Forests

Open AccessEditor’s ChoiceReview

Carbon Sequestration Potential of Commercial Agroforestry Systems in Indo-Gangetic Plains of India: Poplar and Eucalyptus-Based Agroforestry Systems

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Sangram Bhanudas Chavan

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Ravinder Singh Dhillon

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Chhavi Sirohi

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Appanderanda Ramani Uthappa

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Dinesh Jinger

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Hanuman Singh Jatav

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Akash Ravindra Chichaghare

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Forests 2023, 14(3), 559; https://doi.org/10.3390/f14030559 - 12 Mar 2023

Viewed by 1461

Abstract

Climate change, land degradation, and desertification lead to the loss of carbon present in the soil and plants. The carbon dioxide (CO₂) concentration in the atmosphere has reached 412 ppm. This is a rise of 47% since the start of the [...] Read more.

Climate change, land degradation, and desertification lead to the loss of carbon present in the soil and plants. The carbon dioxide (CO₂) concentration in the atmosphere has reached 412 ppm. This is a rise of 47% since the start of the industrial period, when the concentration was close to 280 ppm. Therefore, the sequestration of carbon from the atmosphere to earth is the need of the hour. Many scientists have suggested agroforestry as a potent instrument for climate change mitigation as well as to fetch lucrative benefits. The Indian government is also promulgating tree-based systems for increasing tree cover up to 33% of the total geographical area to mitigate climate change. Therefore, the expansion of the commercial agroforestry system of fast-growing tree species producing higher biomass could be a sustainable and ecologically benign technique to sequester carbon, increase green cover, and improve the financial status of farmers. This review highlights the commercial agroforestry systems, biomass and carbon sequestration potential, and case studies of poplar and eucalyptus. The species such as poplar (Populus deltoides), nilgiri (Eucalyptus spp.), subabul (Leucaena leucocephala), tree of heaven (Ailanthus excelsa), willow (Salix spp.), malabar neem (Melia dubia), cadamba (Neolamarckia cadamba), and white teak (Gmelina arborea) are the suitable tree species for carbon sequestration under agroforestry. Among these species, poplar and eucalyptus are major agroforestry tree species that have been adopted by millions of farmers in India since the 1990s. Indo-Gangetic plains are considered the birthplace of commercial or industrial agroforestry, as poplar and eucalyptus are widely planted. This review reports that poplar and eucalyptus have the potential to sequester carbon stock of 212.7 Mg C ha⁻¹ and 237.2 Mg C ha⁻¹, respectively. Further, the net carbon sequestration rate in poplar and eucalyptus was 10.3 and 12.7 Mg C ha⁻¹ yr⁻¹, respectively. In conclusion, the commercial agroforestry system was very successful in the Indo-Gangetic regions of the country but needs further expansion with suitable compatible crops in different parts of the country. Full article

(This article belongs to the Special Issue Pollution, Heavy Metal, and Emerging Threats in Forest Soil)

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Open AccessEditor’s ChoiceArticle

Biocultural Importance of the Chiuri Tree [Diploknema butyracea (Roxb.) H. J. Lam] for the Chepang Communities of Central Nepal

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Yadav Uprety

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Hugo Asselin

Forests 2023, 14(3), 479; https://doi.org/10.3390/f14030479 - 27 Feb 2023

Viewed by 1311

Abstract

Major socio-economic changes over the last few decades have reduced Indigenous peoples’ engagement in cultural practices, such as harvesting of forest resources. Nevertheless, some species remain important for culture, subsistence and livelihood, such as the chiuri tree (Diploknema butyracea (Roxb.) H. J. [...] Read more.

Major socio-economic changes over the last few decades have reduced Indigenous peoples’ engagement in cultural practices, such as harvesting of forest resources. Nevertheless, some species remain important for culture, subsistence and livelihood, such as the chiuri tree (Diploknema butyracea (Roxb.) H. J. Lam) to the Chepang people of Central Nepal. Using the cultural keystone species framework, we conducted interviews within Chepang communities to assess the biocultural importance of the chiuri tree. It is central to the Chepang culture, and no other species could provide the same benefits. It also provides food and habitat for a number of wildlife species, including bats, which are themselves culturally important. Strictly observed tree ownership rules, as well as a cultural ban on tree cutting and branch lopping, have so far contributed to chiuri conservation. However, these rules are increasingly less adhered to. Other threats to chiuri sustainability are excessive flower foraging by bees (reducing pollen production) and bat hunting (reducing pollen transport). Further studies are needed to quantify these threats and to adjust forest and wildlife management practices so that the cultural landscape continues to provide multiple benefits to the Chepang people. Our study of the chiuri case attests to the usefulness of the cultural keystone species framework in landscape assessment for management and conservation. Full article

(This article belongs to the Special Issue Trees and Their Benefits: Social, Ecological & Economic Considerations)

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Open AccessEditor’s ChoiceArticle

Modeling Climate Change Effects on the Distribution of Oak Forests with Machine Learning

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Forests 2023, 14(3), 469; https://doi.org/10.3390/f14030469 - 24 Feb 2023

Cited by 1 | Viewed by 1256

Abstract

The present study models the effect of climate change on the distribution of Persian oak (Quercus brantii Lindl.) in the Zagros forests, located in the west of Iran. The modeling is conducted under the current and future climatic conditions by fitting the [...] Read more.

The present study models the effect of climate change on the distribution of Persian oak (Quercus brantii Lindl.) in the Zagros forests, located in the west of Iran. The modeling is conducted under the current and future climatic conditions by fitting the machine learning method of the Bayesian additive regression tree (BART). For the anticipation of the potential habitats for the Persian oak, two general circulation models (GCMs) of CCSM4 and HADGEM2-ES under the representative concentration pathways (RCPs) of 2.6 and 8.5 for 2050 and 2070 are used. The mean temperature (MT) of the wettest quarter (bio8), solar radiation, slope and precipitation of the wettest month (bio13) are respectively reported as the most important variables in the modeling. The results indicate that the suitable habitat of Persian oak will significantly decrease in the future under both climate change scenarios as much as 75.06% by 2070. The proposed study brings insight into the current condition and further projects the future conditions of the local forests for proper management and protection of endangered ecosystems. Full article

(This article belongs to the Special Issue Forest Resilience and Resistance to Climate Change)

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Open AccessEditor’s ChoiceArticle

Modelling Climatically Suitable Areas for Mahogany (Swietenia macrophylla King) and Their Shifts across Neotropics: The Role of Protected Areas

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Robinson J. Herrera-Feijoo

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Bolier Torres

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Rolando López-Tobar

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Cristhian Tipán-Torres

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Theofilos Toulkeridis

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Marco Heredia-R

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Rubén G. Mateo

Forests 2023, 14(2), 385; https://doi.org/10.3390/f14020385 - 14 Feb 2023

Viewed by 1245

Abstract

Mahogany (Swietenia macrophylla King) is a species with great economic interest worldwide and is classified as vulnerable to extinction by the IUCN. Deforestation and climate change are the main hazards to this species. Therefore, it is vital to describe possible changes in [...] Read more.

Mahogany (Swietenia macrophylla King) is a species with great economic interest worldwide and is classified as vulnerable to extinction by the IUCN. Deforestation and climate change are the main hazards to this species. Therefore, it is vital to describe possible changes in distribution patterns under current and future climatic conditions, as they are important for their monitoring, conservation, and use. In the current study, we predict, for the very first time, the potential distribution of Mahogany based on data that reflect the total distribution of the species, climatic and edaphic variables, and a consensus model that combines the results of three statistical techniques. The obtained model was projected to future climatic conditions considering two general circulation models (GCM), under two shared socioeconomic pathways (SSP245 and SSP585) for 2070. Predictions under current climatic conditions indicated wide adequate areas in Central American countries such as Mexico and demonstrated a coverage of up to 28.5% within the limits of the protected areas. Under future scenarios, drastic reductions were observed in different regions, particularly in Venezuela, Perú, and Ecuador, with losses of up to 56.0%. On the other hand, an increase in suitable areas for the species within protected areas was also detected. The results of this study are certainly useful for identifying currently unrecorded populations of Mahogany, as well as for identifying locations that are likely to be suitable both now and in the future for conservation management planning. The methodology proposed in this work is able to be used for other forest species in tropical zones as a tool for conducting dynamic conservation and restoration strategies that consider the effects of climate change. Full article

(This article belongs to the Special Issue Biodiversity and Conservation of Forests)

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Open AccessEditor’s ChoiceReview

A Review of Research on Forest Ecosystem Quality Assessment and Prediction Methods

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Ke Guo

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Bing Wang

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Xiang Niu

Forests 2023, 14(2), 317; https://doi.org/10.3390/f14020317 - 06 Feb 2023

Cited by 1 | Viewed by 3195

Abstract

The accurate assessment and prediction of forest ecosystem quality is an important basis for evaluating the effectiveness of regional ecological protection and restoration, establishing a positive feedback mechanism for forest quality improvement and restoration policies, and promoting the construction of an ecological civilization [...] Read more.

The accurate assessment and prediction of forest ecosystem quality is an important basis for evaluating the effectiveness of regional ecological protection and restoration, establishing a positive feedback mechanism for forest quality improvement and restoration policies, and promoting the construction of an ecological civilization in China. Based on the existing studies at home and abroad, this paper mainly analyzes and summarizes the connotation of forest ecosystem quality, assessment index systems, assessment and prediction methods, and outlooks on the existing problems of imperfect forest ecological quality assessment index systems, preliminary assessment and prediction capabilities, and unknown dynamic responses of forest ecological quality to climate change, etc. Efforts should be made to develop a scientific and standardized assessment index system, produce high-quality forest ecological data products, develop localization of assessment model parameters, and explore forest quality–climate change response mechanisms to provide references for in-depth research to realize the transformation of forest ecosystem quality assessments from historical and status quo assessments to future predictions, and to support the construction of a national ecological civilization. Full article

(This article belongs to the Special Issue Forests Research in Beijing Forestry University: Commemorating the University’s 70th Anniversary)

Open AccessEditor’s ChoiceReview

Adhesive-and Metal-Free Assembly Techniques for Prefabricated Multi-Layer Engineered Wood Products: A Review on Wooden Connectors

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Forests 2023, 14(2), 311; https://doi.org/10.3390/f14020311 - 05 Feb 2023

Viewed by 1705

Abstract

Engineered wood products (EWPs) are being increasingly used as construction materials. EWPs are currently being made using synthetic adhesives or metal fasteners, which lead to poor recyclability and reusability. Therefore, this review paper focused on emerging adhesive- and metal-free assembling techniques including wood [...] Read more.

Engineered wood products (EWPs) are being increasingly used as construction materials. EWPs are currently being made using synthetic adhesives or metal fasteners, which lead to poor recyclability and reusability. Therefore, this review paper focused on emerging adhesive- and metal-free assembling techniques including wood dowels, rotary-dowel welding, wooden nails, and dovetail joining as alternative ways of making prefabricated EWPs. This will contribute towards green construction and optimising the building process to minimise its negative impact on the environment and its inhabitants, while maximising the positive aspects of the finished structure. The respective advantages and shortcomings will be compared with those of equivalent EWPs. In general, the dowel-laminated timber (DLT) provides sufficient load-bearing capacity and even better ductility than EWPs of equivalent size, but its relatively low stiffness under a bending load limits its application as a structural element. Optimised manufacturing parameters such as dowel species, dowel spacing, dowel diameter, dowel insertion angle, dowel shape, etc. could be studied to improve the stiffness. The improved mechanical properties and tight fitting due to set-recovery of densified wood support its use as sustainable alternatives to hardwood dowels in DLT to overcome problems such as the loosening of connections over time and dimensional instability. The rotary welding technology could also enhance the strength and long-term performance of dowel-type joints, but its poor water resistance needs further investigation. The main obstacles to implementing DLT products in the market are missing technical information and design guidelines based on national codes. Full article

(This article belongs to the Special Issue Frontiers in Modification of Wood and Wood-Based Composites)

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Open AccessEditor’s ChoiceReview

Distinct Responses of European Beech (Fagus sylvatica L.) to Drought Intensity and Length—A Review of the Impacts of the 2003 and 2018–2019 Drought Events in Central Europe

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Forests 2023, 14(2), 248; https://doi.org/10.3390/f14020248 - 28 Jan 2023

Viewed by 1417

Abstract

A combined severe heatwave and drought, starting in 2018 and lasting for several months, restarted the discussion on the resistance of European beech to climatic changes, with severe growth reductions, early leaf senescence, leaf browning, and diebacks reported across Central Europe. These responses [...] Read more.

