• Journal of Climate Change Research
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• v.7 no.2
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• pp.157-167
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• 2016

This study aims to evaluate the effect of shortened final cutting age by estimating future $CO_2$ absorption in each different scenarios based on each final cutting ages before and after shortening. We used $5^{th}$ Forest Type Map and Forest Yield Table to obtain information to estimate $CO_2$ absorption of forest. We also designed a simulated future scenarios from 2010 to 2100 which repeats cutting and reforestation according to respected each final cutting ages. As the result, number of cuttings and total amount of $CO_2$ absorption of forest were increased with shortened final ages. Total cutting times increased up to 2 in both minimum and maximum amount for Quescus spp. and Larix kaempferi. Maximum number of cutting of Pinus densiflora and minimum number of Pinus koraiensis increased by 1. Total $CO_2$ absorption increased 12％ for Quercus spp. which had the largest number of increase in cutting times, while total $CO_2$ absorption of Pinus koraiensis only increased by 1％. The result could be used to evaluate the changes in forest management plans and policies and then develop optimal final age for efficient sustainable forest management plans.

• Journal of Korean Society of Forest Science
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• v.109 no.4
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• pp.468-476
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• 2020

we developed a stand density management diagram for Quercus variabilis in order to predict the final cutting ages of coppice forests based on management objectives. The sample data were classified into two groups: 603 data points for analysis and 113 data points for verification. Using these data, a stand density management diagram was constructed and a goodness-of-fit test was performed. The explanatory power (R2) of the constituent models for the stand density management diagram was 0.732 for the equivalent height curve and 0.990 for the equivalent diameter curve. According to the analysis of the final cutting age rangeof the highest production, the final cutting ages for 900 buds remaining per hectare was 42-44 years, and that for the 1,800 buds remaining per hectare was 38-42 years. With the third-grade log set as the production target, the final cutting age range with site index 16 and 14 was 25-28 years and 29-33 years, respectively. The results of this study provide baseline data for establishing a management plan for Q. variabilis coppice stands.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.292-304
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• 2011

The purpose of this study is to draw institutional implications for tree cutting permit system improvement in comparison with Korea and foreign countries (German, Japan). A survey about recognition of cutting system and cutting-invigorating factors for two groups in charge of work for cutting permit (forest-official) and cutting operation (forest owner, tree butcher, forestry association, and forestry corporation) was carried out. The survey provides basic information which is necessary to improve current cutting system. The result of analysis about both German and Japan's cutting system show that clear cutting area to hinder function of forests tends to decrease and flexible final age of maturity considering condition of regional forest not uniform cutting age were applied. As a result of German and Japan's cutting system review flexible cutting system on regional characteristics is used to manage for the purpose of forest regeneration. The survey result about awareness and invigorating factors of cutting system represents that only public official group said final age of pine tree (3.13) and cedar (3.05) was proper and final age of other species of trees should have shortened. In matters of cutover area, current standard is less than 5ha per a felling area and the largest total area limit is 30 ha, only tree butcher, forestry corporation said cutover area must expand. Invigorating factors of current cutting system are reinforcement of cutover area, facility support, enrichment of technical training, increase of equipment support, simplification of administrative procedures, and provision of various benefits. The reinforcement of technical training among them especially represents the statistical significance of the participants' differential recognition.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.225-230
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• 2009

Using dynamic programming, which is one of operations research techniques, the best pathway was chosen to maximize the total harvest volume for a Korean white pine (Pinus koraiensis) stand. This study was carried out in an age class III at Chuncheon National Forest, Gangwon province. That stand was assumed to apply 3 different thinning intensities of none, 30% and 50% thinnings. These thinning pathways are planned to implement two times, of thinning at 35 age and 55 age. The final cutting (rotation age) is assumed to carry out in 70 years. A growth function for Korean white pine stand was developed with forest inventory data, the volume was calculated with this growth function. As a result, the best thinning pathway for this Korean white pine stand using dynamic programming is to implement 30% at the first thinning and 50%at the second thinning.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.40 no.3
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• pp.351-358
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• 1995

Since summer growth depression of forage crops limits hay production in Korea, it is important to exploit natural resources which are suitable as forage. In the preliminary experiment it was found that Panicum dichotomiflorum Michx. might be utilized as soiling and hay crop. Effects of seed stratificaion, planting date and number of harvestings on fresh and dry yields of Panicum dichotomiflorum Michx. were investigated in 1993 and 1994. Stratification of seed promoted emergence, while seed age decreased emergence. Although fresh yield was closely related with number of plants estabilished per unit area, effect of number of plants per unit area on yield was less at the later stage of growth. Higher cutting height decreased fresh and dry yield at th early stage, but final yields were not influenced by cutting height. Panicum dichotomiflorum Michx. could be harvested 3~4 times beginning 40~50 days after planting and fresh and dry yields were 9~10 tons /10a and 1.4~1.8 tons /10a, respectively. Fresh and dry yields were significantly influenced by growth duration or accumulated temperature between cuttings. Leaf blade ratio was higher at earlier planting and / or harvesting. Contens of crude protein, crude fat and crude ash were 16.32, 24.01 and 11.59%, respectively.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.613-621
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• 2022

