• Journal of Forest and Environmental Science
• /
• v.40 no.1
• /
• pp.35-42
• /
• 2024

The Japanese larch (Larix kaempferi [Lamb.] Carriere) is a major timber species in Korea. However, studies on bucking rates and merchantable logs of this species are insufficient in South Korea. To bridge these gaps, in this study, the bucking rate of Japanese larch (Larix kaempferi [Lamb.] Carriere) was computed and the number of long logs and merchantable log volumes were analyzed. Sample trees were bucked according to the log grade for trading, and collected from a forest field in Gangwon Province. The bucking rate of all Japanese larch logs was >89%. The highly profitable 2-4 logs of 3.6 m length from trees with ≤30 cm diameter at breast height (DBH) and 5-6 logs with ≥34 cm DBH were produced. The bucking rate of long logs was >84%; thus, Japanese larch was found to be suitable for the supply of high-grade timber. Additionally, to follow reasonable wood supply plans, merchantable volume tables were offered based on 3.6 m-long number of logs and small-end diameter classes. Understanding the proportion of merchantable log volumes, bucking rates, and the number of long and short logs has large-scale applications in practical forestry.

• Journal of the Korean Wood Science and Technology
• /
• v.41 no.2
• /
• pp.141-148
• /
• 2013

The goal of this study was to find the optimum lamina size from red pine (Pinus densiflora) and Japanese cedar (Cryptomeria japonica) logs for the cross laminated timber (CLT) production. From visual inspection of the logs from two species, red pine log showed a larger knot and warp compared to the Japanese cedar. Different cross-sectional sizes of lamina ($110mm{\times}30mm$, $110mm{\times}40mm$, $110mm{\times}50mm$, $50mm{\times}30mm$, $30mm{\times}30mm$) from two species were analyzed for yield and grade. Regardless of the species, the optimized cross sectional size for maximizing the yield was $110mm{\times}30mm$. In grading for the different size laminas from Japanese cedar and red pine, a higher percentage of the first and second grade was found from the $110mm{\times}30mm$ lamina cut.

• Journal of Forest and Environmental Science
• /
• v.28 no.4
• /
• pp.205-211
• /
• 2012

Yield tables are a frequently used data base for regional timber resource forecasting. A normal yield table is based on two independent variables, age and site (species constant), and applies to fully stocked (or normal) stands while empirical yield tables are based on average rather than fully stocked stands. Normal and empirical yield tables essentially have many limitations. The limitations of normal and empirical yield tables led to the development of variable density yield tables. Mathematical models for estimating timber yields are usually developed by fitting a suitable equation to observed data. The model is then used to predict yields for conditions resembling those of the original data set. It may be accurate for the specific conditions, but of unproven accuracy or even entirely useless in other circumstances. Thus, these models tend to be specific rather than general and require validation before applying to other areas. Dalbergia sissoo forms a major portion of irrigated plantations in the hot desert of India and is an important timber tree species where stem wood is primarily used as timber. Variable density yield model is not available for this species which is very crucial in long-term planning for managing the plantations on a sustained basis. Thus, the objective of this study was to develop variable density yield model based on the data collected from 30 sample plots of D. sissoo laid out in IGNP area of Rajasthan State (India) and measured annually for 5 years. The best approximating model was selected based on the fit statistics among the models tested in the study. The model develop was evaluated based on quantitative and qualitative statistical criteria which showed that the model is statistically sound in prediction. The model can be safely applied on D. sissooo plantations in the study area or areas having similar conditions.

• Journal of Korea Technical Association of The Pulp and Paper Industry
• /
• v.43 no.3
• /
• pp.43-51
• /
• 2011

Chemical composition and contents of carbohydrates, lignin, and extractives in Moso(Phyllostachys pubescens Mazel), Henon(Phyllostachys nigra var. henonis Stapf ex. Rendle), and Timber bamboo(Phyllostachys bambusoides Sieb. et Zucc.) known as economically valuable bamboo species in Korea were analyzed as a function of ages. All of tested bamboo species were composed of fucose, arabinose, rhamnose, galactose, glucose, xylose, and mannose. Glucose was the sugar which showed the highest content followed by xylose. The contents of others were below 3%. Sugar contents of bamboo shoots showed the lowest among the tested bamboo samples, and the constant rates were shown after 50 days of growth. Lignin content increased by the growth of one year, and the increasing rates tended to be constant after the growth of three years. Bamboo shoots have the highest contents of acid-soluble lignin, which turned into insoluble lignin after the growth of 50 days. Bamboo shoots showed the highest content of extractives and tend to be decreased by the growth of 50 days and then the content increased slowly in proportion to the period of bamboo growth. No relationship was found between species and chemical composition of bamboo. However, there were significant difference in chemical composition between bamboo shoots and 50-day old bamboo.