A combined severe heatwave and drought, starting in 2018 and lasting for several months, restarted the discussion on the resistance of European beech to climatic changes, with severe growth reductions, early leaf senescence, leaf browning, and diebacks reported across Central Europe. These responses may result in long-term impacts such as reduced vitality of beech, especially under potential future drought periods. While the 2003 drought caused severe crown damage and defoliation and a loss in vitality, resulting in insect and fungal infestations and subsequent dieback, the drought in 2018 was even more severe in terms of geographical scale, duration, and intensity with reports of complete diebacks and severe mortality across Central Europe. These impacts were exacerbated in some regions by the consecutive drought in 2019 and secondary attacks from pathogens, as well as a further loss in vitality. Such enhanced drought exposure of beech trees could push them beyond their hydraulic safety margins. Moreover, growth legacy effects due to past droughts may lead to lower recovery over time, potentially leading to subsequent tree death. In order to better predict the future of beech growth and vitality in Central Europe, both short- and long-term legacy effects of defoliation and their influence on post-drought growth should be explored, and adaptive forest management strategies evaluated. Moreover, synergistic or additive interactions of legacy effects with drought, as well as with biotic disturbances, require further investigation. Long-term forest monitoring data facilitates investigations of drought responses of beech. Full article

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

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Open AccessEditor’s ChoiceArticle

The Differences in Water Repellency in Root Mat (Biomat) and Soil Horizons of Thinned and Non-thinned Chamaecyparis obtusa (Siebold et Zucc.) Endl. Plantations

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Forests 2023, 14(2), 210; https://doi.org/10.3390/f14020210 - 21 Jan 2023

Cited by 1 | Viewed by 828

Abstract

Water repellency (WR) is one cause of root mat (biomat) flow and soil surface runoff in dense Chamaecyparis obutsa (Siebold et Zucc.) Endl. plantations. However, the changes in WR of biomat and soil horizons are unclear in the thinned C. obtusa plantations. This [...] Read more.

Water repellency (WR) is one cause of root mat (biomat) flow and soil surface runoff in dense Chamaecyparis obutsa (Siebold et Zucc.) Endl. plantations. However, the changes in WR of biomat and soil horizons are unclear in the thinned C. obtusa plantations. This study compares the WR of biomat and soil horizons in the thinned and non-thinned C. obtusa plantations by considering the water content and surface temperature of biomat and soil from July 2021 to June 2022. We selected one plot in each thinned and non-thinned area in a catchment at Obora Experimental Forest in Japan. Our results showed that the 40% thinned plot lacked a biomat horizon, whereas the non-thinned plot had a ca. 3 cm depth of biomat. The biomat WR of the non-thinned plot (none to very strong) was higher than the soil WR of the thinned plot (none to strong). There was no relationship between WR and both water content and surface temperature of biomat and/or soil in either thinned or non-thinned plots. Our findings show that the biomat horizon had an essential role in the severity of WR in C. obtusa plantations. The lack of biomat after thinning could substantially impact soil surface hydrology. Full article

(This article belongs to the Special Issue Forest Management Effects on Landscape Hydrological and Biogeochemical Cycles)

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Open AccessEditor’s ChoiceArticle

A Small-Target Forest Fire Smoke Detection Model Based on Deformable Transformer for End-to-End Object Detection

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Forests 2023, 14(1), 162; https://doi.org/10.3390/f14010162 - 16 Jan 2023

Cited by 2 | Viewed by 1536

Abstract

Forest fires have continually endangered personal safety and social property. To reduce the occurrences of forest fires, it is essential to detect forest fire smoke accurately and quickly. Traditional forest fire smoke detection based on convolutional neural networks (CNNs) needs many hand-designed components [...] Read more.

Forest fires have continually endangered personal safety and social property. To reduce the occurrences of forest fires, it is essential to detect forest fire smoke accurately and quickly. Traditional forest fire smoke detection based on convolutional neural networks (CNNs) needs many hand-designed components and shows poor ability to detect small and inconspicuous smoke in complex forest scenes. Therefore, we propose an improved early forest fire smoke detection model based on deformable transformer for end-to-end object detection (deformable DETR). We use deformable DETR as a baseline containing the best sparse spatial sampling for smoke with deformable convolution and relation modeling capability of the transformer. We integrate a Multi-scale Context Contrasted Local Feature module (MCCL) and a Dense Pyramid Pooling module (DPPM) into the feature extraction module for perceiving features of small or inconspicuous smoke. To improve detection accuracy and reduce false and missed detections, we propose an iterative bounding box combination method to generate precise bounding boxes which can cover the entire smoke object. In addition, we evaluate the proposed approach using a quantitative and qualitative self-made forest fire smoke dataset, which includes forest fire smoke images of different scales. Extensive experiments show that our improved model’s forest fire smoke detection accuracy is significantly higher than that of the mainstream models. Compared with deformable DETR, our model shows better performance with improvement of mAP (mean average precision) by 4.2%, AP_S (AP for small objects) by 5.1%, and other metrics by 2% to 3%. Our model is adequate for early forest fire smoke detection with high detection accuracy of different-scale smoke objects. Full article

(This article belongs to the Special Issue Advances in Forest Fire and Other Detection Systems)

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Open AccessEditor’s ChoiceArticle

Effects of Wild Forest Fires on Genetic Diversity and Population Structure of a Boreal Conifer, White Spruce (Picea glauca (Moench) Voss): Implications for Genetic Resource Management and Adaptive Potential under Climate Change

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Om P. Rajora

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Manphool S. Fageria

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Michael Fitzsimmons

Forests 2023, 14(1), 157; https://doi.org/10.3390/f14010157 - 14 Jan 2023

Cited by 1 | Viewed by 1465

Abstract

Climate change is predicted to increase forest fires in boreal forests, which can threaten the sustainability of forest genetic resources. Wildfires can potentially impact genetic diversity and population structure in forest trees by creating population bottlenecks, and influencing demography, effective population size ( [...] Read more.

Climate change is predicted to increase forest fires in boreal forests, which can threaten the sustainability of forest genetic resources. Wildfires can potentially impact genetic diversity and population structure in forest trees by creating population bottlenecks, and influencing demography, effective population size (N_e) and various evolutionary processes. We have investigated this critical issue in a widely-distributed, transcontinental, ecologically and economically important and fire-intolerant boreal conifer, white spruce (Picea glauca (Moench) Voss). We tested the hypothesis that in a predominantly outcrossing species with long distance gene flow, such as white spruce, located in primary undisturbed forests, normal forest fires do not adversely affect genetic diversity and population structure. We used 10 nuclear genic and genomic microsatellite loci to examine genetic diversity and population structure of post-fire pristine old-growth (PF-OG) and adjacent post-fire naturally regenerated young (PF-YR) stands. The genetic diversity, inbreeding and genetic differentiation levels, Bayesian population structure, N_e and latent genetic potential were statistically similar between the PF-OG and PF-YR populations. None of the microsatellites showed any signature of selection. Our study demonstrates that normal wild forest fires do not adversely affect genetic diversity, differentiation, and population genetic structure in white spruce. The results should have wide significance for sustainable forest management. Full article

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

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Open AccessEditor’s ChoiceArticle

The Role of Provenance for the Projected Growth of Juvenile European Beech under Climate Change

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Alena Sliacka Konôpková

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Mohammad Mukarram

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Harish Debta

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Peter Fleischer, Jr.

Forests 2023, 14(1), 26; https://doi.org/10.3390/f14010026 - 23 Dec 2022

Cited by 1 | Viewed by 1761

Abstract

European beech is one of the most common tree species in Europe and is generally suggested to play even more of a prominent role in forestry in the future. It seems to have the potential to partially replace Norway spruce, as it is [...] Read more.

European beech is one of the most common tree species in Europe and is generally suggested to play even more of a prominent role in forestry in the future. It seems to have the potential to partially replace Norway spruce, as it is less sensitive to expected warmer and drier conditions. It is, however, not well known in which regions these new plantings would be particularly favourable and if specific provenances may be better adapted to the new conditions than others. Therefore, we estimated the potential early height growth under climate conditions in 2040–2060 for 20 beech provenances across a region covering the Czech Republic and Slovakia. This Central European region is expected to experience considerably drier and warmer conditions in the future. For this exercise, we implemented a new neural network model developed from height growth information obtained from the open-access BeechCOSTe52 database. The simulations are driven by past and future climate data obtained from the WorldClim database of historical climate data and future climate projections. Simulations revealed that provenances originating from drier regions performed on average significantly better than those from regions with good water supply. Moreover, provenances originating from drier regions had a particularly large advantage in the relatively arid regions of Central Czechia and Southern Slovakia. We can also confirm that all provenances showed a high phenotypic plasticity of height growth across the whole investigated region. Full article

(This article belongs to the Special Issue Impact of Climate Change on Tree Growth)

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Open AccessEditor’s ChoiceReview

Water in Wood: A Review of Current Understanding and Knowledge Gaps

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Emil Engelund Thybring

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Maria Fredriksson

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Samuel L. Zelinka

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Samuel V. Glass

Forests 2022, 13(12), 2051; https://doi.org/10.3390/f13122051 - 02 Dec 2022

Cited by 3 | Viewed by 5610

Abstract

Wood-water interactions are central to the utilization of wood in our society since water affects many important characteristics of wood. This topic has been investigated for more than a century, but new knowledge continues to be generated as a result of improved experimental [...] Read more.

Wood-water interactions are central to the utilization of wood in our society since water affects many important characteristics of wood. This topic has been investigated for more than a century, but new knowledge continues to be generated as a result of improved experimental and computational methods. This review summarizes our current understanding of the fundamentals of water in wood and highlights significant knowledge gaps. Thus, the focus is not only on what is currently known but equally important, what is yet unknown. The review covers locations of water in wood; phase changes and equilibrium states of water in wood; thermodynamics of sorption; terminology including cell wall water (bound water), capillary water (free water), fiber saturation point, and maximum cell wall moisture content; shrinkage and swelling; sorption hysteresis; transport of water in wood; and kinetics of water vapor sorption in the cell wall. Full article

(This article belongs to the Special Issue Reviews on Structure and Physical and Mechanical Properties of Wood)

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Open AccessFeature PaperEditor’s ChoiceArticle

Contribution of Dry Forests and Forest Products to Climate Change Adaptation in Tigray Region, Ethiopia

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Shibire Bekele Eshetu

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Katharina Löhr

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Stefan Sieber

Forests 2022, 13(12), 2026; https://doi.org/10.3390/f13122026 - 29 Nov 2022

Viewed by 2121

Abstract

Despite their ecological importance, dry forests’ contribution to climate change adaptation is often neglected. Hence, this study was initiated to assess the socioeconomic contribution of dry forests to climate change adaptation in Tigray Region, Ethiopia. A mixed quantitative and qualitative research design was [...] Read more.

Despite their ecological importance, dry forests’ contribution to climate change adaptation is often neglected. Hence, this study was initiated to assess the socioeconomic contribution of dry forests to climate change adaptation in Tigray Region, Ethiopia. A mixed quantitative and qualitative research design was used to examine the role of dry forests in climate change adaptation. Household questionnaire survey, key informants, and a focus group discussion were used to collect data. The results indicated that 94% of all households visited a dry forest at least once a month to access the forest and forest products. While the dry forest income level varied significantly (p < 0.05), the overall dry forest income level contributed to 16.8% of the total household income. Dry forest income enabled the reduction of the area between the line of equality and the Lorenz curve by 21% in dry evergreen Afromontane Forest users, by 3.02% in Combretum–Terminalia woodland users, and by 3% in Acacia–Commiphora woodland users. Gender, occupation, wealth status, and distance from the forest to their homes are all factors that significantly affected Combretum–Terminalia woodland users’ income level. Among Acacia–Commiphora woodland users, the respondents’ age influenced the dry forest income level, whereas, among dry evergreen Afromontane Forest users, the family size of the household influenced the dry forest income level. The findings of this study could help policy makers understand the crucial role of dry forest income in the livelihood of the community and in climate change adaptation. Policymakers could reduce the pressure on dry forests by introducing policies that recognize the role of dry forest income in reducing poverty and income inequality and by establishing farmer cooperation in commercializing the non-timber forest products which support the long-term coping and adaptation strategy. Further research is needed to understand the increasing role of dry forest products in climate change adaptation over time and its contribution to the national economy at large. Full article

(This article belongs to the Special Issue Advances in Resilient Adaptation to Climate Change in the Forest Sector)

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Open AccessEditor’s ChoiceReview

Toward the Genetic Improvement of Drought Tolerance in Conifers: An Integrated Approach

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Paolo Baldi

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Nicola La Porta

Forests 2022, 13(12), 2016; https://doi.org/10.3390/f13122016 - 29 Nov 2022

Cited by 2 | Viewed by 1732

Abstract

The constant rise in the global temperature and unpredictable shifts in precipitation patterns are two of the main effects of climate change. Therefore, there is an increasing amount of interest in the identification of tree species, provenances and genotypes capable of withstanding more [...] Read more.

