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17 pages, 6075 KiB

Open AccessArticle

Severe Drought Still Affects Reproductive Traits Two Years Later in a Common Garden Experiment of Frangula alnus

by Kristine Vander Mijnsbrugge, Marc Schouppe, Stefaan Moreels, Yorrick Aguas Guerreiro, Laura Decorte and Marie Stessens

Forests 2023, 14(4), 857; https://doi.org/10.3390/f14040857 - 21 Apr 2023

Cited by 1 | Viewed by 1059

Abstract

Longer periods of intensified droughts in Western Europe are predicted due to ongoing climate change. Studying the responses of woody species during intense drought events can help toward understanding the consequences for forest ecosystems. We studied the effects of an intense summer water [...] Read more.

Longer periods of intensified droughts in Western Europe are predicted due to ongoing climate change. Studying the responses of woody species during intense drought events can help toward understanding the consequences for forest ecosystems. We studied the effects of an intense summer water limitation on several reproductive traits, two years after the treatment, in Frangula alnus Mill. shrubs grown in a common garden. Drought-treated shrubs produced more berries one and two years after the drought event, while the height increment of the second post-treatment year was still significantly retarded. The mean weight of stones from berries picked two years after the drought treatment and their germination percentage, which was corrected for mean stone weight, were higher for the treated shrubs. These results indicate a resource re-allocation toward reproduction, rather than toward growth, which was still in action two years after the water limitation. The higher germination success, which is a transgenerational effect, and which has already been suggested to be an adaptation to survival in more stressful growth conditions, is also still detectable two years after the severe drought. F. alnus produces mature berries continuously during the whole summer. From the middle of July till the end of August, the counts of mature berries, the mean stone weight and the germination percentage, corrected for mean stone weight, decreased, whereas the timing of seedling emergence, also corrected for stone weight, advanced slightly. The timing of seedling emergence correlated weak but significantly with the timing of bud burst in the mother shrubs, with a variance analysis indicating a stronger genetic control for bud burst in comparison to seedling emergence. Several results corroborated previous findings. Population differentiation in the common garden was observed for mature berry counts and for several phenological traits. In conclusion, longer-term effects of drought on reproductive traits in woody species may add more complexity to the consequences of climate change on tree species distributions and survival of forest ecosystems. Full article

(This article belongs to the Special Issue Impact of Climate Warming and Disturbances on Forest Ecosystems)

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19 pages, 2775 KiB

Open AccessArticle

The Effect of Biochar Amendment, Microbiome Inoculation, Crop Mixture and Planting Density on Post-Mining Restoration

by Degi Harja Asmara, Suzanne Allaire, Meine van Noordwijk and Damase P. Khasa

Forests 2023, 14(4), 856; https://doi.org/10.3390/f14040856 - 21 Apr 2023

Cited by 1 | Viewed by 1375

Abstract

Ecological restoration with a multispecies and multifunctional approach can accelerate the re-establishment of numerous ecosystem services. The challenges with land that is degraded, damaged, or destroyed post-mining are the low productivity of soil and the high potential for contaminants. Herein, we evaluated the [...] Read more.

Ecological restoration with a multispecies and multifunctional approach can accelerate the re-establishment of numerous ecosystem services. The challenges with land that is degraded, damaged, or destroyed post-mining are the low productivity of soil and the high potential for contaminants. Herein, we evaluated the multispecies and multifunctional approach to restoration strategy through a mixture of woody and herbaceous species, microsymbiont and biochar amendments, and plant spacing. The experiments were conducted using greenhouse and field trials located in Quebec, Canada. We used a mixture of tree species (Alnus viridis (Chaix) DC. ssp. crispa (Aiton) Turrill, Picea glauca (Moench) Voss, Populus tremuloides Michx. and Salix arbusculoides Andersson) and herbaceous species (Avena sativa L., Festuca rubra L. and Trifolium repens L.) on two types of gold-mine waste materials (fine tailing and waste rock). The biochar amendment and microbial inoculation were applied on both greenhouse and field trials. We found both positive and negative effects of plant spacing, biochar amendment and inoculation depending on their interactions. The net positive effect was shown by combining high plantation density, biochar, and inoculation factors on Alnus viridis ssp. crispa. Overall, plantation density was shown to be the most important factor in generating the net positive effect. We suggest that the mechanism was correlated with the improvement in microclimate through soil plant water conservation and microbial activity enhancement over soil temperature modification. Hence, we propose to put emphasis on microclimate improvement for accelerating the restoration processes, along with other combined factors, including microbial inoculation and biochar amendment. Full article

(This article belongs to the Special Issue Production in Forest Nurseries and Field Performance of Seedlings)

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15 pages, 3453 KiB

Open AccessArticle

Climate Change Vulnerability Assessment and Ecological Characteristics Study of Abies nephrolepis in South Korea

by Seung-Jae Lee, Dong-Bin Shin, Jun-Gi Byeon and Seung-Hwan Oh

Forests 2023, 14(4), 855; https://doi.org/10.3390/f14040855 - 21 Apr 2023

Viewed by 1711

Abstract

Abies nephrolepis is a climate-vulnerable species that inhabits high mountains in the Baekdu–Daegan range and is distributed along the southern limit line in South Korea, making it suitable for climate change research. This study aimed to observe spatial distribution changes according to scenarios [...] Read more.

Abies nephrolepis is a climate-vulnerable species that inhabits high mountains in the Baekdu–Daegan range and is distributed along the southern limit line in South Korea, making it suitable for climate change research. This study aimed to observe spatial distribution changes according to scenarios using species distribution models for Abies nephrolepis, analyze the relationship between various environmental factors and Abies nephrolepis density, and contribute to the future conservation and management of subalpine coniferous forests. We conducted a field survey to identify the growth environment of Abies nephrolepis and observed potentially suitable habitats for Abies nephrolepis based on location information obtained through the survey. We also analyzed the relationship between the density of Abies nephrolepis and various environmental factors using multiple linear regression models. Based on the field survey results, most Abies nephrolepis natural habitats in South Korea showed an unstable form. Vulnerability analysis examining the influence of climate change showed that most of these habitats would be affected. We found that various biological factors were significantly related to the density of Abies nephrolepis (diameter at breast height, DBH ≥ 6 cm) and young tree density (stems/ha). We confirmed that species diversity and rock exposure variables had a relatively high impact. Clarifying the relationship between the density of Abies nephrolepis and various environmental factors can provide new insights for setting future restoration directions. Full article

(This article belongs to the Section Forest Meteorology and Climate Change)

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14 pages, 2340 KiB

Open AccessArticle

Predicting Aboveground Biomass and Carbon Storage for Ma Bamboo (Dendrocalamus latiflorus Munro) Plantations

by Tian-Ming Yen, Pai-Kuan Sun and Long-En Li

Forests 2023, 14(4), 854; https://doi.org/10.3390/f14040854 - 21 Apr 2023

Cited by 1 | Viewed by 1218

Abstract

The purpose of this study was to predict aboveground biomass (AGB) and aboveground carbon storage (AGCS) in Ma bamboo (Dendrocalamus latiflorus Munro) plantations. A total of 25 bamboo samples were selected and felled based on age and diameter at breast height (DBH) [...] Read more.

