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Forests, Volume 11, Issue 7 (July 2020) – 44 articles

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Open AccessReview
Expandable Graphite as a Fire Retardant for Cellulosic Materials—A Review
Forests 2020, 11(7), 755; https://doi.org/10.3390/f11070755 (registering DOI) - 13 Jul 2020
Abstract
A diversity of chemicals is used to produce fire retardants (FRs); some of the main group of chemicals are hazardous to the environment as well as to human life; however, expandable graphite (EG) can be a gateway to a more environmentally friendly FRs [...] Read more.
A diversity of chemicals is used to produce fire retardants (FRs); some of the main group of chemicals are hazardous to the environment as well as to human life; however, expandable graphite (EG) can be a gateway to a more environmentally friendly FRs or intumescent fire retardants (IFRs). Researchers define intumescent as the swelling of a particular substance placed between a heat source and an underlying substrate when they are heated. EG is a material with extraordinary thermophysical and mechanical properties. The referred EG properties are unparalleled. EG is a low-density carbon material having a series of unique properties: developed specific surface, binder-free pressing capacity, stability to aggressive media, and low thermal conductivity. Therefore, EG is a promising material both for research work and for industrial applications. The primary goal of this literature review was to report current knowledge on the use of EG as a fire retardant for cellulose and cellulose-modified materials. EG is produced, among other methods, by thermal shock of graphite oxide under forming gas. When exposed to heat, EG will expand. The expansion mechanism was presented in this review. Equally important to this review is the knowledge related to cellulose thermal degradation and cellulose impact on the development of science and technology. Full article
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Open AccessArticle
Form Factors of an Economically Valuable Sal Tree (Shorea robusta) of Nepal
Forests 2020, 11(7), 754; https://doi.org/10.3390/f11070754 (registering DOI) - 13 Jul 2020
Viewed by 54
Abstract
The accurate prediction of the volume of standing trees is a prerequisite for planning and decision making in sustainable forest management. In Nepal, limited information on form factor (i.e. the ratio of the volume of a tree to the product of its basal [...] Read more.
The accurate prediction of the volume of standing trees is a prerequisite for planning and decision making in sustainable forest management. In Nepal, limited information on form factor (i.e. the ratio of the volume of a tree to the product of its basal area and height) is available for economically important tree species. Thus, current management plans consider a simple approximation for all species irrespective of their height and diameter, which hampers the estimation of a sustainable harvest rate. Therefore, this study elaborates the form factor for Sal (Shorea robusta), an economically valuable tree of Nepal based on a random selection of 100 individual trees representing a wide range of diameters between 10 and 100 cm. Diameter and bark thickness were measured at every 1-meter interval of the length of the stem and branches until the diameter reached 10 cm. The analysis allowed for the estimation of an average form factor for Sal wood with 0.407 over bark and 0.336 under bark, while the form factor for the stem was 0.335 over bark and 0.281 under bark. The results indicate an increasing form factor until 70 cm diameter and a decreasing value for larger diameters, because of the large crowns of the mature Sal trees. We conclude that the default form factor of Sal (0.5) used in management planning results in an overestimation of standing tree volume. Using form factor according to diameter classes will allow a more accurate prediction of the standing volume. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Challenges and Solutions for Non-Timber Forest Product Businesses in FINLAND–An Application of the SODA Analysis
Forests 2020, 11(7), 753; https://doi.org/10.3390/f11070753 (registering DOI) - 12 Jul 2020
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Abstract
This study aims to present a holistic image of the strategic development needs and potential solutions within the Finnish non-timber forest product (NTFP) business sector and demonstrate a new hybrid methodology for collaborative strategy formulation. The perceived challenges and solutions were collected with [...] Read more.
This study aims to present a holistic image of the strategic development needs and potential solutions within the Finnish non-timber forest product (NTFP) business sector and demonstrate a new hybrid methodology for collaborative strategy formulation. The perceived challenges and solutions were collected with the 635 group-working method in a nationwide series of NTFP actor workshops. The analysis applied the Strategic Option Development and Analysis (SODA) approach and the formal network analysis. Business actors emphasised two complex and interrelated aims of development at the core of the business activity: (1) to improve the profitability of the NTFP business and (2) to facilitate the growth of the sector. The present bottleneck is perceived in the raw material acquisition and productising, and many wider development themes, such as business logic and sustainability, received little attention. Full article
(This article belongs to the Section Forest Economics and Human Dimensions)
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Open AccessArticle
Machinability Research of the Most Common Invasive Tree Species in Slovenia
Forests 2020, 11(7), 752; https://doi.org/10.3390/f11070752 (registering DOI) - 12 Jul 2020
Viewed by 177
Abstract
This article investigates the quality of the machining surface of the five most common invasive tree species in Slovenia, i.e., black locust (Robinia pseudoacacia L.), boxelder maple (Acer negundo L.), horse chestnut (Aesculus hippocastanum), honey locust (Gleditsia triacanthos [...] Read more.
This article investigates the quality of the machining surface of the five most common invasive tree species in Slovenia, i.e., black locust (Robinia pseudoacacia L.), boxelder maple (Acer negundo L.), horse chestnut (Aesculus hippocastanum), honey locust (Gleditsia triacanthos) and tree of heaven (Ailanthus altissima). The machining tests were made according to the American Society for Testing and Materials (ASTM) D1666-17 standard, where the quality of the surfaces after planing, routing and turning were evaluated with visual assessment, and the area and profile roughness parameters were also determined on selected specimens. The results showed that boxelder maple, horse chestnut and honey locust can be machined very well in all the studied operations, with the best results in routing and a little less good by turning, whereas the tree of heaven had the best quality in planing, and the worst by turning. Among all studied tree species, the black locust had the worst quality in planing, but the quality at routing was very similar to other tested species. The research also showed that there is little or no significant relationship between the qualities of the various types of machining for tested tree species. Full article
(This article belongs to the Special Issue Performance of Wood and Wood-Based Materials)
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Open AccessArticle
Determinants of Bilateral REDD+ Cooperation Recipients in Kyoto Protocol Regime and Their Implications in Paris Agreement Regime
Forests 2020, 11(7), 751; https://doi.org/10.3390/f11070751 (registering DOI) - 12 Jul 2020
Viewed by 207
Abstract
A cooperative approach for REDD+ between developing and developed countries can be a sound means to achieve national and global mitigation targets. To accomplish the Nationally Determined Contribution (NDC) of countries and the global 2 °C climate target more effectively, it is necessary [...] Read more.