The constant rise in the global temperature and unpredictable shifts in precipitation patterns are two of the main effects of climate change. Therefore, there is an increasing amount of interest in the identification of tree species, provenances and genotypes capable of withstanding more arid conditions and tolerating drought stress. In the present review, we focus our attention on generally more susceptible conifers and describe the different strategies that plants adopt to respond to drought stress. We describe the main approaches taken in studies of conifer adaptations to low water availability, the advantages and limitations of each, and the main results obtained with each of these approaches in the recent years. Then we discuss how the increasing amount of morphological, physiological and genetic data may find practical applications in forest management, and in particular in next-generation breeding programs. Finally, we provide some recommendations for future research. In particular, we suggest extending future studies to a broader selection of species and genera, increasing the number of studies on adult plants, in particular those on gene expression, and distinguishing between the different types of drought stress that a tree can withstand during its life cycle. The integration of data coming from different disciplines and approaches will be a key factor to increasing our knowledge about a trait as complex as drought resistance. Full article

(This article belongs to the Special Issue Tree Genetics: Molecular and Functional Characterization of Genes)

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Open AccessEditor’s ChoiceArticle

The Macroeconomic Implications of the Transition of the Forestry Industry towards Bioeconomy

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Forests 2022, 13(11), 1961; https://doi.org/10.3390/f13111961 - 21 Nov 2022

Viewed by 1418

Abstract

In a global economic system where essential resources are limited, demand is increasing and environmental degradation is more pronounced, the only viable option to ensure sustainable development is to create an environmentally friendly and efficient economy in order to produce more economic value [...] Read more.

In a global economic system where essential resources are limited, demand is increasing and environmental degradation is more pronounced, the only viable option to ensure sustainable development is to create an environmentally friendly and efficient economy in order to produce more economic value with the same or fewer resources. The aim of this paper is to provide insight into the macroeconomic implications determined by the transition to a forest bioeconomy, with a focus on the impact on the national gross value added. More specifically, this analysis assesses the relationship between the potential of the macroeconomic value creation on the forestry industry and the measures of progress on the transition towards sustainable forest management and long-term economic growth. The analysis refers to a period between 2013 and 2019, summing-up 133 observations, data that were reported by Eurostat for 23 European Union members. We propose a model that describes a construct of the potential of the value creation that can be generated by each country included in our sample, translated into an efficiency score determined using the Data Envelopment Analysis(DEA)methodology. The results highlighted that the evolution of economic, social, and environmental (ESG) context positively impacted the efficiency score. This positive evolution in time was mainly driven by the higher awareness of governments, companies, and people on the need for a transition to sustainable economic growth and sustainable forest management. Furthermore, this study highlights that the transition to sustainable economic growth implies negative changes to the cost structure of the economies, which lead to higher operational costs and lower gross value added. Moreover, our study provides more insight, from an econometric methodology perspective, regarding the synergy effect as determined by the transformation of business models in the forestry sector towards sustainable forest management. Full article

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

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Open AccessFeature PaperEditor’s ChoiceArticle

A Dynamical Model Based on the Chapman–Richards Growth Equation for Fitting Growth Curves for Four Pine Species in Northern Mexico

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Joao Marcelo Brazao Protazio

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Marcos Almeida Souza

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Jose Ciro Hernández-Díaz

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Jonathan G. Escobar-Flores

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Carlos Antonio López-Sánchez

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Artemio Carrillo-Parra

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Christian Wehenkel

Forests 2022, 13(11), 1866; https://doi.org/10.3390/f13111866 - 08 Nov 2022

Cited by 1 | Viewed by 1627

Abstract

Tree growth models describe the growth and development of forest ecosystems by considering how the dimensions of each simulated tree change within a certain time. These models have commonly used three growth parameters that describe various biological processes and behaviours, considering a sigmoid [...] Read more.

Tree growth models describe the growth and development of forest ecosystems by considering how the dimensions of each simulated tree change within a certain time. These models have commonly used three growth parameters that describe various biological processes and behaviours, considering a sigmoid growth function: (i) the upper asymptote (θ₁), which is the maximal yield indicated by a final dimension (such as the maximal stem diameter); (ii) the maximum specific growth rate (θ₂), defined as the slope of the tangent at the inflexion point; and (iii) the time elapsed (θ₃), defined by the intercept of this tangent with the abscissas. To the best of our knowledge, however, associations between the three parameters have not been documented for tree species. Using diameter growth data from pine trees located in typical mixed and uneven-aged pine-oak forests in the Sierra Madre Occidental, Mexico, our study aims were: (i) to quantify the putative associations between the three growth parameters and (ii) to test the accuracy of a proposed Hybrid Chapman-Richards growth model based on associations between the three growth parameters, but including only one single parameter, relative to the widely used Generalized Algebraic Difference Approach (GADA) based on the Chapman-Richards, Lundqvist and Hossfeld models and the Hybrid Weibull Model. For statistical comparison of the quality of the models, we used the mean relative percentage error, root mean square error, coefficient of determination and Akaike information criterion to assess the quality of the fit. Although the quality of the five growth models studied was similar, from a practical point of view, the proposed Hybrid Chapman-Richards Model (CR-H) is easier to apply than the other models and has a lower data collection and computational cost. The parameter of CR-H can be easily obtained, by measuring just the dominant trees, especially in coniferous forests with irregular ages. Moreover, in contrast to the Chapman-Richards-GADA factor χ₀, when θ₂ is assumed to be site-specific, the CR-H has always a closed-form solution. Full article

(This article belongs to the Special Issue Spatial Distribution and Growth Dynamics of Tree Species)

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Open AccessEditor’s ChoiceArticle

Linking Bacterial Rhizosphere Communities of Two Pioneer Species, Brachystegia boehmii and B. spiciformis, to the Ecological Processes of Miombo Woodlands

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Ana I. Ribeiro-Barros

Forests 2022, 13(11), 1840; https://doi.org/10.3390/f13111840 - 04 Nov 2022

Cited by 1 | Viewed by 1119

Abstract

Miombo is the most extensive ecosystem in southern Africa, being strongly driven by fire, climate, herbivory, and human activity. Soils are major regulating and supporting services, sequestering nearly 50% of the overall carbon and comprising a set of yet unexploited functions. In this [...] Read more.

Miombo is the most extensive ecosystem in southern Africa, being strongly driven by fire, climate, herbivory, and human activity. Soils are major regulating and supporting services, sequestering nearly 50% of the overall carbon and comprising a set of yet unexploited functions. In this study, we used next-generation Illumina sequencing to assess the patterns of bacterial soil diversity in two pioneer Miombo species, Brachystegia boehmii and Brachystegia spiciformis, along a fire gradient, in ferric lixisol and cambic arenosol soils. In total, 21 phyla, 51 classes, 98 orders, 193 families, and 520 genera were found, revealing a considerably high and multifunctional diversity with a strong potential for the production of bioactive compounds and nutrient mobilization. Four abundant genera characterized the core microbiome among plant species, type of soils, or fire regime: Streptomyces, Gaiella, Chthoniobacter, and Bacillus. Nevertheless, bacterial networks revealed a higher potential for mutualistic interactions and transmission of chemical signals among phylotypes from low fire frequency sites than those from high fire frequency sites. Ecological networks also revealed the negative effects of frequent fires on the complexity of microbial communities. Functional predictions revealed the core “house-keeping” metabolisms contributing to the high bacterial diversity found, suggesting its importance to the functionality of this ecosystem. Full article

(This article belongs to the Special Issue Soil Microorganisms in Forests: Biodiversity, Ecological Function, and Biogeography)

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Open AccessEditor’s ChoiceArticle

Water Retention Characteristics of Mineral Forest Soils in Finland: Impacts for Modeling Soil Moisture

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Forests 2022, 13(11), 1797; https://doi.org/10.3390/f13111797 - 29 Oct 2022

Viewed by 1510

Abstract

Soil hydraulic properties are central for soil quality and affect forest productivity and the impacts of climate change on forests. The water retention characteristics (WRC) of mineral forest soils in Finland are not well known, and practical tools to predict them for hydrological, [...] Read more.

Soil hydraulic properties are central for soil quality and affect forest productivity and the impacts of climate change on forests. The water retention characteristics (WRC) of mineral forest soils in Finland are not well known, and practical tools to predict them for hydrological, biogeochemical and forest models are lacking. We statistically analyzed mineral forest soils WRC from over 130 sites in Finland, focusing on the humus layer and main root zone (0–19 cm depth). We showed that mineral forest soils can be grouped into five WRC classes that are well predictable from soil bulk density, organic matter content and clay fraction. However, the majority of the forest soils are hydrologically rather similar. We found that neither topsoil maps nor any combination of open geospatial data were able to predict WRC. Thus, in the absence of site-specific soil data, parameterizing WRC as a function of forest site fertility type was proposed. We demonstrated the approach in soil moisture modeling at a small forest headwater catchment and showed that the soil moisture response to weather conditions is jointly affected by WRC, stand attributes and topography. We showed that drought risks are highest for dense mature forests at nutrient-poor, coarse-textured sites and lower for young stands on peatlands and lowland herb-rich sites with groundwater influence. The results improve hydrological predictions for Finnish forests, and the open dataset can contribute to the larger synthesis and development of boreal forest soil pedo-transfer functions. Full article

(This article belongs to the Special Issue Forest Management, Hydrology and Biogeochemistry Modelling)

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Open AccessEditor’s ChoiceArticle

Forest Management, Barred Owls, and Wildfire in Northern Spotted Owl Territories

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Monica L. Bond

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Tonja Y. Chi

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Curtis M. Bradley

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Dominick A. DellaSala

Forests 2022, 13(10), 1730; https://doi.org/10.3390/f13101730 - 20 Oct 2022

Viewed by 1618

Abstract

The Northern Spotted Owl (Strix occidentalis caurina) (NSO) was listed as federally threatened in 1992 due to widespread logging of its old-growth forest habitat. The NSO recovery plan in 2011 elevated competition with Barred Owls (Strix varia) (BO) and [...] Read more.

The Northern Spotted Owl (Strix occidentalis caurina) (NSO) was listed as federally threatened in 1992 due to widespread logging of its old-growth forest habitat. The NSO recovery plan in 2011 elevated competition with Barred Owls (Strix varia) (BO) and wildfires as primary NSO threats based partly on the assumption that severely burned forests were no longer NSO nesting and roosting habitat. We quantified amount of logging before and/or after wildfire and opportunistic detections of BOs within two home range scales (0.8 and 2.09 km) at 105 NSO sites that experienced severe wildfire from 2000–2017. Logging affected 87% of severely burned NSO sites, with BO recorded at 22% of burned-and-logged sites. Most (60%) severely burned NSO sites had evidence of logging both before and after fires while only 12% of severely burned sites had no logging or BO detections, indicating rarity of NSO territories subjected to severe fire without the compounding stressors of logging and invasive BOs. We recommend changes to NSO habitat modeling that assume nesting and roosting habitat is no longer viable if severely burned, and to the U.S. Fish and Wildlife Service’s practice of granting incidental take permits for NSOs in logging operations within severely burned owl sites. Full article

(This article belongs to the Special Issue The Extinction Crisis: How Bad, What Can Be Done?)

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Open AccessEditor’s ChoiceArticle

Critical Aspects of People’s Participation in Community-Based Forest Management from the Case of Van Panchayat in Indian Himalaya

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Kazuyo Nagahama

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Satoshi Tachibana

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Randeep Rakwal

Forests 2022, 13(10), 1667; https://doi.org/10.3390/f13101667 - 11 Oct 2022

Cited by 1 | Viewed by 1401

Abstract

The importance of community-based forest management (hereafter, CBFM) is drawing attention to forest policies in finding solutions for deforestation and importantly to also understand the basis of people’s involvement. Focusing on the latter, the study presented here targets a regional CBFM (Van (forest) [...] Read more.