The purpose of this study was to predict aboveground biomass (AGB) and aboveground carbon storage (AGCS) in Ma bamboo (Dendrocalamus latiflorus Munro) plantations. A total of 25 bamboo samples were selected and felled based on age and diameter at breast height (DBH) classes. Two types of allometric equations (with and without an age factor) were used to develop biomass models for foliage, branches, culms and aboveground parts. Moreover, three intensively managed Ma bamboo plantations were used in this study to predict AGB and AGCS. The above two biomass models and a diameter distribution model were used to predict AGB for the three bamboo stands. The AGCS was predicted based on the AGB and percent carbon content. The results showed that the proportions of foliage, branches and culms to AGB were 11.1, 23.7 and 65.2%, respectively, at the individual bamboo level. The mean percent carbon content was predicted to be 41.68, 44.21 and 46.72% for foliage, branches and culms, respectively. The allometric equation with the age factor had better predictive ability than that without the age factor, with the former having higher R² and lower root mean square error values. Compared to the AGB predicted by the allometric model with the age factor at the stand level, the range of relative error was from −16.56 to 5.26% and from −40.0 to 71.7% for the AGB predicted by the allometric model without the age factor and that by the diameter distribution model, respectively. According to the allometric model with the age factor, the AGB and AGCS were predicted to be 35.7 ± 3.4 and 16.3 ± 1.5 Mg ha⁻¹, respectively, in Ma bamboo plantations. The results also reflected that the current status of Ma bamboo management is intensive management, where the focus is on harvesting bamboo shoots. Full article

(This article belongs to the Special Issue Ecological Functions of Bamboo Forests: Research and Application)

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16 pages, 2092 KiB

Open AccessArticle

Short-Term Effects of Bamboo Biochar and Oyster Shell Powder on Soil Organic Carbon Fraction, Microbial Respiration, and Enzymatic Stoichiometry in a Lei Bamboo Plantation

by Haonan Ji, Gensheng Yuan, Yang Liu, Jinzhu Yu, Songhao Li, Qifeng Wu, Hua Qin and Junhui Chen

Forests 2023, 14(4), 853; https://doi.org/10.3390/f14040853 - 21 Apr 2023

Cited by 3 | Viewed by 1519

Abstract

Both biochar and oyster shell powder have been known as promising amendments to ameliorate soil acidity and enhance soil fertility. However, it is still unclear how their application alone and in combination affect the soil organic carbon (C) fraction and microbial activity in [...] Read more.

Both biochar and oyster shell powder have been known as promising amendments to ameliorate soil acidity and enhance soil fertility. However, it is still unclear how their application alone and in combination affect the soil organic carbon (C) fraction and microbial activity in subtropical bamboo plantations. Therefore, to investigate the effects of biochar and oyster shell powder on soil microbial respiration, organic C fractions, microbial biomass, and enzyme activities related to C, N and P cycling, topsoil samples were collected from plots in a bamboo (Phyllostachys praecox) plantation that has been amended with oyster shell powder at 4 t ha⁻¹ (T), bamboo biochar at 10 t ha⁻¹ (B), and their combination (TB, with 4 t ha⁻¹ T and 10 t ha⁻¹ B) for 8 months. Our results showed that T alone significantly increased soil microbial respiration by 21.5%, whereas B alone and TB significantly decreased soil microbial respiration and metabolic quotient compared with T. T alone also increased soil pH, the size of labile C pool and the activities of β−glucosidase and cellobiosidase, whereas TB rather than B increased soil pH, the recalcitrant C pool size and declined these enzyme activities relative to T. T alone significantly enhanced microbial C limitation by 28.6% and decreased P limitation by 13.0%, while TB decreased microbial C limitation and increased microbial C use efficiency (CUE). Structural equation modeling indicated that T enhanced soil microbial respiration through increasing soil pH and enzyme activity, while biochar co-addition weakened the stimulation of T on microbial respiration by increasing soil recalcitrant C pool size and microbial metabolic quotient. Our study suggests that adding bamboo biochar together with oyster shell powder could be a better strategy to decrease soil C loss and ameliorate soil acidity in bamboo plantations compared with the application of oyster shell powder alone. Full article

(This article belongs to the Section Forest Soil)

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14 pages, 3250 KiB

Open AccessArticle

The Classification of Log Decay Classes and an Analysis of Their Physical and Chemical Characteristics Based on Artificial Neural Networks and K-Means Clustering

by Wen Wen, Wenjun Zhang, Shirong He, Haitao Hu, Hailiang Qiao, Xiao Wang, Nan Rao and Jie Yuan

Forests 2023, 14(4), 852; https://doi.org/10.3390/f14040852 - 21 Apr 2023

Cited by 1 | Viewed by 1277

Abstract

Most existing methods for determining log decay levels normally use variations in log surface characteristics, and the results are subject to human subjectivity, which is uncertain and inaccurate. In order to investigate a novel method for the quantitative determination of log decay levels, [...] Read more.

Most existing methods for determining log decay levels normally use variations in log surface characteristics, and the results are subject to human subjectivity, which is uncertain and inaccurate. In order to investigate a novel method for the quantitative determination of log decay levels, we randomly selected log samples from four species (Pinus tabulaeformis, Larix principis-ruprechtii, Betula albosinensis and Quercus aliena var. acuteserrata) with different levels of decay and determined their basic physicochemical characteristics in the laboratory. An artificial neural network (ANN) model was used to predict the hardness values of the log samples with different levels of decay at different moisture contents. The hardness was then used as a clustering factor to quantify the decay levels of the log via K-means clustering analysis. The variations in and correlations between the basic physicochemical factors of the log specimens were investigated between the different decay classes and between the different tree species, and then ANOVA and correlation analysis were used to verify the reliability of the clustering results. The results showed that the prediction of the hardness of the decayed log by the ANN was very effective and that the highly significant variability in the dry matter content, basic density and some basic chemical element contents between the log samples that were classified into different decay grades confirmed the reliability of the clustering results. This study explores an innovative method for the quantitative determination of log decay classes. Full article

(This article belongs to the Special Issue Forest Succession and Leaf Litter Decomposition)

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9 pages, 3009 KiB

Open AccessArticle

Identifying Risk Factors and Evaluating Occupational Safety in South Korean Forestry Sector

by Min-Jae Cho, Yun-Sung Choi and Eunjai Lee

Forests 2023, 14(4), 851; https://doi.org/10.3390/f14040851 - 21 Apr 2023

Cited by 1 | Viewed by 1142

Abstract

The forestry industry poses a higher risk of occupational accidents than other sectors, and understanding the occurrence and characteristics of injuries and fatalities is crucial for improving the safety and health of workers and establishing future strategies. In South Korea, although occupational injuries [...] Read more.

The forestry industry poses a higher risk of occupational accidents than other sectors, and understanding the occurrence and characteristics of injuries and fatalities is crucial for improving the safety and health of workers and establishing future strategies. In South Korea, although occupational injuries have declined since 2010, the number of occupational accidents in forestry remains higher than that in other sectors. Occupational injuries and fatalities present considerable challenges, and thus, our objective was to analyze and compare forestry accidents between 2010 and 2020. The results indicate that the highest average number of injuries occurred among workers older than 51 years and those with less than 6 months of experience. Timber harvesting and silviculture are among the most dangerous operations in forestry. Based on the analyzed dataset, amputation and laceration injuries, as well as slip and trip injuries, were the most common, accounting for 29.2% and 22.3% of total annual occupational accidents, respectively. These results may be explained by the labor-intensive, steep terrain operations in forestry. Our findings represent an essential resource for improving worker safety and health. Full article

(This article belongs to the Special Issue Forest Harvesting, Operations and Management)

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14 pages, 2341 KiB

Open AccessArticle

Optimization of Key Technologies for Induction of Embryogenic Callus and Maturation of Somatic Embryos in Korean Pine (Pinus koraiensis)

by Fang Gao, Yujie Shi, Ruirui Wang, Iraida Nikolaevna Tretyakova, Alexander Mikhaylovich Nosov, Hailong Shen and Ling Yang

Forests 2023, 14(4), 850; https://doi.org/10.3390/f14040850 - 20 Apr 2023

Viewed by 1330

Abstract

Somatic embryogenesis (SE), which leads to the formation of embryonic callus (EC) tissue, is the most promising method for large-scale production and selective breeding of woody plants. However, in many species, SE suffers from low induction and proliferation rates, hindering the production of [...] Read more.

