The site of this study was located on Mt. Moonsu in Gochang-gun, Jeollabuk-do and was created to provide the regeneration and cultivability plans considering the position and stand characteristics based on the ecological stability of forest environment in 1976. This site consisted of the five types ...
The site of this study was located on Mt. Moonsu in Gochang-gun, Jeollabuk-do and was created to provide the regeneration and cultivability plans considering the position and stand characteristics based on the ecological stability of forest environment in 1976. This site consisted of the five types of treatment plots including control, light thinning plot, normal thinning plot, heavy thinning plot, and super-heavy thinning plot. In these treatment plots, Chamaecyparis obtusa was planted as 3,000 by each experimental plot, and each plot was 20×20 size. This study was conducted to serve the basic information for managing Chamaecyparis obtusa stands, so the changes in the ecological characteristics were analyzed and the several kinds of growth models for Chamaecyparis obtusa were developed based on the thinning intensities. The results of this study were below. 1. Analysis on changing the ecological characteristics The total flora of the Chamaecyparis obtusa stand in Mt. Moosu appeared as 47 families 60 genus 70 species. Of these figures, woody plants were 48 taxa(60.7) and herbaceous plants were 31 taxa(39.3). According to the IUCN evaluation criterion, the three levels of the floristic regional indicator plants were verified as 6 taxa for the Ⅰ class, 1 taxon for the Ⅱ class, and 1 taxon for the Ⅲ class. On the other hand, Phytolacca americana and Robinia poseudoacacia appeared as the naturalized plants in the Chamaecyparis obtusa stand, and the naturalized ratio was shown as 8.0 among the vascular plants of 199 taxanomic groups. The number of appearance species was followed by light thinning(30 species), super-heavy thinning(27 species), normal thinning(26 species), heavy thinning(25 species), and control(15 species) regarding the quadrats, and by heavy thinning(31 species), light thinning(29 species), normal thinning(29 species), super-heavy thinning(28 species), and control(17 species) concerning the treatment plots. From the results of the analysis on the dominance index of understory vegetation, Chamaecyparis obtusa showed the highest value as 4.67. There was a delicate difference between the appearance states of each plot based on the thinning intensities. Whereas, there was a very distinct difference between the thinning and non-thinning plots. When analyzing the number of appearance species by using the cover rate, the stronger the thinning intensity, the more is it. Furthermore, there was a positive correlative between the mean height of the shrub layer and the thinning intensities. Once supposing that light intensity in the forest might be the biggest single reason for inducing the vegetation changes according to the thinning intensity, the effect of light intensity and temperature on the plant growth was analyzed. The more increased PPFD, the more increased was the total photosynthesis. The light saturation point was reached at PPFD of more than 1,400 . On the other hand, as a result of analysis on the effect of temperature on the total photosynthesis, if PPFD remained constant, the total photosynthesis was declined after rose according to the increase of temperature because of the breathing capacity increase. 2. Development of the growth models To develop the individual growth models by the treatment plots for the Chamaecyparis obtusa stand on Mt. Moonsu in Gochang-gun, the best suitable models were selected using the anamorphic- and polymorphic-formed equations of Schumacher, Chapman-Richards, Gompertz, and Hossfeld. Some regression equations which get excellent precision, accuracy, credibility, and normality were chosen as the optimal models. When selecting these models, criterion were MSE evaluating the excellence of modeling, Standard deviation showing the distribution of observed value, dispersion denoting how stretched or squeezed is a probability distribution, skewness and kurtosis meaning the measure of the asymmetry and peakedness of the probability distribution of a real-valued random variable about its mean, Shapiro-Wilk testing normality, homoscedasticity showing a sequence or a vector of random variables, and residual plot attempting to show the relationship between a given independent variable and the response variable given that other independent variables are also in the model. The most of all individual growth models was the polymorphic-formed equations except the basal area growth model for the control site, so the polymorphic-formed equations seem to be more suitable for the growth models of Chamaecyparis obtusa in Gochang-gun than the anamorphic-formed equations. Also, every chosen equation had high normality with more than 0.95. The stand growth models of site index and number of trees per in common and basal area per , mean height, mean DBH, mean H to mean DBH, and volume per by the treatment plots were exploited. Site index was shown as 16 for the study area, so using this value as the standard, classified site index curves were developed with the site index range from 12 to 20. The number of trees per was rapidly decreased until the stand age become about 30 years old. Therefore, an asymptote was closely approached at around 2,800. Analyzing the mean height growth models by the treatment sites, although the mean height was slightly gone up after low thinning, there seem to be little difference in the mean height growth between thinning intensities. Also, there was no distinct difference in the increase range caused by thinning. Therefore, it was proved that thinning does not make an effect on the mean stand height growth. The new variable, the number of trees per , was supplemented on the previous stand growth models of basal area at the breast height and volume per unit area to make them more efficient and flexible. From the simulation results, the higher the thinning intensity, the higher is amount of the annual growth of BA and V per unit area after thinning. Therefore, thinning might be judged to have a strong influence on the growth of the Chamaecyparis obtusa stand. Furthermore, by the results of analysis on the relationship between H/D value and stand stability concerning the treatment plots, the stronger the thinning intensity, the better was the mean DBH. As a result, the H/D value was shown to be decreased in process of time, and thinning might be the best way to promote the stand stability.