The importance of community-based forest management (hereafter, CBFM) is drawing attention to forest policies in finding solutions for deforestation and importantly to also understand the basis of people’s involvement. Focusing on the latter, the study presented here targets a regional CBFM (Van (forest) Panchayat; hereafter, VP) at the village level in Uttarakhand, India and looks into characteristics and critical aspect of people’s participation. Participatory observations were conducted in four selected villages, followed by structured interviews with 113 of a total of 131 households and semi-structured interviews with additional 28 female villagers. Some specific findings were (a) the VP members were mostly involved in forest-related activities, e.g., plantation, forest patrols, (b) a greater use of firewood by the management committee (hereafter, MC) where most members were from the higher-caste, and (c) most of the VP forest users were women; however, few women members were involved in decision-making, as they were mostly fixed members and they had not voluntarily chosen their positions. In the above context, it implied a limited participation of women in the decision-making process, i.e., no or little involvement in the management plan by the main VP forest users. Results concluded three stages of local peoples’ participation in forest management: “participation in activities”, “participation in decision-making” and “participation in management plan creation”. In summary, what our study shows is that participation by the VP members in CBFM activities was easy. The most difficult aspect related to the participation of female members was the decision-making process in each VPMC investigated. Full article

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

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Open AccessEditor’s ChoiceReview

Twelve Years into Genomic Selection in Forest Trees: Climbing the Slope of Enlightenment of Marker Assisted Tree Breeding

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Dario Grattapaglia

Forests 2022, 13(10), 1554; https://doi.org/10.3390/f13101554 - 23 Sep 2022

Cited by 7 | Viewed by 2257

Abstract

Twelve years have passed since the early outlooks of applying genomic selection (GS) to forest tree breeding, initially based on deterministic simulations, soon followed by empirical reports. Given its solid projections for causing a paradigm shift in tree breeding practice in the years [...] Read more.

Twelve years have passed since the early outlooks of applying genomic selection (GS) to forest tree breeding, initially based on deterministic simulations, soon followed by empirical reports. Given its solid projections for causing a paradigm shift in tree breeding practice in the years to come, GS went from a hot, somewhat hyped, topic to a fast-moving area of applied research and operational implementation worldwide. The hype cycle curve of emerging technologies introduced by Gartner Inc. in 1995, models the path a technology takes in terms of expectations of its value through time. Starting with a sudden and excessively positive “peak of inflated expectations” at its introduction, a technology that survives the “valley of disappointment” moves into maturity to climb the “slope of enlightenment”, to eventually reach the “plateau of productivity”. Following the pioneering steps of GS in animal breeding, we have surpassed the initial phases of the Gartner hype cycle and we are now climbing the slope of enlightenment towards a wide application of GS in forest tree breeding. By merging modern high-throughput DNA typing, time-proven quantitative genetics and mixed-model analysis, GS moved the focus away from the questionable concept of dissecting a complex, polygenic trait in its individual components for breeding advancement. Instead of trying to find the needle in a haystack, i.e., the “magic” gene in the complex and fluid genome, GS more efficiently and humbly “buys the whole haystack” of genomic effects to predict complex phenotypes, similarly to an exchange-traded fund that more efficiently “buys the whole market”. Tens of studies have now been published in forest trees showing that GS matches or surpasses the performance of phenotypic selection for growth and wood properties traits, enhancing the rate of genetic gain per unit time by increasing selection intensity, radically reducing generation interval and improving the accuracy of breeding values. Breeder-friendly and cost-effective SNP (single nucleotide polymorphism) genotyping platforms are now available for all mainstream plantation forest trees, but methods based on low-pass whole genome sequencing with imputation might further reduce genotyping costs. In this perspective, I provide answers to why GS will soon become the most efficient and effective way to carry out advanced tree breeding, and outline a simple pilot demonstration project that tree breeders can propose in their organization. While the fundamental properties of GS in tree breeding are now solidly established, strategic, logistics and financial aspects for the optimized adoption of GS are now the focus of attentions towards the plateau of productivity in the cycle, when this new breeding method will become fully established into routine tree improvement. Full article

(This article belongs to the Special Issue Using Genomic Information in Forest Tree Breeding, Restoration, and Conservation: Separating Hype from Reality)

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Open AccessEditor’s ChoiceArticle

A Small Target Forest Fire Detection Model Based on YOLOv5 Improvement

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Zhenyang Xue

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Haifeng Lin

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Fang Wang

Forests 2022, 13(8), 1332; https://doi.org/10.3390/f13081332 - 20 Aug 2022

Cited by 18 | Viewed by 3324

Abstract

Forest fires are highly unpredictable and extremely destructive. Traditional methods of manual inspection, sensor-based detection, satellite remote sensing and computer vision detection all have their obvious limitations. Deep learning techniques can learn and adaptively extract features of forest fires. However, the small size [...] Read more.

Forest fires are highly unpredictable and extremely destructive. Traditional methods of manual inspection, sensor-based detection, satellite remote sensing and computer vision detection all have their obvious limitations. Deep learning techniques can learn and adaptively extract features of forest fires. However, the small size of the forest fire target in the long-range-captured forest fire images causes the model to fail to learn effective information. To solve this problem, we propose an improved forest fire small-target detection model based on YOLOv5. This model requires cameras as sensors for detecting forest fires in practical applications. First, we improved the Backbone layer of YOLOv5 and adjust the original Spatial Pyramid Pooling-Fast (SPPF) module of YOLOv5 to the Spatial Pyramid Pooling-Fast-Plus (SPPFP) module for a better focus on the global information of small forest fire targets. Then, we added the Convolutional Block Attention Module (CBAM) attention module to improve the identifiability of small forest fire targets. Second, the Neck layer of YOLOv5 was improved by adding a very-small-target detection layer and adjusting the Path Aggregation Network (PANet) to the Bi-directional Feature Pyramid Network (BiFPN). Finally, since the initial small-target forest fire dataset is a small sample dataset, a migration learning strategy was used for training. Experimental results on an initial small-target forest fire dataset produced by us show that the improved structure in this paper improves mAP@0.5 by 10.1%. This demonstrates that the performance of our proposed model has been effectively improved and has some application prospects. Full article

(This article belongs to the Special Issue Advances in Forest Fire and Other Detection Systems)

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Open AccessEditor’s ChoiceArticle

Assessing Structural Complexity of Individual Scots Pine Trees by Comparing Terrestrial Laser Scanning and Photogrammetric Point Clouds

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Forests 2022, 13(8), 1305; https://doi.org/10.3390/f13081305 - 16 Aug 2022

Cited by 1 | Viewed by 1618

Abstract

Structural complexity of trees is related to various ecological processes and ecosystem services. To support management for complexity, there is a need to assess the level of structural complexity objectively. The fractal-based box dimension (D_b) provides a holistic measure of the [...] Read more.

Structural complexity of trees is related to various ecological processes and ecosystem services. To support management for complexity, there is a need to assess the level of structural complexity objectively. The fractal-based box dimension (D_b) provides a holistic measure of the structural complexity of individual trees. This study aimed to compare the structural complexity of Scots pine (Pinus sylvestris L.) trees assessed with D_b that was generated with point cloud data from terrestrial laser scanning (TLS) and aerial imagery acquired with an unmanned aerial vehicle (UAV). UAV imagery was converted into point clouds with structure from motion (SfM) and dense matching techniques. TLS and UAV measured D_b-values were found to differ from each other significantly (TLS: 1.51 ± 0.11, UAV: 1.59 ± 0.15). UAV measured D_b-values were 5% higher, and the range was wider (TLS: 0.81–1.81, UAV: 0.23–1.88). The divergence between TLS and UAV measurements was found to be explained by the differences in the number and distribution of the points and the differences in the estimated tree heights and number of boxes in the D_b-method. The average point density was 15 times higher with TLS than with UAV (TLS: 494,000, UAV 32,000 points/tree), and TLS received more points below the midpoint of tree heights (65% below, 35% above), while UAV did the opposite (22% below, 78% above). Compared to the field measurements, UAV underestimated tree heights more than TLS (TLS: 34 cm, UAV: 54 cm), resulting in more boxes of D_b-method being needed (4–64%, depending on the box size). Forest structure (two thinning intensities, three thinning types, and a control group) significantly affected the variation of both TLS and UAV measured D_b-values. Still, the divergence between the two approaches remained in all treatments. However, TLS and UAV measured D_b-values were consistent, and the correlation between them was 75%. Full article

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

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Open AccessEditor’s ChoiceArticle

Effect of Wild Boar (Sus scrofa) Rooting on Soil Characteristics in a Deciduous Forest Affected by Sedimentation

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Forests 2022, 13(8), 1234; https://doi.org/10.3390/f13081234 - 03 Aug 2022

Cited by 1 | Viewed by 1486

Abstract

Forest soils are shaped by various processes, like runoff, erosion, sedimentation and bioturbation. A better understanding of the interactions between abiotic and biotic soil-forming processes, including wild boar (Sus scrofa) rooting (i.e., subsurface foraging), enhances adequate management of forest ecosystems. We [...] Read more.

Forest soils are shaped by various processes, like runoff, erosion, sedimentation and bioturbation. A better understanding of the interactions between abiotic and biotic soil-forming processes, including wild boar (Sus scrofa) rooting (i.e., subsurface foraging), enhances adequate management of forest ecosystems. We hypothesized that intense soil sedimentation influences wild boar rooting occurrence and that wild boars modify the outcome of the sedimentation process by redistributing soil layers. This study was conducted in the Babat Valley, Hungary. We estimated the availability of sedimented and non-sedimented patches and the occurrence of boar rooting. Surveys and samplings were done along transects, over consecutive months, where the impact of rooting on the physical and chemical characteristics of soil was measured by comparing them between control and rooted sites. We found that non-sedimented, steep areas were preferred areas for rooting. Sedimentation processes have a higher impact on soil chemical characteristics and soil layer composition than wild boar rooting. We conclude that mitigation of soil degradation can be more effective by reducing adverse abiotic processes rather than wild boar population control. Full article

(This article belongs to the Special Issue Land Use and Other Strategies to Mitigate Climate Change in Carbon-Dense Forests)

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Open AccessEditor’s ChoiceArticle

Recreational Visit to Suburban Forests during the COVID-19 Pandemic: A Case Study of Taiwan

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Forests 2022, 13(8), 1181; https://doi.org/10.3390/f13081181 - 25 Jul 2022

Viewed by 1472

Abstract

COVID-19 global pandemic has caused massive disruption of travel behaviors along with other aspects of human life, such as social distancing, staying at home, and avoiding crowds. People substituted outdoor activities for indoor activities, and the forest environment has become a popular alternative. [...] Read more.

COVID-19 global pandemic has caused massive disruption of travel behaviors along with other aspects of human life, such as social distancing, staying at home, and avoiding crowds. People substituted outdoor activities for indoor activities, and the forest environment has become a popular alternative. Taiwan has a high population density, but it had few COVID-19 confirmed cases in 2020 during the first wave of the COVID-19 pandemic. No forest areas have been closed due to the COVID-19 outbreak. In light of this generally increased demand for suburban forests for recreational uses, the current COVID-19 pandemic situation poses specific challenges regarding forest use, management, and policy. This study integrates visitation numbers of the popular forest recreation area and selects the unblocking index and social distancing index as the COVID-19 index to capture the impacts of forest recreation area on the COVID-19 outbreak in Taiwan. The results show both COVID-19 indices have high explanatory power for suburban forest visitation and both have a significant impact on the number of visitors. Although the number of visitors to suburban forests decreased during the COVID-19 pandemic alert, it bounced when the COVID-19 outbreak was under control. This study provides a brief overview of management implications for recreational visits during COVID-19. We posed an early warning to forest managers for greater revenge traveling post-COVID-19. Full article

(This article belongs to the Special Issue Nature-Based Tourism and Nature Conservation Activation by Tourism)

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Open AccessEditor’s ChoiceArticle

A National Map of Snag Hazard to Reduce Risk to Wildland Fire Responders

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Karin L. Riley

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Christopher D. O’Connor

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Forests 2022, 13(8), 1160; https://doi.org/10.3390/f13081160 - 22 Jul 2022

Cited by 1 | Viewed by 1557

Abstract

Falling trees and tree fragments are one of the top five causes of fatalities for wildland fire responders. In six out of ten recent years, at least one fatality from a tree strike has occurred while a fire responder was on duty, and [...] Read more.