Somatic embryogenesis (SE), which leads to the formation of embryonic callus (EC) tissue, is the most promising method for large-scale production and selective breeding of woody plants. However, in many species, SE suffers from low induction and proliferation rates, hindering the production of improved plant materials. We investigated the effects of the explant sterilization method, 4 °C cryopreservation, basal medium, ethylene removal, liquid medium supplementation, and a combination of PGRs on embryogenic callus (EC) induction of Korean pine, using immature embryos of Korean pine as explants. The effects of sucrose and maltose on EC proliferation and maturation were investigated. The differences in the maturation ability of EC somatic embryos before and after cryopreservation were evaluated using the induced embryonic cell lines. The results showed that zygotic embryos (ZEs) performed better than megagametophytes (MGs) as explants. The induction rate of EC was significantly increased after 28 days of cryopreservation at 4 °C. The induction rate of EC in the #5 family increased from 10.00% to 62.8%. The EC induction rate of the five families cultured with the DCR basal medium was higher than that with the mLV basal medium. Among them, the induction rate of the #5 family cultured with the mLV basal medium was 23.3%, while that with the DCR basal medium was 60.9%, an increase of 2.6 times. There was no significant difference in the maturation ability of EC somatic embryos before and after cryopreservation. In conclusion, this study provides a method to improve the EC induction rate and maturation ability of Korean pine. Full article

(This article belongs to the Special Issue Advances in Tree Germplasm Innovation and High-Efficiency Propagation)

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18 pages, 12927 KiB

Open AccessArticle

Study of the Movement of Chips during Pine Wood Milling

by Chunmei Yang, Tongbin Liu, Yaqiang Ma, Wen Qu, Yucheng Ding, Tao Zhang and Wenlong Song

Forests 2023, 14(4), 849; https://doi.org/10.3390/f14040849 - 20 Apr 2023

Cited by 2 | Viewed by 1178

Abstract

Circumferential milling is used in wood processing, yet it generates vast quantities of dust and chips in a single pass, highlighting the need to predict chip dispersion and prevent associated hazards. This article presents findings from a theoretical and experimental analysis of chip [...] Read more.

Circumferential milling is used in wood processing, yet it generates vast quantities of dust and chips in a single pass, highlighting the need to predict chip dispersion and prevent associated hazards. This article presents findings from a theoretical and experimental analysis of chip size and kinematics of pine wood during cutting. A chip diffusion boundary surface model was established and its key parameters were determined through CCD testing. Results reveal that chip diffusion can be divided into three distinct areas based on motion state: main diffusion, random diffusion, and vortex. Notably, spindle speed and feed rate are most influential on the orthogonal diffusion angle of the main diffusion zone, whereas cutting depth most heavily impacts the top view diffusion angle. Chip scattering on the table showed an exponential increase in average chip size with sampling distance, whereas the boundary surface model accurately characterizes chip motion and demonstrates a reasonable degree of reliability, offering potential in predicting chip morphology and diffusion state. This model has important implications for wood milling practices, particularly in controlling chip dispersion. Full article

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

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13 pages, 2915 KiB

Open AccessArticle

The Impact of the Method of Reclamation of the Coal Ash Dump from the “Adamów” Power Plant on the Survival, Viability, and Wood Quality of the Introduced Tree Species

by Paweł Szadek, Marek Pająk, Krzysztof Michalec, Radosław Wąsik, Krzysztof Otremba, Michał Kozłowski and Marcin Pietrzykowski

Forests 2023, 14(4), 848; https://doi.org/10.3390/f14040848 - 20 Apr 2023

Cited by 1 | Viewed by 1088

Abstract

The aim of this research was to determine the survival rate, dimensions, and wood quality of black locust, ash-leaf maple, common maple, and American ash introduced to the landfill of the “Adamów” Power Plant as part of the reclamation process. The experimental area [...] Read more.

The aim of this research was to determine the survival rate, dimensions, and wood quality of black locust, ash-leaf maple, common maple, and American ash introduced to the landfill of the “Adamów” Power Plant as part of the reclamation process. The experimental area consisted of 13 research plots. On the three plots where the trees were planted directly into the ash, the trees completely collapsed. As a result of this research, it was found that the black locust had the best survival rates, whereas the American ash had the worst. The black locust and ash-leaf maple reached larger sizes on the plots where the ashes were covered with a 50-centimetre layer of sewage sludge (S50) or with a 50-centimetre layer of clay (C50), while the common maple grew the largest on the plots where a 25-centimetre layer of sewage sludge (S25) was used. Our research shows that about 40% of the examined species of wood were of good quality (Q1, Q2), which in the future will make it possible to obtain sawmill raw material. On the other hand, lower quality wood (Q3, Q4), which accounted for over 50% of the assessed wood material, can be successfully used as a biomass for energy purposes. Full article

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

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10 pages, 3247 KiB

Open AccessArticle

Distribution and Prolonged Diapause of the Rowan Seed Predators Argyresthia conjugella (Lepidoptera: Yponomeutidae) and Megastigmus brevicaudis (Hymenoptera: Torymidae) and their Parasitoids in Norway

by Nina Trandem, Karin Westrum, Trond Hofsvang and Sverre Kobro

Forests 2023, 14(4), 847; https://doi.org/10.3390/f14040847 - 20 Apr 2023

Viewed by 1153

Abstract

The seed predator Argyresthia conjugella Zeller has rowan as its preferred host plant. In years of poor fruiting in rowan, it oviposits on apples. To improve the knowledge of this apple pest, rowanberries were collected from localities all over Norway from 1971 to [...] Read more.

The seed predator Argyresthia conjugella Zeller has rowan as its preferred host plant. In years of poor fruiting in rowan, it oviposits on apples. To improve the knowledge of this apple pest, rowanberries were collected from localities all over Norway from 1971 to 1985, and seed predators and their parasitoids were allowed to emerge for up to five years. Two species of seed predators, A. conjugella and Megastimus brevicaudis Ratzeburg, and seven species of parasitic Hymenoptera were common. The distribution of these species is shown on EIS (European Invertebrate Survey) maps of Norway. The biology of the parasitoids is summarized based on the published literature and their behavior during emergence. The tendency for delayed emergence, which is an indication of prolonged diapause, was more pronounced in M. brevicaudis than in A. conjugella, the former appearing in all five years. Five of the parasitoids also delayed their emergence, and three of them to a high degree, up to five years. Prolonged diapause must be taken into account in studies of rowanberry insect guilds. Full article

(This article belongs to the Special Issue Biodiversity and Ecology of Organisms Associated with Woody Plants)

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17 pages, 3774 KiB

Open AccessArticle

Heavy Metal Concentrations and Accumulation Characteristics of Dominant Woody Plants in Iron and Lead−Zinc Tailing Areas in Jiangxi, Southeast China

by Yanglong Li, Chaoqun Wang, Chaowu Yan, Shaowen Liu, Xiangteng Chen, Mansheng Zeng, Yuhong Dong and Ruzhen Jiao

Forests 2023, 14(4), 846; https://doi.org/10.3390/f14040846 - 20 Apr 2023

Cited by 4 | Viewed by 1570

Abstract

Phytoremediation using woody plants can effectively reduce heavy metal (HM) concentrations in soils. However, the remediation capacity of woody plants depends greatly on plant species and soil environmental conditions. In order to evaluate the HM remediation potential of woody plants from different tailing [...] Read more.