A cooperative approach for REDD+ between developing and developed countries can be a sound means to achieve national and global mitigation targets. To accomplish the Nationally Determined Contribution (NDC) of countries and the global 2 °C climate target more effectively, it is necessary to explore the coordination options, based on the understanding of bilateral REDD+ cooperation. This study explains the current status of bilateral REDD+ cooperation and investigates determinants affecting REDD+ recipient decisions of donor countries, by analyzing bilateral REDD+ arrangements, which has been promoted for 10 years under the the Kyoto Protocol regime from 2006 until 2015. The results show that Norway and Japan supported more than half of the total financial pledges for bilateral REDD+ projects for 10 years. Out of 87 REDD+ recipients, four countries—Brazil, India, Indonesia, and China—accounted for more than half of the 10-year financial pledges. Approximately 78% of total financing was found to be concentrated in the top 10 recipients. The aid darlings and orphans problem, the concentration of bilateral supports in a few developing countries and the exclusion of several developing countries from the recipient selection process, which has been discussed in ODA researches, was also observed. Applying a shared frailty model, recipient need, recipient merit, and donor interest was found to be the main determinants of donors’ REDD+ recipient decision. Donor interest and recipient merit were found to have more significant effects on the decision than recipient need. A balanced two-track approach is further required, in which, along with the bilateral REDD+ cooperation in the REDD+ darling countries, international organizations and multilateral funds for REDD+ need to increase financial accessibility, including the result-based compensation system for the REDD+ orphan countries. Full article
(This article belongs to the Section Forest Economics and Human Dimensions)
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Open AccessArticle
Quantifying Land Cover Changes in a Mediterranean Environment Using Landsat TM and Support Vector Machines
Forests 2020, 11(7), 750; https://doi.org/10.3390/f11070750 (registering DOI) - 11 Jul 2020
Viewed by 173
Abstract
The rapid advent in geoinformation technologies, such as Earth Observation (EO) and Geographical Information Systems (GIS), has made it possible to observe and monitor the Earth’s environment on variable geographical scales and analyze those changes in both time and space. This study explores [...] Read more.
The rapid advent in geoinformation technologies, such as Earth Observation (EO) and Geographical Information Systems (GIS), has made it possible to observe and monitor the Earth’s environment on variable geographical scales and analyze those changes in both time and space. This study explores the synergistic use of Landsat EO imagery and Support Vector Machines (SVMs) in obtaining Land Use/Land Cover (LULC) mapping and quantifying its spatio-temporal changes for the municipality of Mandra–Idyllia, Attica Region, Greece. The study area is representative of typical Mediterranean landscape in terms of physical structure and coverage of species composition. Landsat TM (Thematic Mapper) images from 1993, 2001 and 2010 were acquired, pre-processed and classified using the SVMs classifier. A total of nine basic classes were established. Eight spectral band ratios were created in order to incorporate them in the initial variables of the image. For validating the classification, in-situ data were collected for each LULC type during several field surveys that were conducted in the area. The overall classification accuracy for 1993, 2001 and 2010 Landsat images was reported as 89.85%, 91.01% and 90.24%, respectively, and with a statistical factor (K) of 0.96, 0.89 and 0.99, respectively. The classification results showed that the total extent of forests within the studied period represents the predominant LULC, despite the intense human presence and its impacts. A marginal change happened in the forest cover from 1993 to 2010, although mixed forest decreased significantly during the studied period. This information is very important for future management of the natural resources in the studied area and for understanding the pressures of the anthropogenic activities on the natural environment. All in all, the present study demonstrated the considerable promise towards the support of geoinformation technologies in sustainable environmental development and prudent resource management. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle
Detecting Vegetation Recovery after Fire in A Fire-Frequented Habitat Using Normalized Difference Vegetation Index (NDVI)
Forests 2020, 11(7), 749; https://doi.org/10.3390/f11070749 (registering DOI) - 10 Jul 2020
Viewed by 181
Abstract
Research Highlights: Fire-frequented savannas are dominated by plant species that regrow quickly following fires that mainly burn through the understory. To detect post-fire vegetation recovery in these ecosystems, particularly during warm, rainy seasons, data are needed on a small, temporal scale. In the [...] Read more.
Research Highlights: Fire-frequented savannas are dominated by plant species that regrow quickly following fires that mainly burn through the understory. To detect post-fire vegetation recovery in these ecosystems, particularly during warm, rainy seasons, data are needed on a small, temporal scale. In the past, the measurement of vegetation regrowth in fire-frequented systems has been labor-intensive, but with the availability of daily satellite imagery, it should be possible to easily determine vegetation recovery on a small timescale using Normalized Difference Vegetation Index (NDVI) in ecosystems with a sparse overstory. Background and Objectives: We explore whether it is possible to use NDVI calculated from satellite imagery to detect time-to-vegetation recovery. Additionally, we determine the time-to-vegetation recovery after fires in different seasons. This represents one of very few studies that have used satellite imagery to examine vegetation recovery after fire in southeastern U.S.A. pine savannas. We test the efficacy of using this method by examining whether there are detectable differences between time-to-vegetation recovery in subtropical savannas burned during different seasons. Materials and Methods: NDVI was calculated from satellite imagery approximately monthly over two years in a subtropical savanna with units burned during dry, dormant and wet, growing seasons. Results: Despite the availability of daily satellite images, we were unable to precisely determine when vegetation recovered, because clouds frequently obscured our range of interest. We found that, in general, vegetation recovered in less time after fire during the wet, growing, as compared to dry, dormant, season, albeit there were some discrepancies in our results. Although these general patterns were clear, variation in fire heterogeneity and canopy type and cover skewed NDVI in some units. Conclusions: Although there are some challenges to using satellite-derived NDVI, the availability of satellite imagery continues to improve on both temporal and spatial scales, which should allow us to continue finding new and efficient ways to monitor and model forests in the future. Full article
(This article belongs to the Special Issue Remote Sensing of Forest Disturbance and Recovery)
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Open AccessArticle
Mediterranean Heathland as a Key Habitat for Fire Adaptations: Evidence from an Experimental Approach
Forests 2020, 11(7), 748; https://doi.org/10.3390/f11070748 - 10 Jul 2020
Viewed by 156
Abstract
Some fire ecology studies that have focused on garrigue-like vegetation suggest a weak selective pressure of fire in the Mediterranean Basin compared to other Mediterranean-type regions. However, fire-prone Mediterranean heathland from the western end of the Mediterranean Basin has been frequently ignored [...] Read more.
Some fire ecology studies that have focused on garrigue-like vegetation suggest a weak selective pressure of fire in the Mediterranean Basin compared to other Mediterranean-type regions. However, fire-prone Mediterranean heathland from the western end of the Mediterranean Basin has been frequently ignored in the fire ecology literature despite its high proportion of pyrogenic species. Here, we explore the evolutionary ecology of seed traits in the generalist rockrose Cistus salviifolius L. (Cistaceae) aiming to ascertain the role of the Mediterranean heathland for fire adaptations in the Mediterranean Region. We performed a germination experiment to compare the relationship of seed size to (i) heat-stimulated germination, (ii) dormancy strength, and (iii) heat survival in plants from ‘high-fire’ heathland vs. ‘low-fire’ coastal shrubland. Germination after heat-shock treatment was higher in large seeds of both ‘high-fire’ and ‘low-fire’ habitats. However, dormancy was weaker in small seeds from ‘low-fire’ habitats. Finally, seed survival to heat shock was positively related to seed size. Our results support that seed size is an adaptive trait to fire in C. salviifolius, since larger seeds had stronger dormancy, higher heat-stimulated germination and were more resistant to heat shock. This seed size–fire relationship was tighter in ‘high-fire’ Mediterranean heathland than ‘low-fire’ coastal shrubland, indicating the existence of differential fire pressures and evolutionary trends at the landscape scale. These findings highlight the Mediterranean heathland as a relevant habitat for fire-driven evolution, thus contributing to better understand the role of fire in plant evolution within the Mediterranean region. Full article
(This article belongs to the Special Issue From Traits to Rates: Fire Effects on Plant Evolution)
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Open AccessArticle
The Agroforestry Heritage System of Sabana De Morro in El Salvador
Forests 2020, 11(7), 747; https://doi.org/10.3390/f11070747 - 09 Jul 2020
Viewed by 286
Abstract
Traditional agroforestry systems are recognized as having great importance for providing multiple benefits for local communities all over the world, especially in tropical countries. Thanks to their multifunctional role, they can support small farmers, contribute to hydrogeological risk reduction, water regulation, preservation of [...] Read more.
