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Forests, Volume 13, Issue 4 (April 2022) – 143 articles

Cover Story (view full-size image): The European spruce bark beetle, Ips typographus (L.), is a major pest of Norway spruce. During outbreaks, the beetles can colonize moderately stressed trees via mass attacks mediated by aggregation pheromones, while at endemic population levels, beetles infest trees with impaired defenses. I. typographus introduces ophiostomatoid fungi into the phloem, which can support host colonization. Low-density fungal infections are locally contained by hypersensitive wound reactions; larger necrotic lesions indicate lower tree resistance. Here, we made links between drought stress, susceptibility to fungal infections, and the attractiveness of spruce for host-searching I. typographus males. We sampled bark cores from roofed, non-roofed and untreated control trees of a rainfall exclusion field site. View this paper
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Article
Caveat emptor: On the Need for Baseline Quality Standards in Computer Vision Wood Identification
Forests 2022, 13(4), 632; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040632 - 18 Apr 2022
Viewed by 763
Abstract
Computer vision wood identification (CVWID) has focused on laboratory studies reporting consistently high model accuracies with greatly varying input data quality, data hygiene, and wood identification expertise. Employing examples from published literature, we demonstrate that the highly optimistic model performance in prior works [...] Read more.
Computer vision wood identification (CVWID) has focused on laboratory studies reporting consistently high model accuracies with greatly varying input data quality, data hygiene, and wood identification expertise. Employing examples from published literature, we demonstrate that the highly optimistic model performance in prior works may be attributed to evaluating the wrong functionality—wood specimen identification rather than the desired wood species or genus identification—using limited datasets with data hygiene practices that violate the requirement of clear separation between training and evaluation data. Given the lack of a rigorous framework for a valid methodology and its objective evaluation, we present a set of minimal baseline quality standards for performing and reporting CVWID research and development that can enable valid, objective, and fair evaluation of current and future developments in this rapidly developing field. To elucidate the quality standards, we present a critical revisitation of a prior CVWID study of North American ring-porous woods and an exemplar study incorporating best practices on a new dataset covering the same set of woods. The proposed baseline quality standards can help translate models with high in silico performance to field-operational CVWID systems and allow stakeholders in research, industry, and government to make informed, evidence-based modality-agnostic decisions. Full article
(This article belongs to the Section Wood Science and Forest Products)
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Article
Damage Modes Recognition of Wood Based on Acoustic Emission Technique and Hilbert–Huang Transform Analysis
Forests 2022, 13(4), 631; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040631 - 18 Apr 2022
Viewed by 611
Abstract
Identifying the different damage modes of wood is of great significance for monitoring the occurrence, development, and evolution of wood material damage. This paper presents the research results of the application of acoustic emission (AE) technology to analyze and evaluate the mapping relationship [...] Read more.
Identifying the different damage modes of wood is of great significance for monitoring the occurrence, development, and evolution of wood material damage. This paper presents the research results of the application of acoustic emission (AE) technology to analyze and evaluate the mapping relationship between the damage pattern of wood in the fracture process and the AE signal. For the three-point bending specimen with pre-crack, the double cantilever beam specimen, the single fiber tensile specimen, and the uniaxial compression specimen, the bending tensile compression test and the AE monitoring were performed, respectively. After the post-processing and analysis of the recorded AE signal, the results show that the peak frequency of AE is an effective parameter for identifying different damage modes of wood. In this study, the empirical mode decomposition (EMD) of the AE signal can separate and extract a variety of damage modes contained in the AE signal. The Hilbert–Huang transform (HHT) of the AE signal can clearly describe the frequency distribution of intrinsic mode function (IMF) components in different damage stages on the time scale, and can calculate instantaneous energy accurately, which provides a basis for damage mode recognition and lays a foundation for further accurate evaluation of the wood damage process. Full article
(This article belongs to the Section Wood Science and Forest Products)
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Article
Whole Body Vibrations during Fully Mechanised Logging
Forests 2022, 13(4), 630; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040630 - 17 Apr 2022
Viewed by 723
Abstract
This paper seeks to answer the question of whether the magnitude of vibrations affecting the whole body of the harvester operator (WBV) that are generated by the harvester boom is affected by the size of the processed trunk volume, to specify closer, the [...] Read more.
This paper seeks to answer the question of whether the magnitude of vibrations affecting the whole body of the harvester operator (WBV) that are generated by the harvester boom is affected by the size of the processed trunk volume, to specify closer, the magnitude of WBVs generated during forest logging, and to localise these WBVs in individual partial operations. For these purposes, the production process, i.e., forest logging, was divided into six partial operations (Searching; Felling; Processing; Unproductive time; Machine movement; Stationary position). WBVs were scanned in the respective partial operations according to standard ISO 2631-1:1997 and the European Directive 2002/44/EC, and then the values were mutually compared. Volumes of processed trunks were recorded, which were then assigned to the given WBV during the respective operations. Research results did not demonstrate a correlation between the size of the transmitted vibrations and the volumes of cut trunks in the partial work operations of Felling and Processing. Neither a difference was found between the individual partial operations with two exceptions: Searching and Felling/Processing and Unproductive time. The research further showed that the average WBV of three partial operations did not meet the daily limit of 0.50 m/s2 permitted by European Directive 2002/44/EC, within a range from 12.20% to 27.02%. Full article
(This article belongs to the Section Forest Operations and Engineering)
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Article
Distributions and Influencing Factors of Soil Organic Carbon Fractions under Different Vegetation Restoration Conditions in a Subtropical Mountainous Area, SW China
Forests 2022, 13(4), 629; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040629 - 17 Apr 2022
Viewed by 687
Abstract
Vegetation type is known to affect soil organic carbon (SOC) storage. However, the magnitudes and distributions of SOC sequestration and driving factors for different vegetation types are still largely unknown. Thus, we studied the changes in SOC fractions along soil profiles for different [...] Read more.
Vegetation type is known to affect soil organic carbon (SOC) storage. However, the magnitudes and distributions of SOC sequestration and driving factors for different vegetation types are still largely unknown. Thus, we studied the changes in SOC fractions along soil profiles for different vegetation restoration types and their relationships with soil properties. We selected five vegetation types and collected soil samples from depth intervals of 0–10, 10–30, 30–60, and 60–90 cm. Five soil carbon fractions and the soil properties were tested to evaluate the soil carbon fraction distributions and influencing factors. Our results demonstrated that the concentrations of total organic carbon (TOC) and five carbon fractions were strongly affected by vegetation types and soil depths. The concentrations of all five soil carbon fractions in 0–10 cm depth were higher than those in the other three soil depths and generally increased with vegetation complexity. The Pearson correlations and redundancy analysis showed that the fractions of soil glomalin-related soil protein (GRSP) and Fe oxides as well as the soil bulk densities, were the most significant related to soil TOC levels and carbon fractions, which suggests that soil biochemical and physicochemical processes are among the most important mechanisms that contribute to SOC persistence. Considering the sensitive indices of the soil carbon variables and PCA results, soil permanganate oxidizable carbon (POXC) was considered to be the most sensitive index for differentiating the effects of vegetation types. These results provide important information regarding the distributions and driving factors of the carbon fractions that result from different vegetation restoration types and will help to improve our understanding of soil carbon sequestration during vegetation restoration processes. Full article
(This article belongs to the Special Issue Soil Carbon Storage in Forests: Mechanisms, Dynamics, and Management)
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Article
Genome-Wide Investigation of the MiR166 Family Provides New Insights into Its Involvement in the Drought Stress Responses of Tea Plants (Camellia sinensis (L.) O. Kuntze)
Forests 2022, 13(4), 628; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040628 - 17 Apr 2022
Viewed by 789
Abstract
MicroRNA166 (miR166) is a highly conserved plant miRNA that plays a crucial role in plant growth and the resistance to various abiotic stresses. However, the miR166s in tea (Camellia sinensis (L.) O. Kuntze) have not been comprehensively identified and analyzed. This study [...] Read more.