Phytoremediation using woody plants can effectively reduce heavy metal (HM) concentrations in soils. However, the remediation capacity of woody plants depends greatly on plant species and soil environmental conditions. In order to evaluate the HM remediation potential of woody plants from different tailing areas, the HM accumulation characteristics of roots, shoots, and leaves of 12 dominant native woody plants growing in iron and lead-zinc tailing areas were analyzed. The results showed that the concentrations of Cd, As, Ni, Mn, and Cr in most plants in the two tailing areas exceeded the level of normal plants. The distribution of different elements in plants was generally as follows: root > leaf > shoot for Pb and As; root > shoot > leaf for Cr; and leaf > shoot > root for Zn, Ni, and Mn. The distribution of Cu and Cd in plants varied with the type of HM pollution in the two tailing areas. There were significant (p < 0.05) negative correlations between available phosphorus in the soil and Pb, Cd, and Zn in the plant roots when the soil was heavily polluted with Pb, Cd, and As; similarly, there were significant (p < 0.01) negative correlations between readily available potassium in the soil and Pb, Zn, and Ni in plant roots. Based on the higher than average concentration of HMs in plants, and higher bioconcentration factors and translocation factors, some plants were considered woody plant species with phytoremediation. Slash pine (Pinus elliottii) and indian azalea (Rhododendron simsii) had strong enrichment and translocation abilities for Cd, oriental white oak (Quercus glauca) and beautiful sweetgum (Liquidambar formosana) for Mn and paulownia (Paulownia fortunei) for Zn. The plants listed above can be used as potential species for phytoremediation in iron and lead-zinc tailing areas. Full article

(This article belongs to the Special Issue Forest Vegetation and Soils: Interaction, Management and Alterations)

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29 pages, 11893 KiB

Open AccessArticle

Agroforestry Ecosystem Structure and the Stability Improvement Strategy in Control of Karst Desertification

by Shilian Jiang, Kangning Xiong, Jie Xiao, Yiling Yang, Yunting Huang and Zhigao Wu

Forests 2023, 14(4), 845; https://doi.org/10.3390/f14040845 - 20 Apr 2023

Cited by 1 | Viewed by 1256

Abstract

Agroforestry systems (AFS) are priority semi-natural ecosystems in fragile ecological zones. The complexity and diversity of their species structure play a crucial role in maintaining AFS stability. To explore the optimization of improvement strategies in AFS’ structure and stability for control of karst [...] Read more.

Agroforestry systems (AFS) are priority semi-natural ecosystems in fragile ecological zones. The complexity and diversity of their species structure play a crucial role in maintaining AFS stability. To explore the optimization of improvement strategies in AFS’ structure and stability for control of karst desertification (KD), in this study, we chose typical desertification control areas in the southern China karst region. The study included homegarden (HG), agrisilviculture (ASV), and multipurpose woodlots (MWLs) as three AFS. We quantified the AFS’ structural characteristics using descriptive statistics and spatial structure parameters. We used the fuzzy integrated evaluation method with structural and functional indicators as guidelines, and stand structure, plant species diversity, soil fertility, and environmental factors as first-level evaluation indicators. The entropy weight method calculates the weights of indicators at all levels. The fuzzy comprehensive evaluation method establishes an evaluation index system to evaluate the grading of AFS’ stability. The results showed that: (i) The species composition of the AFS in the KD control areas had a simple structure, the overall diversity level was low, and the diversity level of herbaceous plants was better than that of woody plants. (ii) The overall distribution curves of diameter at breast height (DBH), tree height (TH), and crown width (CW) of woody plants in the AFS in the KD control areas were slight to the left, with a single-peaked pattern, mostly randomly and unevenly distributed in space, with a low degree of tree species isolation and relatively weak stand stability. (iii) There was variability in the stability classes of different types of AFS, overall reflecting the ranking HG > ASV > MWLs. (iv) When structural optimization was applied, corresponding measures can be taken according to farmers’ wishes for different types of AFS and their primary business purposes. The improvement of stability depends mainly on the utility of the structural optimization applied coupled with positive human interference (for example, pruning, dwarfing, and dense planting). This study provides a scientific reference for maintaining the stability of AFS and promoting service provision. Full article

(This article belongs to the Special Issue Improvement of Forest Ecosystem Functions in Karst Desertification Control)

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26 pages, 10896 KiB

Open AccessArticle

Coupling of SWAT and EPIC Models to Investigate the Mutual Feedback Relationship between Vegetation and Soil Erosion, a Case Study in the Huangfuchuan Watershed, China

by Zeyu Luo, Huilan Zhang, Jianzhuang Pang, Jun Yang and Ming Li

Forests 2023, 14(4), 844; https://doi.org/10.3390/f14040844 - 20 Apr 2023

Cited by 1 | Viewed by 1417

Abstract

Identifying the feedback relationship between soil erosion and vegetation growth would contribute to sustainable watershed management. In order to study the long-term interaction between soil erosion and vegetation change, a comprehensive modeling framework was proposed by combining the Soil and Water Assessment Tool [...] Read more.

Identifying the feedback relationship between soil erosion and vegetation growth would contribute to sustainable watershed management. In order to study the long-term interaction between soil erosion and vegetation change, a comprehensive modeling framework was proposed by combining the Soil and Water Assessment Tool (SWAT) and the Environmental Policy Integrated Climate (EPIC) model. The Huangfuchuan Watershed was taken as an example area due to serious erosion and large-scale conversion of farmland to forest. Based on long-term variation analyses from 1956 to 2020, the effect of land cover change on runoff and sediment discharge was quantified using SWAT to create scenario simulations, and then environmental stresses factors (i.e., soil water content, nitrogen, and phosphorus contents) output by SWAT were input into EPIC to evaluate effects of soil erosion on potential biomass of vegetation. Results showed that the annual runoff reduction was 32.5 million m3 and the annual sediment reduction was 15 million t during the past 65 years. The scenario we created using the SWAT simulation showed that both forest and grassland reduced water yield, while bare land increased water yield by 10%. In addition, grassland and forest reduced soil erosion by 20% and 18%, respectively, while bare land increased sand production by 210%. The EPIC model results exhibited a negative correlation between the potential for vegetation biomass and erosion intensity. The average annual potential biomass of forest and grass under micro-erosion was 585.7 kg/ha and 485.9 kg/ha, respectively, and was 297.9 kg/ha and 154.6 kg/ha, respectively, under the extremely strong erosion. The results of this study add to the body of information regarding how soil erosion and vegetation biomass interact with each other. The proposed coupled SWAT-EPIC strategy may provide a way for further investigating the quantitative relationship between soil erosion and vegetation cover. Full article

(This article belongs to the Section Forest Hydrology)

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15 pages, 12061 KiB

Open AccessArticle

Influence of Different Planting Combinations on the Amino Acid Concentration in Pericarp of Zanthoxylum planispinum ‘Dintanensis’ and Soil

by Yitong Li, Yanghua Yu, Yanping Song and Changsheng Wei

Forests 2023, 14(4), 843; https://doi.org/10.3390/f14040843 - 20 Apr 2023

Cited by 1 | Viewed by 931

Abstract

In this study, the effect of different planting combinations on the amino acid concentration in the pericarp of Zanthoxylum planispinum ‘dintanensis’ (hereafter referred to as Z. planispinum) was studied, and the response of amino acid concentration to soil factors was clarified. The [...] Read more.