Traditional agroforestry systems are recognized as having great importance for providing multiple benefits for local communities all over the world, especially in tropical countries. Thanks to their multifunctional role, they can support small farmers, contribute to hydrogeological risk reduction, water regulation, preservation of soil, agrobiodiversity and landscape, as well as being examples of mitigation and adaptation towards climate change. The Globally Important Agricultural Heritage Systems (GIAHS) programme of the Food and Agriculture Organization (FAO) aims to identify agricultural systems of global importance, preserving landscape, agrobiodiversity and traditional knowledge, through dynamic conservation principles. The Sabana de Morro is a traditional agroforestry system located in El Salvador based on cattle grazing in pastures with the presence of Crescentia alata and Crescentia cujete trees, locally called Morro or Jícaro. We documented the main characteristics of this system, that has never been deeply studied, in the Municipality of Dolores, in accordance with the five GIAHS criteria, and through detailed land use mapping, to assess the relations between landscape structure, agrobiodiversity and traditional silvopastoral practices. Sabana de Morro proved to be based on strong interactions between trees, cattle and farmers. The pulp of the Morro fruits is eaten by grazing cattle, completing their feeding and giving a peculiar taste to the locally produced cheese. Morro trees provide shade for the animals while cattle contribute by spreading their seeds that also take advantage of the manure. Results show that this agroforestry system contributes to the preservation of a rich agrobiodiversity and of the traditional landscape. At the same time, it supports local farmers’ livelihood and is consistent with the aim of the GIAHS programme, even if further surveys and research are needed to assess the real possibility of the inclusion in this FAO programme. Full article
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Open AccessArticle
Evaluation of Environmental Impact on Selected Properties of Lime (Tilia Cordata Mill.) Wood
Forests 2020, 11(7), 746; https://doi.org/10.3390/f11070746 - 09 Jul 2020
Viewed by 276
Abstract
The external and internal factors in the tree development process affect wooden structures and properties. They depend on, for example, a plant species, its age, part and growth conditions. The present study investigated the chemical structure and physical properties of the common urban [...] Read more.
The external and internal factors in the tree development process affect wooden structures and properties. They depend on, for example, a plant species, its age, part and growth conditions. The present study investigated the chemical structure and physical properties of the common urban tree species: small-leaved lime (Tilia cordata Mill.). The properties of trees growing in an urban agglomeration, by a roadside and in a forest, i.e., areas varying in degrees of an environmental stress impact, were compared. Tree-ring width and density, selected hygroscopic properties (sorption hysteresis and isotherms), wood chemical content (percentage content of: holocellulose, cellulose, pentosanes, lignin and substances soluble in 1% NaOH and EtOH) as well as the content of selected chemical elements (Fe, Zn, Cu, Pb, Cd, K, Na, Mg and Ca) were studied. The analysis of the case shows no impact of the environmental stress on the growth patterns characterized by ring width index (RWI). Two-factor analysis of variance (ANOVA) revealed impact significance of growth environment and cambial age on the content of each of the investigated components and chemical elements. There was a relationship demonstrated that for a tree growing in an agglomeration with the highest environmental stress the content of cellulose and lignin was the lowest, whereas the content of substances soluble in NaOH and EtOH was the highest. For mature wood growing under the same conditions, the results corresponded to the highest Zn, Cu, K, Na, Mg and Ca content. It was also shown that the environmental stress affected hygroscopicity which was the consequence of chemical component percentage content. The research proved that Tilia cordata Mill. responded to environmental stress with alternations in its chemical or/and physical properties. Full article
(This article belongs to the Section Wood Science)
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Open AccessArticle
Norway Spruce Survival Rate in Two Forested Landscapes, 1975–2016
Forests 2020, 11(7), 745; https://doi.org/10.3390/f11070745 - 09 Jul 2020
Viewed by 241
Abstract
The increasing frequency and severity of natural disturbances (e.g., storms and insect outbreaks) due to climate change are expected to reduce the abundance of Norway spruce stands in the European forests. Under such conditions, the assessment of status quo on focusing on survival [...] Read more.
The increasing frequency and severity of natural disturbances (e.g., storms and insect outbreaks) due to climate change are expected to reduce the abundance of Norway spruce stands in the European forests. Under such conditions, the assessment of status quo on focusing on survival of Norway spruce stands are essential for the agility of forest management strategies. The dynamics (mortality rate) of Norway spruce stands in hemiboreal forests based on forest inventories for the period from 1975 to 2016 (inventories of 1975, 1985, 1999, 2011 and 2016) were analyzed in two forest landscapes in the western and eastern parts of Latvia (Vane and Dviete, respectively). The spatiotemporal changes in age-dependent mortality differing by abundance of Norway spruce and disturbance regime were assessed, focusing on the transitions of stands between age groups (inventories). The age-related changes in probability of stands transitioning into the next age group contrasted (p < 0.001) between sites. In Vane, the survival of stands between inventories was constant (ca. 90%), while in Dviete, it decreased sharply from 85.7% during 1985–1999 inventories to 49.3% in 2011–2016. Age-related decreases in stand survival showed local dependencies between both landscapes, namely, in Vane, notable decreases started from 61 years, while in Dviete, the downward trends started already from 31 years, probably due to different disturbance regimes. This suggests that, in forest management planning, the different outcomes for mortality patterns between both landscapes must be considered and should not be generalized for a whole country. Full article
(This article belongs to the Special Issue Natural Disturbance Dynamics Analysis for Forest Ecosystem Management)
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Open AccessArticle
Using Mixed Integer Goal Programming in Final Yield Harvest Planning: A Case Study from the Mediterranean Region of Turkey
Forests 2020, 11(7), 744; https://doi.org/10.3390/f11070744 - 09 Jul 2020
Viewed by 241
Abstract
A mixed integer goal programming model is developed to address the regeneration planning problems of even-aged forests in the Mediterranean region of Turkey. The unique aspect of the goal programming formulation is to minimize deviations in scheduled wood product volumes and the size [...] Read more.
