Jungkee Choi

Nonlinear Height-DBH Growth Models for Larix kaempferi in Gangwon and North Gyeongsang Province

Abstract This study was conducted to estimate the best-fit nonlinear height-DBH growth models for Larix kaempferi in Gangwon and North Gyeongsang province in South Korea. Exponential, Modified Logistic, Chapman-Richards, and Weibull function were used for estimating height-DBH models. To evaluate the selected models, R 2 , RMSE, MD, MAD, and residual plots were performed in each model. Also, the coefficients and patterns in models of the previous studies were compared with those in this study. The result showed that Weibull equation was found to be the best-fit model with R 2 =0.9837, RMSE=2.6133, MD=0.0089, and MAD=2.0896. All model parameters in our study had similar values to those in the previous models except for asymptotic parameter a. Our research result showed that Gangwon and North Gyeongsang province were superior to other provinces with regard to height growth for Larix kaempferi.Key Words: Nonlinear growth models, Exponential, Modified Logistic, Chapman-Richards, Weibull Received: May 6, 2014. Revised: May 10, 2014. Accepted: May 11, 2014.Corresponding author: Jungkee ChoiDepartment of Forest Management, College of Forest and Environm ental Sciences, Kangwon National University, Chuncheon 200-701, Republic of KoreaTel: 82-33-250-8337, Fax: 82-33-259-5617, E-mail: jungkee@kangw on.ac.kr

Estimation and validation of stem volume equations for Pinus densiflora, Pinus koraiensis, and Larix kaempferi in South Korea

ABSTRACT Stem volume models using diameter at breast height (DBH) and height were developed for Pinus densiflora, Pinus koraiensis, and Larix kaempferi. The data were obtained from Gangwon, Gyeonggi, and North Gyeongsang provinces in South Korea, and the sample trees felled were used to provide the parameter estimates of volume equations. The combined-variable function, , was shown to be the best model through the validation of the equation. Also, the model using only DBH, was also evaluated to be applicable in the field. These models revealed higher accuracy when compared with previous studies. Both equations are considered to be easily used in the field.

Growth pattern analysis of major coniferous tree species in South Korea

ABSTRACT The size growth patterns of major coniferous trees species Pinus densiflora (Pd), Pinus koraiensis (Pk), and Larix kaempferi (Lk) in South Korea were found and compared using stem analysis. A dominant or co-dominant tree selected from each of 131 sites (39 sites for Pd, 47 sites for Pk, and 45 sites for Lk) was stemmed and analyzed for the study. Total increment (TI), periodic annual increments (PAI), mean annual increments (MAI), and growth percentage of diameter at breast height (DBH), height, and volume were numerically and statistically compared among the three tree species. As the trees age the total DBH growths of Pk and Lk were similar to each other but higher than that of Pd. A noticeable difference of total height growth was shown among the trees and the total height increment was Lk > Pk > Pd. Like the total height growth, the volume difference was noticeably different among the trees and the growth was Lk > Pk > Pd. Given no difference of DBH between Lk and Pk, the volume difference between the two species was due to height. Unlike DBH and height, MAI and PAI of volume did not meet together.. This inferred that the volume growth was still vigorous to reach the rotation age. Growth percentages of DBH, height, and volume tended to decrease with age and no difference was shown among the tree species. The growth percentage of volume was higher than that of DBH and height, while there was no difference between DBH and height.

Economic analysis of a small-sized combined heat and power plant using forest biomass in the Republic of Korea

ABSTRACT Economic analysis was conducted on the feasibility of operating a small-sized (500kW/hour) gasification power plant producing heat and electricity in a rural town surrounded by forests in the Republic of Korea. Cost factors that were considered over the plants 20-year life included wood procurement, a wood grab loader, a chipper, a chip dryer, a gasifier, a generator, land and building, wages, and office management. All the cost factors were calculated based on the 2016 market values for logs, information from machine manufacturers, and a literature review. Revenues were estimated from selling heat and electricity using the 2016 average prices that were sourced from Korea District Heating Corporation and Korea Power Exchange, respectively. Using a spreadsheet program, cash flows for costs and revenues were arranged to calculate net present value, internal rate of return, and payback period of the plant. Also, sensitivity analyses were performed on the cost of wood procurement and revenues from selling heat and electricity, which were the most significant factors affecting the economic feasibility. The results, as reinforced by the sensitivity analysis, suggest an investment in the small-sized gasification power plant may be attractive from a financial standpoint, especially if the owners are in a position to get additional revenue from heat sales and to take advantage of Renewable Energy Credits.

