Wood Resources Research Articles

What Is the Current Ergonomic Condition of Chainsaws in Non-Professional Use? A Case Study to Determine Vibrations and Noises in Small-Scale Agroforestry Farms

Agroforestry or agricultural forestry is an important resource for the exploitation of wood resources commonly based on a low level of mechanization and integrating agriculture crops land-management. Agroforestry areas consist often of buffer strip forest along the farms’ boundaries or on small forest stands within the same farms. Felling is commonly based on the use of chainsaws which are used occasionally, and are often aged models and with little maintenance done on them. In this context, the present study analyzes the vibration and noise generated by chainsaws in the specific contest of the agroforestry farms. The aim is to verify the hand-arm vibrations and noise level, which self-employed agroforest operators are exposed with the occasional use of aged and rarely maintained chainsaws. The main results show that vibration exposures are significantly affected by the model and condition of use of the chainsaw and at lower level, but still significant, by the wood and the position of the handle. Regarding noise levels, the chainsaw model and condition of use also has significant effects. In summary, this study highlights that the importance of the condition of use of the chainsaw has an important effect on the vibrations and noise exposition and that these, although limited due to the limited daily use by operators, must be carefully taken into consideration, and provide for containment actions through adequate information and training.

Investigation of physical properties of paper produced by blending of water hyacinth and dried flowers.

The production of paper is a key component for global civilization. Around 300 million tonnes of paper are produced every day globally, with matured pulpwood being the major contributor. Due to rising demand for paper and the depletion of available wood resources, researchers are now focused on finding alternative non-wood resources that are suitable for pulp and paper production. The current study aims to produce eco-friendly and biodegradable paper using a combination of Eichhornia crassipes (water hyacinth) and dried flowers. Water hyacinth is considered as a lignocellulose plant which contains 57% lignocellulose, and dried flower contains 40% cellulose, which is the prime source for paper production. Various sections of water hyacinth, including wet and dry petiole, leaves, and root, were blended with dried flowers through the soda process. Then, the physical properties and FTIR analysis was carried out to identify the quality of the paper produced. The paper produced from root and dried petiole has a lower thickness (1.0mm and 0.5mm) than other mix proportions. The opacity of the leaves was found to be 0.5% (light passing) and forthe root 0.7% (light passing). Also, the dry petiole and root paperhave a good dry tensile strength of 1.30Kpa and 1.20Kpa, respectively. Hence, paper made from dry petiole and root was found to be efficient and suitable for the paper industry.

Thermal performance of cross-laminated timber (CLT) and cross-laminated bamboo and timber (CLBT) panels

ABSTRACT Cross-laminated timber (CLT) is increasingly being utilized in Europe, North America and elsewhere due to its superior mechanical properties and environmental-friendly performance. Considering regions and countries, such as China, those are scarce in structural wood resource but rich in bamboo forest, an idea of introducing bamboo into CLT system has been proposed to form a novel composite material, named as cross-laminated bamboo and timber (CLBT). This paper focuses on the comparison of thermal insulation performance of CLBT and CLT panels. The thermal resistance and transmittance of CLT and CLBT wall specimens were measured by the Guarded Hot Box test. A calculation method provided by ISO standard and a finite element (FE) model were also used to evaluate the thermal resistance of CLT and CLBT panels. Based on the proposed FE model, some parametric analysis was performed through 11 CLBT panels with different compositions, including the layer number of glubam and timber, the thickness of extruded polystyrene and the use of gypsum board and screws. Moreover, the feasibilities of these CLBT panels were evaluated for the application in different climate regions of China and the United States in accordance with the corresponding Chinese and American building energy efficiency standards, respectively. It can be finally concluded that, the development and application of CLBT contributes to achieving the low carbon sustainable features of structures, which is due to the good carbon sequestration ability of its component materials (i.e., timber and bamboo) as well as the good insulation performance of CLBT panels.