A mixed integer goal programming model is developed to address the regeneration planning problems of even-aged forests in the Mediterranean region of Turkey. The unique aspect of the goal programming formulation is to minimize deviations in scheduled wood product volumes and the size of harvest areas within each time period, as these are important goals for the management area. About 98% of the forests in Turkey are considered even-aged, and 2% are uneven-aged. Therefore, an age class method is used for the planning of even-aged forests. For the areas where this method is applied, reaching the optimal age class structure is the first priority. This involves implementing final harvests (clearcuts) to regenerate an amount of forest area into each age class. To meet the local market’s needs, forest enterprises also require the final yield to be fairly equal each year. Further, it is desired that the harvest area (regeneration area) is relatively equal each year, to address operational considerations. A linear goal programming model is developed to address the problem. The minimization of deviations from both the harvest area and harvest volume targets are incorporated as goals in the objective function of the model. Several scenarios are solved using the extended version of Lingo 16. A scenario with weights of 0.8 for area and 0.2 for volume produces the best results. Here, the total deviation for 20 years is 3.8 ha in area and 2889 m3 in volume. In the actual regeneration plan, the area deviation for 10 years is 54.72 ha (6.2% of total regeneration area), and the volume deviation is 20,472 m3 (9.8% of harvest volume). The model described through this study can be developed further and integrated into forest management planning software and processes used for the planning of even-aged forests in the Mediterranean region. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Effect of Day or Night and Cumulative Shift Time on the Frequency of Tree Damage during CTL Harvesting in Various Stand Conditions
Forests 2020, 11(7), 743; https://doi.org/10.3390/f11070743 - 08 Jul 2020
Viewed by 135
Abstract
Thinning is one of the most important tools of forest management, although thinning operations require the use of machines which ultimately cause damage to the remaining stand. The level of damage largely depends on the human factor, and a tired, less focused operator [...] Read more.
Thinning is one of the most important tools of forest management, although thinning operations require the use of machines which ultimately cause damage to the remaining stand. The level of damage largely depends on the human factor, and a tired, less focused operator will create more injuries in the forest. With this in mind, the objectives of this research were to find out whether the probability of tree damage caused by an operator is also affected by: (1) the part of the day (dawn/day/dusk/night), and (2) the cumulative shift time. The research was carried out in pure pine stands of different ages, density and thinning intensities. Sample plots were selected that had an increasing number of trees per hectare and growing thinning intensities were applied. The same Komatsu 931.1 harvester was used for the thinning operations in each stand. In all the age classes combined, 5.41% of the remaining trees were wounded. There was a significant influence of the part of the day on the percentage of damaged trees, which was positively correlated with the cumulative shift time. Stand conditions, such as age class and stand density, as well as thinning characteristics—thinning intensity, number of harvested trees and productivity—have different effects on the distribution of damage intensity and on probability. The results may improve the planning of operators’ work shifts in forests of various ages and densities, allowing harvester productivity to be maintained while at the same time inflicting the lowest possible level of damage. Full article
(This article belongs to the Section Wood Science)
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Open AccessArticle
Assessing Post-Harvest Regeneration in Northern Hardwood and Mixedwood Stands: Evolution of Species Composition and Dominance within 15-Year-Old Group Selection and Patch Cutting
Forests 2020, 11(7), 742; https://doi.org/10.3390/f11070742 - 08 Jul 2020
Viewed by 128
Abstract
Multi-cohort forest management in northern hardwood stands may well be the best way to successfully regenerate tree species of intermediate shade tolerance, such as yellow birch (Betula alleghaniensis Britt.). The creation of large enough gaps in the canopy favors increased light availability [...] Read more.
Multi-cohort forest management in northern hardwood stands may well be the best way to successfully regenerate tree species of intermediate shade tolerance, such as yellow birch (Betula alleghaniensis Britt.). The creation of large enough gaps in the canopy favors increased light availability within the opening, while soil scarification provides suitable germination seedbeds. Evidence of these methods’ success nonetheless remains mostly the purview of experimental studies rather than operational tests. In Quebec, Canada, the multi-cohort methods promoted include group selection cutting and patch cutting. The present study tested their implementation at an operational scale and over a large territory in both hardwood-dominated and mixedwood stands. We assessed their efficacy in promoting natural regeneration of commercial hardwood trees, notably yellow birch and sugar maple (Acer saccharum Marsh.). We conducted regeneration surveys at 2, 5, 10, and 15 years after harvest. Overall, group selection and patch cuttings were successful in regenerating the target species. Yellow birch, for instance, showed a mean stocking around 60% and a mean sapling density around 3400 stems ha1 after 15 years. We compared several variables for measuring regeneration in early years, and found that the relative abundance, the stocking based on one stem per sampling unit, and the mean maximum height were good predictors of the relative presence of yellow birch and sugar maple in 15-year-old canopy openings. Using smaller sampling units (6.25 m2 rather than 25 m2) and waiting until year 5 may be more useful for making such predictions. In addition, there was an important turnover in vertical dominance in these openings. Non-commercial woody competitors were frequently dominant in early years but were often replaced by commercial hardwoods, notably yellow birch. We propose certain thresholds for assessing the success of post-harvest regeneration and for evaluating the need for a cleaning treatment. Full article
(This article belongs to the Section Forest Ecology and Management)
Open AccessArticle
Natural Regeneration Following Partial and Clear-Cut Harvesting in Mature Aspen-Jack Pine Stands in Eastern Canada
Forests 2020, 11(7), 741; https://doi.org/10.3390/f11070741 - 08 Jul 2020
Viewed by 167
Abstract
Over the last three decades, the ecological basis for the generalized use of even-aged silviculture in boreal forests has been increasingly challenged. In boreal mixed-wood landscapes, the diminishing proportion of conifers, to the benefit of intolerant hardwoods, has been a primary concern, coupled [...] Read more.
Over the last three decades, the ecological basis for the generalized use of even-aged silviculture in boreal forests has been increasingly challenged. In boreal mixed-wood landscapes, the diminishing proportion of conifers, to the benefit of intolerant hardwoods, has been a primary concern, coupled with the general rarefication of old-growth conifer-dominated stands. In this context, partial cutting, extended rotations and forest renewal techniques that eliminate or reduce regenerating hardwoods have been proposed as means of regaining greater conifer cover. As a result, experimentation and industrial application of various forms of both variable retention and partial harvesting are occurring across the commercial Canadian boreal forest. In this study, we compared the effects of two harvesting intensities, clearcutting and low-intensity partial cutting (removal of 25–31% of tree basal area), on hardwood and conifer regeneration levels 7–19 years following treatments in aspen (Populus tremuloides)-dominated stands and verified whether regeneration differences existed between micro-sites on and off machinery trails. The abundance of aspen regeneration increased with percent basal area removal and was positively correlated to the abundance of mature aspen prior to harvesting. The abundance of fir (Abies balsamea) regeneration after partial cutting was similar to controls and higher than after clear-cutting and was positively correlated with ground cover of mixed litter (i.e., mixture of needles and leaves) and negatively correlated with ground cover of broadleaf litter. These results suggest that it is possible in boreal mixed-woods to control aspen abundance and promote or maintain conifer regeneration through silvicultural treatments that limit canopy opening and promote mixed forest floor litter. Full article
Open AccessArticle
Surface Canopy Position Determines the Photosystem II Photochemistry in Invasive and Native Prosopis Congeners at Sharjah Desert, UAE
Forests 2020, 11(7), 740; https://doi.org/10.3390/f11070740 - 08 Jul 2020
Viewed by 180
Abstract
Plants have evolved photoprotective mechanisms in order to counteract the damaging effects of excess light in hyper-arid desert environments. We evaluated the impact of surface canopy positions on the photosynthetic adjustments and chlorophyll fluorescence attributes (photosystem II photochemistry, quantum yield, fluorescence quenching, and [...] Read more.