Falling trees and tree fragments are one of the top five causes of fatalities for wildland fire responders. In six out of ten recent years, at least one fatality from a tree strike has occurred while a fire responder was on duty, and others were injured. We used TreeMap, a national map of forest characteristics, including individual tree height, diameter, and status (live or dead), to generate a map of snag hazard for forested areas of the continental U.S. at 30 × 30 m resolution. Snag hazard was classified into categories of low, moderate, high, or extreme based on snag density and height. Within-class accuracy was as high at 86%, suggesting that the Snag Hazard map can help wildland fire managers identify and avoid exposing fire responders to hazardous conditions. Accuracy was higher outside recently disturbed areas (88%) than inside (79%), perhaps reflecting strong spatial patterns and heterogeneity of mortality within disturbed areas. The Snag Hazard map is a frequently requested product from the Forest Service’sRisk Management Assistance Group. The goal of RMA is to provide analytics to decision makers and fire leadership to facilitate risk-informed decision-making to improve safety, effectiveness, and outcomes. We present a case study showing how the Snag Hazard 2016 map was used to inform fire responders during an active wildfire incident in California during the 2020 fire season. Full article

(This article belongs to the Special Issue Decision Support System Development of Wildland Fire)

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Open AccessEditor’s ChoiceArticle

Culturable Endophytic Fungi in Fraxinus excelsior and Their Interactions with Hymenoscyphus fraxineus

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Marek Barta

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Katarína Pastirčáková

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Radovan Ostrovský

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Marek Kobza

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Miriam Kádasi Horáková

Forests 2022, 13(7), 1098; https://doi.org/10.3390/f13071098 - 13 Jul 2022

Cited by 2 | Viewed by 1539

Abstract

The species diversity of culturable endophytic fungi was studied in the leaves and twigs of symptomatic and asymptomatic Fraxinus excelsior trees. Endophytic mycobiota was dominated by Ascomycota species, with Pleosporales (44.17%) and Diaporthales (23.79%) endophytes being the most frequently observed in the tree [...] Read more.

The species diversity of culturable endophytic fungi was studied in the leaves and twigs of symptomatic and asymptomatic Fraxinus excelsior trees. Endophytic mycobiota was dominated by Ascomycota species, with Pleosporales (44.17%) and Diaporthales (23.79%) endophytes being the most frequently observed in the tree samples. The number of endophytic isolates and species richness varied depending on the sampling date (May and October) and tissue location. Of the 54 species identified based on ITS sequences, 14 were classified as dominant. The most frequently isolated species were Diaporthe eres, followed by Alternaria alternata, Dothiorella gregaria, and Fraxinicola fraxini. The inhibitory effect of 41 species (75 isolates) of endophytes on the radial growth of a Hymenoscyphus fraxineus isolate was studied under in vitro conditions (dual cultures). The radial growth of H. fraxineus was the most inhibited by four endophytic fungi from twigs (Fusarium lateritium, Didymella aliena, Didymella macrostoma, and Dothiorella gregaria). The inhibitory effect of the four isolates was also studied under in planta conditions. The isolates artificially inoculated into the trunks of ash trees reduced the length of necroses formed by H. fraxineus co-inoculated in the same trunks. This effect depended on the isolate, and the inhibition was most prominent only on trunks inoculated with F. lateritium and D. aliena. Although the total length of necrotic lesions formed by the H. fraxineus infection was shorter in the ash trunks co-inoculated with the endophytes, the difference was not significant. Full article

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

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Open AccessEditor’s ChoiceArticle

Psychological Well-Being and Nature Relatedness

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Olga Grabowska-Chenczke

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Sandra Wajchman-Świtalska

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Marcin Woźniak

Forests 2022, 13(7), 1048; https://doi.org/10.3390/f13071048 - 02 Jul 2022

Cited by 4 | Viewed by 2330

Abstract

The way people perceive contact with nature may impact their environmental attitudes and psychological well-being (WB). Nature relatedness (NR) refers to the affective, cognitive, and experiential aspects of individuals’ connection to nature. The aim of the presented research concentrates on the assessment of [...] Read more.

The way people perceive contact with nature may impact their environmental attitudes and psychological well-being (WB). Nature relatedness (NR) refers to the affective, cognitive, and experiential aspects of individuals’ connection to nature. The aim of the presented research concentrates on the assessment of the relationship between well-being, self-control and connectedness with the natural environment. The data was collected via online questionnaire between March and April 2022. In the study, we combined descriptive statistics with analysis of variance. We also quantitatively assessed correlations between major components of NR scale and psychological WB across men’ and women’ inquires. The results showed that there is a statistically significant relationship between the general index of NR and overall psychological WB. Furthermore, correlation between specific aspects of NR and WB subscales were also observed. These interactions are considerable among both men and women. We have also identified a major correlation between NR and self-control, which indicates the link between the way a person approaches oneself and natural environment. Finally, the analysis provides evidence that women are on average more related to nature, although the men may benefit more from this kind of relationship. Further gender differences could be observed in terms of nature-relatedness perspective component, general self-control, score and overall NR score These relationships are highly vital among men while irrelevant among women. Full article

(This article belongs to the Special Issue Forest and Other Natural Landscapes and Human Health)

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Open AccessEditor’s ChoiceArticle

Towards Continuous Stem Water Content and Sap Flux Density Monitoring: IoT-Based Solution for Detecting Changes in Stem Water Dynamics

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Shahla Asgharinia

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Martin Leberecht

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Luca Belelli Marchesini

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Forests 2022, 13(7), 1040; https://doi.org/10.3390/f13071040 - 01 Jul 2022

Cited by 2 | Viewed by 1673

Abstract

Taking advantage of novel IoT technologies, a new multifunctional device, the “TreeTalker”, was developed to monitor real-time ecophysical and biological parameters of individual trees, as well as climatic variables related to their surrounding environment, principally, air temperature and air relative humidity. Here, IoT [...] Read more.

Taking advantage of novel IoT technologies, a new multifunctional device, the “TreeTalker”, was developed to monitor real-time ecophysical and biological parameters of individual trees, as well as climatic variables related to their surrounding environment, principally, air temperature and air relative humidity. Here, IoT applied to plant ecophysiology and hydrology aims to unravel the vulnerability of trees to climatic stress via a single tree assessment at costs that enable massive deployment. We present the performance of the TreeTalker to elucidate the functional relation between the stem water content in trees and respective internal/external (stem hydraulic activity/abiotic) drivers. Continuous stem water content records are provided by an in-house-designed capacitance sensor, hosted in the reference probe of the TreeTalker sap flow measuring system, based on the transient thermal dissipation (TTD) method. In order to demonstrate the capability of the TreeTalker, a three-phase experimental process was performed including (1) sensor sensitivity analysis, (2) sensor calibration, and (3) long-term field data monitoring. A negative linear correlation was demonstrated under temperature sensitivity analysis, and for calibration, multiple linear regression was applied on harvested field samples, explaining the relationship between the sample volumetric water content and the sensor output signal. Furthermore, in a field scenario, TreeTalkers were mounted on adult Fagus sylvatica L. and Quercus petraea L. trees, from June 2020 to October 2021, in a beech-dominated forest near Marburg, Germany, where they continuously monitored sap flux density and stem volumetric water content (stem VWC). The results show that the range of stem VWC registered is highly influenced by the seasonal variability of climatic conditions. Depending on tree characteristics, edaphic and microclimatic conditions, variations in stem VWC and reactions to atmospheric events occurred. Low sapwood water storage occurs in response to drought, which illustrates the high dependency of trees on stem VWC under water stress. Consistent daily variations in stem VWC were also clearly detectable. Stem VWC constitutes a significant portion of daily transpiration (using TreeTalkers, up to 4% for the beech forest in our experimental site). The diurnal–nocturnal pattern of stem VWC and sap flow revealed an inverse relationship. Such a finding, still under investigation, may be explained by the importance of water recharge during the night, likely due to sapwood volume changes and lateral water distribution rather than by a vertical flow rate. Overall, TreeTalker demonstrated the potential of autonomous devices for monitoring sap density and relative stem VWC in the field of plant ecophysiology and hydrology. Full article

(This article belongs to the Topic Challenges, Development and Frontiers of Smart Agriculture and Forestry)

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Open AccessEditor’s ChoiceArticle

Wood Preservation Practices and Future Outlook: Perspectives of Experts from Finland

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Jami Järvinen

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Hüseyin Emre Ilgın

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Markku Karjalainen

Forests 2022, 13(7), 1044; https://doi.org/10.3390/f13071044 - 01 Jul 2022

Cited by 8 | Viewed by 1846

Abstract

This paper examined wood preservation practices and outlook considering climate change from the perspective of Finnish experts through interviews. Key findings highlighted that: (1) pressure impregnated wood will continually evolve and secure its market, and it seems worthy of developing modified wood products, [...] Read more.

This paper examined wood preservation practices and outlook considering climate change from the perspective of Finnish experts through interviews. Key findings highlighted that: (1) pressure impregnated wood will continually evolve and secure its market, and it seems worthy of developing modified wood products, especially with the increasing attention to recyclability and lifecycle concepts; (2) demand for highly processed surface treatment products is high; (3) opportunities for more sustainable and environmentally friendly wood preservation methods, and thus production volume will increase in the future; (4) increasing mold problems in Finland due to climate change make surface treatment more important than ever; (5) demands for fire protection treatments are increasing, but fire testing fees and processes have slowed product development; (6) although the possibility of the spread of termites triggered by global warming to Finland seems to be a future scenario, this issue needs to be considered in products exported to hot countries; and (7) preservatives have become more critical to protect untreated wood from the adverse effects of climate change. It is believed that this study will help accelerate the transition of innovative and environmentally friendly wood treatments on the Finnish market, thereby promoting the use of wood in the building construction industry. Full article

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

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Open AccessEditor’s ChoiceReview

Review of Wood Modification and Wood Functionalization Technologies

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Forests 2022, 13(7), 1004; https://doi.org/10.3390/f13071004 - 26 Jun 2022

Cited by 15 | Viewed by 4675

Abstract

Wood modifications are becoming popular as a way to enhance the performance of wood, either to make it more durable, improve the performance of wood, or give it new functionality as a multifunctional or smart material. While wood modifications have been examined since [...] Read more.

Wood modifications are becoming popular as a way to enhance the performance of wood, either to make it more durable, improve the performance of wood, or give it new functionality as a multifunctional or smart material. While wood modifications have been examined since the early 1900s, the topic has become a dominant area of study in wood science over the past decade. This review summarizes recent advances and provides future perspective on a selection of wood modifications, i.e., the methods that are currently commercialized (acetylation, furfurylation, and thermal modification), a rediscovered ancient practice (charring), a family of polymerization modifications that have so far made it to the pilot scale, and examples of novel wood-based functional materials explored at laboratory scale. Full article

(This article belongs to the Special Issue Reviews on Structure and Physical and Mechanical Properties of Wood)

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Open AccessEditor’s ChoiceReview

Recent Advances in Forest Insect Pests and Diseases Monitoring Using UAV-Based Data: A Systematic Review

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Forests 2022, 13(6), 911; https://doi.org/10.3390/f13060911 - 10 Jun 2022

Cited by 14 | Viewed by 3158

Abstract

Unmanned aerial vehicles (UAVs) are platforms that have been increasingly used over the last decade to collect data for forest insect pest and disease (FIPD) monitoring. These machines provide flexibility, cost efficiency, and a high temporal and spatial resolution of remotely sensed data. [...] Read more.