In this study, the effect of different planting combinations on the amino acid concentration in the pericarp of Zanthoxylum planispinum ‘dintanensis’ (hereafter referred to as Z. planispinum) was studied, and the response of amino acid concentration to soil factors was clarified. The aim of this study was to screen optimal planting combinations and provide a theoretical basis for improving pericarp quality. Five planting combinations of Z. planispinum in a karst rocky desertification area were selected as the research objects, and the concentration and accumulation of free amino acids in the pericarp of Z. planispinum were analyzed. Then, combined with existing soil quality data, the pericarp quality of Z. planispinum was comprehensively evaluated by principal component analysis, and the effect of soil factors on amino acid concentrations was clarified by redundancy analysis. The results are as follows: (1) except for arginine, serine, proline, alanine, tyrosine and cystine, the concentrations of other free amino acids significantly differed among the five planting combinations. In general, the planting combination has a great influence on the concentration of free amino acids in the pericarp of Z. planispinum, especially essential amino acids; (2) free amino acid concentration in the pericarp of Z. planispinum mostly increased in combination with Sophora tonkinensis Gagnep. (hereafter referred to as S. tonkinensis) and decreased in combination with Prunus salicina Lindl; (3) principal component analysis showed that the concentration of free amino acid in the pericarp of Z. planispinum was generally at a high level when combined with S. tonkinensis or Lonicera japonica Thunb. (hereafter referred to as L. japonica). Among them, the amino acids in the pericarp of Z. planispinum with S. tonkinensis were closer to the ideal protein standard of FAO/WHO; (4) soil-available potassium, available phosphorus, microbial biomass nitrogen, available calcium and microbial biomass phosphorus in soil factors had significant effects on amino acid concentration after a redundancy analysis. It can be seen that the available nutrients and soil microbial biomass contribute greatly to the amino acid concentration of the pericarp. According to the soil quality and the amino acid quality of the pericarp, planting with L. japonica can improve the amino acid quality of the pericarp of Z. planispinum, as well as selecting Z. planispinum + L. japonica as the optimal planting combination. Full article

(This article belongs to the Special Issue Improvement of Forest Ecosystem Functions in Karst Desertification Control)

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16 pages, 3600 KiB

Open AccessArticle

Comparative RNA-Seq Analysis Reveals the Organ-Specific Transcriptomic Response to Zinc Stress in Mulberry

by Shuai Huang, Xiaoru Kang, Ting Yu, Keermula Yidilisi, Lin Zhang, Xu Cao, Nan Chao and Li Liu

Forests 2023, 14(4), 842; https://doi.org/10.3390/f14040842 - 20 Apr 2023

Cited by 1 | Viewed by 1402

Abstract

Mulberry (Morus, Moraceae) is an important economic plant that is considered zinc-rich. Zinc (Zn) is a micronutrient that plays vital roles in various bio-processes in plants and animals. In the present study, a comparative transcriptome analysis associated with physiological indicators [...] Read more.

Mulberry (Morus, Moraceae) is an important economic plant that is considered zinc-rich. Zinc (Zn) is a micronutrient that plays vital roles in various bio-processes in plants and animals. In the present study, a comparative transcriptome analysis associated with physiological indicators was performed to reveal the potential mechanism in different organs in response to zinc toxicity in mulberry. Physiological indicators in mulberry plants treated with increasing concentrations of zinc were monitored to reveal the tolerance limits to zinc concentration. Transcriptome analysis of different organs in mulberry under excess zinc stress was performed to reveal the spatial response to zinc stress. The results show that the hormone signaling pathway and secondary metabolism including lignin biosynthesis, flavonoid biosynthesis and sugar metabolism are important for excess zinc treatment responses. In addition, the organ-based spatial response of these pathways is indicated. Lignin biosynthesis mainly responds to zinc stress in lignified tissues or organs such as stems, flavonoid biosynthesis is the main response to zinc stress in leaves, and sugar metabolism is predominant in roots. Further co-expression network analysis indicated candidate genes involved in the organ-based spatial response. Several transcription factors and genes involved in phenylpropanoid biosynthesis, cell wall biogenesis and sugar metabolism were further validated and designed as organ-based response genes for zinc stress. Full article

(This article belongs to the Special Issue Strategies for Tree Improvement under Stress Conditions)

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16 pages, 3471 KiB

Open AccessArticle

Generalized Linear Models for Describing Tree Gaps in Forest Management Areas in the Brazilian Amazon

by Suzana Ligoski Zeferino, Natally Celestino Gama, Deivison Venicio Souza, Alex Soares de Souza, Emil José Hernández Ruz and Sandra Dezuite Balieiro da Silva

Forests 2023, 14(4), 841; https://doi.org/10.3390/f14040841 - 20 Apr 2023

Viewed by 953

Abstract

Gap size is one of the main variables used to quantify the environmental consequences of forest management that can help in quantifying and monitoring changes in clearing areas. This study aimed to characterize gaps from harvested individuals, quantify the resulting forest damage, and [...] Read more.

Gap size is one of the main variables used to quantify the environmental consequences of forest management that can help in quantifying and monitoring changes in clearing areas. This study aimed to characterize gaps from harvested individuals, quantify the resulting forest damage, and adjust equations to describe gaps after tree cutting. Our research was conducted in three phytophysiognomies of the eastern Pará Amazon. We performed descriptive analyses using data on gap size and damage to the remaining individuals in each phytophysiognomy. We then applied predictive modeling to estimate clearing size using a generalized linear model. Modeling parameters included Gaussian, gamma, and inverse Gaussian families, with linking and transforming functions of the analyzed variables. Among the three phytophysiognomies, the largest clearings were observed in open ombrophilous forests with lianas (27,650 to 548,460 m²), with 56 large gaps, 148 medium, and 113 small. The model with three linear predictors (diameter, height, and phytophysiognomy), inverse Gaussian distribution, and logarithmic link function showed the best fit. There were notable differences in clearing size across phytophysiognomies, suggesting that the phytophysiognomy should be considered when planning measures to mitigate the impacts of forest management. Full article

(This article belongs to the Special Issue Efficacy of Sustainable Forest Management for Biodiversity Conservation)

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11 pages, 6723 KiB

Open AccessFeature PaperArticle

Age Estimation of Dracaena cinnabari Balf. f. on Socotra Island: A Direct Method to Determine Its Lifespan

by Lucie Bauerová, Petr Maděra, Martin Šenfeldr and Hana Habrová

Forests 2023, 14(4), 840; https://doi.org/10.3390/f14040840 - 20 Apr 2023

Cited by 1 | Viewed by 1564

Abstract

Background: Dracaena cinnabari is a monocot species that does not form annual tree rings; thus, its age can only be estimated. This species is threatened by low natural regeneration, with an evident absence of younger individuals most likely caused by overgrazing; therefore, knowing [...] Read more.