MicroRNA166 (miR166) is a highly conserved plant miRNA that plays a crucial role in plant growth and the resistance to various abiotic stresses. However, the miR166s in tea (Camellia sinensis (L.) O. Kuntze) have not been comprehensively identified and analyzed. This study identified 30 mature miR166s and twelve pre-miR166s in tea plants. An evolutionary analysis revealed that csn-miR166s originating from the 3′ arm of their precursors were more conserved than the csn-miR166s derived from the 5′ arm of their precursors. The twelve pre-miR166s in tea were divided into two groups, with csn-MIR166 Scaffold364-2 separated from the other precursors. The Mfold-based predictions indicated that the twelve csn-MIR166s formed typical and stable structures comprising a stem-loop hairpin, with minimum free energy ranging from −110.90 to −71.80 kcal/mol. An analysis of the CsMIR166 promoters detected diverse cis-acting elements, including those related to light responses, biosynthesis and metabolism, abiotic stress defenses, and hormone responses. There was no one-to-one relationship between the csn-miR166s and their targets, but most csn-miR166s targeted HD-Zip III genes. Physiological characterization of tea plants under drought stress showed that leaf water content proportionally decreased with the aggravation of drought stress. In contrast, tea leaves’ malondialdehyde (MDA) content proportionally increased. Moreover, the cleavage site of the ATHB-15-like transcript was identified according to a modified 5′ RNA ligase-mediated rapid amplification of cDNA ends. The RT-qPCR data indicated that the transcription of nine csn-miR166s was negatively correlated with their target gene. Full article
(This article belongs to the Special Issue Tree Genetics: Molecular and Functional Characterization of Genes)
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Article
Impact of Growing Season Precipitation Regime on the Performance of Masson Pine Saplings
Forests 2022, 13(4), 627; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040627 - 16 Apr 2022
Viewed by 673
Abstract
The growth and physiological effects of either decreased precipitation (e.g., drought) or increased one (e.g., flooding) on trees have been extensively studied. However, less attention has been paid to the questions of whether and how trees respond to changes in precipitation regime with [...] Read more.
The growth and physiological effects of either decreased precipitation (e.g., drought) or increased one (e.g., flooding) on trees have been extensively studied. However, less attention has been paid to the questions of whether and how trees respond to changes in precipitation regime with different rainfall amounts. To investigate the effects of water availability on sapling’s growth, tissue levels of non-structural carbohydrates (NSCs), and nutrients, we carried out a greenhouse experiment with Masson pine (Pinus massoniana Lamb.) saplings grown in precipitation amounts of 300, 500, and 700 mm (3 levels) in combination with two levels of a watering regime (i.e., regular watering vs. pulsed watering, i.e., frequent low rainfall coupled with fewer instances of heavy rain) for a growing season in subtropical China. Pulsed watering caused higher soil pH (>7.5) but lower soil organic carbon and soil nutrients, and consequently led to smaller plant biomass and height of the saplings than regular watering, especially in the water amount treatment of 300 and 500 mm. Additionally, higher levels of NSCs in plant tissue concentrations were observed under pulsed watering than under regular watering, due to greater carbon consumption for supporting higher growth rate and a dilution effect by bigger plant size and biomass in the latter. Our results indicated that the growing season precipitation amount of 300 mm is sufficient for the drought-tolerant tree species P. massoniana. In such a case, the growing season precipitation regime rather than the precipitation amount will have a much stronger impact on the tree performance. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Article
Comparative Analyses of 35 Complete Chloroplast Genomes from the Genus Dalbergia (Fabaceae) and the Identification of DNA Barcodes for Tracking Illegal Logging and Counterfeit Rosewood
Forests 2022, 13(4), 626; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040626 - 16 Apr 2022
Cited by 1 | Viewed by 745
Abstract
The genus Dalbergia contains more than 200 species, several of which are trees that produce traditional medicines and extremely high-value timber commonly referred to as rosewood. Due to the rarity of these species in the wild, the high value of the timber, and [...] Read more.
The genus Dalbergia contains more than 200 species, several of which are trees that produce traditional medicines and extremely high-value timber commonly referred to as rosewood. Due to the rarity of these species in the wild, the high value of the timber, and a growing international illicit trade, CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) has listed the entire genus in appendix II and the species Dalbergia nigra in appendix I because species in this genus are considered at risk of extinction. Given this, and the fact that species or even genus level determination is nearly impossible from cut timber morphology, alternative molecular methods are needed to identify and track intercepted rosewood. To better identify rosewood using molecular methods, we sequenced and assembled eight chloroplast genomes including D. nigra as well as conducted comparative analyses with all other available chloroplast genomes in Dalbergia and closely related lineages. From these analyses, numerous repeats including simple sequence repeats (SSR) and conserved nucleotide polymorphisms unique to subclades within the genus were detected. From phylogenetic analysis based on the CDS from 77 chloroplast genes, the groups Siam rosewood and scented rosewood resolved as monophyletic, supporting the morphological traits used to delimit these species. In addition, several instances of paraphyly and polyphyly resulting from mismatches between taxonomic determinations and phylogenetic tree topology were identified. Ultimately, the highly variable regions in the chloroplast genomes will provide useful plastid markers for further studies regarding the identification, phylogeny, and population genetics of Dalbergia species, including those frequently intercepted in illegal trade. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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Article
Variation in Soil Bacterial and Fungal Community Composition at Different Successional Stages of a Broad-Leaved Korean Pine Forest in the Lesser Hinggan Mountains
Forests 2022, 13(4), 625; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040625 - 16 Apr 2022
Viewed by 745
Abstract
Soil microorganisms are an integral part of the soil and are highly sensitive to environmental changes. The shift in plant community and soil properties following forest succession may cause differences in soil bacterial and fungal community composition. Some studies suggested following the succession [...] Read more.