Latest advancements in high-performance bio-based wood adhesives: A critical review

Over the last 50 years, the use of wood adhesives in the manufacturing of wood-based panel goods has increased the efficiency of wood resources. Wood adhesives are becoming more popular as the need for wood-based panels grows. By 2028, the global market for wood adhesives is expected to reach 21.8 billion dollars. Even though urea-formaldehyde (UF), phenol-formaldehyde (PF), melamine-formaldehyde (MF), phenol-resorcinol-formaldehyde (PRF), and resorcinol-formaldehyde (RF) resins are excellent in terms of bonding performance, workability, quality, and economy, they consist of harmful or toxic chemical agents derived from fossil resources, which make their application severely limited. This review aims to go through the most significant ‘green’ wood adhesives for manufacturing high-performance wood-based panels, such as lignin, tannin, protein, natural rubber, emulsion polymer isocyanate (EPI), 1C PUR polyurethane (for glue-laminated wood and cross-laminated timber), PMDI (for particleboards, medium-density and low-density fiberboards), carboxylic acid, and vegetable oil. The physical and mechanical characteristics of bio-based wood adhesives, as well as the development of sustainable, greener, and high-performance bio-based wood adhesives, are discussed in this work. Original research papers and review articles are among the most important sources since they provide complete information on the most recent developments in sustainable, eco-friendly, and high-performance bio-based wood adhesives.

Historic timber roofs in Belgium: overview of materials and structures (1150-1960)

Belgium has a remarkable heritage of historic timber roofs that can be traced back to the 12th century. This contribution provides a review of 60 years of research on Belgian timber roofs and outlines their developments from 1150 to 1960. The focus is firstly put on wood resources, a crucial parameter for roof construction in a scarcely forested landscape. Then, the evolution of structural concepts over 800 years is discussed based on illustrations of remarkable roofs. Moreover, this broad overview raises several questions that open up new prospects for future investigations.

Dating Coastal Archaeological Wood From Pingusugruk (15th–17th CE), Northern Alaska:

Abstract Along the coasts of northern Alaska, in a treeless tundra environment, the primary wood resource for coastal populations is driftwood, a seasonal and exogenous resource carried by the major rivers of western North America. The potential of Alaskan coastal archaeological wood for tree-ring research was first assessed in the 1940s by archaeologist and tree-ring research pioneer J. L. Giddings. Despite his success, the difficulties of dendrochronological studies on driftwood and the development of radiocarbon dating during the 1950s resulted in the near-abandonment of dendrochronology to precisely date archaeological sites and build long sequences using archaeological wood in Alaska. In this study, we explored the possibilities and limitations of standard ring-width dendrochronological methods for dating Alaskan coastal archaeological wood. We focus on the site of Pingusugruk, a late Thule site (15th–17th CE) located at Point Franklin, northern Alaska. The preliminary results have been obtained from the standard dendrochronological analyses of 40 timber cross-sections from two semi-subterranean houses at Pingusugruk. We cross-correlated individual ring-width series and built floating chronologies between houses before cross-dating them with existing regional 1000-year-long master chronologies from the Kobuk and Mackenzie rivers (available on the International Tree-Ring Databank, ITRDB). Additional work on various dendro-archaeological collections using an interdisciplinary approach (geochemical analyses of oxygen isotopes and radiocarbon dating) will help develop and expand regional tree-ring chronologies and climatic tree-ring sequences in Alaska.

Bibliometric Analysis of the Green Gluing Technique (2000–2020): Trends and Perspectives

Wood is a sustainable and renewable material with a lower carbon footprint than other materials. However, its transformation into engineered products industrially, such as glulam, requires kiln drying, which implies energy consumption and loss of wood resources. Recent research has carried out green gluing, a variant of glulam characterized by a reduction of the drying process. Interest in it has increased as a new method of improving the use of wood that does not meet industry standards. It has been accomplished by developing adhesives for wood with high moisture content, but the variables involved are not yet completely understood. Therefore, conducting further research and analyzing the relevant publications is necessary. Bibliometric analysis was the method used, which included documents stored (from 2000 to 2020) in Scopus (Elsevier), Web of Science (Clarivate Analytics), and SciELO Citation Index (Web of Science—Clarivate Analytics) databases. The bibliometric analysis identified three main areas to develop: glue wood, glue properties, and analysis methods. The studies were concentrated on a few countries and research groups. The main progress has been made in synthetic and natural (or environmentally friendly) glue topics. The improvement of technique could enlarge the opportunities for collaboration and innovation in wood material science.

