• The Korean Journal of Ecology
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• v.23 no.2
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• pp.83-88
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• 2000

When interpreting change over time in forest ecosystems, distinguishing the effects of forest succession from the effects of environmental stress can be difficult. The result may be a simplistic interpretation. citing a specific successional or environmental cause of forest change when both types may be occurring. We present two case studies of changes in the forest floor in northern hardwoods. First, the belief that 50% of soil organic matter is lost in the first 20 years after logging was based on a study comparing northern hardwood stands of different ages. We resampled a series of 13 such stands after an interval of 15 years, and found that the young stands were not, in fact. losing organic matter as rapidly as predicted from the original chronosequence study. The pattern of higher organic matter content in the forest floors of older stands compared to young stands could be equally well explained by changes in logging practices over the last century as by the aging of the stand. The observed pattern of forest floor organic matter as a function of stand age was previously interpreted as a successional pattern, ignoring changes in treatment history. In the second case study, observed losses of base cations from the forest floor were attributed to cation depletion caused by acid rain and declining calcium deposition. We found that young stands were gaining base cations in the forest floor; losses of base cations were restricted to older stands. Differences in litter chemistry in stands of different ages may explain some of the pattern in cation gains and losses. In this case, the contribution of successional processes to cation loss had been overlooked in favor of environmental stress as the dominant mechanism behind the observed changes. Studies of environmental stress use repeated measures over time. but often don't consider stand age as a factor. Studies of successional change often assume that environmental factors remain constant. We were able to consider both forest succession and external factors because we repeatedly sampled stands of different ages.

• Journal of Korean Society of Forest Science
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• v.101 no.4
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• pp.592-598
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• 2012

Forest stand yield and its changes along with 10 thinning scenarios were estimated using a forest stand yield model for six major tree species in Korea, such as Pinus densiflora in Gangwon province, Pinus densiflora in other regions, Pinus koraiensis, Larix leptolepis, Quercus acutissima Carruth, Quercus mongolica. The 10 thinning scenarios were generated based on a number of constraints and assumptions. For instance, it was assumed that thinning is implemented between 15 years and 40 years with 5 year period and its duration should be at least 10 years. Also, the overall removal rate from the thinning treatments was assumed to be not greater than 60%. Under the 10 scenarios, the overall stand yield volumes from thinning and final harvesting were estimated for each species and site index. The results showed that highest yield volumes were obtained for Pinus densiflora in Gangwon province, Pinus koraiensis and Quercus mongolica when 30% of basal areas were thinned at 20 and 40 years, while highest yield volumes were obtained for Pinus densiflora in other regions and Larix leptolepis when 20% of basal areas were thinned at 20, 30 and 40 years. Those two scenarios gave the same amount of highest yield volume for Quercus acutissima Carruth. Also the results indicated that thinning treatment is effective to increase overall stand yield volume and its effects are larger with a higher site index. The largest thinning effects were found in Pinus densiflora in Gangwon province (28%) and Larix leptolepis (25%), while limited in Pinus koraiensis (12%). The forest stand yield model, used in this research, could be an effective tool for estimating the stand dynamics with various thinning treatments, but it could be improved in a further research that validates its applicability in the field.

• Journal of Korean Society of Forest Science
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• v.82 no.2
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• pp.188-194
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• 1993