Soil microorganisms are an integral part of the soil and are highly sensitive to environmental changes. The shift in plant community and soil properties following forest succession may cause differences in soil bacterial and fungal community composition. Some studies suggested following the succession of the community, the species composition tends to switch from r-strategy groups to k-strategy groups. However, generalization on the changing pattern has not been worked out. Three forests at an early-, intermediate-, and late-stage (ES, IS, LS) of the succession of broad-leaved Korean pine forest in the Lesser Hinggan Mountains were surveyed to study the variation in soil bacterial and fungal community composition as the succession proceeds. Soil microbial community composition and related soil factors were analyzed by systematic sampling. Significant differences in soil microbial community composition were detected between forests at different stages. The bacterial diversity increased, while the fungal diversity decreased (p < 0.05) from the early to the late successional forest. The fungi to bacteria ratio (F/B) and the (Proteobacteria + Bacteroidetes) to (Actinobacteria + Acidobacteria) ratio increased substantially with succession (p < 0.05). At the phylum level, Bacteroidetes, Ascomycota and Mortierellomycota were dominant in the ES forest, while Actinobacteria and Basidiomycota were prevalent in the LS forest. At the class level, Gammaproteobacteria, Acidobacteriia, Bacteroidia, Sordariomycetes and Mortierellomycetes were dominant in the ES forest, whereas Subgroup_6, Agaricomycetes, Geminibasidiomycetes and Tremellomycetes were dominant in the LS forest. Soil water content (SWC) and available phosphorus (AP) had significant effects on the bacterial community composition (p < 0.05). Soil organic carbon (SOC), total nitrogen (TN), the carbon–nitrogen ratio (C/N), total potassium (TK) and SWC had significant effects on the fungal community composition (p < 0.05). SOC and TN were positively correlated with r-strategy groups (p < 0.05) and were significantly negatively correlated with k-strategy groups (p < 0.05). Our results suggest that the soil bacterial and fungal community composition changed significantly in forests across the successional stages, and the species composition switched from r-strategy to k-strategy groups. The bacterial and fungal community diversity variation differed in forests across the successional stages. The changes in soil organic carbon and nitrogen content resulted in the shifting of microbial species with different ecological strategies. Full article
(This article belongs to the Section Forest Ecology and Management)
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Article
Characterization on the Copolymerization Resin between Bayberry (Myrica rubra) Tannin and Pre-Polymers of Conventional Urea–Formaldehyde Resin
Forests 2022, 13(4), 624; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040624 - 16 Apr 2022
Viewed by 704
Abstract
By focusing on the disadvantages of weak water resistance and high formaldehyde emission of urea–formaldehyde resin (UF), this research provides a new method to overcome these shortages of UF resin by using tannin for partial substitution of urea. Furthermore, plasma pretreatment of wood [...] Read more.
By focusing on the disadvantages of weak water resistance and high formaldehyde emission of urea–formaldehyde resin (UF), this research provides a new method to overcome these shortages of UF resin by using tannin for partial substitution of urea. Furthermore, plasma pretreatment of wood was introduced to strengthen the bonding performance of plywood. The investigation of the chemical structure of UF resin and tannin–urea–formaldehyde resin (TUF) were performed with Fourier transform infrared spectroscopy (FT-IR) and solid-state 13C nuclear magnetic resonance (13C NMR). The results of investigations confirmed the joining of tannin into the resin structure, which may enhance structural rigidity of TUF adhesives and improve hydrolysis stability. Then, thermal performance of UF resin and TUF resins were tested by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis. The DSC results indicated that the curing temperature did not change significantly. However, the TG analysis showed that the thermal stability of TUF resin was considerably improved. In bonding performance test, tannin–urea–formaldehyde resin (TUF) revealed an excellent water resistance, comparable to UF resin and can fulfill the standard requirement for plywood (Type II according to the Norm GB/T 17657-2013). It is interesting that the shear strength of wood specimens, bonded with TUF6 resin, after low-pressure cold plasma equipment (CLP plasma) and jet type atmospheric low-temperature plasma (JTLP plasma) treatment, reached 0.80 MPa and 0.85 MPa, respectively, after being soaked in boiling water for 3 h. In addition, most of the bonded plywood samples with TUF resin exhibited a lower formaldehyde emission, especially those prepared at 70 °C and 1.5 h, in which the formaldehyde emission amount could be reduced by approximately 39%. Full article
(This article belongs to the Special Issue Wood-Based Products and Renewable Materials)
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Article
A Cork Cell Wall Approach to Swelling and Boiling with ESEM Technology
Forests 2022, 13(4), 623; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040623 - 15 Apr 2022
Viewed by 643
Abstract
The bark of cork oak (Quercus suber L.) is mostly used for cork stopper production; when bark undergoes a series of industrial procedures, boiling usually leads to changes in the characteristics of its tissue. Trees are traditionally grown under natural conditions; however, [...] Read more.
The bark of cork oak (Quercus suber L.) is mostly used for cork stopper production; when bark undergoes a series of industrial procedures, boiling usually leads to changes in the characteristics of its tissue. Trees are traditionally grown under natural conditions; however, irrigation is now being used in plantations. This permanent water availability affects cork oak development, while its effects on industrial procedures are unknown. This study provides the first insight into the behaviour of the cell walls of cork during the process of swelling and boiling when trees have been grown under irrigation, that is, subject to a specific water regime. Cork tissue is analysed using environmental and scanning electron microscopy under three regimes: raw conditions, following immersion in water, and after boiling. Additionally, the radial expansion of samples is determined. The results show greater cell wall expansion in cork from the irrigated site than in cork from the traditional rainfed plot when hydrated for 24 h. After boiling, the cell walls of the cork from the rainfed site are thinner than in the raw stage, which is in contrast to the irrigated cork. This study suggests that irrigation during cork oak growth produces a higher capacity for adsorption, increasing cell wall thickness from the raw stage to the boiling stage. Full article
(This article belongs to the Section Wood Science and Forest Products)
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Article
Climatic and Anthropogenic Drivers of Forest Succession in the Iberian Pyrenees during the Last 500 Years: A Statistical Approach
Forests 2022, 13(4), 622; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040622 - 15 Apr 2022
Viewed by 636
Abstract
Anticipating future successional forest trends in the face of ongoing global change is an essential conservation target. Mountain forests are especially sensitive to environmental shifts, and their past responses to climatic and anthropogenic (external) drivers may provide a basis for improving predictions of [...] Read more.
Anticipating future successional forest trends in the face of ongoing global change is an essential conservation target. Mountain forests are especially sensitive to environmental shifts, and their past responses to climatic and anthropogenic (external) drivers may provide a basis for improving predictions of future developments. This paper uses independent high-resolution palynological and paleoclimatic reconstructions to statistically analyze the long-term effects of external drivers on regional forest succession in the central Iberian Pyrenees during the last 500 years. The statistical methods used are Gaussian response analysis, cluster analysis, rate-of-change analysis, principal component analysis, and redundancy analysis. The dominant taxa of these forests (Quercus, Betula, Pinus) showed significant relationships with summer temperature, summer drought, and autumn precipitation. Immediate and delayed (by two or more decades) responses of these trees to climatic drivers were identified. Regional succession showed a closed path, starting at the end points around the attraction domain of pine-dominated forests. This trajectory was determined by a trend toward anthropogenic forest clearing (16th to 18th centuries) and a reverse trend of natural forest recovery (18th to 20th centuries). Forest clearing was due to burning, facilitated by drought, and was followed by the expansion of cropping and grazing lands. Forest recovery was fostered by reduced human pressure and rising temperatures. The statistical approach used in this work has unraveled ecological relationships that remained unnoticed in previous works and would be important for predicting future successional trends under changing climates. The reported response lags of individual taxa to climatic drivers may complicate the establishment of reliable ecological relationships and should be addressed in future studies. Full article
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Article
Development and Structural Organization of Mexico’s Mangrove Monitoring System (SMMM) as a Foundation for Conservation and Restoration Initiatives: A Hierarchical Approach
Forests 2022, 13(4), 621; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040621 - 15 Apr 2022
Viewed by 879
Abstract
Mangroves provide ecosystem services worth billions of dollars worldwide. Although countries with extensive mangrove areas implemented management and conservation programs since the 1980s, the global area is still decreasing. To recuperate this lost area, both restoration and rehabilitation (R/R) projects have been implemented [...] Read more.
