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Computing the Bucking Rate of Japanese Larch Logs for Timber Harvesting
Daesung Lee,Yonghee Lee,Ilsub Lee,Jungkee Choi Institute of Forest Science 2024 Journal of Forest Science Vol.40 No.1
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.
Daesung Lee,Huiyoung Jang,Jungkee Choi 강원대학교 산림과학연구소 2018 강원대학교 산림과학연구소 학술대회 Vol.2018 No.09
This study was carried out to compare the growth of diameter at breast height (DBH) between artificial coniferous forest and natural broad-leaved forest. Data was collected from permanent monitoring plots in Research Forest of Kangwon National University, which is located at Chuncheon-si, Gangwon province of Korea. For artificial coniferous forest, 8 plots with 20 m x 20 m size were investigated in 1996, 2001, 2008, and 2014. For natural broad-leaved forest, 8 plots with the same plot size were investigated in 1996, 2001, 2008, 2014, and 2018. Before and after first measurement, silvicultural treatment was operated with various thinning intensity of 40~81% based on the number of trees. After thinning, the density ranged 500 ~ 2,500 trees/ha for natural broad-leaved forest and 800 ~ 3,200 trees/ha for artificial coniferous forest. As a result, periodic annual increment was higher in artificial coniferous forest than in natural broad-leaved forest as compared based on similar stand density. When the upper 10% dominant trees and the lower 10% recessive tree compared, the growth difference was apparently shown between artificial coniferous forest and natural broad-leaved forest. In addition, the periodic annual increment according to stand density was higher in artificial coniferous forest and it decreased as time went by. Overall, when the stand characteristics such as stand density and average DBH was similar, DBH growth was superior in artificial coniferous forest.
Daesung Lee,Jari Hynynen 강원대학교 산림과학연구소 2021 강원대학교 산림과학연구소 학술대회 Vol.2021 No.10
Hybrid aspen, a hybrid between the European aspen and North American trembling aspen (Populus tremula L. × P. tremuloides Michx.), is a promising tree species in northern Europe especially for plywood and biomass because of the fast-growing tree characteristics and short rotation period for final cutting. This research was carried out to analyze the tree diameter at breast height (DBH) and tree height of hybrid aspen plantations based on the repeatedly measured clonal trials in southern Finland. The experiments were established in four locations from 1997 to 1999 and measured 7-12 times by experiments. In each experiment, trees were planted with different initial planting density ranging from 400 trees per ha to 1600 trees per ha (5.0 m × 5.0 m spacing to 2.5 m × 2.5 m spacing). The results showed that the DBH distribution by stand density was the same in the beginning of the measurement, but it differed in all experiments over time. As the stand age increased, the DBH distribution was skewed to the right, which means the stand mean and median DBH were larger in the stands with 5.0 m × 5.0 m spacing than in the stands with 2.5 m × 2.5 m spacing. On the other hand, height distribution displayed the different growing rate characteristics. As the stand density increased, a larger proportion of trees’ heights were located in higher classes. The findings are considered to be useful for stand management of hybrid aspen.
Daesung Lee,Jouni Siipilehto,Jari Hynynen 강원대학교 산림과학연구소 2022 강원대학교 산림과학연구소 학술대회 Vol.2022 No.10
Hybrid aspen is a hybrid between Populus tremula L. × P. tremuloides Michx. and is known as a prospective broadleaved species in northern Europe. The usage for pulpwood and bioenergy is expected with vigorous growth characteristics, but the studies on growth and yield modelling based on empirical data are still insufficient. This research aimed to present the main modelling results regarding diameter and height and to provide an extended idea for model application in practice. The materials applied for modelling were collected from the experimental sites located in southern Finland. The selected clones of hybrid aspen were planted on the sites, and at the same time, plots were established during 1997–1999 with proper site preparation and fencing by experiment. The plots were measured repeatedly at 1–3 years interval with 7–12 times in total by experiment. As a result, the diameter distribution and tree height-dbh allometry were figured out over time and appropriate modelling methods were applied using 2-parameter Weibull function and Näslund’s model, respectively. In the Weibull distribution with parameter recovery method, the basal area-weighted mean diameter (DG) with the number of trees per ha (TPH) and stand basal area (BA) presented the best fit compared to other type of stand diameter statistics. The Näslund’s nonlinear mixed-effects model was fitted for tree height estimation with driving variables of age, BA, DG, and basal area-weighted mean height (HG) in addition to tree dbh. Furthermore, it was feasible to simulate these models in combination with the predicted stand characteristics such as BA, DG, and HG based on stand age, site index, and TPH. This will enable one to simulate the growth and yield of hybrid aspen plantations for stand management. Overall, our models were considered to be practical and applicable on a basis of monitoring data of field trials.
Merchantable volume estimation using ratio equations and taper models
Daesung Lee,Yeongwan Seo,Jungkee Choi 강원대학교 산림과학연구소 2017 강원대학교 산림과학연구소 학술대회 Vol.2017 No.11
This study was carried out to predict and compare the merchantable volume by using two kinds of methods through ratio equations and taper models. To develop the merchantable volume model, the 131 stemmed sample trees were used as the data collected from the Korean red pine (Pinus densiflora), Korean white pine (Pinus koraiensis), and Japanese larch (Larix kaempferi) stands in Gangwon and North Gyeongsang provinces of South Korea. For volume ratio equations, general ratio forms and exponential ratio forms were used to predict merchantable volume up to any top diameter or top height. For stem taper models, well-developed Demaerschalk, Max & Burkhart, Kozak, Muhairwe, and Lee models were applied to predict merchantable volume up to any top height. The best equation was general ratio form for estimating up to any top height and exponential ratio form for estimating up to any top diameter according to the fit statistics and residual plots. Also, Kozak and Muhairwe models were shown as the best models for estimating up to any top height. Using the best models, estimated volumes were applicable with small RMSE. In addition, when comparing the predicted volumes between ratio form and taper model, it was not largely different. Consequently, two types of prediction were reasonable, and ratio form was considered to be more useful because of the convenience in the field.