• Korean Journal of Environmental Biology
• /
• v.40 no.4
• /
• pp.567-578
• /
• 2022

Various social and environmental problems have recently emerged due to global climate change. In South Korea, coniferous forests in the highlands are decreasing due to climate change whereas the distribution of subtropical species is gradually increasing. This study aims to respond to changes in the distribution of forest species in South Korea due to climate change. This study predicts changes in future suitable areas for Pinus koraiensis, Cryptomeria japonica, and Chamaecyparis obtusa cultivated as timber species based on climate, topography, and environment. Appearance coordinates were collected only for natural forests in consideration of climate suitability in the National Forest Inventory. Future climate data used the SSP scenario by KMA. Species distribution models were ensembled to predict future suitable habitat areas for the base year(2000-2019), near future(2041-2060), and distant future(2081-2100). In the baseline period, the highly suitable habitat for Pinus koraiensis accounted for approximately 13.87% of the country. However, in the distant future(2081-2100), it decreased to approximately 0.11% under SSP5-8.5. For Cryptomeria japonica, the habitat for the base year was approximately 7.08%. It increased to approximately 18.21% under SSP5-8.5 in the distant future. In the case of Chamaecyparis obtusa, the habitat for the base year was approximately 19.32%. It increased to approximately 90.93% under SSP5-8.5 in the distant future. Pinus koraiensis, which had been planted nationwide, gradually moved north due to climate change with suitable habitats in South Korea decreased significantly. After the near future, Pinus koraiensis was not suitable for the afforestation as timber species in South Korea. Chamaecyparis obtusa can be replaced in most areas. In the case of Cryptomeria japonica, it was assessed that it could replace part of the south and central region.

• Journal of the Korean Wood Science and Technology
• /
• v.38 no.4
• /
• pp.282-291
• /
• 2010

As compared with existing center-boring timber, skin timber which be hollowed out of its considerable inner parts has some merits as like short drying time, less developed checks during drying, a advantage of lower MC (8~%), more easy injection of chemicals, a possibility of using as a lighter structural heavy timber including Hanok and heavy timber construction, a possibility for the various living necessaries and furniture materials. However, development of hybrid skin timber is required for using as a value-added materials and giving a confidence for the structural safety of skin timber to general user. Thus, improved pine skin timber (IPST) and improved larch skin timber (ILST) were manufactured using the lighter steel plate possible. And compressive capacity of improved skin timber was analyzed. From the results of this study, the following conclusions have been made: 1. Both of IPST and ILST can give a uniformity of material capacity compared with non-treated skin timber. 2. Both IPST and ILST, there was not statistical significancy among the thickness of steel plate. Therefore, it concluded that it was not necessary to use thicker steel plate. 3. There was also not statistical significancy between IPSR and ILST, so it need not to be selective about the species of improved skin timber. 4. IPST showed various failure types, but most failure types of ILST is a splitting type.

• Journal of Korean Society of Forest Science
• /
• v.94 no.5 s.162
• /
• pp.291-301
• /
• 2005

Robinia pseudoacacia is one of most widely cultivated exotic species in Bulgaria. The total area of black locust plantations amounts to 2.9% of the total forest area of the country. 15.34% of the plantations are of management afforestations category, where the priority is given to timber production. They have been created on rich and moisture soils, which are the most appropriate for the species in order to achieve its biological potentials of high productivity. The rest of the available plantations in the country are planted on poorer and drier soils up to 600~800 m altitude. The high adaptive ability of the species to unsuitable environmental conditions as well as the high sprout potential was used for their creation. These stands are mainly done with the aim to protect and ameliorate damaged environments and production of small-size timber and fire woods. They are cultivated until 15-20 years and are revived by sprouts. Therefore the management goals searched, 45.69% of those forests are low productive and 38.97% with average productiveness. The present report deals with growth and productivity capacity of black locust plantations; production of sowing materials; production of reproductive and vegetative saplings for afforestation; the technological aspects of afforestation works; the management and use of black locust plantations as well as some more important diseases and pests affecting the species. The report is entirely based on Bulgarian scientific research works and experience with the Robinia preudoacacia. Recommendations for optimizing the use of species are given.