Estimation of Site Index for Larix kaempferi and Pinus koraiensis in Gangwon and North Gyeongsang Provinces

Abstract Site index curves were developed for Larix kaempferi and Pinus koraiensis in Gangwon and North Gyeongsang provinces in Korea. For the development of site index, Schumacher and Chapman-Richards model were applied using the data collected from 2012 to 2014. Base age was set to 40 years for Larix kaempferi and Pinus koraiensis in site index of this study. Coefficient of determination and root mean square error of site index models were provided by species, and the models were compared with the previous studies to check the suitability. Overall, site index models developed in this study fitted in the current data well. Thus, the site indexes are considered to be properly used in Gangwon and North Gyeongsang provinces.Key Words: Schumacher model, Chapman-Richards model, Base age, Dominant tree height Received: August 6, 2015. Revised: August 13, 2015. Accepted: August 13, 2015.Corresponding author: Jungkee ChoiDepartment of Forest Management, College of Forest and Environm ental Sciences, Kangwon National University, Chuncheon 24341, R epublic of KoreaTel: 82-33-250-8337, Fax: 82-33-259-5617, E-mail: jungkee@kangw on.ac.kr

Comparing forest structures in the border areas of the demilitarized zone of South Korea

ABSTRACT This study was conducted to inventory forest structures focusing on the border areas of the demilitarized zone, which are Goseong, Inje, Yanggu, Hwacheon, Cheolwon, Yeoncheon, and Paju, in South Korea. A total of 707 points were inventoried using a point sampling method. Forest type, tree species, diameter at breast height (DBH), and stand volume per hectare were analyzed and compared. The broad-leaved had the highest frequency with an average of 88%, followed by mixed (7%) and coniferous (5%) forest types in the border areas. A total of 62 tree species were observed and Quercus mongolica had the highest frequency with an average of 28%. By DBH class, small had the highest percentage with 63%, medium was 30%, and large was 7%. Mean DBH was relatively low (16.1 cm) with a range of 13.2 cm to 20.3 cm and the mean stand volume was 107 m3 ha−1 with a range of 80 m3 ha−1 to 123 m3 ha−1. Compared to the stand volume (137 m3 ha−1 in average) of the administrative district of the Korea Forest Service, our results showed that the stand volume of the border area is relatively low.

Growth Analysis of Red Pine (Pinus densiflora) by Stem Analysis in the Eastern Region of Korea

Abstract The study was performed to analyze the growth of the red pine (Pinus densiflora) in the Eastern Region of Korea. Stem profile data from a total of 8 dominant trees of which each tree represents its site were collected and used for the analysis. The stem volumes were calculated using Smalian’s formula and much higher than the ones by Korea Forest Research Institute in larger than dbh 40 cm. The total bark volumes were more proportionally related to dbh and stem volume than to height and age. The bark thickness and volume decreased as relative height increases but increased as relative dbh increased. The average PAI of dbh and height reached the highest at 0.8 cm/yr (age 15) and at 0.45 m/yr (age 30) respectively, while the average PAI of volume steadily tended to increase up to age 80. The growth percentages of dbh, height and volume tended to decrease with age and volume growth percentage was higher than dbh and height.Key Words: bark thickness, diameter growth, height growth, volume growth, periodic annual increment (PAI)

Height Growth Models for Pinus thunbergii in Jeju Island

Abstract Height growth models for Pinus thunbergii in Jeju Island were developed in this study using four widely used nonlinear growth models; Exponential, Modified Logistic, Chapman-Richards, and Weibull. All functions were found to be significant at the 1% level. Chapman-Richards model for height-DBH allometry and Weibull model for height-age allometry was chosen as the best model on the all validation. All the model curves showed the similar pattern. Additionally, there was no abnormal pattern when the previous studies were compared. Therefore, these models are highly expected to be used to estimate the tree height using DBH or age for Pinus thunbergii especially in Jeju Island.Key Words: Nonlinear growth models, Height, DBH, Age, Pinus thunbergii Received: November 10, 2015. Revised: November 12, 2015. Accept ed: November 16, 2015.Corresponding author: Jungkee ChoiDepartment of Forest Management, College of Forest and Environm ental Sciences, Kangwon National University, 188-77, Gongji-ro, Chuncheon 24345, Republic of KoreaTel: 82-33-250-8337, Fax: 82-33-259-5617, E-mail: jungkee@kangw on.ac.kr

Growth pattern analysis by stem analysis of Korean white pine (Pinus koraiensis) in the central northern region of Korea

The study was performed to find the growth pattern by stem analysis of Korean white pine (Pinus koraiensis) in the Central Northern Region of Korea. One standard tree from each of 16 sites was stemmed and analyzed for the study. For sampled trees, the age range was 16–77 years, diameter at breast height (DBH) was 15.8–44.4 cm, height was 9.3–24.0 m, and stem volume was 0.1002–1.8518 m3. The stem volumes by our study had higher values over 40 DBH compared to Korea Forest Research Institute measurements. The bark volume had no particular trend with DBH and height, while bark ratio tended to decrease with DBH and height. The DBH and height curves by age had a concave shape whereas volume curve had a convex shape. The average periodic annual increment (PAI) of DBH was the highest at age 15 (1.0 cm/yr), and the highest value of the mean annual increment (MAI) of DBH was 0.7 cm/yr at age 30. The highest values of PAI and MAI of height were 0.6 m/yr (age 15) and 0.5 m/year (age 25) respectively. The average PAI and MAI of volume continued to increase even after age 75. Growth percentages of DBH, height and volume tended to decrease with age, particularly rapidly at age 20–30. Volume growth percentage was much higher than diameter and height.