Plants have evolved photoprotective mechanisms in order to counteract the damaging effects of excess light in hyper-arid desert environments. We evaluated the impact of surface canopy positions on the photosynthetic adjustments and chlorophyll fluorescence attributes (photosystem II photochemistry, quantum yield, fluorescence quenching, and photon energy dissipation), leaf biomass and nutrient content of sun-exposed leaves at the south east (SE canopy position) and shaded-leaves at the north west (NW canopy position) in the invasive Prosopis juliflora and native Prosopis cineraria in the extreme environment (hyper-arid desert area, United Arab Emirates (UAE)). The main aim of this research was to study the photoprotection mechanism in invasive and native Prosopis congeners via the safe removal—as thermal energy—of excess solar energy absorbed by the light collecting system, which counteracts the formation of reactive oxygen species. Maximum photosynthetic efficiency (Fv/Fm) from dark-adapted leaves in P. juliflora and P. cineraria was higher on NW than SE canopy position while insignificant difference was observed within the two Prosopis congeners. Greater quantum yield was observed in P. juliflora than P. cineraria on the NW canopy position than SE. With the change of canopy positions from NW to SE, the reduction of the PSII reaction center activity in the leaves of both Prosopis congeners was accelerated. On the SE canopy position, a significant decline in the electron transport rate (ETR) of in the leaves of both Prosopis congeners occurred, which might be due to the blockage of electron transfer from QA to QB on the PSII acceptor side. On the SE canopy position; Prosopis leaves dissipated excess light energy by increasing non-photochemical quenching (NPQ). However, in P. cineraria, the protective ability of NPQ decreased, which led to the accumulation of excess excitation energy (1 − qP)/NPQ and the aggravation of photoinhibition. The results also explain the role of different physiological attributes contributing to invasiveness of P. juliflora and to evaluate its liaison between plasticity of these characters and invasiveness. Full article
(This article belongs to the Section Forest Ecophysiology and Biology)
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Open AccessArticle
Testing the Capability of Low-Cost Tools and Artificial Intelligence Techniques to Automatically Detect Operations Done by a Small-Sized Manually Driven Bandsaw
Forests 2020, 11(7), 739; https://doi.org/10.3390/f11070739 - 07 Jul 2020
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Abstract
Research Highlights: A low-cost experimental system was developed to enable the production monitoring of small-scale wood processing facilities by the means of sensor-collected data and the implementation of artificial intelligence (AI) techniques, which provided accurate results for the most important work operations. [...] Read more.
Research Highlights: A low-cost experimental system was developed to enable the production monitoring of small-scale wood processing facilities by the means of sensor-collected data and the implementation of artificial intelligence (AI) techniques, which provided accurate results for the most important work operations. Background and Objectives: The manufacturing of wood-based products by small-scale family-held business is commonly affected by a lack of monitoring data that, on the one hand, may prevent the decision-making process and, on the other hand, may lead to less technical efficiency that could result in business failure. Long-term performance of such manufacturing facilities is limited because data collection and analysis require significant resources, thus preventing the approaches that could be pursued for competitivity improvement. Materials and Methods: An external sensor system composed of two dataloggers—a triaxial accelerometer and a sound pressure level meter—was used in combination with a video camera to provide the input signals and meta-documentation for the training and testing of an artificial neural network (ANN) to check the accuracy of automatic classification of the time spent in operations. The study was based on a sample of ca. 90 k observations collected at a frequency of 1 Hz. Results: The approach provided promising results in both the training (ca. 20 k) and testing (ca. 60 k) datasets, with global classification accuracies of ca. 85%. However, the events characterizing the effective sawing, which requires electrical power, were even better recognized, reaching a classification accuracy of 98%. Conclusions: The system requires low-cost devices and freely available software that could enable data feeding on local computers by their direct connection to the devices. As such, it could collect, analyze and plot production data that could be used for maintaining the competitiveness of traditional technologies. Full article
(This article belongs to the Section Wood Science)
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Open AccessArticle
Evaluation of Soil Biodiversity in Alpine Habitats through eDNA Metabarcoding and Relationships with Environmental Features
Forests 2020, 11(7), 738; https://doi.org/10.3390/f11070738 - 07 Jul 2020
Viewed by 183
Abstract
Soil biodiversity is fundamental for ecosystems, ensuring many ecosystem functions, such as nutrient cycling, organic matter decomposition, soil formation, and organic carbon pool increase. Due to these roles, there is a need to study and completely understand how soil biodiversity is composed through [...] Read more.
Soil biodiversity is fundamental for ecosystems, ensuring many ecosystem functions, such as nutrient cycling, organic matter decomposition, soil formation, and organic carbon pool increase. Due to these roles, there is a need to study and completely understand how soil biodiversity is composed through different habitats. The aim of this study was to describe the edaphic soil community of the alpine environments belonging to the Gran Paradiso National Park, thus detecting if there are any correlation with environmental features. We studied soil fauna through environmental DNA metabarcoding. From eDNA metabarcoding, 18 families of arthropods were successfully detected, and their abundance expressed in terms of the relative frequency of sequences. Soil faunal communities of mixed coniferous forests were characterized by Isotomidae, Entomobriydae, Hypogastruridae, and Onychiuridae; while mixed deciduous forests were composed mostly by Isotomidae, Cicadidae, Culicidae, and Neelidae. Calcicolous and acidic grasslands also presented families that were not detected in forest habitats, in particular Scarabaeidae, Curculionidae, Brachyceridae, and had in general a more differentiated soil community. Results of the Canonical Component Analysis revealed that the main environmental features affecting soil community for forests were related to vegetation (mixed deciduous forests, tree basal area, tree biomass, Shannon index), soil (organic layers and organic carbon stock), and site (altitude); while for prairies, soil pH and slope were also significant in explaining soil community composition. This study provided a description of the soil fauna of alpine habitats and resulted in a description of community composition per habitat and the relation with the characteristic of vegetation, soil, and topographic features of the study area. Further studies are needed to clarify ecological roles and needs of these families and their role in ecosystem functioning. Full article
(This article belongs to the Special Issue Relationship between Forest Biodiversity and Soil Functions)
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Open AccessArticle
Plastic Responses of Magnolia schiedeana Schltdl., a Relict-Endangered Mexican Cloud Forest Tree, to Climatic Events: Evidences from Leaf Venation and Wood Vessel Anatomy
Forests 2020, 11(7), 737; https://doi.org/10.3390/f11070737 - 07 Jul 2020
Viewed by 233
Abstract
The Mexican tropical montane cloud forest trees occur under special and limited climatic conditions; many of these species are particularly more sensitive to drought stress. Hydric transport in leaf veins and wood features are influenced by climatic variations and individual intrinsic factors, which [...] Read more.