An Integrated Similarity Analysis of Anatomical and Physical Wood Properties of Tropical Species from India, Mozambique, and East Timor

Tropical species are highly valued timber sources showing a large diversity of wood characteristics. Since there are major concerns regarding the sustainability of these tropical species in many tropical regions, knowledge of the variability in wood properties is therefore a valuable tool to design targeted exploitation and to enlarge the wood resources base, namely by identifying alternatives for CITES-listed species. In this study, 98 tropical wood species belonging to 73 genera from India, Mozambique, and East Timor were investigated regarding wood anatomy and physical properties. Numerical taxonomy, by means of cluster analysis and principal component analysis grouped species with anatomical and physical similarities from different geographical origins. In addition to wood density, ray and vessel characteristics as well as wood moisture and wood shrinkage properties explained the main variability of these species. The contribution of wood color patterns was highlighted as consistently separating the Mozambique woods. A distinct geographical pattern was not observed, reinforcing that species from India, Mozambique, and East Timor show similar anatomical and physical wood properties, which could be useful to increase timber trade diversity. The multivariate analysis showed that species from Mozambique, such as Morus mesozygia, and Millettia stuhlmannii and Swartzia madagascariensis, could be alternatives for the CITES-listed species Cedrela odorata and Dalbergia melanoxylon, respectively.

Effect of natural tung oil on wood shrinkage during the thermal modification process

The non-negligible shrinkage and volume loss caused by heat treatment would reduce the availability and product value of wood. In this study, natural tung oil was innovatively used to alleviate heat-reduced shrinkage in thermal modification. The mass changes, dimensional shrinkage and volume loss, chemical structures, morphological characteristics, as well as pore structures of wood were studied. The results demonstrated that the volume loss was significantly reduced after tung oil heat treatment, especially at high temperatures (reduced by 85.27% at 210 °C for 6 h). Tung oil could separate oxygen and mitigate the thermal decomposition of wood components. Additionally, tung oil had impregnated the wood and occupied transportation passages of volatile degradation products, such as vessels and pits. Although severe shrinkage appeared in air heat-treated samples, the porosity increased and part of the micropores transformed into mesopores and macropores. While tung oil heat-treated samples had a lower proportion of macropores and porosity than that of the control and the air heat-treated ones. Overall, tung oil heat treatment was facile, eco-friendly and highly efficient in maximizing actual lumber recovery and improving the product value of wood without any harmful chemicals, as well as saving wood resources.

Changes in Mangrove Cover and Exposure to Coastal Hazards in Kenya

Mangroves are effective carbon sinks, support coastal fisheries and provide wood and non-wood resources to coastal communities. They are threatened by natural and human-induced stresses including over-exploitation, conversion pressures, pollution and climate change. Understanding changes in this important ecosystem is essential to inform the sustainable management of mangroves and assess the implications related to the loss of ecosystem services. This study used global remote sensing mangrove forest data to quantify changes in mangrove cover in Kenya between 2010 and 2016 and applied the InVEST coastal vulnerability model to assess the implications concerning the provision of natural coastal protection services in Kenya. The results indicate that the annual rates of mangrove cover loss in Kenya were 0.15% between 2010 and 2016. Currently, 16% of the Kenyan coastline is at higher levels of exposure to coastal hazards but this could increase to 41% if coastal ecosystems (mangroves, corals and seagrasses) are lost. The study further identified that higher rates of mangrove loss are observed in areas at higher risk of exposure in the southern and northern counties of Kwale and Lamu, where monitoring and management efforts should be prioritized.