Mangroves provide ecosystem services worth billions of dollars worldwide. Although countries with extensive mangrove areas implemented management and conservation programs since the 1980s, the global area is still decreasing. To recuperate this lost area, both restoration and rehabilitation (R/R) projects have been implemented but with limited success, especially at spatial scales needed to restore functional properties. Monitoring mangroves at different spatial scales in the long term (decades) is critical to detect potential threats and select cost-effective management criteria and performance measures to improve R/R program success. Here, we analyze the origin, development, implementation, and outcomes of a country-level mangrove monitoring system in the Neotropics covering >9000 km2 over 15 years. The Mexico’s Mangrove Monitoring System (SMMM) considers a spatiotemporal hierarchical approach as a conceptual framework where remote sensing is a key component. We analyze the role of the SMMM’s remote sensing products as a “hub” of multi- and interdisciplinary ecological and social-ecological studies to develop national priorities and inform local and regional mangrove management decisions. We propose that the SMMM products, outcomes, and lessons learned can be used as a blueprint in other developing countries where cost-effective R/R projects are planned as part of mangrove protection, conservation, and management programs. Full article
(This article belongs to the Special Issue Mangrove Wetland Restoration and Rehabilitation)
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Article
Application of Remote Sensing Data for Assessment of Bark Beetle Attacks in Pine Plantations in Kirkovo Region, the Eastern Rhodopes
Forests 2022, 13(4), 620; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040620 - 15 Apr 2022
Viewed by 658
Abstract
Intensive forest afforestation with native pine species was developed in the 1960s on degraded and deforested lands in the region of the Eastern Rhodopes (south-eastern Bulgaria). Severe damage by wet snow was registered in the coniferous forests of the Rhodopes in March 2015. [...] Read more.
Intensive forest afforestation with native pine species was developed in the 1960s on degraded and deforested lands in the region of the Eastern Rhodopes (south-eastern Bulgaria). Severe damage by wet snow was registered in the coniferous forests of the Rhodopes in March 2015. In the following years, bark beetle attacks were registered on the broken and felled fresh wood. As a result, bark beetle infestation spots appeared in the pine plantations. In the period 2019–2021, damage caused by bark beetles was assessed in the region of State Forestry Kirkovo (the Eastern Rhodopes, south-eastern Bulgaria). An integrated approach using the data of the information system of the Executive Forest Agency (ISEFA), remote sensing data obtained by an “eBee SQ” unmanned aerial vehicle (UAV) equipped with a “Parrot Sequoia” multispectral camera, and subsequent terrestrial observations, was applied. ISEFA data showed that there was no serious damage caused by abiotic and biotic factors in the pine forests of SF Kirkovo until 2014. Snow damage in 2015 affected 513 ha of pine plantations, and bark beetle infestations reached up to 1316 ha in 2016. In 2019, a total of 226.87 ha of pine plantations were captured in three localities—Fotinovo, Kirkovo, and Kremen. The relative share of damage caused by bark beetles was greater in P. sylvestris plantations (15.3–23.0%), compared to damage in P. nigra (2.3%). Four different categories of normalised difference vegetation index (NDVI) were separated in bark beetle infestation spots—living trees, dead trees, grass and shrub vegetation, stones and rocks. The NDVI values in locations with living trees varied between 0.500 (spaces between tree crowns) and 0.700 (central part of the crown projection) (an average of 0.617). In the locations with dead trees, the average values of NDVI of lying trees was 0.273, and in standing trees, NDVI varied between 0.275 (central part of crown projections) and 0.424 (spaces between tree crowns). In the locations with grass and shrub vegetation, stones and rocks, the average NDVI was 0.436 and 0.329, respectively. In the field study, average defoliation of 31.2–32.3% was registered in P. sylvestris plantations, and 47.4% in P. nigra plantations. Defoliations mainly were caused by pine processionary moth (Thaumetopoea pityocampa) and fungal pathogens (Dothistroma septosporum and Lecanosticta acicola). The damage was caused by Ips acuminatus (in P. sylvestris only), and I. sexdentatus, Tomicus piniperda and T. minor (in P. sylvestris and P. nigra). Infestations by other xylophages, such as Phaenops cyanea, Rhagium inquisitor, and Pissodes spp., were also found on pine stems. Full article
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Review
Research Advances in Plant Physiology and Ecology of Desert Riparian Forests under Drought Stress
Forests 2022, 13(4), 619; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040619 - 15 Apr 2022
Cited by 1 | Viewed by 582
Abstract
Under drought stress, desert riparian forest plants are highly self-regulating and have their own unique water use and regulation strategies, which can respond positively in several aspects such as physiology, ecology, and individual phenotypes when coping and adapting to the stresses brought by [...] Read more.
Under drought stress, desert riparian forest plants are highly self-regulating and have their own unique water use and regulation strategies, which can respond positively in several aspects such as physiology, ecology, and individual phenotypes when coping and adapting to the stresses brought by external environmental changes. In addition, as an important component of arid zone ecosystems, desert riparian forest plants maintain the cycling process of energy and material in desert areas. Therefore, it is of great ecological value to study the role played by desert riparian forest plants in desertification control and biodiversity conservation in arid zones. The purpose of this study is to provide basic data and scientific basis for the conservation, and restoration of desert riparian forests in the inland river basin of arid zone. In this paper, the physiological and ecological responses of desert riparian plants under drought stress were analyzed by reviewing the literature and focusing on the key scientific issues such as drought avoidance mechanisms, water use, and water redistribution, and the relationship between interspecific water competition and resource sharing of desert riparian plants. The results showed that: (1) In the inland river basin of arid zone, desert riparian plants show a mutual coordination of increasing soluble sugars, proline, malondialdehyde (MDA), and decreasing peroxidase (POD), to form a unique drought avoidance mechanism, and improve their drought tolerance by changing leaf stomatal conductance resulted from regulating abscisic acid (ABA) and cytokinin (CTK) content. (2) Desert riparian forest plants have their own unique water use and regulation strategies. When the degree of drought stress increased, Populus euphratica enhanced the water flow of dominant branches by actively sacrificing the inferior branches to ensure and improve the overall survival chances of the plant, while Tamarix ramosissima weaken hydraulic conductance, and increase subsurface material inputs by reducing plant height to cope with drought stress. (3) The root systems of desert riparian plants have hydraulic uplift and water redistribution functions, and, in the hydraulic uplift process of P. euphratica and T. ramosissima root systems, there is a possibility of assisting with other species in water utilization and the existence of a resource sharing mechanism. Full article
(This article belongs to the Section Forest Hydrology)
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Article
Phenotypic Diversity Analysis and Superior Family Selection of Industrial Raw Material Forest Species-Pinus yunnanensis Franch
Forests 2022, 13(4), 618; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040618 - 15 Apr 2022
Viewed by 552
Abstract
Pinus yunnanensis Franch is a major forest species in southwest China as a source of timber and industrial raw materials. The genetic quality of the species is declining and the differentiation of offspring is strong as affected by environmental change and improper management [...] Read more.