The Mexican tropical montane cloud forest trees occur under special and limited climatic conditions; many of these species are particularly more sensitive to drought stress. Hydric transport in leaf veins and wood features are influenced by climatic variations and individual intrinsic factors, which are essential processes influencing xylogenesis. We assessed the plastic response to climatic oscillation in two relict-endangered Magnolia schiedeana Schltdl. populations and associated the architecture of leaf vein traits with microenvironmental factors and wood anatomy features with climatic variables. The microenvironmental factors differed significantly between the two Magnolia populations and significantly influenced variation in M. schiedeana leaf venation traits. The independent chronologies developed for the two study forests were dated back 171–190 years. The climate-growth analysis showed that M. schiedeana growth is strongly related to summer conditions and growth responses to Tmax, Tmin, and precipitation. Our study highlights the use of dendroecological tools to detect drought effects. This association also describes modifications in vessel traits recorded before, during, and after drought events. In conclusion, our results advance our understanding of the leaf vein traits and wood anatomy plasticity in response to microenvironmental fluctuations and climate in the tropical montane cloud forest. Full article
(This article belongs to the Special Issue Dendroecological Wood Anatomy and Xylogenesis)
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Open AccessArticle
Biogeographic, Atmospheric, and Climatic Factors Influencing Tree Growth in Mediterranean Aleppo Pine Forests
Forests 2020, 11(7), 736; https://doi.org/10.3390/f11070736 (registering DOI) - 06 Jul 2020
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Abstract
There is a lack of knowledge on how tree species respond to climatic constraints like water shortages and related atmospheric patterns across broad spatial and temporal scales. These assessments are needed to project which populations will better tolerate or respond to global warming [...] Read more.
There is a lack of knowledge on how tree species respond to climatic constraints like water shortages and related atmospheric patterns across broad spatial and temporal scales. These assessments are needed to project which populations will better tolerate or respond to global warming across the tree species distribution range. Warmer and drier conditions have been forecasted for the Mediterranean Basin, where Aleppo pine (Pinus halepensis Mill.) is the most widely distributed conifer in dry sites. This species shows plastic growth responses to climate, being particularly sensitive to drought. We evaluated how 32 Aleppo pine forests responded to climate and atmospheric patterns during the second half of the 20th century by using dendrochronology. Climatic constraints of radial growth were inferred by fitting the Vaganov–Shashkin (VS-Lite) growth model. Aleppo pine growth decreased and showed the highest common coherence among trees in dry, continental sites, such as those situated in southeastern and eastern inland Spain and Algeria. Growth increased in wetter sites. Tree growth was enhanced by prior wet winter conditions and cool and wet spring conditions, whilst warm summers were associated with decreased growth. The relationships between site ring-width chronologies were spatially structured, which explains why Aleppo pine growth was distinctly linked to indices describing atmospheric circulation patterns, showing a stronger influence in western sites (Western Mediterranean Oscillation and Northern Atlantic Oscillation). The climatic constraints of growth and their biogeographical variability were captured by the VS-Lite model, with better fits in dry and continental sites, showing strong growth coherence between trees and climatic limitations of growth. Further research using similar broad-scale approaches to climate–growth relationships and in drought-prone regions deserves more attention. Full article
(This article belongs to the Special Issue Dendrochronology and Dendroclimatology in the Mediterranean)
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Open AccessArticle
Plus Tree Selection of Quercus salicina Blume and Q. glauca Thunb. and Its Implications in Evergreen Oaks Breeding in Korea
Forests 2020, 11(7), 735; https://doi.org/10.3390/f11070735 - 06 Jul 2020
Viewed by 236
Abstract
This study was conducted to select plus trees of two evergreen oaks, Quercus salicina and Q. glauca, in Korea. Evergreen oaks are distributed in subtropical region in Korea and have recently emerged as one of the alternative tree species against climate change. [...] Read more.
This study was conducted to select plus trees of two evergreen oaks, Quercus salicina and Q. glauca, in Korea. Evergreen oaks are distributed in subtropical region in Korea and have recently emerged as one of the alternative tree species against climate change. Accordingly, a tree breeding program is underway to foster evergreen oaks as a reforestation species for the future. Through intensive survey on the distribution range, 15 stands (8 for Q. salicina, 3 for Q. glauca, and 4 for both species) were selected as base populations. To select candidate trees, we developed a subjective grading system with six characteristics in three categories and introduced a weighted generalized value (GVIw) to compare superiority of candidate trees. The candidate trees were screened using baseline value ‘0’, i.e., if GVIw > 0, then accepted and if GVIw < 0, then rejected. After then, adjustment was conducted to avoid biasing the selection of plus trees for a particular location. Through this process, 44 candidate trees in Q. salicina and 41 candidate trees in Q. glauca were selected as plus trees. Finally, the results and implications were discussed in relation to evergreen oak breeding in Korea. Full article
(This article belongs to the Special Issue Genetic and Phenotypic Variation in Tree Crops Biodiversity)
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Open AccessArticle
Marker-Assisted Selection of Trees with MALE STERILITY 1 in Cryptomeria japonica D. Don
Forests 2020, 11(7), 734; https://doi.org/10.3390/f11070734 - 06 Jul 2020
Viewed by 205
Abstract
The practical use of marker-assisted selection (MAS) is limited in conifers because of the difficulty with developing markers due to a rapid decrease in linkage disequilibrium, the limited genomic information available, and the diverse genetic backgrounds among the breeding material collections. First, in [...] Read more.
The practical use of marker-assisted selection (MAS) is limited in conifers because of the difficulty with developing markers due to a rapid decrease in linkage disequilibrium, the limited genomic information available, and the diverse genetic backgrounds among the breeding material collections. First, in this study, two families were produced by artificial crossing between two male-sterile trees, ‘Shindai11’ and ‘Shindai12’, and a plus tree, ‘Suzu-2’ (Ms1/ms1) (S11-S and S12-S families, respectively). The segregation ratio between the male-sterile and male-fertile trees did not deviate significantly from the expected 1:1 ratio in either family. These results clearly suggested that the male-sterile gene of ‘Shindai11’ and ‘Shindai12’ is MALE STERILITY 1 (MS1). Since it is difficult to understand the relative positions of each marker, due to the lack of a linkage map which all the closely linked markers previously reported are mapped on, we constructed a partial linkage map of the region encompassing MS1 using the S11-S and S12-S families. For the S11-S and S12-S families, 19 and 18 markers were mapped onto the partial linkage maps of the MS1 region, respectively. There was collinearity (conserved gene order) between the two partial linkage maps. Two markers (CJt020762_ms1-1 and reCj19250_2335) were mapped to the same position as the MS1 locus on both maps. Of these markers, we used CJt020762 for the MAS in this study. According to the MAS results for 650 trees from six prefectures of Japan (603 trees from breeding materials and 47 trees from the Ishinomaki natural population), five trees in Niigata Prefecture and one tree in Yamagata Prefecture had heterozygous ms1-1, and three trees in Miyagi Prefecture had heterozygous ms1-2. The results obtained in this study suggested that ms1-1 and ms1-2 have different geographical distributions. Since MAS can be used effectively to reduce the labor and time required for selection of trees with a male-sterile gene, the research should help ensure that the quantity of breeding materials will increase to assist future tree-breeding efforts. Full article
(This article belongs to the Special Issue Genetics and Improvement of Forest Trees)
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Open AccessArticle
Policy Responses to Direct and Underlying Drivers of Deforestation: Examining Rubber and Coffee in the Central Highlands of Vietnam
Forests 2020, 11(7), 733; https://doi.org/10.3390/f11070733 - 06 Jul 2020
Viewed by 266
Abstract
Viet Nam’s Central Highlands are a priority region for its National REDD+ Action Plan (NRAP) to reduce emissions from deforestation and forest degradation but are under strong pressures from rubber and coffee production and expansion into forests, and future climate stress. This research [...] Read more.