A natural Quercus variabilis forest and a Populus alba${\times}$P. glandulosa plantation in Mt. Mohu area were studied to investigate aboveground biomass and net production. A $20m{\times}30m$ quadrat was set up in each stand, and 10 sample trees each of Quercus variabilis and Populus alba ${\times}$ P. glandulosa were cut for dimension analysis. There was little difference in accuracy among three biomass regression models of logWt=A+BlogD, $logWt=A+BlogD^2H$, and logWt=A+BlogD+ClogH, where Wt. D, and H were dry weight, DBH, and height, respectively. Aboveground total biomass of Quercus variabilis stand was 31,275kg/ha, and that of Populus alba ${\times}$ P. glandulosa was 55,581kg/ha. In both of Quercus variabilis stand and Populus alba ${\times}$ P. glandulosa stand, the proportion of each tree component to abovegound total biomass was high in order of stem wood, branches, stem bark, and leaves. Quercus variabilis stand was higher in the proportion of stem bark, branches and leaves than Populus alba ${\times}$ P. glandulosa stand, while the former was lower in that of stem wood than the latter. Aboveground total net production of Quercus variabilis stand was 4,267kg/ha/yr., and that of Populus alba ${\times}$ P. glandulosa stand was 3,903kg/ha/yr. The proportion of each tree component to aboveground total net production of Quercus variabilis stand was high in order of leaves, stem wood, branches, and stem bark. That of Populus alba ${\times}$ P. glandulosa stand was high in order of stem wood, leaves, branches, and stem bark. Net assimilation rate and efficiency of leaf to produce stem of Quercus variabilis stand were 2.121 and 0.840, respectively. Those of Populus alba ${\times}$ P. glandulosa stand were 3.376 and 2.085, respectively. Though Populus alba${\times}$P. glandulosa stand was lower in aboveground total net production than Quercus variabilis stand, the former was higher in aboveground total biomass than the latter. The reason was that Populus alba${\times}$P. glandulosa stand was higher in net production of stem wood of accumulation organs than Quercus variablis stand.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.512-514
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• 2005

Accurate DEM surface of forest floor is very important to extract any meaningful information regarding forest stand structure, such as tree heights, stand density, crown morphology, and biomass. In airborne lidar data processing, DEM data of forest floor is mostly generated by interpolating those elevation points obtained from last laser returns. In this study, we try to analyze the property of the last laser return under relatively dense forest canopy. Airborne laser data were obtained over the study area in relatively dense pine plantation forest. Two DEM data were generated by using all the points in the last laser returns and using only those points after removing non-ground points. From the preliminary analysis on these DEM data, we found that more than half of points among the last laser returns are actually hit from canopy, branches, and understory vegetation that should be removed before generating the surface DEM data.

• The Korean Journal of Ecology
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• v.23 no.2
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• pp.131-134
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• 2000

Forest vegetation in Korea can be largely divided into warm temperate, cool temperate and frigid forest zone. The cool temperate forest zone of them occupies the largest part of the Korean peninsula and it is generally divided into three subdivisions such as northern, central and southern subzone. The Forestry Research Institute established three long-term ecological research sites at Kwangnung Experiment Forest in the central subzone of the cool temperate forest zone, at the Mt. Kyebangsan Forest in the northern subzone of the cool temperate forest zone. and at the Mt. Keumsan Forest in the warm temperate forest zone. The objectives of long-term ecological research in the Forestry Research Institute, Korea are to study long-term changes of the forest ecosystems in energy fluxes, water and nutrient cycling, forest stand structure, biological diversity, to quantify nutrient budgets and fluxes among forest ecosystem compartments and to integrate ecological data with a GIS - assisted model. To achieve the objectives, forest stand dynamics. environmental changes in soil properties, stream water quality, nutrient cycling, air pollution and biological diversity have been investigated and plant phonology as an indicator of climate change has been monitored in the LTER sites.

• Journal of Ecology and Environment
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• v.30 no.4
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• pp.281-285
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• 2007

We conducted research to determine the effects of forest tending works (FTW) on forest carbon (C) storage in Korean red pine forests by estimating changes in the quantity and distribution of stored organic C in an approximately 40-year-old red pine stand after FTW. We measured organic C storage (above- and belowground biomass C, forest floor C, and soil C at 50 cm depth) in the Hwangmaesan Soopkakkugi model forest in Sancheonggun, Gyeongsangnam-do before and after the forest was thinned from a density of 908 trees/ha to 367 trees/ha. The total C stored in tree biomass was 69.5 Mg C/ha before FTW and 38.6 Mg C/ha after FTW. The change in total C storage in tree biomass primarily resulted from the loss of 19.9 Mg C/ha stored in stem biomass after FTW. The total C pool in this red pine stand was 276 Mg C/ha before FTW and 245.1 Mg C/ha after FTW. Prior to FTW, 71.5% of the total C pool was stored in mineral soil, 25.2% in tree biomass, and 3.3% in the forest floor, where as after FTW 80.5% of the total C pool was stored in mineral soil, 15.7% in tree biomass and 3.7% in the forest floor. These results suggest that the development of site-specific tending techniques may be required to minimize the loss of tree biomass C storage capacity in red pine stands from FTW.