Pinus yunnanensis Franch is a major forest species in southwest China as a source of timber and industrial raw materials. The genetic quality of the species is declining and the differentiation of offspring is strong as affected by environmental change and improper management measures. To assess the phenotypic diversity of natural populations, the evaluation of twelve phenotypic traits in nine populations from its whole distribution was performed. Studies revealed plentiful phenotypic variations within and among populations. The phenotypic variation within the population was 4.03%, and was lower than that among populations (21.04%), indicating that the phenotypic variation among populations was the main source. The mean differentiation coefficient was 91.23%, and the mean coefficient of variation of twelve traits was 28.27%, ranging from 14.18% (length of needles) to 70.11% (height under the branches). No significant correlation between plant height and environmental factors was found. Mean annual temperature, mean temperature of the driest quarter, mean temperature of the wettest quarter, and latitude were significantly correlated to diameter breast height, respectively. Temperature is the most important factor affecting the diameter of breast height. Three principal components that represent plant shape, needle, and lateral branch trait, respectively, were obtained while the cumulative contribution rate reached 74.40%. According to the unweighted pair-group method with arithmetic means (UPGMA) cluster analysis, nine populations were divided into three clusters. However, populations were not clustered strictly according to geographic distance, implying that there is a discontinuity in the variation of phenotypic traits. Compared with other populations, the Lufeng population contains obvious advantages in plant height, diameter breast height, crown diameter, and needle length and width, whereas the Yongren population has the worst performance in plant height, crown diameter, and the number of lateral branches. Moreover, for selecting superior families, both the comprehensive scoring method and principal component analysis were combined. By comparing trait values from 258 families, eleven superior families with an actual gain of each trait ranging from 0.02% to 32.23% were successfully screened out. This study provides a certain reference significance for the breeding of improved varieties and plantation management of P. yunnanensis. Full article
(This article belongs to the Section Genetics and Molecular Biology)
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Article
Rural Community Agency in Cameroon: Interactions with Forest Policies and the REDD+ Climate Change Regime
Forests 2022, 13(4), 617; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040617 - 15 Apr 2022
Viewed by 550
Abstract
Community forestry around the world has demonstrated its potential for implementing the Reducing Emissions from Deforestation and Degradation (REDD+) climate change program. Secure tenure rights and access to rule-making are known as contributing to successful community forestry outcomes. Still, the effects of different [...] Read more.
Community forestry around the world has demonstrated its potential for implementing the Reducing Emissions from Deforestation and Degradation (REDD+) climate change program. Secure tenure rights and access to rule-making are known as contributing to successful community forestry outcomes. Still, the effects of different aspects of rural ‘community agency’ are not well established. We investigate forest governance and conflicts and the relationships between aspects of rural community agency under the REDD+ climate change program in two forest communities—the villages of Fabe and Mosongiseli—near the southern portion of the Korup National Park in Cameroon. Using data from a survey instrument and interviews, we analyze, using “agency theory”, the concept of rural community agency according to dimensions of attitudes, understandings, and empowerment in the two communities in relation to forest governance and conflicts under REDD+. Our findings indicate a variety of power relations (e.g., on the communities’ use and management rights of their lands) and existential threats of conflicts within the communities (e.g., violation of the communities’ free, prior, and informed consent). The results also show that both communities share many of the patterns of diversity and integration to a similar extent. Although there is no definitive distinction between the two communities, the findings suggest that some differences exist in their degree of integration. Understanding and describing the nature of the power relations and threats of conflicts comprises an important component to begin an appreciation for the communities’ user group characteristics as these relate to the REDD+ program when implemented. The implication of this study is that threats of conflicts may increase when the villagers’ perception of the potential costs of losing their lands to REDD+ is formed by their experiences with current restrictions on the use and management rights of their lands. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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Review
A Review of General Methods for Quantifying and Estimating Urban Trees and Biomass
Forests 2022, 13(4), 616; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040616 - 15 Apr 2022
Viewed by 731
Abstract
Understanding the biomass, characteristics, and carbon sequestration of urban forests is crucial for maintaining and improving the quality of life and ensuring sustainable urban planning. Approaches to urban forest management have been incorporated into interdisciplinary, multifunctional, and technical efforts. In this review, we [...] Read more.
Understanding the biomass, characteristics, and carbon sequestration of urban forests is crucial for maintaining and improving the quality of life and ensuring sustainable urban planning. Approaches to urban forest management have been incorporated into interdisciplinary, multifunctional, and technical efforts. In this review, we evaluate recent developments in urban forest research methods, compare the accuracy and efficiency of different methods, and identify emerging themes in urban forest assessment. This review focuses on urban forest biomass estimation and individual tree feature detection, showing that the rapid development of remote sensing technology and applications in recent years has greatly benefited the study of forest dynamics. Included in the review are light detection and ranging-based techniques for estimating urban forest biomass, deep learning algorithms that can extract tree crowns and identify tree species, methods for measuring large canopies using unmanned aerial vehicles to estimate forest structure, and approaches for capturing street tree information using street view images. Conventional methods based on field measurements are highly beneficial for accurately recording species-specific characteristics. There is an urgent need to combine multi-scale and spatiotemporal methods to improve urban forest detection at different scales. Full article
(This article belongs to the Special Issue Advances in Forest Growth and Site Productivity Modeling)
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Article
Effects of Salinity and Oil Contamination on the Soil Seed Banks of Three Dominant Vegetation Communities in the Coastal Wetland of the Yellow River Delta
Forests 2022, 13(4), 615; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040615 - 14 Apr 2022
Viewed by 582
Abstract
In view of the important role of vegetation in the integrity of structures and functions of coastal wetland ecosystems, the restoration of degraded coastal wetland vegetation has attracted increased attention. In this paper, the newborn coastal wetland in the Yellow River Delta (YRD) [...] Read more.
In view of the important role of vegetation in the integrity of structures and functions of coastal wetland ecosystems, the restoration of degraded coastal wetland vegetation has attracted increased attention. In this paper, the newborn coastal wetland in the Yellow River Delta (YRD) of China was selected to research the effect of salinity and oil exploitation on the germination of soil seed banks of three dominant vegetation communities. The germination experiment with three concentration gradients of NaCl and three concentration gradients of diesel treatments showed that there were 14 species present in the soil seed bank of the multi-species community: three species in the Phragmites australis community, and five species in the P. australis—Suaeda glauca community. The species in the seed bank of the three communities were much richer than the above-ground vegetation in this study. Soil salinity had a significant inhibitory effect on the seedling numbers of germinated species, the seedling density, and the species diversity of the soil seed banks, while the inhibitory effect of diesel was indistinctive under the designed concentrations. There existed significant interactions between the vegetation community type and soil salinity on the number of germinated species, the seedling density, and the Margalef index. Soil salinity is considered an important factor for wetland vegetation restoration in the YRD, but its effect had species-specific differences. Soil seed banks of the present three communities could be used to promote the restoration of degraded wetlands within certain soil salinity and oil concentration ranges. Full article
(This article belongs to the Special Issue Plant Adaptation to Extreme Environments in Drylands)
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Article
An Approach to Estimate Individual Tree Ages Based on Time Series Diameter Data—A Test Case for Three Subtropical Tree Species in China
Forests 2022, 13(4), 614; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040614 - 14 Apr 2022
Viewed by 558
Abstract
Accurate knowledge of individual tree ages is critical for forestry and ecological research. However, previous methods suffer from flaws such as tree damage, low efficiency, or ignoring autocorrelation among residuals. In this paper, an approach for estimating the ages of individual trees is [...] Read more.