Urbanization filters woodpecker assemblages: Habitat specialization limits population abundance of dead wood dependent organisms in the urban landscape

Although urban landscapes are regarded as unsuitable for dead wood dependent organisms, some species, including woodpeckers, commonly occur in cities. As the availability of trees and dead wood resources is a primary dimension of the habitat-niche for most woodpeckers, we hypothesized that increasing habitat specialization (decreasing habitat-niche-volume) would limit species abundance within an urban landscape. We surveyed the woodpecker assemblage in the urban landscape, and for seven species we quantified the habitat-niche relying on four dimensions (the availability of trees, snags, fallen logs and dead tree branches). Then, we analysed the habitat preferences and habitat-niche partitioning of the woodpecker assemblage. For each species, we calculated the habitat-niche-volume and tested whether this trait correlated with species abundance in the urban landscape. Woodpeckers selected habitats with a high availability of either trees or dead wood (especially dead tree branches). The habitat-niches partially overlapped, but varied between species in terms of the availability of trees, dead tree branches, snags or fallen logs. The habitat-niche-volume varied among species and was positively associated with species abundance in the urban landscape. The regional abundance of species, body size and relative brain size did not affect the abundance of urban woodpecker populations. Our study highlights that urbanization filters woodpecker assemblages by limiting habitat-specialists and promoting habitat-generalists. We suggest that the alteration of woodpecker assemblages in the urban landscape may have a cascading effect on entire assemblages of dead wood dependent organisms, including cavity-nesters, saproxylic insects and wood-decomposing fungi. Urban development, which limits dead wood resources, is therefore a serious threat to biodiversity, whereas sustainable management of urban green spaces, e.g. the preservation of dead wood, may mitigate biodiversity loss.

Naming, relocating and dating the woods of Notre-Dame “forest”, first results based on collated data and archaeological surveys of the remains

The tragic fire of Notre-Dame Cathedral in Paris on April 15th 2019 has provided researchers with a wide variety of materials to study. The condition of the framework remains does not allow any reuse, which creates an unprecedented opportunity to study the charred pieces of the frame: about 10,000 for the highest estimates. But upstream from the wooden items study, an inventory is required to establish methods that are consistent with the potential of the charred remains of the cathedral's framework. The purpose of this article is therefore to present the problems raised, the methods applied, the potential of the remains of the n-dame's frame - so called the "forest" - and the first results.

Flexural behavior of wood in the transverse direction investigated using novel computer vision and machine learning approach

Abstract A deep-learning-based semantic segmentation approach (U-Net) was used to partition the anatomical features in the cross-section of hinoki (Chamaecyparis obtusa) wood during a micro three-point bending test. Using the Crocker–Grier linking algorithm, thousands of cells were successfully extracted, and several parameters (area, eccentricity, fitted ellipse aspect ratio, bounding box aspect ratio) were used to evaluate the intensity of the cells’ deformation. Thus, the 2D map of the deformation intensity distribution was constructed. By analyzing flat-sawn, quarter-sawn, and rift-sawn specimens, it was confirmed that the annual ring orientation affects the flexural behavior of wood in the transverse direction. The quarter-sawn specimens exhibited the largest modulus of elasticity (MOE) and modulus of rupture (MOR). The ray tissue aligned against the load may have contributed to the restriction of cell deformation. The rift-sawn specimens exhibited the smallest MOE and MOR, possibly owing to the loading of the specimen in the in-plane off-axial direction, which induced the shear deformation of the cell wall. For all three specimen types, the fracture had high occurrence probability in the tension part of the specimen, which exhibited large cell deformation. Therefore, the proposed method can be adapted to the prediction of wood specimen fractures. With different test wood species, this approach can be of great help in elucidating the relationship between the anatomical features and the mechanical behavior of wood to improve the effective utilization of wood resources.

Improving the wet adhesive bonding of bamboo urea‐formaldehyde adhesive using styrene acrylate by controlling monomer ratios