The site of this study was located on Mt. Moonsu in Gochang-gun, Jeollabuk-do and was created to provide the regeneration and cultivability plans considering the position and stand characteristics based on the ecological stability of forest environment in 1976. This site consisted of the five types of treatment plots including control, light thinning plot, normal thinning plot, heavy thinning plot, and super-heavy thinning plot. In these treatment plots, Chamaecyparis obtusa was planted as 3,000 by each experimental plot, and each plot was 20×20 size. This study was conducted to serve the basic information for managing Chamaecyparis obtusa stands, so the changes in the ecological characteristics were analyzed and the several kinds of growth models for Chamaecyparis obtusa were developed based on the thinning intensities. The results of this study were below. 1. Analysis on changing the ecological characteristics The total flora of the Chamaecyparis obtusa stand in Mt. Moosu appeared as 47 families 60 genus 70 species. Of these figures, woody plants were 48 taxa(60.7) and herbaceous plants were 31 taxa(39.3). According to the IUCN evaluation criterion, the three levels of the floristic regional indicator plants were verified as 6 taxa for the Ⅰ class, 1 taxon for the Ⅱ class, and 1 taxon for the Ⅲ class. On the other hand, Phytolacca americana and Robinia poseudoacacia appeared as the naturalized plants in the Chamaecyparis obtusa stand, and the naturalized ratio was shown as 8.0 among the vascular plants of 199 taxanomic groups. The number of appearance species was followed by light thinning(30 species), super-heavy thinning(27 species), normal thinning(26 species), heavy thinning(25 species), and control(15 species) regarding the quadrats, and by heavy thinning(31 species), light thinning(29 species), normal thinning(29 species), super-heavy thinning(28 species), and control(17 species) concerning the treatment plots. From the results of the analysis on the dominance index of understory vegetation, Chamaecyparis obtusa showed the highest value as 4.67. There was a delicate difference between the appearance states of each plot based on the thinning intensities. Whereas, there was a very distinct difference between the thinning and non-thinning plots. When analyzing the number of appearance species by using the cover rate, the stronger the thinning intensity, the more is it. Furthermore, there was a positive correlative between the mean height of the shrub layer and the thinning intensities. Once supposing that light intensity in the forest might be the biggest single reason for inducing the vegetation changes according to the thinning intensity, the effect of light intensity and temperature on the plant growth was analyzed. The more increased PPFD, the more increased was the total photosynthesis. The light saturation point was reached at PPFD of more than 1,400 . On the other hand, as a result of analysis on the effect of temperature on the total photosynthesis, if PPFD remained constant, the total photosynthesis was declined after rose according to the increase of temperature because of the breathing capacity increase. 2. Development of the growth models To develop the individual growth models by the treatment plots for the Chamaecyparis obtusa stand on Mt. Moonsu in Gochang-gun, the best suitable models were selected using the anamorphic- and polymorphic-formed equations of Schumacher, Chapman-Richards, Gompertz, and Hossfeld. Some regression equations which get excellent precision, accuracy, credibility, and normality were chosen as the optimal models. When selecting these models, criterion were MSE evaluating the excellence of modeling, Standard deviation showing the distribution of observed value, dispersion denoting how stretched or squeezed is a probability distribution, skewness and kurtosis meaning the measure of the asymmetry and peakedness of the probability distribution of a real-valued random variable about its mean, Shapiro-Wilk testing normality, homoscedasticity showing a sequence or a vector of random variables, and residual plot attempting to show the relationship between a given independent variable and the response variable given that other independent variables are also in the model. The most of all individual growth models was the polymorphic-formed equations except the basal area growth model for the control site, so the polymorphic-formed equations seem to be more suitable for the growth models of Chamaecyparis obtusa in Gochang-gun than the anamorphic-formed equations. Also, every chosen equation had high normality with more than 0.95. The stand growth models of site index and number of trees per in common and basal area per , mean height, mean DBH, mean H to mean DBH, and volume per by the treatment plots were exploited. Site index was shown as 16 for the study area, so using this value as the standard, classified site index curves were developed with the site index range from 12 to 20. The number of trees per was rapidly decreased until the stand age become about 30 years old. Therefore, an asymptote was closely approached at around 2,800. Analyzing the mean height growth models by the treatment sites, although the mean height was slightly gone up after low thinning, there seem to be little difference in the mean height growth between thinning intensities. Also, there was no distinct difference in the increase range caused by thinning. Therefore, it was proved that thinning does not make an effect on the mean stand height growth. The new variable, the number of trees per , was supplemented on the previous stand growth models of basal area at the breast height and volume per unit area to make them more efficient and flexible. From the simulation results, the higher the thinning intensity, the higher is amount of the annual growth of BA and V per unit area after thinning. Therefore, thinning might be judged to have a strong influence on the growth of the Chamaecyparis obtusa stand. Furthermore, by the results of analysis on the relationship between H/D value and stand stability concerning the treatment plots, the stronger the thinning intensity, the better was the mean DBH. As a result, the H/D value was shown to be decreased in process of time, and thinning might be the best way to promote the stand stability.
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