Accurate knowledge of individual tree ages is critical for forestry and ecological research. However, previous methods suffer from flaws such as tree damage, low efficiency, or ignoring autocorrelation among residuals. In this paper, an approach for estimating the ages of individual trees is proposed based on the diameter series of Cinnamomum camphora (Cinnamomum camphora (L.) Presl), Schima superba (Schima superba Gardn. et Champ.), and Liquidambar formosana (Liquidambar formosana Hance). Diameter series were obtained by stem analysis. Panel data contains more information, more variability, and more efficiency than pure time series data or cross-sectional data, which is why diameter series at stump and breast heights were chosen to form the panel data. After choosing a base growth equation, a constraint was added to the equation to improve stability. The difference method was used to reduce autocorrelation and the parameter classification method was used to improve model suitability. Finally, the diameter increment equation of parameter a-classification was developed. The mean errors of estimated ages based on the panel data at breast height for C. camphora, S. superba, and L. formosana were 0.47, 2.46, and −0.56 years and the root mean square errors were 2.04, 3.15 and 2.47 years, respectively. For C. camphora and L. formosana, the estimated accuracy based on the panel data was higher at breast height than at stump height. This approach to estimating individual tree ages is highly accurate and reliable, and provides a feasible way to obtain tree ages by field measurement. Full article
(This article belongs to the Special Issue Advances in Forest Growth and Site Productivity Modeling)
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Article
Evaluating Dimensional Stability in Modified Wood: An Experimental Comparison of Test Methods
Forests 2022, 13(4), 613; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040613 - 14 Apr 2022
Viewed by 508
Abstract
Dimensional stability is a commonly targeted property for improvement through wood modification. Here four different tests have been performed on three types of modified wood to compare methods of measuring dimensional stability behavior. These tests cover long and short time periods, as well [...] Read more.
Dimensional stability is a commonly targeted property for improvement through wood modification. Here four different tests have been performed on three types of modified wood to compare methods of measuring dimensional stability behavior. These tests cover long and short time periods, as well as dimensional changes caused by contact with liquid water, or from changes in air humidity. All the tests showed increased dimensional stability of the modified samples relative to the unmodified controls; however, the relative behavior of the different modifications varied between tests. Soaking in water until maximum swelling showed no differences between thermally modified and furfurylated samples, but a subsequent test showed large differences in the rate of swelling for each wood type, with the furfurylated samples swelling very slowly. Long-term swelling in humid air showed similar results to soaking in water, but with the thermally modified samples having significantly greater dimensional stability than the furfurylated samples. Swelling for a short period in humid air showed no difference in swelling between the modified wood types, but there was a threefold reduction in swelling compared to the unmodified controls. For a more complete understanding of dimensional stability, several tests employing different test conditions should be used. Full article
(This article belongs to the Special Issue Wood Production Stabilisation and Functionalization)
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Article
Application of Stubble and Root Cutting in Artificial Cultivation of Non-Timber Forest Products (NTFPs): A Study Case of Aralia elata (Miq.) Seem
Forests 2022, 13(4), 612; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040612 - 14 Apr 2022
Viewed by 513
Abstract
The increased demand for non-timber forest products (NTFPs) has led to the over-exploitation and disordered utilization of wild NTFP resources. Thus, it is important to determine how to sustainably utilize and cultivate NTFPs. Stubble and root cutting are two important methods for artificial [...] Read more.
The increased demand for non-timber forest products (NTFPs) has led to the over-exploitation and disordered utilization of wild NTFP resources. Thus, it is important to determine how to sustainably utilize and cultivate NTFPs. Stubble and root cutting are two important methods for artificial cultivation, but little is known about their effects on the artificial cultivation of NTFP species with strong sprouting ability. Aralia elata is an important understory economic plant with high medicinal and edible values, and its wild resources are decreasing rapidly due to increasing demand. Therefore, A. elata, with its strong sprouting ability, was taken as an example to explore the effects of stubble (plant size × stubble height) and root cutting (root-cutting distance × root-cutting ratio) on its growth and sprouting ability for three years. The results showed that both stubble and root-cutting treatments could effectively facilitate the root sprouting ability of A. elata. The short stubble height treatment (6–15 cm) was the optimum stubble method for large A. elata (the mean height and basal diameter of plants were 256.65 cm and 4 cm, respectively). For small A. elata (plant basal diameter ranged from 1.5 cm to 3.4 cm), the optimal root-cutting method was 100% root-cutting ratio at a root-cutting distance of 0.25 m. However, the effects of stubble and root cutting on the growth and sprouting ability of A. elata were time-dependent, and repetitive treatment might be applied at an interval of two years to maintain its continuous growth and sprouting. Full article
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Article
Spatial Variations in Fine Root Turnover, Biomass, and Necromass of Two Vegetation Types in a Karst Ecosystem, Southwestern China
Forests 2022, 13(4), 611; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040611 - 14 Apr 2022
Cited by 1 | Viewed by 530
Abstract
Revealing the patterns of fine root turnover traits can aid our understanding of the mechanisms of fine roots in adapting to soil nutrient changes. In a karst ecosystem of southwest China, the fine root turnover rate, production, biomass, necromass, biomass/necromass ratio, as well [...] Read more.
Revealing the patterns of fine root turnover traits can aid our understanding of the mechanisms of fine roots in adapting to soil nutrient changes. In a karst ecosystem of southwest China, the fine root turnover rate, production, biomass, necromass, biomass/necromass ratio, as well as the soil total and available nitrogen (N) and phosphorus (P) concentrations, and root carbon (C) and N concentrations were analyzed in upper, middle, and lower slope positions of two vegetation types (shrubland and forest). The results showed that the soil total and available N and P and fine root production, biomass, and necromass were significantly higher in upper slope positions than those in lower slope positions in both vegetation types. However, the fine root turnover rates were slightly higher in upper positions than those in lower positions. In addition, fine root necromass was significantly lower in shrubland than that in forest, while the biomass/necromass ratio was the opposite. Therefore, fine root production and biomass were significantly affected by slope position, while the fine root biomass/necromass ratio was significantly influenced by vegetation type. Additionally, fine root necromass was significantly influenced by the slope position and vegetation, but the turnover rate was slightly impacted by the two factors. It was also found that fine root production, biomass, and necromass had significant positive correlations with the soil total and available N and P and root C concentrations, and had significant negative correlations with root N concentrations. Moreover, the biomass/necromass ratio was positively and negatively related to the root N concentrations and C/N ratios, respectively. Thus, the variations in these five parameters of fine root turnover were mainly explained by fine root nutrients and the interactive effects between fine root and soil nutrients. The above results indicated that these variations in fine roots responding to soil and root nutrient changes might be an adaptive mechanism to enhance plant nutrient acquisition in nutrient-poor karst ecosystems. Full article
(This article belongs to the Special Issue Plant–Soil Interactions in Karst Regions)
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Article
Geochemical Behavior of Sedimentary Phosphorus Species in Northernmost Artificial Mangroves in China
Forests 2022, 13(4), 610; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040610 - 14 Apr 2022
Viewed by 655
Abstract
Mangroves are typically found in tropical coastal areas, and these ecosystems face deterioration and loss due to threats from climate and human factors. In this study, sediment cores were collected from human-planted mangroves in sub-tropical Ximen Island, China, and were determined for sedimentary [...] Read more.