AbstractThe utilization of bamboo resources can significantly alleviate the wood shortage and facilitate CO2 neutralization. However, the adhesive bonding performance of bamboo is not ideal, which greatly limits its application. Therefore, the biggest challenge is to explore a simple and effective method to enhance the bonding between bamboo and adhesive. In this study, we synthesized three butyl acrylate‐styrene (BS) emulsions with different monomer ratios and incorporated them into urea‐formaldehyde (UF) resins to prepare butyl acrylate‐styrene modified urea‐formaldehyde (BUF) adhesives. Results show that BS emulsion not only prolongs the workability time of UF adhesives (95 s–108 s), but also reduces the free formaldehyde content (0.38%–0.26%). Specifically, BS emulsion with the highest hard/soft monomer ratio makes BUF adhesive the lowest activation energy, showing the accelerated curing reaction. Specifically, the prepared laminated bamboo‐veneer lumber (LBVL) exhibits the best wet‐bonding strength and meets the Chinese National Standard, suggesting that BS emulsion with a higher hard/soft monomer ratio can enhance bonding performance. Thus, this efficient method can not only enhance various adhesive properties, but also improves the bonding performance on LVBL, which can greatly ease the shortage of wood resources and speed up the development of the bamboo industry.

Performance and environmental implication assessments of green bio-composite from rice straw and bamboo

The clean and eco-efficient utilization of agro-industrial lignocellulose wastes is imperative for social development. This study proposes a viable strategy combining rice straw and waste bamboo particles into bio-composites using green adhesives. These new bio-composites can displace the traditional wood-particle boards, which is a viable strategy to economize on wood resources. The internal bonding strength reached 0.57 MPa, and the thickness swelling rate was 7.00% (24h), which met the ISO requirements for P-FN MR1 particleboard in humid conditions. The characterizations of profile density distribution and microstructure were used to elucidate the mechanical strength and water resistance of bio-composites associated with the surface morphology of biomass and the density variation of bio-composites. The obtained green bio-composites can be utilized with long service life to realize carbon sequestration from agro-industrial lignocellulose wastes. According to the LCA, the net carbon flux could reach −1198.49 kg CO2 eq. when producing 1 m3 bio-composite. Meanwhile, if this strategy is successfully extended to the global particleboard market, the utilization of 23.97 million tonnes of rice straw per year can economize on 1.61 million hm2 of the forest, and decrease the emission of CO2 by 63.76 million tonnes. This study provided a new straw/bamboo-based bio-composite. While using agro-industrial lignocellulose wastes efficiently, this new strategy can appreciably favour carbon neutrality.

Life cycle assessment of utilizing freshly cut urban wood: A case study

Large amounts of urban wood resources are generated through tree removals in urban areas. Therefore, there is a growing interest to improve the environmental performance of the urban wood supply chain by quantifying the environmental impacts of creating high-value products from urban tree removals to enhance its utilization. By surveying existing urban wood utilization operations for primary data in two major cities: Baltimore, Maryland, and Milwaukee, Wisconsin, a new life cycle inventory (LCI) dataset per m3 of dry urban hardwood lumber and live edge slabs was created. Incorporating the new LCI data into life cycle assessment method, the total global warming (GW) impact of converting urban trees to kiln-dried lumber was estimated to be 122 kg CO2 eq and 336 kg CO2eq per m3 of lumber produced for Baltimore and Milwaukee, respectively. In both cases, the total environmental impact of the product was dominated by the conversion of urban trees to kiln dried lumber at the sawmill processing stage. Using scenario analysis for the source of heat generation used in kiln (force) drying wood, substituting wood fuel from coproducts for natural gas in a boiler for Milwaukee resulted in a substantial reduction in fossil-derived GW impact. Urban and traditional hardwood lumber production follow similar GW impact trajectories over their life-cycle stages with the lumber processing stage having the highest environmental impacts for both. Increasing the overall lumber yield and decreasing kiln (force) drying would substantially improve the environmental performance of urban hardwood lumber and help make it comparable to traditional lumber.

Ecological and economic assessment of forest ecosystem services on the example of SE "Vovchanske forestry"