Background: Dracaena cinnabari is a monocot species that does not form annual tree rings; thus, its age can only be estimated. This species is threatened by low natural regeneration, with an evident absence of younger individuals most likely caused by overgrazing; therefore, knowing trees’ ages is important for possible conservation strategies; Methods: Data collection was conducted on the Firmihin Plateau on Socotra Island (Yemen) in 2021, and the diameter at breast height (DBH) of 1077 individuals was measured, the same as those established on monitoring plots 10 years before the current measurement. The 10-year radial stem increment and DBH obtained in 2011 served as a basis for the linear model from which the equations for the age calculation were derived. Results and Conclusions: A direct model of age estimation for D. cinnabari was developed. According to the fit model, the age in the first (10.1–15 cm) DBH class was estimated to be 111 years, while that in the last DBH class (90.1–95 cm) was estimated to be 672 years. The results revealed that the previously used indirect methods for D. cinnabari age estimation were accurate. Full article

(This article belongs to the Special Issue New Knowledge in Dragon Tree Research)

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12 pages, 3232 KiB

Open AccessArticle

The Effect of Heat Treatment and Acetylation on Formaldehyde Emission in Cellulose: A Molecular Dynamics Simulation Study

by Ning Li, Youna Hua, Jia Wang, Juncheng Li and Wei Wang

Forests 2023, 14(4), 839; https://doi.org/10.3390/f14040839 - 20 Apr 2023

Viewed by 1035

Abstract

Formaldehyde emission from cellulosic materials is an important consideration, especially for wood products, which are regulated by many countries in terms of legislation and may affect the health of users. In this study, molecular dynamics simulations were performed at different temperatures using two [...] Read more.

Formaldehyde emission from cellulosic materials is an important consideration, especially for wood products, which are regulated by many countries in terms of legislation and may affect the health of users. In this study, molecular dynamics simulations were performed at different temperatures using two common wood-modification methods, heat treatment, and acetylation, and the diffusion coefficients of the models as well as the mechanical properties, were discussed. The results showed that the mean square displacement of the common heat treatment model was best at 493 K. The acetylated cellulose model at 483 K was able to achieve four times the diffusion coefficient of the common cellulose model, while the acetylated cellulose material would be weaker than the common heat-treated cellulose material in terms of mechanical properties. These findings provide some reference for formaldehyde pretreatment of wood products. Full article

(This article belongs to the Special Issue Wood Treatments and Modification Technologies)

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23 pages, 6161 KiB

Open AccessArticle

Omni-Dimensional Dynamic Convolution Meets Bottleneck Transformer: A Novel Improved High Accuracy Forest Fire Smoke Detection Model

by Jingjing Qian, Ji Lin, Di Bai, Renjie Xu and Haifeng Lin

Forests 2023, 14(4), 838; https://doi.org/10.3390/f14040838 - 19 Apr 2023

Cited by 10 | Viewed by 2075

Abstract

The frequent occurrence of forest fires in recent years has not only seriously damaged the forests’ ecological environments but also threatened the safety of public life and property. Smoke, as the main manifestation of the flame before it is produced, has the advantage [...] Read more.

The frequent occurrence of forest fires in recent years has not only seriously damaged the forests’ ecological environments but also threatened the safety of public life and property. Smoke, as the main manifestation of the flame before it is produced, has the advantage of a wide diffusion range that is not easily obscured. Therefore, timely detection of forest fire smoke with better real-time detection for early warnings of forest fires wins valuable time for timely firefighting and also has great significance and applications for the development of forest fire detection systems. However, existing forest fire smoke detection methods still have problems, such as low detection accuracy, slow detection speed, and difficulty detecting smoke from small targets. In order to solve the aforementioned problems and further achieve higher accuracy in detection, this paper proposes an improved, new, high-accuracy forest fire detection model, the OBDS. Firstly, to address the problem of insufficient extraction of effective features of forest fire smoke in complex forest environments, this paper introduces the SimAM attention mechanism, which makes the model pay more attention to the feature information of forest fire smoke and suppresses the interference of non-targeted background information. Moreover, this paper introduces Omni-Dimensional Dynamic Convolution instead of static convolution and adaptively and dynamically adjusts the weights of the convolution kernel, which enables the network to better extract the key features of forest fire smoke of different shapes and sizes. In addition, to address the problem that traditional convolutional neural networks are not capable of capturing global forest fire smoke feature information, this paper introduces the Bottleneck Transformer Net (BoTNet) to fully extract global feature information and local feature information of forest fire smoke images while improving the accuracy of small target forest fire target detection of smoke, effectively reducing the model’s computation, and improving the detection speed of model forest fire smoke. Finally, this paper introduces the decoupling head to further improve the detection accuracy of forest fire smoke and speed up the convergence of the model. Our experimental results show that the model OBDS for forest fire smoke detection proposed in this paper is significantly better than the mainstream model, with a computational complexity of 21.5 GFLOPs (giga floating-point operations per second), an improvement of 4.31% compared with the YOLOv5 (YOLO, you only look once) model mAP@0.5, reaching 92.10%, and an FPS (frames per second) of 54, which is conducive to the realization of early warning of forest fires. Full article

(This article belongs to the Special Issue Artificial Intelligence and Machine Learning Applications in Forestry)

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22 pages, 1112 KiB

Open AccessArticle

Understanding Urban Residents’ Perceptions of Street Trees to Develop Sustainable Maintenance Guidelines in the Seoul Metropolitan Area, Korea

by Na-Ra Jeong, Seung-Won Han and Baul Ko

Forests 2023, 14(4), 837; https://doi.org/10.3390/f14040837 - 19 Apr 2023

Cited by 3 | Viewed by 1470

Abstract

Street trees play a crucial role in improving urban environments, and their management depends on the perceptions and preferences of urban residents. This study surveyed 884 urban residents’ preferences and perceptions towards street trees in a metropolitan area in Korea and proposed guidelines [...] Read more.

Street trees play a crucial role in improving urban environments, and their management depends on the perceptions and preferences of urban residents. This study surveyed 884 urban residents’ preferences and perceptions towards street trees in a metropolitan area in Korea and proposed guidelines for their sustainable management. Urban residents were aware of the presence of street trees based on visual changes and were generally satisfied with their shape, size, and growth. They preferred trees that provide environmental and ecological services, such as offering shade, purifying the air, and preserving the ecosystem, while viewing the generation of debris from street trees as the most significant problem. Urban residents’ perspectives on street tree preference and issues varied based on age, income, and housing type. Although urban residents acknowledged the need for the maintenance and management of street trees, they believed that this was the responsibility of central and local governments, not local residents. Collectively, the residents had a positive view of urban street trees and believed that maintenance and management are necessary to address problems caused by their presence. Our research findings provide valuable information to help city and landscaping experts select street tree species and establish maintenance and management strategies. Full article

(This article belongs to the Section Urban Forestry)

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16 pages, 14252 KiB

Open AccessArticle

Furnishing a Recreational Forest—Findings from the Hallerwald Case Study

by Renate Cervinka, Markus Schwab Spletzer and Daniela Haluza

Forests 2023, 14(4), 836; https://doi.org/10.3390/f14040836 - 19 Apr 2023

Viewed by 1244

Abstract

While the beneficial effects of forests on health and well-being are broadly investigated, little is known on the restorative effects of forest infrastructure. Thus, this study assessed the perceptions of installing furniture in a recreational forest in forest visitors. We surveyed 220 volunteers [...] Read more.