Mangroves are typically found in tropical coastal areas, and these ecosystems face deterioration and loss due to threats from climate and human factors. In this study, sediment cores were collected from human-planted mangroves in sub-tropical Ximen Island, China, and were determined for sedimentary phosphorus (P) species. The objective was to investigate the ability of mangroves planted in a zone bordering their temperature limit to preserve and regulate P. Our results showed that bioavailable P (BAP), which includes exchangeable-P (Ex-P), iron-bound P (Fe-P), and organic P (OP), accounted for approximately 64% of total P (TP). Apatite P (Ca-P), which accounted for 24% of TP, most likely originated from aquaculture activities surrounding the island. The vertical distribution of sedimentary P species along the sediment cores showed a rather constant trend along the salt marsh stand but considerable fluctuations for the mangroves and bare mudflat. These results indicate that mangroves accumulated P when there was a high P discharge event, and that this P was eventually released during organic matter decomposition and contributed to Ca-P formation. Nevertheless, old and young mangroves accumulated higher sedimentary P species, OP, and BAP compared to the salt marsh stand and bare mudflat areas. This study showed the potential of mangroves planted outside their suitable climate zone to preserve and regulate P. Full article
(This article belongs to the Special Issue Mangrove Wetland Restoration and Rehabilitation)
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Article
The Efficiency of Forest Management Investment in Key State-Owned Forest Regions under the Carbon Neutral Target: A Case Study of Heilongjiang Province, China
Forests 2022, 13(4), 609; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040609 - 14 Apr 2022
Cited by 1 | Viewed by 624
Abstract
To explore the temporal and spatial evolution of carbon sinks in state-owned forest regions (SOFRs) and the efficiency of increased carbon sinks, this study used panel data from 19 periods in 40 key SOFRs in Heilongjiang Province from 2001 to 2019. Additionally, combined [...] Read more.
To explore the temporal and spatial evolution of carbon sinks in state-owned forest regions (SOFRs) and the efficiency of increased carbon sinks, this study used panel data from 19 periods in 40 key SOFRs in Heilongjiang Province from 2001 to 2019. Additionally, combined with geographic information system (GIS) and remote sensing (RS) technology, the individual fixed-effect model was used to estimate the number of forest management investment (FMI) lagging periods, and the panel threshold model was used to investigate the differences in the FMI efficiency in various forest regions. From 2001 to 2019, the carbon sink of key SOFRs in Heilongjiang Province showed an upward trend over time, with a growth rate of 20.17%. Spatially, the phenomenon of “increasing as a whole and decreasing in a small area” was found, and the carbon sink of each forest region varied greatly. The standard deviation ellipse of the carbon sink presented a “southeast–northwest” pattern and had “from southeast to northwest” migration characteristics. The FMI amount from 2001 to 2019 showed an upward trend, with a total of CNY 46.745 billion, and varied greatly among forest regions. Additionally, the carbon sink amount in each SOFR affected the FMI efficiency. The threshold of the model was 5,327,211.8707 tons, and the elastic coefficients of the impact of FMI below and above the threshold on the carbon sink were 0.00953 and 0.02175, respectively. The latter’s FMI efficiency was 128.23% higher than that of the former. Finally, the increase in FMI to a carbon sink followed the law of diminishing marginal benefits. Therefore, the government should rationally plan the level of FMI in each SOFR to improve the FMI cost-effectiveness and help achieve the goal of “carbon neutrality”. Full article
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Review
Wood Formation under Changing Environment: Omics Approaches to Elucidate the Mechanisms Driving the Early-to-Latewood Transition in Conifers
Forests 2022, 13(4), 608; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040608 - 13 Apr 2022
Viewed by 696
Abstract
The global change scenarios highlight the urgency of clarifying the mechanisms driving the determination of wood traits in forest trees. Coniferous xylem is characterized by the alternation between earlywood (EW) and latewood (LW), on which proportions the wood density depend, one of the [...] Read more.
The global change scenarios highlight the urgency of clarifying the mechanisms driving the determination of wood traits in forest trees. Coniferous xylem is characterized by the alternation between earlywood (EW) and latewood (LW), on which proportions the wood density depend, one of the most important mechanical xylem qualities. However, the molecular mechanisms triggering the transition between the production of cells with the typical features of EW to the LW are still far from being completely elucidated. The increasing availability of omics resources for conifers, e.g., genomes and transcriptomes, would lay the basis for the comprehension of wood formation dynamics, boosting both breeding and gene-editing approaches. This review is intended to introduce the importance of wood formation dynamics and xylem traits of conifers in a changing environment. Then, an up-to-date overview of the omics resources available for conifers was reported, focusing on both genomes and transcriptomes. Later, an analysis of wood formation studies using omics approaches was conducted, with the aim of elucidating the main metabolic pathways involved in EW and LW determination. Finally, the future perspectives and the urgent needs on this research topic were highlighted. Full article
(This article belongs to the Special Issue Tree Genetics: Molecular and Functional Characterization of Genes)
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Article
Assessment of Different Measurement Methods/Techniques in Predicting Modulus of Elasticity of Plantation Eucalyptus nitens Timber for Structural Purposes
Forests 2022, 13(4), 607; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040607 - 13 Apr 2022
Cited by 1 | Viewed by 582
Abstract
The mechanical properties of plantation Eucalyptus Nitens timber are currently assessed by applying visual stress grading (VSG) designed for the sawn timber from the mature plantation and do not represent the actual characteristics of the resource. However, the well-known limitation of VSG application [...] Read more.
The mechanical properties of plantation Eucalyptus Nitens timber are currently assessed by applying visual stress grading (VSG) designed for the sawn timber from the mature plantation and do not represent the actual characteristics of the resource. However, the well-known limitation of VSG application for this resource led to the discovery of other methods to grade the timber to its relevant structural grade. There is potential for hardwood plantations in Australia to supply wood to the timber industry and be used in structural applications. However, it is necessary to employ criteria to evaluate the structural properties of this resource before it could be satisfactorily used for structural purposes. This research aimed to assess the use of non-destructive technique (NDT) through acoustic wave velocity (AWV), machine stress grading (MSG), and multiple linear regression (MLR) model to predict the modulus of elasticity (MOE) as a grade-determining factor. The results showed that there was a strong correlation (R2 = 0.88) between the dynamic MOE (MOEdyn) and static MOE (MOEs) of the boards, proving the NDT as a reliable method for the MOE estimations of E. nitens timber. The results from the MLR model also showed that the density and AWV are effective parameters and their combination can be practical to estimate the MOE. There was a high correlation between the MOE obtained from MSG and MOE obtained from four-point bending, demonstrating that the MSG method through the flat-wise bending can be a suitable method for fast grading. The results also indicated that the measured MOE in the edgewise direction correlates with both the flatwise and longitudinal directions. The results also showed that the E. nitens timber resource has the potential to be used in structural applications with a wide range of MOE from 7 GPa to 21 GPa. Full article
(This article belongs to the Special Issue Wood Production Stabilisation and Functionalization)
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Article
Representative Group Decision-Making in Forest Management: A Compromise Approach
Forests 2022, 13(4), 606; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040606 - 13 Apr 2022
Viewed by 478
Abstract
The correct aggregation of stakeholders’ preferences is a vital aspect of solving problems associated with natural resources. In fact, there is no one solution that permits the incorporation of those preferences into techniques that, in turn, address multiple objectives in the management of [...] Read more.