Viet Nam’s Central Highlands are a priority region for its National REDD+ Action Plan (NRAP) to reduce emissions from deforestation and forest degradation but are under strong pressures from rubber and coffee production and expansion into forests, and future climate stress. This research explores to what extent REDD+ and sectoral policy interventions have addressed both the direct and underlying drivers of deforestation and forest degradation in this region, with particular focus on the actors and scales that policy interventions must reach to affect driver pressure. National-level policy responses to driver pressures are assessed, with the results indicating poor correlations between the direct drivers and related underlying drivers. The research proposes a framework to guide the policy design and evaluation of response options to enable identification of the causal connections between direct and underlying drivers, and consider future pressures, which actors to target (or not miss) and which scales are best suited for interventions (from international to national, sub-national and local). This is highly relevant for countries pursuing forest and land use sector solutions through Nationally Determined Contributions to the Paris Agreement and REDD+. Full article
(This article belongs to the Special Issue REDD+: Protecting Climate, Forests and Livelihoods)
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Open AccessArticle
National Forest Ecosystem Inventory System of China: Methodology and Applications
Forests 2020, 11(7), 732; https://doi.org/10.3390/f11070732 - 04 Jul 2020
Viewed by 210
Abstract
The technical framework of China’s Forest Ecosystem Inventory System (CFEIS) was recently developed based on ecological indicators assessed continuously in the field at forest ecosystem research stations and China’s Forest Resource Inventory (CNFRI) conducted every 5 years. The CFEIS consists of Field Observations [...] Read more.
The technical framework of China’s Forest Ecosystem Inventory System (CFEIS) was recently developed based on ecological indicators assessed continuously in the field at forest ecosystem research stations and China’s Forest Resource Inventory (CNFRI) conducted every 5 years. The CFEIS consists of Field Observations (FOs)of ecological indicators and Distributed Valuations (DVs)of forest ecosystem services. The CFEIS can be used with the CNFRI to observe and monitor the ecological status of forests in China. This paper provides a brief review of the CFEIS by introducing its establishment and summarizing its application coupled with the CNFRI. For the FOs, the principles of the monitoring system layout are provided. The Chinese Forest Ecosystem Research Network (CFERN) was set up, which was the largest nationwide network of forest ecological stations in the world. The facilities and equipment were systematically assembled. The national forestry standards were drawn up for describing and measuring the ecological indicators of forest ecosystems, and these standards were used to specify data collection and transmission. For DVs, a distributed measurement method was created, and an indicator system of evaluation was studied and established, with the CNFRI integrated; a series of evaluation formulas and a package of models were also integrated with the DVs. The CFEIS integrated with the CNFRI estimates forest ecosystem services in China and the ecological benefits derived from the Grain for Green program, and a green national economic accounting system will provide an important case for monitoring and inventorying forest ecosystems at a national scale. The CFEIS can provide important experiences for forest ecosystem inventory systems in China and many other parts of the world. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle
Short-Term Recovery of Residual Tree Damage during Successive Thinning Operations
Forests 2020, 11(7), 731; https://doi.org/10.3390/f11070731 - 04 Jul 2020
Viewed by 202
Abstract
In this study, damage to residual trees during thinning performed by motor-manual felling and whole tree skidding was studied in a loblolly pine (Pinus taeda L.) plantation. Forest intervention was carried out in 2016 and tree wounds were studied and examined over [...] Read more.
In this study, damage to residual trees during thinning performed by motor-manual felling and whole tree skidding was studied in a loblolly pine (Pinus taeda L.) plantation. Forest intervention was carried out in 2016 and tree wounds were studied and examined over a period of three years. The results indicated that 8% of the residual trees suffered damage, of which 52% was caused by felling operations and 48% by extraction operations. Among the damaged trees, 13% had damage to the root system, 53% to the bole, and 34% to the crown area. The average wound size at the time of occurrence was 71.3 cm2. This was found to be reduced to 54.4 cm2 after a three year period. Wound intensity decreased with higher wound height and increased size. Three years after wound occurrence, only 6.6% were closed, 90.6% were still open, and 2.8% were decayed. The diameter growth in damaged trees was 1.7% lower than in undamaged trees (p > 0.05). Damage to the root system of residual trees reduced diameter growth by 3% (p < 0.05). Intensive wounds (damaged wood) caused a reduction of 22.7% in diameter growth (p < 0.01). In addition, the diameter growth in trees with decayed wounds was 27.4% lower than unwounded trees (p < 0.01). Pre-harvest planning, directional tree felling, marking of the extraction path before logging operations, employment of skilled logging workers, and post-harvest assessment of damaged residual trees are essential implementations in timber plantations. Full article
(This article belongs to the Special Issue Forest Stand Management and Biomass Growth)
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Open AccessArticle
Optimizing the Tending of Forest Stands with Interactive Decision Maps to Balance the Financial Incomes and Ecological Risks according to Owner Demands: Case Study in Rakovník, the Czech Republic
Forests 2020, 11(7), 730; https://doi.org/10.3390/f11070730 - 04 Jul 2020
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Abstract
Sustainability and the optimal provision of the various ecosystem services is an essential task in forest management. In this study, we deal with the optimization of forest tending to achieve the maximal long-term provision of financial incomes from wood at a minimal level [...] Read more.
Sustainability and the optimal provision of the various ecosystem services is an essential task in forest management. In this study, we deal with the optimization of forest tending to achieve the maximal long-term provision of financial incomes from wood at a minimal level of ecological risks for selected small ownership unit. The methods of interactive decision maps and reasonable goals (IDM/RGM) were connected with a modern forest growth simulator to investigate the four-dimensional optimization space and to produce the complete set of Pareto optimal solutions. The four different types of forest owners as potential decision-makers were simulated, and precise management goals in multidimensional target space were defined. Then, the optimal tending system for each forest owner in three stands, differing by the degree of the naturalness of the species composition, was detected. The multi-criteria analysis suggests that predominantly economically oriented forest management still prevails in the Czech and Slovak Republics, which can be as a source of conflicts among forest owners and other stakeholders. The existence of trade-offs between biodiversity, ecological stability and wood production and different owners’ demands must be taken into account. The possibility of balancing the management risks and wood provision according to the owner’s and other stakeholders’ demands with the aid of the easy-to-apply IDM/RGM methods (and the careful assistance of a specialist experienced in multi-criteria optimization) was introduced. At the same time, the application of real integrative management in small forest areas was demonstrated in practice. After the change of paradigm in forest management, the applied methods should prevent increasing conflicts among owners and society in former socialist countries, which have undergone a fundamental transformation in terms of forest ownership in recent decades. Full article
(This article belongs to the Section Forest Ecology and Management)
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Open AccessArticle
Predicting Aggregate Degradation in Forest Roads in Northwest Oregon
Forests 2020, 11(7), 729; https://doi.org/10.3390/f11070729 - 03 Jul 2020
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Abstract
In the Pacific Northwest, forest roads have the potential to cause significant environmental degradation, especially to water resources due to increased sediment production. The goal of this research is to improve the understanding of road degradation during hauling by improving our understanding of [...] Read more.