• Journal of the Korean Wood Science and Technology
• /
• v.47 no.3
• /
• pp.324-335
• /
• 2019

Timber from plantation forests has inferior physical and mechanical properties compared to timber from natural forest because it is mostly from fast-growing tree species that are cut at a young age. Filling cell voids with methyl methacrylate (MMA) can improve the wood properties. The purpose of this study was to determine the physical and mechanical properties of MMA-impregnated wood from three fast-growing wood species, namely jabon (Anthocephalus cadamba (Roxb.) Miq.), mangium (Acacia mangium Willd) and pine (Pinus merkusii Jungh. & de Vriese). Wood samples were either immersed in MMA monomer or impregnated with it and then heated to induce the polymerization process. Jabon, which was the lowest density wood, had the highest polymer loading, followed by pine and mangium. The physical and mechanical properties of samples were affected by wood species and the presence of MMA, with higher-density wood having better properties than wood with a lower density. Physical and mechanical properties of MMA wood were enhanced compared to untreated wood. Furthermore, the impregnation process was better than immersion process resulting the physical and mechanical properties. Based on MOR values, the MMA woods were one strength class higher compared to untreated wood with regard to Strength Classification of Indonesian Wood.

• Journal of Korean Society of Forest Science
• /
• v.109 no.4
• /
• pp.454-460
• /
• 2020

The goal of this study was to classify the area of Larix kaempferi forest available for timber production, considering the legal, physical, environmental, and technical constraints, and to optimize the forest resources and the potential of timber production in South Korea for 50 years. The results showed that the area of Larix kaempferi forest available for timber production is limited to 124,000 ha, 48% of the total area. Without further efforts in resource management, sustainable timber production of Larix kaempferi cannot be guaranteed even at the current level of timber supply. To enhance the potential of timber production for this species, two alternatives were considered: a 705-km annual increment of forest roads (alternative 1) and a 1,000-kmannual increment of forest roads (alternative 2) to enlarge forest areas available for timber production. The results showed that alternative 1 is feasiblefor sustainable timber production both at the current level and with a 5% increment of timber supply. However, alternative 1 is not sufficient in the case of a 10% increment of timber supply with a low growing stock, whereas alternative 2 is sufficient. Therefore, an increase in forests roads as well as regeneration efforts are required to improve the timber production potential of Larix kaempferi in South Korea.

• Journal of the Korean Wood Science and Technology
• /
• v.51 no.5
• /
• pp.419-430
• /
• 2023

In this study, the floor impact sound insulation performance of Korean domestic Cross-Laminated Timber (CLT) slabs was evaluated according to their joint types, species and thicknesses in laboratory experiments. The sound insulation performance of the CLT has not been investigated before, thus, this study was conducted to quantify basic data on floor impact sound insulation performance of CLT slabs. 5-ply and 150 mm thick CLT panels made of 2 species, Larix kaempferi and Pinus densiflora, were used for the study. The CLT panels were assembled by 3 types of inter-panel joints to form floor slabs: spline, butt and half-lap. And the 150 mm thick Larix CLT slabs were stacked to the thicknesses of 300 mm and 450 mm. The heavy-weight floor impact sound insulation performance of the 150 mm CLT slabs were evaluated to be 70 dB for the Larix slabs and 71.6 dB for the Pinus slabs, and the light-weight floor impact sound insulation performance, 78.3 dB and 79.6 dB, respectively. No significant difference in the sound insulation performance was found between the slabs of the 2 species or among the 3 types of joints. The reduction of 1 dB in the heavy-weight floor impact sound and 1.6 dB in the light-weight floor impact sound per 30 mm increase in thickness were confirmed through the experiments. This study can be viewed as the basic research for the evaluation of floor impact sound insulation performance of CLT.