The correct aggregation of stakeholders’ preferences is a vital aspect of solving problems associated with natural resources. In fact, there is no one solution that permits the incorporation of those preferences into techniques that, in turn, address multiple objectives in the management of those resources. In this context, this work aims to assign, analyse, and compare the weights of importance to groups of stakeholders (representativity) starting from different approaches and methodologies: pairwise comparison matrices (using a subjective approach) and the voting power notion (when an objective approach is deployed). For the latter, a variant of the extended goal programming model is employed. The results show different weight values and, therefore, scenarios, in which the social groups defined acquire diverse importance. It is also observed that there are scenarios determined by different values of the control parameter, in which the results of the two above-mentioned approaches are similar. Finally, it is demonstrated how the affiliation of stakeholders to other social groups (different identities) affects the results obtained. Full article
(This article belongs to the Section Forest Economics, Policy, and Social Science)
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Article
Influence of the Canopy Drip Effect on the Accumulation of Atmospheric Metal and Nitrogen Deposition in Mosses
Forests 2022, 13(4), 605; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040605 - 12 Apr 2022
Viewed by 517
Abstract
Wet, dry, and occult atmospheric deposition may be modified by vegetation canopies. The aim of this study was to verify canopy drip effect studies conducted in 2012, in 2013, and in 2015/2016. For this purpose, 26 moss samples were taken at each of [...] Read more.
Wet, dry, and occult atmospheric deposition may be modified by vegetation canopies. The aim of this study was to verify canopy drip effect studies conducted in 2012, in 2013, and in 2015/2016. For this purpose, 26 moss samples were taken at each of eight monitoring sites of the European Moss Survey 2020/2021 in Germany from a corresponding number of subplots, each representing the site categories “under tree canopy” and adjacent “open land”. The sampling, as well as the chemical analyses, of 12 metals (Al, As, Cd, Cr, Cu, Fe, Hg, Pb, Ni, Sb, V, Zn) and nitrogen (N) and the recording of sample- and site-describing metadata were conducted according to the ICP Vegetation experimental protocol. The results demonstrate an overall higher metal and nitrogen accumulation in moss samples of “canopy” sites compared to neighboring “open land sites” (grassland, heath). The ratios between the “canopy” and “open land” sites of 1.18 to 1.69 and significant correlations of r > 0.8 in case of five elements agree well with corresponding values from samplings in 2012, 2013, and 2015/2016. These results should be used for modeling atmospheric deposition aiming at more realistic results. With regard to the question of whether, and to what extent, moss samples should preferably be taken from “open land” or “canopy” sites, the following can be concluded: The recommendations of ICP Vegetation with regard to the minimum distance to be maintained from trees and shrubs should not be interpreted to mean that “open” sites are fundamentally more suitable for moss sampling in Germany than, for example, clearings in forests. The mostly higher variability of the measured values compared to the “canopy” sites rather suggests that in the open country a much higher number of influencing factors could be significant for the element accumulation in mosses in addition to the background pollution through atmospheric deposition. This is also supported by the fact that the metal contents in the moss samples of the “open” sites can clearly exceed those of the neighboring “canopy” sites in individual cases. With regard to “open” land, grassland sites seem to be less suitable for moss sampling than bog and heathland sites. In grassland, moss occurrences are often sparser and/or cut short by meadow mowing, so that the removal of three-year shoots on grassland, as recommended by ICP Vegetation, must be replaced in places by one-year shoots. The comparatively higher state dynamics of grassland sites also make the resampling of moss at previously sampled sites more difficult. Full article
(This article belongs to the Special Issue Biomonitoring with Lichens and Mosses in Forests)
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Article
Developing Tree Mortality Models Using Bayesian Modeling Approach
Forests 2022, 13(4), 604; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040604 - 12 Apr 2022
Viewed by 559
Abstract
The forest mortality models developed so far have ignored the effects of spatial correlations and climate, which lead to the substantial bias in the mortality prediction. This study thus developed the tree mortality models for Prince Rupprecht larch (Larix gmelinii subsp. principis-rupprechtii [...] Read more.
The forest mortality models developed so far have ignored the effects of spatial correlations and climate, which lead to the substantial bias in the mortality prediction. This study thus developed the tree mortality models for Prince Rupprecht larch (Larix gmelinii subsp. principis-rupprechtii), one of the most important tree species in northern China, by taking those effects into account. In addition to these factors, our models include both the tree—and stand—level variables, the information of which was collated from the temporary sample plots laid out across the larch forests. We applied the Bayesian modeling, which is the novel approach to build the multi-level tree mortality models. We compared the performance of the models constructed through the combination of selected predictor variables and explored their corresponding effects on the individual tree mortality. The models precisely predicted mortality at the three ecological scales (individual, stand, and region). The model at the levels of both the sample plot and stand with different site condition (block) outperformed the other model forms (model at block level alone and fixed effects model), describing significantly larger mortality variations, and accounted for multiple sources of the unobserved heterogeneities. Results showed that the sum of the squared diameter was larger than the estimated diameter, and the mean annual precipitation significantly positively correlated with tree mortality, while the ratio of the diameter to the average of the squared diameter, the stand arithmetic mean diameter, and the mean of the difference of temperature was significantly negatively correlated. Our results will have significant implications in identifying various factors, including climate, that could have large influence on tree mortality and precisely predict tree mortality at different scales. Full article
(This article belongs to the Special Issue Advances in Forest Growth and Site Productivity Modeling)
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Brief Report
Bio-Based Phase Change Materials for Wooden Building Applications
Forests 2022, 13(4), 603; https://0-doi-org.brum.beds.ac.uk/10.3390/f13040603 - 12 Apr 2022
Cited by 1 | Viewed by 539
Abstract
Solid wood can serve multifunctionality for energy savings in buildings. The study reveals the results of biodeterioration and degradation of solid Scots pine wood used to incorporate single or multicomponent fatty acid mixtures as bio-based phase change materials (BPCMs). The sapwood samples were [...] Read more.
Solid wood can serve multifunctionality for energy savings in buildings. The study reveals the results of biodeterioration and degradation of solid Scots pine wood used to incorporate single or multicomponent fatty acid mixtures as bio-based phase change materials (BPCMs). The sapwood samples were impregnated with capric acid (CA), methyl palmitate (MP), lauryl alcohol (LA) and a mixture of coconut oil fatty acids and linoleic acid (CoFA-LA). The samples were tested against subterranean termites by an Italian species (Reticulitermes lucifugus), the wood boring beetle Hylotrupes bajulus and mold through a discoloration test. Tested against termites, the impregnated samples were significantly less susceptible to the attack than the controls, i.e., the tested BPCMs were resistant to R. lucifugus. The only test with MP terminated at the moment against H. bajulus showed positive results with no larvae surviving. The mold discoloration test revealed that the wood impregnated with CoFA-LA was identically susceptible to mold discoloration when compared to the control, nonimpregnated samples. This pioneer study verifies that solid wood employed for the encapsulation of BPCMs for building purposes can serve identically or somewhat better than similar wooden building elements regarding attacks of the above microorganisms and insects. Such multifunctional building elements will be tested further in a pilot scale building to characterize better the durability aspects of the new materials. Full article
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