The study aim was to investigate changes in the diameter, number of standing trees, stand volume per ha and site index by the forest survey order, climate zone (northern temperate, central temperate, southern temperate, and warm temperate regions), and altitude in 100 m intervals) by collecting samples of Robinia pseudoacacia from the fifth, sixth, and seventh national forest survey datasets. The rotation cutting age, which is a standard used for wood, was calculated. The changes were statistically analyzed by performing ANOVA and the Duncan multiple test. Diameter growth naturally increased according to the forest survey order and was lowest in the southern temperate region by climate zone and lowest at the 301-400 m altitude. The number of standing trees per ha did not change according to the forest survey order and altitude, and the density was highest in the central temperate region and lowest in the southern temperate region. The stand volume per ha increased according to the forest survey order, and the climate zone was divided into two groups: ① northern temperate region and central temperate region, ② southern temperate region and warm temperate region. The stand volume growth was highest at the 201-300 m point. Thesite index showed results similar to the change pattern of the stand volume per ha. The growth curve, which can be seen by the change in stand volume per ha, was estimated by applying theWeibull formula, and the stand volume per ha was estimated to reach approximately 200 m³/ha at 50-60 years. The rotation of the highest production in volume, which is the standard for using trees as wood rather than honey sources, was calculated to be 34 years.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.396-403
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• 2009

Male broiler chicks were fed graded levels of organic zinc (zinc-methionine) supplementation to investigate the effects of partial or complete substitution of the organic zinc source for inorganic ones on the development of lymphoid organs and immunological responses. A total of 450 day-old male broilers were distributed into groups of 10 chicks and randomly assigned to nine experimental diets during a 42-day feeding trial. Dietary treatments consisted of two basal diets supplemented with 40 mg/kg added zinc as feed-grade Zn sulfate or Zn oxide in which, Zn was replaced with that provided from zinc-methionine (ZnMet) complex at the levels of 25, 50, 75 or 100%. Two randomly-selected birds from each pen replicate were bled and then slaughtered by cervical cutting on the final day of the trial to measure leukocyte subpopulations and relative weights of lymphoid organs. Among lymphoid organs, only thymus weight was affected (p<0.05) by dietary treatments. The sulfate-supplemented birds were heavier (p<0.01) in relative weight of thymus than oxide-supplemented birds. The 10 days of age-assessed cutaneous hypersensivity reaction was stronger in chicks fed ZnMet-containing diets. Dietary ZnMet supplementation caused (p<0.05) an increase in proportion of lymphocytes and consequently a decrease in heterophil to lymphocyte ratio. Diet fortification by zinc-methionine complex increased (p<0.01) Newcastle antibody titer at 19 days of age. Also, a similar response was observed in antibody titers at 6 and 12 d after infectious bronchitis vaccine administration. There was no significant effect of replacement of dietary zinc on antibody titer against infectious bursal disease virus (IBDV) at the 6th d post-vaccine inoculation; however, at d 12 after vaccination, ZnMet-fortified diets improved antibody titer against IBDV. Although dietary inclusion of ZnMet had no marked effect on primary antibody titer against sheep erythrocytes, effective responses were observed during secondary reaction from the viewpoint of both total antibody and immunoglobulin Y (IgY) titers. From the present findings, it can be concluded that dietary supplementation with organic zinc improves both cellular and humoral immune responses. It is necessary to replace 75% of supplemental inorganic zinc with organic ZnMet complex to achieve the optimum immunological responses in broiler chicks.

• Journal of Korean Society of Forest Science
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• v.110 no.4
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• pp.648-657
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• 2021

This study was conducted to estimate the volume growth by forest type and major species using the national forest resource inventory and to predict the final age of maturity by deriving the mean annual increment (MAI) and the current annual increment (CAI). We estimated the volume growth using the Chapman-Richards model. In the volume estimation equations by forest type, coniferous forests exhibited the highest growth. According to the estimation formula for each major species, Larix kaempferi will grow the highest among coniferous tree species and Quercus mongolica among broad-leaved tree species. And these estimation formulas showed that the fitness index was generally low, such as 0.32 for L. kaempferi and 0.21 for Quercus variabilis. In the analysis of residual amount, which indicates the applicability of the volume estimation formula, the estimates of the estimation formula tended to be underestimated in about 30 years or more, but most of the residuals were evenly distributed around zero. Therefore, these estimation formulas have no difficulty estimating the volume of actual forest species in Korea. The maximum age attained by calculating MAI was 34 years for P. densiflora, 35 years for L. kaempferi, and 31 years for P. rigida among coniferous tree species. In broad-leaved tree species, we discovered that the maximum age was 32 years for Q. variabilis, 30 years for Q. acutissima, and 29 years for Q. mongolica. We calculated MAI and CAI to detect the point at which these two curves intersected. This point was defined by the maximum volume harvesting age. These results revealed no significant difference between the current standard cutting age in public and private forests recommended by the Korea Forest Service, supporting the reliability of forestry policy data.