• Journal of agriculture & life science
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• v.43 no.6
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• pp.19-27
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• 2009

This study was carried out to obtain the basic model to estimate damage degree from the correlation analysis between forest fire and site environment factors and to clarify the restoration trends thorough multi-temporal survey by observing species diversity followed by various treatments at damaged forest area over time. From the derived model, the damage degree of forest fire was higher in the area of dense coniferous stands composed of simple story at the elevation of about 100m and 200m, and on steeper slope area over 30 degree. As results of this study, fire damaged trees are needed to cut down and a mixed stand with deciduous and coniferous species from the same area is desirable for the future species composition on fire damaged forest. Thus, site characteristics, local species, and mixed stands are the main consideration to enhance the vegetation recovery.

• Journal of Korean Society of Forest Science
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• v.104 no.3
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• pp.411-420
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• 2015

This study examined methods for stand density control by using shape ratio (tree height/DBH) and its application for effective management of Pinus thunbergii coastal disaster prevention forests. We analyzed the present conditions (height, DBH, and density) of P. thunbergii coastal disaster prevention forests at 123 study sites on Jeju Island and west, south, and east coasts of South Korea and compared them with results from previous studies. The average shape ratio for P. thunbergii showed positive correlations with stand density and was significantly higher on the west coast (66.32) than on the south (49.57) and east (48.19) coasts and Jeju Island (48.29). Stands with shape ratio higher than 70 accounted for 50% of the total study sites on the west coast, indicating a decrease in their disaster prevention function compared to that of other previous studies. The stand density in most coastal areas, except the east coast, was significantly higher than the standards recommended by the Korea Forest Service and the Forestry and Forest Products Research Institute of Japan, indicating the need for stand density control. According to the growth estimation equation for P. thunbergii in the coastal area of South Korea, density control is required for young stands less than 14 years old, which show drastic increase in the shape ratio, to conserve their disaster prevention function. Particularly, the first thinning of P. thunbergii forests should be implemented before the stand age of 8 years that a shape ratio exceeds 70. For disaster-prone young stands (${\leq}20cm$ DBH) of P. thunbergii, the stand density was higher in the standard of Japan considering shape ratio than in that of Korea aiming timber production. Hence, the standard guidelines employed in Japan, which assign higher importance to disaster prevention function based on field surveys, can be applied effectively for controlling the stand density of P. thunbergii coastal forests in South Korea, to improve their disaster prevention function.

• The Korean Journal of Ecology
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• v.24 no.6
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• pp.371-376
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• 2001

The rate of soil respiration to varying stand ages was studied in four Robinia pseudoacacia stands(18-, 23-, 28- and 35-year old) throughout one year from September 1998 to August 1999. Soil temperatures showed a pronounced seasonal pattern, in contrast to soil moisture. The highest rate of soil respiration was generally found in August when soil temperatures were the highest, and the lowest in January. The daily rate of soil respiration amounted to 5.51($g\;CO_2{\cdot}m^{-2}{\cdot}day^{-1}$) for 18-year old stand, 5.28 for 23-year old stand, 8.29 for 28-year stand, and 2.67 for 35-year old black locust stand, respectively. The $Q_{10}$ values were ranged between 1.63 and 1.66, averaging 1.65 for the R. pseudoaca'cia stands. The results indicate significant correlation between soil temperature and soil respiration for all four stands(r=0.96 to 0.97). Among the study stands, the annual rate of soil respiration was the highest ($3.03kg\;CO_2{\cdot}m^{-2}{\cdot}yr^{-1}$) for 28-year old stand.

• Journal of Korean Society of Forest Science
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• v.84 no.1
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• pp.63-70
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• 1995

This paper discusses applications of neural network to stand stocking control problems. The scope of this research was to develop a neural network model for finding optimal stand management regimes and examining the performance of the model for field application. Performance was analyzed in consideration of the number of training examples and structural aspects of neural network. Research on network performance was based on extensive optimization studies for pure longleaf pine(Pinus palustris) stands. For experimental purposes. an existing nonlinear even-aged stand optimization model with a whole-stand growth and yield simulator was used to generate data samples required for the performance analysis.