Unmanned aerial vehicles (UAVs) are platforms that have been increasingly used over the last decade to collect data for forest insect pest and disease (FIPD) monitoring. These machines provide flexibility, cost efficiency, and a high temporal and spatial resolution of remotely sensed data. The purpose of this review is to summarize recent contributions and to identify knowledge gaps in UAV remote sensing for FIPD monitoring. A systematic review was performed using the preferred reporting items for systematic reviews and meta-analysis (PRISMA) protocol. We reviewed the full text of 49 studies published between 2015 and 2021. The parameters examined were the taxonomic characteristics, the type of UAV and sensor, data collection and pre-processing, processing and analytical methods, and software used. We found that the number of papers on this topic has increased in recent years, with most being studies located in China and Europe. The main FIPDs studied were pine wilt disease (PWD) and bark beetles (BB) using UAV multirotor architectures. Among the sensor types, multispectral and red–green–blue (RGB) bands were preferred for the monitoring tasks. Regarding the analytical methods, random forest (RF) and deep learning (DL) classifiers were the most frequently applied in UAV imagery processing. This paper discusses the advantages and limitations associated with the use of UAVs and the processing methods for FIPDs, and research gaps and challenges are presented. Full article

(This article belongs to the Special Issue Advanced Applications of UAV Remote Sensing in Forest Structure)

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Open AccessEditor’s ChoiceArticle

Invasion of Emerald Ash Borer Agrilus planipennis and Ash Dieback Pathogen Hymenoscyphus fraxineus in Ukraine—A Concerted Action

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Forests 2022, 13(5), 789; https://doi.org/10.3390/f13050789 - 19 May 2022

Cited by 4 | Viewed by 2645

Abstract

Emerald Ash Borer (EAB), Agrilus planipennis, is a beetle that originates from East Asia. Upon invasion to North America in the early 2000s, it killed untold millions of ash trees. In European Russia, EAB was first detected in Moscow in 2003 and [...] Read more.

Emerald Ash Borer (EAB), Agrilus planipennis, is a beetle that originates from East Asia. Upon invasion to North America in the early 2000s, it killed untold millions of ash trees. In European Russia, EAB was first detected in Moscow in 2003 and proved to have the potential to also kill native European ash (Fraxinus excelsior). The beetle has since spread in all geographic directions, establishing itself in eastern Ukraine by 2019 and possessing potential for further westward spread towards the EU. Apart from the approaching EAB, F. excelsior is currently threatened by the dieback disease (ADB) caused by the invasive ascomycete fungus Hymenoscyphus fraxineus. The infestation by EAB combined with ADB infection is expected to be more lethal than either of them alone, yet the potential consequences are unknown. To date, eastern Ukraine represents the geographic area in which both invasions overlap, thus providing the opportunity for related investigations. The aims of the study were to investigate: (i) the EAB expansion range in Ukraine, (ii) the relative susceptibility of F. excelsior and American ash (Fraxinus pennsylvanica) to EAB and ADB, and (iii) the combined effect/impact on ash condition imposed by both the pest and disease in the area subjected to the invasion. The results have demonstrated that (i) the invasion of EAB is currently expanding both in terms of newly infested trees and invaded geographic area; (ii) F. excelsior is more resistant to EAB than F. pennsylvanica, while F. excelsior is more susceptible to ADB than F. pennsylvanica; and (iii) the infection by ADB is likely to predispose F. excelsior to the infestation by EAB. It was concluded that inventory and mapping of surviving F. excelsior, affected by both ADB and EAB, is necessary to acquire genetic resources for the work on strategic, long-term restoration of F. excelsior in devastated areas, thereby tackling a possible invasion of EAB to the EU. Full article

(This article belongs to the Special Issue Management of Forest Pests and Diseases)

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Open AccessEditor’s ChoiceArticle

Comparing Geography and Severity of Managed Wildfires in California and the Southwest USA before and after the Implementation of the 2009 Policy Guidance

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Forests 2022, 13(5), 793; https://doi.org/10.3390/f13050793 - 19 May 2022

Cited by 3 | Viewed by 2916

Abstract

Managed wildfires, i.e., naturally ignited wildfires that are managed for resource benefits, have the potential to reduce fuel loads, minimize the effects of future wildfires, and restore critical natural processes across many forest landscapes. In the United States, the 2009 federal wildland fire [...] Read more.

Managed wildfires, i.e., naturally ignited wildfires that are managed for resource benefits, have the potential to reduce fuel loads, minimize the effects of future wildfires, and restore critical natural processes across many forest landscapes. In the United States, the 2009 federal wildland fire policy guidance was designed to provide greater flexibility in the use of managed wildfires, but the effects of this policy on wildfires in the western US are not yet fully understood. Our goal was to compare managed and full suppression wildfires and to also analyze the differences between managed wildfires across space (Arizona/New Mexico and California) and time (before and after 2009) using four metrics for each wildfire: (1) distance to wilderness, (2) distance to the wildland–urban interface (WUI), (3) the percentage of area burned with high severity, and (4) the number of land management agencies. Across the study area, we found that managed wildfires were significantly closer to wilderness areas, were farther from the WUI, had a lower percentage of area that was burned at high severity, and had fewer agencies involved in managing the fire compared to full suppression wildfires. In California, managed wildfires occurred closer to wilderness and had a larger percentage of high-severity burn area compared to those in the southwest US (Arizona and New Mexico). Within each region, however, there were no significant geographic differences between managed wildfires before and after the implementation of the 2009 policy guidance. Despite the greater flexibility of the 2009 policy guidance, the basic geographic properties of managed wildfires in these two regions have not changed. As the climate warms and droughts intensify, the use of managed wildfires will need to expand during favorable weather conditions in order to address the threat of large and uncharacteristic wildfires to people and ecosystems. Full article

(This article belongs to the Special Issue Social and Ecological Effects of Wildfires and Effectiveness of Fuels Management)

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Open AccessEditor’s ChoiceArticle

The Historical Complexity of Tree Height Growth Dynamic Associated with Climate Change in Western North America

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Yassine Messaoud

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Anya Reid

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Nadezhda M. Tchebakova

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Jack A. Goldman

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Annika Hofgaard

Forests 2022, 13(5), 738; https://doi.org/10.3390/f13050738 - 09 May 2022

Viewed by 1813

Abstract

The effect of climate on tree growth has received increased interest in the context of climate change. However, most studies have been limited geographically and with respect to species. Here, sixteen tree species of western North America were used to investigate the response [...] Read more.

The effect of climate on tree growth has received increased interest in the context of climate change. However, most studies have been limited geographically and with respect to species. Here, sixteen tree species of western North America were used to investigate the response of trees to climate change. Forest inventory data from 36,944 stands established between 1600 and 1968 throughout western North America were summarized. The height growth (top height at a breast-height age of 50 years) of healthy dominant and co-dominant trees was related to annual and summer temperatures, the annual and summer Palmer Drought Severity Indexes (PDSIs), and the tree establishment date (ED). Climate-induced height growth patterns were then tested to determine links to the spatial environment (geographic locations and soil properties), the species’ range (coastal, interior, or both), and traits (shade tolerance and leaf form). Analysis was performed using a linear mixed model (total species) and a general linear model (species scale). Climate change was globally beneficial, except for Alaska yellow-cedar (Chamaecyparis nootkatensis (D. Don) Spach), and growth patterns were magnified for coastal-ranged, high-shade-tolerant, and broadleaf species, and mostly at the northernmost extents of these species’ ranges. Nevertheless, growth patterns were more complex with respect to soil properties. A growth decline for some species was observed at higher latitudes and elevations and was possibly related to increased cloudiness, precipitation, or drought (in interior areas). These results highlight the spatio-temporal complexity of the growth response to recent global climate change. Full article

(This article belongs to the Special Issue Forest Species Distribution and Diversity under Climate Change)

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Open AccessEditor’s ChoiceArticle

An Ecological-Economic Approach to Assess Impacts of the Expansion of Eucalyptus Plantations in Agroforest Landscapes of Northern Ethiopia

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Forests 2022, 13(5), 686; https://doi.org/10.3390/f13050686 - 28 Apr 2022

Viewed by 1999

Abstract

The conversion of fertile croplands to Eucalyptus woodlots in Ethiopian highlands, due to its business attractiveness to smallholders, raises concerns related to food production, water resources, carbon and other ecosystem services. This study was therefore designed to examine land allocation and plantation management [...] Read more.

The conversion of fertile croplands to Eucalyptus woodlots in Ethiopian highlands, due to its business attractiveness to smallholders, raises concerns related to food production, water resources, carbon and other ecosystem services. This study was therefore designed to examine land allocation and plantation management decisions. Our emphasis was on the analysis of tradeoffs between the economic gains obtained from harvesting Eucalyptus timber and food production, carbon and water use. For that purpose, we considered a 1987 ha agroforest landscape in the Amhara region, Northern Ethiopia. With a planning horizon covering nine one-year periods, we developed and used nine Model I single objective linear programming (LP) models, and analyzed tradeoffs between objectives (e.g., land expectation value (LEV), Carbon, volume of ending inventory (VolEI), crop production and water use) using an LP-based Pareto frontier approach. The study revealed that the objective of maximizing the total economic gain from the sale of Eucalyptus wood poles favored a complete conversion of the available cropland into Eucalyptus woodlots. To meet the minimum annual crop production/consumption/requirements of households in the study area, the land under Eucalyptus should be limited to 1772 ha, with a sequestration potential of 1.5 to 1.57 × 10⁷ kg yr⁻¹ of carbon in the aboveground biomass. However, this land cover limit should be decreased to 921 ha so as to limit the total annual water use (for biomass production) below the amount available from rainfall (11,000 m³ ha⁻¹ yr⁻¹). Moreover, the study highlighted that maximizing the harvested wood volume or LEV would come at the cost of a decreased aboveground carbon stock and volume of ending inventory and higher total water use. It also provided alternative optimal Pareto-front points, among which decision makers will be able to select their preferred targets. The current study also showed the potential for the application of Pareto frontier approaches to support the development of effective ecological/economic management strategies and the design of land use policies in an Ethiopian context. Full article

(This article belongs to the Special Issue Multiple-Use and Ecosystem Services of Forests)

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Open AccessEditor’s ChoiceReview

Cultivation Potential and Uses of Paulownia Wood: A Review

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Marcin Jakubowski

Forests 2022, 13(5), 668; https://doi.org/10.3390/f13050668 - 26 Apr 2022

Cited by 10 | Viewed by 3868

Abstract

This review aimed to determine the current state of research on the growth conditions and use pertaining to paulownia wood, mainly in European countries where paulownia has been introduced only relatively recently. Several studies carried out on Paulownia hybrids have shown significant differences [...] Read more.

This review aimed to determine the current state of research on the growth conditions and use pertaining to paulownia wood, mainly in European countries where paulownia has been introduced only relatively recently. Several studies carried out on Paulownia hybrids have shown significant differences in the growth dynamics of individual clones in their response to local environmental and climatic conditions. For example, dry biomass production yields in the second year of cultivation range from 1.5 t ha⁻¹ to as much as 14 t ha⁻¹. This diversity has manifested itself not only in growth characteristics but also in the properties of the wood and the possibilities for its use. Despite having clear similarities to the genus Paulownia, the cultivation of species and hybrids under different conditions has produced varying results. The best growing conditions for this wood (that make economic sense) are in the Middle East and Southern Europe. These regions have accumulated the most experience because of the earlier establishment of the crop. Today, paulownia cultivation is dominated by hybrids with selected traits that are propagated mainly in vitro. The most commonly planted hybrids include the clones in vitro 112, Cotevisa 2 and Shan Tong. The growth results and production capacity in central European countries are lower compared to Southern Europe. Experiments on paulownia cultivation are still relatively young, mainly consisting of replicating the cultivation of hybrids developed in Asia or Southern Europe. However, agronomic procedures are being developed and reactions to local climatic conditions are being studied. It is likely that, in the next few years, the profitability of growing paulownia in these regions will become apparent. Full article

(This article belongs to the Special Issue Wood as Biomechanical Structure)

Open AccessEditor’s ChoiceArticle

Mangrove Forests in Ecuador: A Two-Decade Analysis

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Ramiro Morocho

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Ivonne González

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Tiago Osorio Ferreira

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Xosé Luis Otero

Forests 2022, 13(5), 656; https://doi.org/10.3390/f13050656 - 23 Apr 2022

Cited by 2 | Viewed by 2343

Abstract

Mangroves are one of the most important ecosystems especially due to the services they provide, but in contrast are one of the most threatened by human activities at a global level. In Ecuador, mangrove forests are currently fragile and threatened due to the [...] Read more.