While the beneficial effects of forests on health and well-being are broadly investigated, little is known on the restorative effects of forest infrastructure. Thus, this study assessed the perceptions of installing furniture in a recreational forest in forest visitors. We surveyed 220 volunteers attending guided walks before (n = 99) and after (n = 121) furnishing the Hallerwald. The questionnaire assessed restorative qualities of four places in the forest before and after furnishing, and changes in visitors’ self-perceptions pre and post visiting the forest for 2.5 h. Further, visitors evaluated the furniture and the visit. The four sites in the forest under study benefited differently from furnishing. We found mixed outcomes with respect to the restorative qualities of places by furnishing, and a similar improvement of human restoration pre- and post-walk, irrespective of furnishing, but received mainly positive ratings for the installed furniture. The participants expected positive effects of visiting the forest to last one to two days. Our findings suggest that furnishing the forest made this forest a unique place for pedagogy, health interventions, and tourism. We concluded that furnishing, designed to fit the characteristics of a specific place, can support health and well-being in restorative forests and should be recognized by sustainable forest management. Full article

(This article belongs to the Special Issue Forest, Trees, Human Health and Wellbeing)

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12 pages, 3767 KiB

Open AccessArticle

Weighted Gene Co-Expression Network Analysis Reveals Key Pathways and Hub Genes Associated with Successful Grafting in Pecan (Carya illinoinensis)

by Zhenghai Mo, Xiaozhuang Jiang, Yan Zhang, Min Zhai, Longjiao Hu and Jiping Xuan

Forests 2023, 14(4), 835; https://doi.org/10.3390/f14040835 - 19 Apr 2023

Cited by 2 | Viewed by 1146

Abstract

Patch budding (bud grafting) is a commonly used method for pecan reproduction; however, the grafting survival rate varies with cultivars. Clarifying the underlying mechanisms of successful grafting is pivotal for graft technique improvement. Here, weighted gene co-expression network analysis (WGCNA) was conducted to [...] Read more.

Patch budding (bud grafting) is a commonly used method for pecan reproduction; however, the grafting survival rate varies with cultivars. Clarifying the underlying mechanisms of successful grafting is pivotal for graft technique improvement. Here, weighted gene co-expression network analysis (WGCNA) was conducted to dissect the key pathways and genes related to the successful grafting of pecan. Based on the transcriptome data of two contrasting cultivars (an easy-to-survive cultivar ‘Pawnee’ and a difficult-to-survive cultivar ‘Jinhua’) in response to budding, all the genes with variable transcripts were grouped into 18 modules. There were two modules that were significantly correlated with the trait of different cultivars. Enrichment analysis showed that several enriched gene ontology (GO) terms were related to oxidative detoxification and genes associated with hormone signaling pathway occupied a high ratio for the two modules. A total of 52 hub genes were identified, and 48 showed promoter polymorphisms between the two cultivars. Our study suggested that oxidative detoxification and hormone signaling were probably the key pathways for the successful grafting of pecan. The 48 hub genes identified here might be the key genes that led to the divergence of graft survival rates among different pecan cultivars. Our results will lay a foundation for future graft technique improvement in pecan. Full article

(This article belongs to the Special Issue Advances in Tree Germplasm Innovation and High-Efficiency Propagation)

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14 pages, 2480 KiB

Open AccessArticle

Leaf Phenological Responses of Juvenile Beech and Oak Provenances to Elevated Phosphorus

by Marko Bačurin, Saša Bogdan, Ida Katičić Bogdan and Krunoslav Sever

Forests 2023, 14(4), 834; https://doi.org/10.3390/f14040834 - 18 Apr 2023

Cited by 1 | Viewed by 897

Abstract

The few studies dealing with leaf phenological responses to elevated nutrients in forest trees have given ambiguous results, i.e., while some reported delayed leaf-out and autumn leaf senescence, others reported advanced leaf phenology caused by increased nutrition. This study aimed to determine the [...] Read more.

The few studies dealing with leaf phenological responses to elevated nutrients in forest trees have given ambiguous results, i.e., while some reported delayed leaf-out and autumn leaf senescence, others reported advanced leaf phenology caused by increased nutrition. This study aimed to determine the effects of experimentally increased phosphorus (+P treatment) on the leaf phenologies of two juvenile provenances of common beech and sessile oak. Other objectives were to determine whether there were interspecific differences as well as intraspecific variations. Saplings were excavated in two mixed beech–oak stands and transplanted into four wooden boxes filled with a commercial soil substrate. Phosphorus fertilizer was added to two of the boxes, while the remaining boxes served as controls. Both species responded to +P treatment with advanced autumn leaf senescence in the first year of the experiment. Leaf senescence in common beech began significantly earlier, while in both species, the process was accelerated compared to that in the control. In the second year, the leaf senescence response to +P treatment was even more pronounced in both species. The +P effect on leafing phenology was absent in both common beech provenances and in an oak provenance. However, the other oak provenance showed advanced leafing, indicating the existence of intraspecific differences. Full article

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

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13 pages, 5095 KiB

Open AccessArticle

An Improved Forest Fire and Smoke Detection Model Based on YOLOv5

by Junhui Li, Renjie Xu and Yunfei Liu

Forests 2023, 14(4), 833; https://doi.org/10.3390/f14040833 - 18 Apr 2023

Cited by 7 | Viewed by 2594

Abstract

Forest fires are destructive and rapidly spreading, causing great harm to forest ecosystems and humans. Deep learning techniques can adaptively learn and extract features of forest fires and smoke. However, the complex backgrounds and different forest fire and smoke features in captured forest [...] Read more.

Forest fires are destructive and rapidly spreading, causing great harm to forest ecosystems and humans. Deep learning techniques can adaptively learn and extract features of forest fires and smoke. However, the complex backgrounds and different forest fire and smoke features in captured forest fire images make detection difficult. Facing the complex background of forest fire smoke, it is difficult for traditional machine learning methods to design a general feature extraction module for feature extraction. Deep learning methods are effective in many fields, so this paper improves on the You Only Look Once v5 (YOLOv5s) model, and the improved model has better detection performance for forest fires and smoke. First, a coordinate attention (CA) model is integrated into the YOLOv5 model to highlight fire smoke targets and improve the identifiability of different smoke features. Second, we replaced YOLOv5s original spatial pyramidal ensemble fast (SPPF) module with a receptive field block (RFB) module to enable better focus on the global information of different fires. Third, the path aggregation network (PANet) of the neck structure in the YOLOv5s model is improved to a bi-directional feature pyramid network (Bi-FPN). Compared with the YOLOv5 model, our improved forest fire and smoke detection model at mAP@0.5 improves by 5.1%. Full article

(This article belongs to the Special Issue Artificial Intelligence and Machine Learning Applications in Forestry)

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16 pages, 12341 KiB

Open AccessArticle

A 278-Year Summer Minimum Temperature Reconstruction Based on Tree-Ring Data in the Upper Reaches of Dadu River

by Jinjian Li, Liya Jin and Zeyu Zheng

Forests 2023, 14(4), 832; https://doi.org/10.3390/f14040832 - 18 Apr 2023

Viewed by 1694

Abstract

In the context of global warming, climate change in river headwater regions and its drivers have attracted increasing attention. In this study, tree-ring width (TRW) chronology was constructed using tree-ring samples of fir (Abies faxoniana) in Dadu River Basin in the [...] Read more.

In the context of global warming, climate change in river headwater regions and its drivers have attracted increasing attention. In this study, tree-ring width (TRW) chronology was constructed using tree-ring samples of fir (Abies faxoniana) in Dadu River Basin in the central part of the western Sichuan Plateau, China. Correlation analysis with climatic factors implies that the radial growth of trees in the region is mainly limited by temperature and has the highest correlation with the mean minimum temperature in summer (June and July) (R = 0.602, p < 0.001). On this basis, the TRW chronology was adopted to reconstruct variations in the mean minimum temperatures in summer from 1733 to 2010 in the upper reaches of Dadu River. The reconstruction equation was stable and reliable and offered a variance explanation rate of 36.2% in the observed period (1962~2010). In the past 278 years, the region experienced nine warm periods and ten cold periods. The warmest and coldest years occurred in 2010 and 1798, respectively, with values of 13.6 °C and 11.0 °C. The reconstruction was highly spatiotemporally representative and verified by temperatures reconstructed using other tree-ring data in surrounding areas. A significant warming trend was found in the last few decades. Moreover, the multi-taper method (MTM) analysis indicated significant periodic changes in quasi-2-year and 21–35-year periods, for which the El Niño Southern Oscillation (ENSO) and the Pacific decadal oscillation (PDO) could be the key controlling factors. Full article

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

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15 pages, 5447 KiB

Open AccessArticle

Simulation and Prediction of Sea Level Rise Impact on the Distribution of Mangrove and Spartina alterniflora in Coastal China

by Yaqi Zhang, Lina Cui, Deyu Xie and Jiang Jiang

Forests 2023, 14(4), 831; https://doi.org/10.3390/f14040831 - 18 Apr 2023

Cited by 3 | Viewed by 1730

Abstract

Sea level rise (SLR) has a significant impact on the vegetation ecosystem in coastal wetlands. Taking coastal China as the study area, the SLAMM (sea level rise affecting marsh model) was used to simulate the continuous long-term (2015–2100) effects of the spatiotemporal changes [...] Read more.

