• Journal of Environmental Science International
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• v.17 no.8
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• pp.891-898
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• 2008

This study was conducted to develop the effects of site environmental factors on estimation of site index function for Chamaecyparis obtusa Endlicher stands. We derived nonlinear growth equation and the draw site index curves by applying this estimated equation. This study with Chapman-Richards function showed significant P-value which was less then 0.0001 and $R^2$ value 0.5947. This study was conducted to develop the feasible site index equation of Chamaecyparis obtusa Endlicher. For the table, the data of 82 sample areas that were thought to be without errors among the data of Chamaecyparis obtusa Endlicher sample area located on the value-oriented forest location chart were used and estimated. After analyzing the quantification method I based on 13 environmental factors to develop the score table for the site-index estimation of Chamaecyparis obtusa Endlicher, $R^2$ value of the model was 0.7555. It has been analyzed that the scope value of Soil moisture in horizon A was 7.5045, that of total soil depth was 6.3896, that of topography was 5.3471, that of slope was 4.7000 and that of aspect was 3.2038. After analyzing the partial correlation to examine the factors that affected most the site-index of Chamaecyparis obtusa Endlicher, it has been noted that the partial correlation of climatic zone was 0.4987, which was highest, and it was followed by Soil moisture in horizon A (0.4592), slope (0.4537), topography (0.3299) and total soil depth (0.1035). As a result of conducting the significance test for partial correlation, it has been found that topography, climatic zone, parent rock, slope, altitude, aspect, Soil moisture in horizon A, soil hardness in horizon A and total soil depth were recognized significant with 1% of significance level and sedimentary type and soil texture in horizon A were recognized significant with 5% of significance level.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2010.04a
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• pp.70-73
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• 2010

• Journal of Forest and Environmental Science
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• v.30 no.1
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• pp.36-44
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• 2014

We measured radial growth of Cryptomeria japonica and Chamaecyparis obtusa growing in Gangneung, Boseong, Yangsan and Ulleung-do, respectively and analyzed its relationship with temperature and precipitation. We found from the result of tree ring counting that forest stands of Cryptomeria japonica in Gangneung and Boseong was 40 to 50 years old and 50 to 70 years old in Yangsan and Ulleung-do. According to climate change, the mean temperature in Gangneung was found to be $12^{\circ}C$ to $13^{\circ}C$ which was similar to that of Boseong and Yangsan 40 to 50 years ago. While the result of the radial growth measured from Cryptomeria japonica in Gangneung showed a slightly decreasing tendency compared to the other areas, Chamaecyparis obtusa showed an increasing tendency. In the case of Cryptomeria japonica, a strong negative correlation between radial growth and climate related variables including both mean temperature and mean precipitation existed in Ulleung. There was a strong negative correlation between radial growth and mean temperature for Chamaecyparis obtusa in Yangsan, although there was a positive correlation in Gangneung and Yangsan.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.2
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• pp.71-79
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• 2023

The quantification of soil respiration rates is important to understand carbon cycles of forest ecosystems. Soil respiration rates were assessed using Li-8100A soil flux system in one evergreen broadleaved (Quercus glauca Thunb.) and two coniferous (Cryptomeria japonica D. Don and Chamaecyparis obtusa Endl.) stands from May 2020 to April 2022 in southern Korea. Monthly variations of soil respiration rates were higher in the Q. glauca stand than in the C. japonica and the C. obtusa stands. The mean soil respiration rates were significantly higher in the Q. glauca stand (2.63µmol m^-2 s^-1) than in the C. japonica (0.93µmol m^-2 s^-1) and C. obtusa (0.99µmol m^-2 s^-1) stands. The three stands showed exponential relationships between soil respiration rates and soil temperature (R² = 0.44-0.80). The sensitivity of temperature (Q10 values) to soil respiration rates was highest in the Q. glauca stand (5.13), followed by the C. obtusa (3.10) and C. japonica (2.58) stands. These results indicate that soil respiration rates can be increased more in evergreen broadleaved stands than in coniferous stands under enhanced soil temperature.