Mangroves are one of the most important ecosystems especially due to the services they provide, but in contrast are one of the most threatened by human activities at a global level. In Ecuador, mangrove forests are currently fragile and threatened due to the great anthropic pressure, which has largely reduced the area they occupy. However, there is already evidence that certain actions are contributing both to their conservation and the recovery of the lost mangrove area. In this study, we assessed the multitemporal dynamics of changes in mangrove cover in four coastal provinces of the country over a period of 20 years (1998–2018) based on remote sensing data analyzed using GIS tools. Our results showed that the area affected by mangrove forest destruction reached its maximum during the 1998–2010 period, when 4.56% (194.57 km²) of the mangrove forest was lost. This situation especially affected the provinces of El Oro and Guayas. The main cause for the loss of mangrove cover was the expansion of shrimp farms, followed by agriculture and construction. However, a slight recovery of ~2.9% has been observed, although loss remains constant. Mangrove ecosystem conservation policies, mainly applied to zones within protected areas; the establishment of use and custody agreements and the halt of shrimp farm expansion; the development of mangrove forests on areas with sediment deposits; and natural mangrove recovery processes are key factors for mangrove restoration. These results suggest that it is possible to continue restoring mangrove cover and thus maintain some of the main ecosystem services they provide for the benefit of humans. Full article

(This article belongs to the Special Issue Mangrove Wetland Restoration and Rehabilitation)

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Open AccessEditor’s ChoiceArticle

Seed Dispersal Models for Natural Regeneration: A Review and Prospects

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Forests 2022, 13(5), 659; https://doi.org/10.3390/f13050659 - 23 Apr 2022

Cited by 7 | Viewed by 3128

Abstract

Natural regeneration in forest management, which relies on artificial planting, is considered a desirable alternative to reforestation. However, there are large uncertainties regarding the natural regeneration processes, such as seed production, seed dispersal, and seedling establishment. Among these processes, seed dispersal by wind [...] Read more.

Natural regeneration in forest management, which relies on artificial planting, is considered a desirable alternative to reforestation. However, there are large uncertainties regarding the natural regeneration processes, such as seed production, seed dispersal, and seedling establishment. Among these processes, seed dispersal by wind must be modeled accurately to minimize the risks of natural regeneration. This study aimed to (1) review the main mechanisms of seed dispersal models, their characteristics, and their applications and (2) suggest prospects for seed dispersal models to increase the predictability of natural regeneration. With improving computing and observation systems, the modeling technique for seed dispersal by wind has continued to progress steadily from a simple empirical model to the Eulerian-Lagrangian model. Mechanistic modeling approaches with a dispersal kernel have been widely used and have attempted to be directly incorporated into spatial models. Despite the rapid development of various wind-dispersal models, only a few studies have considered their application in natural regeneration. We identified the potential attributes of seed dispersal modeling that cause high uncertainties and poor simulation results in natural regeneration scenarios: topography, pre-processing of wind data, and various inherent complexities in seed dispersal processes. We suggest that seed dispersal models can be further improved by incorporating (1) seed abscission mechanisms by wind, (2) spatiotemporally complex wind environments, (3) collisions with the canopy or ground during seed flight, and (4) secondary dispersal, long-distance dispersal, and seed predation. Interdisciplinary research linking climatology, biophysics, and forestry would help improve the prediction of seed dispersal and its impact on natural regeneration. Full article

(This article belongs to the Special Issue Ecological Forestry and Restoration)

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Open AccessEditor’s ChoiceArticle

Climate Adaptation, Drought Susceptibility, and Genomic-Informed Predictions of Future Climate Refugia for the Australian Forest Tree Eucalyptus globulus

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Josquin F. G. Tibbits

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Brad M. Potts

Forests 2022, 13(4), 575; https://doi.org/10.3390/f13040575 - 05 Apr 2022

Cited by 2 | Viewed by 1982

Abstract

Understanding the capacity of forest tree species to adapt to climate change is of increasing importance for managing forest genetic resources. Through a genomics approach, we modelled spatial variation in climate adaptation within the Australian temperate forest tree Eucalyptus globulus, identified putative [...] Read more.

Understanding the capacity of forest tree species to adapt to climate change is of increasing importance for managing forest genetic resources. Through a genomics approach, we modelled spatial variation in climate adaptation within the Australian temperate forest tree Eucalyptus globulus, identified putative climate drivers of this genomic variation, and predicted locations of future climate refugia and populations at-risk of future maladaptation. Using 812,158 SNPs across 130 individuals from 30 populations (i.e., localities) spanning the species’ natural range, a gradientForest algorithm found 1177 SNPs associated with locality variation in home-site climate (climate-SNPs), putatively linking them to climate adaptation. Very few climate-SNPs were associated with population-level variation in drought susceptibility, signalling the multi-faceted nature and complexity of climate adaptation. Redundancy analysis (RDA) showed 24% of the climate-SNP variation could be explained by annual precipitation, isothermality, and maximum temperature of the warmest month. Spatial predictions of the RDA climate vectors associated with climate-SNPs allowed mapping of genomically informed climate selective surfaces across the species’ range under contemporary and projected future climates. These surfaces suggest over 50% of the current distribution of E. globulus will be outside the modelled adaptive range by 2070 and at risk of climate maladaptation. Such surfaces present a new integrated approach for natural resource managers to capture adaptive genetic variation and plan translocations in the face of climate change. Full article

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

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Open AccessEditor’s ChoiceArticle

Detecting Coastal Wetland Degradation by Combining Remote Sensing and Hydrologic Modeling

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Forests 2022, 13(3), 411; https://doi.org/10.3390/f13030411 - 03 Mar 2022

Cited by 2 | Viewed by 2980

Abstract

Sea-level rise and climate change stresses pose increasing threats to coastal wetlands that are vital to wildlife habitats, carbon sequestration, water supply, and other ecosystem services with global significance. However, existing studies are limited in individual sites, and large-scale mapping of coastal wetland [...] Read more.

Sea-level rise and climate change stresses pose increasing threats to coastal wetlands that are vital to wildlife habitats, carbon sequestration, water supply, and other ecosystem services with global significance. However, existing studies are limited in individual sites, and large-scale mapping of coastal wetland degradation patterns over a long period is rare. Our study developed a new framework to detect spatial and temporal patterns of coastal wetland degradation by analyzing fine-scale, long-term remotely sensed Normalized Difference Vegetation Index (NDVI) data. Then, this framework was tested to track the degradation of coastal wetlands at the Alligator River National Wildlife Refuge (ARNWR) in North Carolina, United States, during the period from 1995 to 2019. We identified six types of coastal wetland degradation in the study area. Most of the detected degradation was located within 2 km from the shoreline and occurred in the past five years. Further, we used a state-of-the-art coastal hydrologic model, PIHM-Wetland, to investigate key hydrologic processes/variables that control the coastal wetland degradation. The temporal and spatial distributions of simulated coastal flooding and saltwater intrusion confirmed the location and timing of wetland degradation detected by remote sensing. The combined method also quantified the possible critical thresholds of water tables for wetland degradation. The remote sensing–hydrologic model integrated scheme proposed in this study provides a new tool for detecting and understanding coastal wetland degradation mechanisms. Our study approach can also be extended to other coastal wetland regions to understand how climate change and sea-level rise impact wetland transformations. Full article

(This article belongs to the Special Issue Carbon and Water Cycles in Coastal Forests under Climate Change and Variability)

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Open AccessEditor’s ChoiceArticle

Combustion of Aboveground Wood from Live Trees in Megafires, CA, USA

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Mark E. Harmon

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Chad T. Hanson

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Dominick A. DellaSala

Forests 2022, 13(3), 391; https://doi.org/10.3390/f13030391 - 27 Feb 2022

Cited by 3 | Viewed by 4976

Abstract

Biomass combustion is a major biogeochemical process, but uncertain in magnitude. We examined multiple levels of organization (twigs, branches, trees, stands, and landscapes) in large, severe forest fires to see how combustion rates for live aboveground woody parts varied with tree species, size, [...] Read more.

Biomass combustion is a major biogeochemical process, but uncertain in magnitude. We examined multiple levels of organization (twigs, branches, trees, stands, and landscapes) in large, severe forest fires to see how combustion rates for live aboveground woody parts varied with tree species, size, and fire severity in Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and mixed conifer-dominated forests of the Sierra Nevada, California, USA. In high severity fire patches, most combustion loss was from branches < 2 cm diameter; in low to moderate severity patches, most was from bole charring. Combustion rates decreased as fire severity declined and with increasing tree size. Pinus species had little branch combustion, leading them to have ≈50% the combustion rate of other taxa. Combustion rates could be 100% for small branch segments and up to 57% for small tree aboveground woody biomass in high severity fire patches. However, combustion rates are very low overall at the stand (0.1%–3.2%) and landscape level (0.6%–1.8%), because large trees with low combustion rates comprise the majority of biomass, and high severity fire patches are less than half of the area burned. Our findings of low live wood combustion rates have important implications for policies related to wildfire emissions and forest management. Full article

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

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Open AccessEditor’s ChoiceArticle

Fungal and Bacterial Communities in Tuber melanosporum Plantations from Northern Spain

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María Hernández-Rodríguez

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Olaya Mediavilla

Forests 2022, 13(3), 385; https://doi.org/10.3390/f13030385 - 26 Feb 2022

Cited by 2 | Viewed by 3122

Abstract

Tuber melanosporum (Ascomycota, Pezizales) is an ectomycorrhizal fungus that produces highly appreciated hypogeous fruiting bodies called black truffles. The aim of this paper was to research the composition of ectomycorrhiza-associated fungal and bacterial communities in T. melanosporum oak plantations. Results of this paper [...] Read more.

Tuber melanosporum (Ascomycota, Pezizales) is an ectomycorrhizal fungus that produces highly appreciated hypogeous fruiting bodies called black truffles. The aim of this paper was to research the composition of ectomycorrhiza-associated fungal and bacterial communities in T. melanosporum oak plantations. Results of this paper showed the competitive effect of T. melanosporum on other fungal species, especially other mycorrhizal and pathogenic species. T. melanosporum was shown to be associated mainly with bacteria, some of them important for their properties as mycorrhizal helper bacteria. A dendrogram analysis of co-occurrence showed that T. melanosporum tended to co-occur with the following bacteria species: Singulisphaera limicola, Nannocistis excedens and Sporosarcina globispora. In addition, it was linked to fungal species such as Mortierella elongata, M. minutissima, Cryptococcus uzbekistanensis, C. chernovii and C. aerius. This study provides an exhaustive analysis of the diversity, structure and composition of fungal and bacterial communities associated with T. melanosporum to enhance understanding of the biology, composition and role of these communities in truffle plantations. Full article

(This article belongs to the Special Issue Forest Soil–Plant–Microorganisms Interactions)

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Open AccessFeature PaperEditor’s ChoiceArticle

Experimental Characterization of Particulate and Gaseous Emissions from Biomass Burning of Six Mediterranean Species and Litter

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Forests 2022, 13(2), 322; https://doi.org/10.3390/f13020322 - 16 Feb 2022

Cited by 2 | Viewed by 2620

Abstract

Wildfires across the Mediterranean ecosystems are associated with safety concerns due to their emissions. The type of biomass determines the composition of particulate matter (PM) and gaseous compounds emitted during the fire event. This study investigated simulated fire events and analysed biomass samples [...] Read more.

Wildfires across the Mediterranean ecosystems are associated with safety concerns due to their emissions. The type of biomass determines the composition of particulate matter (PM) and gaseous compounds emitted during the fire event. This study investigated simulated fire events and analysed biomass samples of six Mediterranean species and litter in a combustion chamber. The main aims are the characterization of PM realized through scanning electron microscopy (SEM/EDX), the quantification of gaseous emissions through gas chromatography (GC-MS) and, consequently, identification of the species that are potentially more dangerous. For PM, three size fractions were considered (PM10, 2.5 and 1), and their chemical composition was used for particle source-apportionment. For gaseous components, the CO, CO₂, benzene, toluene and xylene (BTXs) emitted were quantified. All samples were described and compared based on their peculiar particulate and gaseous emissions. The primary results show that (a) Acacia saligna was noticeable for the highest number of particles emitted and remarkable values of KCl; (b) tree species were related to the fine windblown particles as canopies intercept PM10 and reemit it during burning; (c) shrub species were related to the particles resuspended from soil; and (d) benzene and toluene were the dominant aromatic compounds emitted. Finally, the most dangerous species identified during burning were Acacia saligna, for the highest number of particles emitted, and Pistacia lentiscus for its high density of particles, the presence of anthropogenic markers, and the highest emissions of all gaseous compounds. Full article

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

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Open AccessEditor’s ChoiceReview

The Potential of Low-Cost 3D Imaging Technologies for Forestry Applications: Setting a Research Agenda for Low-Cost Remote Sensing Inventory Tasks

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Forests 2022, 13(2), 204; https://doi.org/10.3390/f13020204 - 28 Jan 2022

Cited by 9 | Viewed by 2928

Abstract

Limitations with benchmark light detection and ranging (LiDAR) technologies in forestry have prompted the exploration of handheld or wearable low-cost 3D sensors (<2000 USD). These sensors are now being integrated into consumer devices, such as the Apple iPad Pro 2020. This study was [...] Read more.