Problem. Forests are the most important natural resource that has shaped the history and culture of each region. The economic assessment of forest ecosystem services is essential for improving the environmental situation, and acts as the basis for making informed management decisions. The economic assessment of ecosystem services is a complex scientific and methodological problem and is characterized by certain contradictions. One of these problems is the diversity and specificity of individual ecosystem services, in connection with which it greatly complicates the process of formation of standardized scientific and methodological approaches to the assessment of ecosystem services. Goal. The aim is to analyze methodological approaches to the cost assessment of forest ecosystem services and give an economic assessment of forest ecosystem services on the example of SE "Vovchanske forestry" of Kharkiv region. Methodology. Analytical research methods were used to determine standardized scientific and methodological approaches to the economic evaluation of ecosystem services and to identify forest ecosystem services for which there is sufficient source information for calculating the cost. The calculation method was used for the economic assessment of certain categories of forest ecosystem services and for the consolidated assessment of the cost of providing and regulating forest services of SE "Vovchanske forestry". Results. The result is a number of key principles of best practice for the cost assessment of ecosystem services “The Economics of Ecosystems and Biodiversity” (ТЕЕВ). Analysis of the main approaches to the commodification of ecosystem services made it possible to determine the established practice of their cost assessment on the basis of the Belarusian methodology "The procedure for carrying out a cost assessment of ecosystem services". The paper considers the main ecosystem services of the forest, identifies services for which there is enough initial information to calculate the cost. This is the characteristic of forestry SE "Vovchansky forestry". Of all the ecosystem services, forests are currently involved in market turnover and have an established cost of direct actual use services – providing services, and of the latter – the provision of wood. To calculate the cost of harvested wood, the average price was taken (taking into account the price of wood – firewood) per 1 m3 – 857 UAH/m3. The calculated cost of wood resources with a specific volume of felling 28.9 m3/ha is 24767 UAH/ha. In addition to wood, the forest also supplies the so-called non-wood resources, food resources and medicinal plants. The cost of wood and non-wood-providing forest services is 55297 UAH/ha. At the same time, the cost of non-wood resources exceeds the cost of harvested wood. Among the regulating ecosystem services of the forest, carbon dioxide assimilation is most often considered, which is an economically important factor in light of the problem of climate change and the Paris Agreement. In this paper, the estimate of the average annual absorption of carbon dioxide is carried out for the generalized age of plantings due to the inability to obtain data on the age indicators of certain areas of forestry and their growth areas. The calculation of the amount of carbon dioxide absorbed determines the assimilation capacity of the forest at 13.48 t/ha. At the existing rate per ton of $ 15 US (~ 420 UAH), the price of assimilation service is 5660 UAH/ha. Directly related to the assimilation of carbon dioxide, another regulatory service is the production of oxygen. At the cost of industrial oxygen production of 110.00 UAH/m3, the cost of the service is 55000 UAH/ha. Forests act as a filter, purify atmospheric air from various kinds of harmful impurities. The object of economic assessment of the assimilation potential of forest vegetation is the limiting content of pollutants in the phyto mass of the main forest-forming rocks. At the rates of environmental tax on substances emitted into the air, the cost of assimilation of pollutants is calculated, which is 17412 UAH/ha. The total cost of regulating ecosystem services of the forest is 81767,00 UAH/ha. Thus, the consolidated assessment of the cost of providing and regulating services of the forest SE "Vovchanske forestry" is 137054 UAH/ha. Originality. An economic assessment of the ecosystem services of the Volchanske forestry was carried out, the excess of the cost of regulatory services over services for the harvesting and delivery of timber and other “gifts” of the forest was determined. Practical value. The assessment of forest ecosystem services shows that the main value of the forest is not the provision of wood, but in the assimilation potential of the forest, its ability to maintain the cycle of substances and biodiversity. This must be taken into account when making environmental decisions and in order to develop paid nature management.

Comparative studies of the macro- and microstructures of stump-root wood and stemwood