• Journal of Korean Society of Forest Science
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• v.80 no.4
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• pp.393-407
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• 1991

The vegetation structure within Chamaecyparis obtusa plantation was analyzed for the purpose of applying the effective forestation method for Chmaecyparis obtusa plantation, tending and regeneration in the southern districts of korea. The results were as follows ; 1. The importance percentage was high in the order of Eurya japonica, Rhus verniciflua, Chamaecyparis obtusa, Lindera erythrocarpa, Carpinus laxiflora, Styrax japonica, Viburnum dilatatum, Zanthoxylum piperitum and Smilax china among the vegetation of Chamaecyparis obtusa. Importance percentage of natural seedling of Chamaecyparis obtusa was high in lower story but gradually decreased in middle story. 2. The basal area of upper trees had a negative correlation with the density of natural seedlings in the middle and lower story, and it represents that the basal area of upper trees had some effect on the density of natural seedlings within understories. 3. The rate of the A and B class by Raunkiaer's frequency was higher in the vegetation of middle story than that of lower story. 4. By Morisita's index, the species of Chamaecyparis obtusa, Rhus verniciflua, Lindera erythrocarpa, Smilax china. Callicarpa japonica and Lindera obtusiloba were randomly distributed at lower story, but they were aggregatively distributed at middle story. At all of middle and lower story, Eurya japonica and Viburum dilatatum were randomly distributed, and Carpinus laxiflora, Zanthoxylum piperitum and Picrasma quassioides were aggregatively distributed. 5. The number of appearance species and the value of species diversity in western survey area were more than that of eastern survey area. 6. The value of species diversity at lower story was higher than that of middle story, and it represents that the number of individuals of appearance species was composed more even at lover story than middle story. 7. According to cluster analysis by similarity index, the survey areas were separated from inland and seacoast districts. 8. Judging from each stories ordination analysis by dissimilarity index, the vegetation was separated from lower and middle story, and the vegetation of lower story was more progressed succession stage than that of middle story. 9. In Chamaecyparis obtusa stands, Eurya japonica had a positive correlation with Sorbus alnifolia, Hex macropoda. Ficus erecta and Trachelospermum asiaticum, but it had a negative correlation with Zanthoxylum piperitum, Carpinus laxiflora and Parthenocissus tricuspidata. 10. In estimation of the productivity of Chamaecyparis obtusa stands, the value of SC (Conic surface) and VP (Parabolic volume) for upper trees was 94.5% and 99.63%, respectively and SC and VP of middle story was 5.49% and 0.37%, respectively. In the species of middle story, material productivity was high in order of Eurya japonica. Lindera eryhrocarpa, Rhus verniciflua. Carpinus laxiflora and Styrax japonica.

• Journal of Korean Society of Forest Science
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• v.108 no.3
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• pp.349-356
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• 2019

This study examines the effect of thinning in terms of changes in the growth characteristics of Chamaecyparis obtusa stands after they were thinned with varying intensity in Gochang, North Jeolla Province, Korea. Thinning was carried out in 2000 on Chamaecyparis obtusa stands (22 years old), and the stands were categorized in terms of the thinning intensity in the experiment: very heavy, heavy, medium, light, and control. The results of monitoring up to 2018 revealed that the diameter at breast height and the growth rate of individual trees after thinning had a positive correlation with the thinning intensity, whereas the stand volume showed a negative correlation. The height to diameter (H/D) ratio decreased by up to 70-80 due to the increased diameter at breast height after thinning and thereby resulted in better quality. The relative yield index right after the first thinning was between 0.75 and 0.95, which suggests the best timing for the first thinning had been missed. This study's findings are expected to serve as a basic reference in establishing the thinning system for Chamaecyparis obtusa forests.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.515-522
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• 2023

The aim of this study was to quantitatively evaluate a new stem volume table for estimating the growth, carbon storage, and greenhouse gas (GHG) absorption in Cryptomeria japonica and Chamaecyparis obtusa stands and to provide suggestions for improving the domestic GHG inventory. Carbon storage and GHG absorption were estimated using growing stock data obtained from invariable sub-sample plots between the 6^th and 7^th national forest inventories. We assessed changes in growing stock using the parameters employed by Kozak (1988) and Versions 1 and 2 of the stem volume table. Version 2 has new stem tables for 16 species, including Cryptomeria japonica, which were unavailable in Version 1. Version 2 also includes new data for trees with diameters at breast height equal to or greater than 30 cm. We found greater growing stock values using Version 2 than Version 1 for both stands, and the differences were statistically significant (p<0.001). Applying the new stem volume table increased GHG absorption by 22% for the Cryptomeria japonica stand and 13% for the Chamaecyparis obtusa stand. The growing stock estimation method used in this study should therefore be applied to re-estimate GHG absorptions in the forestry sector to produce accurate statistics for the IPCC guidelines.