Limitations with benchmark light detection and ranging (LiDAR) technologies in forestry have prompted the exploration of handheld or wearable low-cost 3D sensors (<2000 USD). These sensors are now being integrated into consumer devices, such as the Apple iPad Pro 2020. This study was aimed at determining future research recommendations to promote the adoption of terrestrial low-cost technologies within forest measurement tasks. We reviewed the current literature surrounding the application of low-cost 3D remote sensing (RS) technologies. We also surveyed forestry professionals to determine what inventory metrics were considered important and/or difficult to capture using conventional methods. The current research focus regarding inventory metrics captured by low-cost sensors aligns with the metrics identified as important by survey respondents. Based on the literature review and survey, a suite of research directions are proposed to democratise the access to and development of low-cost 3D for forestry: (1) the development of methods for integrating standalone colour and depth (RGB-D) sensors into handheld or wearable devices; (2) the development of a sensor-agnostic method for determining the optimal capture procedures with low-cost RS technologies in forestry settings; (3) the development of simultaneous localisation and mapping (SLAM) algorithms designed for forestry environments; and (4) the exploration of plot-scale forestry captures that utilise low-cost devices at both terrestrial and airborne scales. Full article

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

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Open AccessEditor’s ChoiceArticle

Forest Structure and Composition Are Critical to Hurricane Mortality

by

Jiaying Zhang

,

Tamara Heartsill-Scalley

and

Rafael L. Bras

Forests 2022, 13(2), 202; https://doi.org/10.3390/f13020202 - 28 Jan 2022

Cited by 5 | Viewed by 2346

Abstract

Hurricanes can cause severe damage to tropical forests. To understand the nature of hurricane impacts, we analyze and compare immediate effects from category-4 hurricane María in 2017 and category-3 hurricane Hugo in 1989 at Bisley Experimental Watersheds (BEW) in the Luquillo Experimental Forest, [...] Read more.

Hurricanes can cause severe damage to tropical forests. To understand the nature of hurricane impacts, we analyze and compare immediate effects from category-4 hurricane María in 2017 and category-3 hurricane Hugo in 1989 at Bisley Experimental Watersheds (BEW) in the Luquillo Experimental Forest, Puerto Rico. We show that hurricane María caused lower mortality than hurricane Hugo, even though hurricane María was a stronger event with higher sustained wind. The lower mortality was due to the combination of lower accumulated cyclone energy at the site and more wind-resistant forest structure and composition at the time of disturbance. We compare our study site with a nearby location that has the same forest type, Luquillo Forest Dynamics Plot (LFDP), and describe the similarities and differences of mortality and impact factors between the two sites during the two events. During hurricane Hugo, LFDP experienced much lower mortality than BEW, even though the accumulated cyclone energy at LFDP was higher. The difference in mortality was due to contrasting forest structure and composition of the two sites. Our results demonstrate that forest structure and composition at the time of the disturbance were more critical to hurricane-induced mortality at the two sites than accumulated cyclone energy. Full article

(This article belongs to the Section Natural Hazards and Risk Management)

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Open AccessFeature PaperEditor’s ChoiceArticle

Restoration Trajectories and Ecological Thresholds during Planted Urban Forest Successional Development

by

K. J. Wallace

,

Bruce D. Clarkson

and

Bridgette Farnworth

Forests 2022, 13(2), 199; https://doi.org/10.3390/f13020199 - 27 Jan 2022

Cited by 4 | Viewed by 3335

Abstract

Successfully reconstructing functioning forest ecosystems from early-successional tree plantings is a long-term process that often lacks monitoring. Many projects lack observations of critical successional information, such as the restoration trajectory of key ecosystem attributes and ecological thresholds, which signal that management actions are [...] Read more.

Successfully reconstructing functioning forest ecosystems from early-successional tree plantings is a long-term process that often lacks monitoring. Many projects lack observations of critical successional information, such as the restoration trajectory of key ecosystem attributes and ecological thresholds, which signal that management actions are needed. Here, we present results from a 65 ha urban temperate rainforest restoration project in Aotearoa New Zealand, where trees have been planted annually on public retired pasture land, forming a 14 years chronosequence. In 25 plots (100 m² each), we measured key ecosystem attributes that typically change during forest succession: native tree basal area, canopy openness, non-native herbaceous ground cover, leaf litter cover, ground fern cover, dead trees, and native tree seedling abundance and richness. We also monitored for the appearance of physiologically-sensitive plant guilds (moss, ferns, and epiphytes) that may be considered ecological indicators of succession. Linear regression models identified relationships between all but one of the key ecosystem attributes and forest age (years since planting). Further, using breakpoint analysis, we found that ecological thresholds occurred in many ecosystem attributes during their restoration trajectories: reduced canopy openness (99.8% to 3.4%; 9.6 years threshold), non-native herbaceous ground cover (100% to 0; 10.9 years threshold), leaf litter cover (0 to 95%; 10.8 years threshold), and increased tree deaths (0 to 4; 11 years threshold). Further, juvenile native plant recruitment increased (tree seedling abundance 0 to ~150 per 4 m²), tree seedling species richness (0 to 13 per 100 m²) and epiphytes colonized (0 to 3 individuals per 100 m²). These and other physiologically-sensitive plant guilds appeared around the 11 years mark, confirming their utility as ecological indicators during monitoring. Our results indicate that measurable, ecological thresholds occur during the restoration trajectories of ecosystem attributes, and they are predictable. If detected, these thresholds can inform project timelines and, along with use of ecological indicators, inform management interventions. Full article

(This article belongs to the Special Issue Urban Forestry and Ecological Restoration)

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Open AccessEditor’s ChoiceArticle

Upward Treeline Shifts in Two Regions of Subarctic Russia Are Governed by Summer Thermal and Winter Snow Conditions

by

,

,

,

,

Vladimir V. Kukarskikh

,

Arina A. Vyukhina

,

Jesús Julio Camarero

and

Pavel A. Moiseev

Forests 2022, 13(2), 174; https://doi.org/10.3390/f13020174 - 24 Jan 2022

Cited by 4 | Viewed by 2375

Abstract

Climate warming impacts on alpine treeline dynamics. However, we still lack robust assessments of the long-term impacts of climate on tree recruitment at the treeline, particularly in remote areas such as the subarctic regions of Russia subjected to different climate influences. We expected [...] Read more.

Climate warming impacts on alpine treeline dynamics. However, we still lack robust assessments of the long-term impacts of climate on tree recruitment at the treeline, particularly in remote areas such as the subarctic regions of Russia subjected to different climate influences. We expected that the treelines in two regions may have different features and dynamics patterns. We analyzed climate variables and assessed treeline dynamics by quantifying recruitment using the tree rings of ca. 7000 trees of four species (Betula pubescens Ehrh. ssp. tortuosa, Pinus sylvestris L., Picea abies Ledeb. ssp. obovata, Larix gmelinii Rupr.) along 14 altitudinal transects (series of study plots). We compared the Khibiny Massif (Kola Peninsula) and the western Putorana Plateau, subjected to oceanic and continental influences, respectively. In both regions, summers became warmer, and winters became snowier during the past century. At the low part of the treeline ecotone, tree recruitment has slowly increased since the mid-18th century at the Putorana Plateau and the mid-19th century at the Khibiny but accelerated in the early 20th century at both regions and reached a maximum peak in the second half of the past century. Treeline encroachment intensified in the 1930s at the Khibiny and the 1950s at the Putorana Plateau. Trees encroached in the tundra leading to upward treeline shifts in the late 20th century. The slope exposure affected the rates of treeline shift with higher upward advances on southern-oriented slopes. Tree recruitment and early-winter precipitation were positively correlated. The differences in species composition, treeline altitude and influences of slope orientation on treeline dynamics can be explained primarily by differences in the degree of continentality. The abundance of saplings in both regions allows the future encroachment of trees into tundra and further treeline upward shifts to be forecast. Full article

(This article belongs to the Special Issue The Impact of Climate Change on Alpine Treelines and Vegetation Dynamics)

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Open AccessEditor’s ChoiceArticle

Development and Validation of a 36K SNP Array for Radiata Pine (Pinus radiata D.Don)

by

,

,

,

,

,

and

Forests 2022, 13(2), 176; https://doi.org/10.3390/f13020176 - 24 Jan 2022

Cited by 4 | Viewed by 2423

Abstract

Radiata pine (Pinus radiata D.Don) is one of the world’s most domesticated pines and a key economic species in New Zealand. Thus, the development of genomic resources for radiata pine has been a high priority for both research and commercial breeding. Leveraging [...] Read more.

Radiata pine (Pinus radiata D.Don) is one of the world’s most domesticated pines and a key economic species in New Zealand. Thus, the development of genomic resources for radiata pine has been a high priority for both research and commercial breeding. Leveraging off a previously developed exome capture panel, we tested the performance of 438,744 single nucleotide polymorphisms (SNPs) on a screening array (NZPRAD01) and then selected 36,285 SNPs for a final genotyping array (NZPRAD02). These SNPs aligned to 15,372 scaffolds from the Pinus taeda L. v. 1.01e assembly, and 20,039 contigs from the radiata pine transcriptome assembly. The genotyping array was tested on more than 8000 samples, including material from archival progenitors, current breeding trials, nursery material, clonal lines, and material from Australia. Our analyses indicate that the array is performing well, with sample call rates greater than 98% and a sample reproducibility of 99.9%. Genotyping in two linkage mapping families indicated that the SNPs are well distributed across the 12 linkage groups. Using genotypic data from this array, we were also able to differentiate representatives of the five recognized provenances of radiata pine, Año Nuevo, Monterey, Cambria, Cedros and Guadalupe. Furthermore, principal component analysis of genotyped trees revealed clear patterns of population structure, with the primary axis of variation driven by provenance ancestry and the secondary axis reflecting breeding activities. This represents the first commercial use of genomics in a radiata pine breeding program. Full article

(This article belongs to the Special Issue Using Genomic Information in Forest Tree Breeding, Restoration, and Conservation: Separating Hype from Reality)

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Open AccessFeature PaperEditor’s ChoiceReview

Impacts of Climate Change on Blue Carbon Stocks and Fluxes in Mangrove Forests

by

Daniel Michael Alongi

Forests 2022, 13(2), 149; https://doi.org/10.3390/f13020149 - 19 Jan 2022

Cited by 11 | Viewed by 4807

Abstract

Mangroves store blue carbon (693 Mg C_ORG ha⁻¹) disproportionate to their small area, mainly (74%) in deep soil horizons. Global stock estimates for mangroves (5.23–8.63 Pg C_ORG) are equivalent to 15–24% of those in the tropical coastal ocean. [...] Read more.

Mangroves store blue carbon (693 Mg C_ORG ha⁻¹) disproportionate to their small area, mainly (74%) in deep soil horizons. Global stock estimates for mangroves (5.23–8.63 Pg C_ORG) are equivalent to 15–24% of those in the tropical coastal ocean. Carbon burial in mangrove soils averages 184 g C_ORG m⁻² a⁻¹ with global estimates (9.6–15.8 Tg C_ORG a⁻¹) reflecting their importance in carbon sequestration. Extreme weather events result in carbon stock losses and declines in carbon cycling and export. Increased frequency and ferocity of storms result in increasingly negative responses with increasing strength. Increasing temperatures result in increases in carbon stocks and cycling up to a critical threshold, while positive/negative responses will likely result from increases/decreases in rainfall. Forest responses to sea-level rise (SLR) and rising CO₂ are species- and site-specific and complex due to interactive effects with other drivers (e.g., temperature, salinity). The SLR critical threshold is ≈ 6 mm a⁻¹ indicating survival only under very low-low CO₂ emissions scenarios. Under low coastal squeeze, landward migration could result in sequestration and CO₂ losses of 1.5 and −1.1 Pg C with net stock gains and losses (−0.3 to +0.5 Pg C) and CO₂ losses (−3.4 Pg) under high coastal squeeze. Full article

(This article belongs to the Special Issue Carbon and Water Cycles in Coastal Forests under Climate Change and Variability)

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