Abstract It is found that the existing problem of wood resources can be partially solved by attracting additional reserves, in particular, stump-root wood (SRW). In order to apply SRW in woodworking and to fill the scientific base with indicators of the macro- and microstructures of the stump-root systems of individual species, studies were carried out on the main characteristics that are decisive for using composite materials in the industrial production. Based on the study results, it was found that there are differences in the internal structure between SRW and stemwood (SW). It was found that in all species, the width of annual rings in the SRW was greater than that in the SW, in particular, in pine (Pinus sylvestris L.) – by 84.62%; in spruce (Picea abies Karst.) – by 73.68%; in fir (Abies alba) – by 93.75%; in aspen (Populus tremula L.) – by 35.71% and in birch (Betula pendula Roth.) – by 105.00%. It has been found that the content of late wood in the SRW of coniferous tree species is less than that in the SW, on average by 20–25%, and the number of annual rings per 1 cm in the SRW is 40–52% less than in the SW. Differences in the microscopic structure between SRW and SW are revealed, which consist in the difference in the size of tracheids in softwoods and of vessels and fibres of libriform in hardwoods. It was found that the transverse dimensions of early tracheids in the SRW were larger than in the SW, in particular, in the radial direction by 19–33% and in the tangential direction by no more than 15%, and the interval of dimensions in the radial direction was 1.5–2.5. It was found that the early tracheids of root wood had thinner walls (by 19–28%) and a larger internal cavity (by 15–25%) compared to similar elements of SW. It was revealed that the diameters of vessels and fibres of libriform in SRW are greater than in SW, in particular, in aspen (Populus tremula L.) – by 20.41% for vessels and by 12.95% for libriform fibres and in birch (Betula pendula Roth.) – by 20.69% for vessels and by 18.41% for libriform fibres. The practical significance of the studies lies in the fact that the obtained characteristics of the structural components of the SRW can be used to predict the strength indicators of composite materials.

Value chain and sustainability of mangrove wood harvesting in Lamu, Kenya

Mangrove forests provide harvestable wood and non-wood resources to human society globally. The current study evaluated value chain of mangrove wood products from Lamu, Kenya, and how these impacts on resources’ sustainability. Results show that, exploitation of mangrove wood products in Kenya involves several actors, including national regulator, licensees, cutters, transporters, stockists and the consumers. Based on the differences between allowable and harvest data, Lamu mangroves can be said to be under-exploited. For the 1992–2018 period, an average of 223.5 scores ha−1yr−1 of mangrove poles were target for harvesting from Lamu. During the same period, the harvest data indicate an average of 6.2 scores ha−1yr−1 of mangrove poles were removed. However, based on stand level data generated as part of this study, mangroves in Lamu are over-exploited and stocked with non-merchantable poles. There are differentiated net income among various actors in mangrove trade in Kenya. Mangrove cutters are among the ‘losers’ in mangrove trade value chain earning a monthly net income of USD118.6 ± 17.9. Winners in mangrove trade is the Kenya Forest Service, Licensees, transporters, and mangrove dealers (or stockists) in urban centers. The findings of this study are critical in development of the harvesting plan for Lamu mangroves. The results will provide insights toward streamlining mangrove trade for community development, revenue generation and environmental sustainability.

Relationship between the xylem maturation process based on radial variations in wood properties and radial growth increments of stems in a fast-growing tree species, Liriodendron tulipifera

Promoting wood utilization from fast-growing tree species is one solution to address supply and demand issues relating to wood resources while sequestering carbon dioxide in large quantities. Information on the quality of wood from fast-growing tree species and its relationship with changes in stem size is essential for promoting the establishment of plantations and wood utilization of fast-growing tree species. To explore the relationship between the xylem maturation process and radial growth increments of stems in fast-growing tree species, we examined radial variations in annual ring widths and wood properties in Liriodendron tulipifera in Japan. The cambial ages at which current annual increment and mean annual increment values were greatest were 4.9 years and 7.4 years, respectively. Based on radial variations evaluated by mixed-effects modeling of wood properties, all properties increased or decreased near the pith before becoming stable towards the cambium. Changing ratios of multiple wood properties at 1-year intervals became stable after a cambial age of 9 years. These results point to an ecological strategy in L. tulipifera, in which there is a tradeoff between radial growth increments and wood properties. As part of this strategy, in response to competition among individual trees within a stand, the tree produces a large volume of xylem with lower physical and mechanical properties, allowing it to increase its volume faster than that of the surrounding trees. Subsequently, it produces xylem that is more stable, with greater physical and mechanical properties. This wood forms at a slower growth rate compared to the xylem that forms at the time of initial tree growth. Based on the ecological strategy adopted by L. tulipifera, wood that forms before a cambial age of 9 years can be used for utility applications, and wood that forms after a cambial age of 9 years can be used for structural applications.