• Journal of Korean Society of Forest Science
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• v.109 no.2
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• pp.169-178
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• 2020

This study aimed to compare the organic carbon stocks of Cryptomeria japonica and Chamaecyparis obtusa stands established under a similar-site environmental condition in South Korea. C. japonica and C. obtusa stands adjacent to each other from 13 representative regions were chosen to evaluate the carbon stocks of tree biomass, forest floor, and mineral soils. Mean stand ages were 45 years for C. japonica and 43 years for C. obtusa, respectively. Tree density was significantly lower in C. japonica (989 tree ha^-1) than in C. obtusa (1,223 tree ha^-1) stands, whereas diameter at breast height and dominant tree height values were significantly higher in C. japonica (27.4 cm and 20.4 m, respectively), compared with C. obtusa (23.9 cm and 17.9 m, respectively) stands. The total carbon stocks of tree biomass were linearly related with stand basal area (C. japonica: r² = 0.82; C. obtusa: r²= 0.92; P< 0.05), whereas stand density and site index were not correlated with the carbon stocks of tree biomass (P > 0.05). The carbon stocks of aboveground tree biomass were significantly higher in C. obtusa (117.7 Mg C ha^-1), compared with C. japonica (95.5 Mg C ha^-1) stands, whereas carbon concentration and stocks of the forest floor and mineral soil layers were insignificantly different between the C. japonica and C. obtusa stands. The results indicated that trees in C. obtusa stands sequestrated more carbon dioxide, compared with C. japonica stands, whereas carbon stocks in the forest floor and mineral soil layers were unaffected by stand development processes of the different tree species.

• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.477-483
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• 2020

We constructed a stand yield table for Chamaecyparis obtusa based on data from an actual forest. The previous stand yield table had a number of disadvantages because it was based on actual forest information. In the present study we used data from more than 200 sampling plots in a stand of Chamaecyparis obtusa. The analysis included theestimation, recovery and prediction of the distribution of values for diameter at breast height (DBH), and the result is a valuable process for the preparation ofstand yield tables. The DBH distribution model uses a Weibull function, and the site index (base age: 30 years), the standard for assessing forest productivity, was derived using the Chapman-Richards formula. Several estimation formulas for the preparation of the stand yield table were considered for the fitness index, and the optimal formula was chosen. The analysis shows that the site index is in the range of 10 to 18 in the Chamaecyparis obtusa stand. The estimated stand volume of each sample plot was found to have an accuracy of 62%. According to the residuals analysis, the stands showed even distribution around zero, which indicates that the results are useful in the field. Comparing the table constructed in this study to the existing stand yield table, we found that our table yielded comparatively higher values for growth. This is probably because the existing analysis data used a small amount of research data that did not properly reflect. We hope that the stand yield table of Chamaecyparis obtusa, a representative species of southern regions, will be widely used for forest management. As these forests stabilize and growth progresses, we plan to construct an additional yield table applicable to the production of developed stands.

• Journal of Korean Society of Forest Science
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• v.94 no.2 s.159
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• pp.121-126
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• 2005

This study was carried out to construct a single diameter and a single height model that could localize Chamaecyparis obtusa stand grown in 3 Southern regions of Korea. Dummy variables, which convert qualitative information such as geographical regions into quantitative information by means of a coding scheme (0 or 1), were used to localize growth models. In results, modified form of Gompertz equation, $Y_2={\exp}({\ln}(Y_1){\exp}(-{\beta}(T_2-T_1)+{\gamma}({T_2}^2-{T_1}^2))+({\alpha}+{\alpha}_1Al+{\beta}_1k_1+{\beta}_2k_2)(1-{\exp}(-{\beta}(T_2-T_1)+{\gamma}({T_2}^2-{T_1}^2))$, for diameter and height was successfully disaggregated to provide different projection equation for each of the 3 regions individually. The use of dummy variables on a single equation, therefore, provides potential capabilities for testing the justification of having different models for different sub-populations, where a number of site variables such as altitude, annual rainfall and soil type can be considered as possible variables to explain growth variation across regions.