Sea level rise (SLR) has a significant impact on the vegetation ecosystem in coastal wetlands. Taking coastal China as the study area, the SLAMM (sea level rise affecting marsh model) was used to simulate the continuous long-term (2015–2100) effects of the spatiotemporal changes in mangrove and Spartina alterniflora in the four shared socioeconomic pathway scenarios (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5) of sea level rise by 2100; then, ArcGis was used to assess and compare the impact of SLR on land use. The results are as follows. (1) The dramatic reduction in the vegetation area is positively correlated with the rate of sea level rise. (2) Tidal differences and sedimentation rates affect the response of mangrove and S. alterniflora distribution to sea level rise, as well as interactions between organisms. (3) The reasonable land use of coastal wetlands is important to researchers. Land use is one of the tools for effective mangrove conservation. In conclusion, in scientific research and production practice, it is important to combine the biotic and abiotic factors affecting the distribution of mangroves and S. alterniflora. Full article

(This article belongs to the Special Issue Coastal Forested Wetland Conservation and Carbon Function)

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14 pages, 1391 KiB

Open AccessArticle

Effects of Trace Elements on Traits and Functional Active Compounds of Camellia oleifera in Nutrient-Poor Forests

by Qiuyue Dai, Zheng Deng, Lan Pan, Lang Nie, Yunyuan Yang, Yongfang Huang and Jiuxiang Huang

Forests 2023, 14(4), 830; https://doi.org/10.3390/f14040830 - 18 Apr 2023

Cited by 2 | Viewed by 974

Abstract

Camellia oleifera is a major woody oilseed species in China, but it is typically cultivated in nutrient-poor soils and may be affected by various trace elements. This study examined how spraying selenium, boron, and zinc trace elements affected the traits and functional active [...] Read more.

Camellia oleifera is a major woody oilseed species in China, but it is typically cultivated in nutrient-poor soils and may be affected by various trace elements. This study examined how spraying selenium, boron, and zinc trace elements affected the traits and functional active compounds of C. oleifera under nutrient deficiency. The results revealed significant variations in the effects of different trace element combinations on C. oleifera. Optimal concentrations of zinc and selenium are critical for promoting the growth and development of C. oleifera fruit. The transverse diameter of the fruit, the single fruit weight, the number of seeds per fruit, the single fresh seed weight, the oil content in the fruit, and the oil yield per plant of other treatments can be increased by up to 3.07%, 10.57%, 23.66%, 30.23%, 7.94%, and 21.95%, respectively, at most, compared to the control group. Diluting zinc from 1000 to 1500 times and maintaining a selenium concentration from 100 to 200 mg/L has been found to be beneficial for fruit growth. While low concentrations of selenium may promote an increase in fruit transverse diameter, high concentrations of selenium, along with high dilutions of zinc, can have the opposite effect, leading to a reduction in fruit diameter. However, a high concentration of selenium can positively impact the number of seeds per fruit. The most effective combination was found to be a selenium concentration of 0 mg/L, a boron concentration of 4 mg/L, and a zinc dilution of 1500. Interestingly, lower concentrations of selenium and boron, as well as lower dilutions of zinc, were found to increase the oil yield per plant. This suggests that a careful balance of trace elements is required to promote both fruit growth and oil content. The total sterol, squalene, total flavonoid, and polyphenol content of other treatments can be increased by up to 28.81%, 32.07%, 188.04%, and 92.61%, respectively, at most, compared to the control group. Selenium fertilizer and boron fertilizer increased the total sterol content in Camellia oil and had a significant positive correlation at the 0.01 level, but zinc fertilizer had little influence on it. High concentration selenium fertilizer generally increased the squalene, total flavonoid, and polyphenol content in Camellia oil, but boron and zinc fertilizers had little effect on these components. The results suggested that choosing appropriate fertilizer combinations could improve nutrient deficiency in C. oleifera and enhance the functional active compounds of its oil, thereby enhancing its value. Full article

(This article belongs to the Special Issue Strategies for Tree Improvement under Stress Conditions)

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15 pages, 3225 KiB

Open AccessArticle

Seed Harvesting and Climate Change Interact to Affect the Natural Regeneration of Pinus koraiensis

by Kai Liu, Hang Sun, Hong S. He and Xin Guan

Forests 2023, 14(4), 829; https://doi.org/10.3390/f14040829 - 18 Apr 2023

Cited by 1 | Viewed by 1023

Abstract

The poor natural regeneration of Pinus koraiensis is a key limitation for restoring the primary mixed Pinus koraiensis forests. Seed harvesting and climate change are the important factors that influence the natural regeneration of Pinus koraiensis; however, it is hard to illustrate [...] Read more.

The poor natural regeneration of Pinus koraiensis is a key limitation for restoring the primary mixed Pinus koraiensis forests. Seed harvesting and climate change are the important factors that influence the natural regeneration of Pinus koraiensis; however, it is hard to illustrate how, in synergy, they affect its regeneration at the landscape scale. In this study, we coupled an ecosystem process model, LINKAGES, with a forest landscape model, LANDIS PRO, to evaluate how seed harvesting and climate change influenced the natural regeneration of Pinus koraiensis over large temporal and spatial scales. Our results showed that seed harvesting decreased the abundance of Pinus koraiensis juveniles by 1, 14, and 18 stems/ha under the historical climate, and reduced by 1, 17, and 24 stems/ha under the future climate in the short- (years 0–50), medium- (years 60–100), and long-term (years 110–150), respectively. This indicated that seed harvesting intensified the poor regeneration of Pinus koraiensis, irrespective of climate change. Our results suggested that seed harvesting diminished the generation capacity of Pinus koraiensis over the simulation period. Seed harvesting reduced the abundance of Pinus koraiensis at the leading edge and slowed down its shift into high-latitude regions to adapt to climate change. Our results showed that the effect magnitudes of seed harvesting, climate change, their interaction and combination at the short-, medium- and long-term were −61.1%, −78.4%, and −85.7%; 16.5%, 20.9%, and 38.2%; −10.1%, −16.2% and −32.0%; and −54.7%, −73.8%, and −79.5%, respectively. Seed harvesting was a predominant factor throughout the simulation; climate change failed to offset the negative effect of seed harvesting, but the interactive effect between seed harvesting and climate change almost overrode the positive effect of climate change. Seed harvesting, climate change, and their interaction jointly reduced the natural regeneration of Pinus koraiensis. We suggest reducing the intensity of seed harvesting and increasing silvicultural treatments, such as thinning and artificial plantation, to protect and restore the primary mixed Pinus koraiensis forests. Full article

(This article belongs to the Special Issue Impact of Climate Warming and Disturbances on Forest Ecosystems)

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Forests, Volume 14, Issue 4 (April 2023) – 202 articles

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