In the Pacific Northwest, forest roads have the potential to cause significant environmental degradation, especially to water resources due to increased sediment production. The goal of this research is to improve the understanding of road degradation during hauling by improving our understanding of the aggregate degradation process. We correlate the wear rates to standard material property tests that may allow for improved prediction of the impacts from forest roads based on the selection of aggregate surfacing. Finally, we determine the changes in stress distribution between the subgrade and aggregate interface. High-, medium-, and low-quality aggregates were used from three quarries in western Oregon for this project. These aggregates are indicative of the range of materials used on forest roads in the region. Two material property tests, namely the Los Angeles (LA) abrasion and micro-Deval tests, were used to determine their ability to predict aggregate performance during hauling by relating values for aggregate wear to these aggregate properties. Eighteen nonwoven geotextile bags were created, measuring 60 cm (two-feet long) and 20 cm (eight inches) in diameter, with a pore size equivalent to a 0.149 mm (# 100) sieve. They were filled with a known quantity and particle size distribution of aggregate and embedded into a newly constructed forest road. Stress gages were installed in the road surface between the aggregate and subgrade levels to record the changes in stress at the subgrade level. Samples were subjected to three levels of traffic (500, 950, and 1500 passes) using a loaded dump-truck that had a steering axle and one tandem drive axle, weighing 25,038 kg or 55,200 lb. The results showed that less breakage occurred with the medium- and high-quality aggregates than the low-quality aggregate. There was a correlation between the material property test (either the micro-Deval or the LA abrasion test) and the fine index, indicating the predictability of these tests in terms of aggregate performance. Finally, the higher quality aggregate was able to better distribute the stresses from the wheel better than the lower quality aggregate and was able to reduce the stress reaching the subgrade. Although the results are limited to the three types of rock used in this study, they indicate the ability of the high-quality aggregate to lessen the environmental impacts from forest roads. Full article
(This article belongs to the Special Issue Planning, Design, and Maintenance of Forest Road Networks)
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Open AccessArticle
Landscape Preference for Trees Outside Forests along an Urban–Rural–Natural Gradient
Forests 2020, 11(7), 728; https://doi.org/10.3390/f11070728 (registering DOI) - 03 Jul 2020
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Abstract
In densely populated areas, essential sources of ecosystem services are represented by green infrastructure, which includes trees outside forests (TOF) that, regardless of their cover extension, are found on agricultural or urban land. This research aims to assess landscape preference for TOF along [...] Read more.
In densely populated areas, essential sources of ecosystem services are represented by green infrastructure, which includes trees outside forests (TOF) that, regardless of their cover extension, are found on agricultural or urban land. This research aims to assess landscape preference for TOF along an urban-rural-natural gradient in relation to different levels of landscape heterogeneity. Analyses are based on the integration of a visual choice experiment (360 respondents) with a GIS-based landscape analysis at regional scale in a Mediterranean region in Central Italy. Main findings revealed that correlation between landscape preference and heterogeneity varies along the urban–rural–natural gradient and on the basis of the spatial configuration of the surrounding landscape. The additional value of TOF to landscape preference is closely and positively linked to the degree of landscape anthropization. Conversely, TOF contribution to landscape preference resulted negative in natural landscapes where they can be perceived as a disturbance of the wilderness. Considering the influence that landscape preference plays on cultural ecosystem services provisioning and, in turn, on decision making processes, our results can support landscape policy and planning in fostering or hampering TOF diffusion depending on the different territorial contexts. These findings endorse the importance of multi-functional approaches in future-oriented strategies, which should mediate between the human preference for TOF, their ecological role and the provision of other services. Full article
(This article belongs to the Section Forest Inventory, Quantitative Methods and Remote Sensing)
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Open AccessArticle
Frugivory by Coyotes Decreases the Time to Germination and Increases the Growth of Netleaf Hackberry (Celtis reticulata) Seedlings
Forests 2020, 11(7), 727; https://doi.org/10.3390/f11070727 - 03 Jul 2020
Viewed by 171
Abstract
Research Highlights: Frugivory by mammals is a common plant–animal interaction, but additional studies that examine the effects of frugivory on woody plants are needed. We show that ingestion of netleaf hackberry (Celtis reticulata Torr.) fruits by coyotes (Canis latrans Say) cuts [...] Read more.
Research Highlights: Frugivory by mammals is a common plant–animal interaction, but additional studies that examine the effects of frugivory on woody plants are needed. We show that ingestion of netleaf hackberry (Celtis reticulata Torr.) fruits by coyotes (Canis latrans Say) cuts the time to germination nearly in half and results in seedlings that are taller than the controls. Background and Objectives: Netleaf hackberry is a deciduous shrub to small tree that can be long-lived, but newly established stands are rare. The lack of juvenile hackberry in its native range of southwestern North America could be due to low percentages of germination and seedling survival. We hypothesized that passage through the digestive tract of a coyote would increase the germination and subsequent growth of netleaf hackberry. Materials and Methods: In the Wasatch Mountains of Utah, we collected coyote scats containing visible hackberry fruits and picked fresh fruits from nearby hackberry shrubs. All samples were cleaned and cold-stratified. We sowed 20 seeds from each of the 34 samples into containers in the greenhouse (a total of 680 seeds). We noted the date of emergence and final height of each seedling after 131 days. Results: The germination percentage of the coyote-treatment seeds did not differ from that of the controls. However, the coyote-ingested seeds took just over half as many days to germinate as did the undigested controls (35 days vs. 69 days, respectively; p < 0.001) and the resulting seedlings were 9.5% taller by the end of the growing season (6.4 vs. 5.8 cm, respectively; p < 0.001). Conclusions: Consumption by coyotes can benefit hackberries by enabling their seeds to germinate earlier in the year when conditions are wetter and cooler. The additional time for establishment and growth afforded by frugivory likely increases the fitness of netleaf hackberry seedlings that emerge into the unpredictable conditions of a semi-arid region. Full article
(This article belongs to the Special Issue Impacts of Herbivory on Plant Communities)
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Open AccessArticle
Paraffin Pickering Emulsion Stabilized with Nano-SiO2 Designed for Wood Impregnation
Forests 2020, 11(7), 726; https://doi.org/10.3390/f11070726 - 02 Jul 2020
Viewed by 216
Abstract
Wax impregnation is an effective approach to improve wood water resistance. However, melted waxes require special equipment and cannot penetrate deep enough into wood. Recently, wax emulsions show excellent efficiency in wood modification. In this study, paraffin Pickering emulsion stabilized by low dispersed [...] Read more.
Wax impregnation is an effective approach to improve wood water resistance. However, melted waxes require special equipment and cannot penetrate deep enough into wood. Recently, wax emulsions show excellent efficiency in wood modification. In this study, paraffin Pickering emulsion stabilized by low dispersed SiO2 nanospheres was used to impregnate poplar wood. The microstructure and storage stability of the emulsion were evaluated. The dimensional stability, water uptake, wettability, and thermal stability of treated wood were also investigated. After homogenization, a milk-white oil-in-water (O/W) paraffin Pickering emulsion stabilized by the nano-SiO2 (diameter of ~76 nm) was formed and demonstrated excellent storage stability. Paraffin Pickering emulsion could penetrate into the wood structure. The emulsion-treated wood was endowed with a moderate anti-swelling efficiency (ASE), high water resistance, and low wettability. Moreover, the addition of nano-SiO2 could improve the thermal stability of the treated wood. Full article
(This article belongs to the Special Issue Methods and New Technologies for Wood Modification)
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