• Journal of Korean Society of Forest Science
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• v.106 no.2
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• pp.204-212
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• 2017

Soil disturbance caused by timber harvesting is widely recognized as a potential threat to forest utilization. The degree and extent of soil disturbance is believed to vary with respect to harvesting methods and logging machines. This study has conducted to assess the degree of soil disturbance associated with ground-based cut-to-length (GC) and cable yarding with whole tree (CW) harvesting methods. Soil disturbance was classified using a visual assessment of harvest unit. The properties of soils in different disturbance levels were also evaluated to understand the influence of timber harvesting on soil structure with soil core sampling method. The deep disturbance and soil compaction were observed in sites by 48% and 23% through harvesting areas for GC and CW logging methods, respectively. The results showed that logging machine and number of machine passage had significant influences on soil bulk density and porosity. Soil disturbance types such as rutted, slash cover, and compact were influenced by equipment travel trends in a GC method.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.196-196
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• 2011

산림연료 특성별 산불피해도 분석을 위하여 산불피해의 조사지역은 2009년, 2010년 산불이 발생했던 강원도 고성지역과 양양지역, 강릉지역과 삼척지역을 조사 대상지역으로 선정하였으며, 고성군의 경우 숲구조가 유령림인 활엽수림이 2개소, 칩엽수림 1개소, 장령림인 활엽수림 2개소로 총 5개소, 양양군은 숲구조가 유령림인 침엽수림이 1개소, 장령림 침엽수림 2개소 총 3개소, 삼척시의 경우는 숲구조가 유령림인 침엽수림이 1개소 외 대조구 장령림 침엽수림 1개소, 강릉시의 경우 숲구조가 장령림인 침엽수림이 3개소 총 13개소를 각각 대상지로 선정하였다. 산림연료 특성별 산불피해도를 조사하기 위한 조사지 규모는 $10m{\times}10m$로 하였으며, 현장 조사 항목은 조사지내의 산불피해 상태, 조사지 지형특성으로 나누어 조사를 실시하였다. 산불피해 상태는 산불진행방향, DBH, 총수고, 지하고, 고사여부, 편면연소, 밀도, 수간피해율, 수관피해율 등을 조사하였고, 조사지의 지형특성을 알아보기 위해 조사지의 위치(GPS), 해발고도, 사면방위, 산지경사, 지형을 조사하였다. 현장조사를 위한 조사장비로는 조사지의 지형도, 야장, 디지털 카메라, GPS, 수고측정기, 직경테이프, 캘리퍼, 50m 줄자 2개, 2m 폴대, 클리노메타, 바인더끈 등을 사용하였다. 산불사례 현장조사를 통해 임목고사여부, 편면연소, 수간피해율, 수관피해율 등의 산불피해 특성을 분석한 결과 연료의 특성별 유령림과 장령림의 편면연소율은 유령림은 97.3%, 장령림은 16.5%로 유령림의 편면연소율이 장령림보다 80.8% 더 피해를 받는 것으로 나타났으며, 수관피해율은 유령림은 95.4%, 장령림은 19.9%로 유령림의 수관피해율이 장령림보다 75.5%더 피해를 입은 것으로 조사 되었다. 또한 임목고사율은 유령림은 73.8%, 장령림은 24.5%로 유령림의 임목고사율이 장령림보다 49.3% 더 피해를 받는 것으로 분석 되었다.

• Journal of the Korean Geotechnical Society
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• v.34 no.9
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• pp.19-32
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• 2018

In this study, the applicability and practicality of landslides monitoring by using wireless sensor network (WSN) was analysed. WSN system consists of a sensor node for collecting and transmitting data using IEEE 802.14e standard, a gateway for collecting data and transmitting the data to the monitoring server. In the topology of the sensor network, a highly flexible and reliable mesh type was adopted, and three testbeds were chosen in each location of Seoul metropolitan area. Soil moisture sensors, tensiometers, inclinometers, and a rain gauge were installed at each testbed and sensor node to monitor the landslide. For the estimation of the optimal network topology between sensor nodes, the susceptibility assessment of landslides, forest density and viewshed analysis of terrain were conducted. As a result, the network connection works quite well and measured value of the volumetric water content and matric suction simulates well the general trend of the soil water characteristic curve by the laboratory test. As such, it is noted that WSN system, which is the reliable technique, can be applied to the landslide monitoring.

• Korean Journal of Environment and Ecology
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• v.32 no.5
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• pp.507-512
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• 2018

Three natural Pinus thunbergii stands in southern Korea were studied to investigate stem density, biomass expansion factors, allometric equations and stand biomass. Stand ages of stand 1, 2 and 3 were 15, 29 and 45 years old, respectively. Three $10m{\times}10m$ plots were set up, five sample trees were cut and roots of three sample trees were excavated for dimension analysis in each stand. Stem density of stand 1, 2 and 3 were $0.450g/cm^3$, $0.440/cm^3$ and $0.457g/cm^3$, respectively, and there was no significant difference among the three stands. Biomass expansion factors of above-ground and total tree decreased with increasing stand age. Above-ground biomass expansion factor of stand 1 was significantly higher than those of stand 2 and 3, and total tree biomass expansion factor of stand 1 was significantly higher than that of stand 3. Allometric equations were developed for the 15 sample trees of the three stands based on D or $D^2H$. Above-ground biomass of stand 1, 2 and 3 were 50.72t/ha, 89.92t/ha, 194.07t/ha, respectively, and total tree biomass of stand 1, 2 and 3 were 61.62t/ha, 113.12t/ha, 248.36t/ha, respetively.

• Journal of Korean Society of Forest Science
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• v.99 no.6
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• pp.914-921
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• 2010

This study analyzed the above-and belowground biomass, net primary production, stem density, and biomass expansion factors for Pinus densiflora stands of Cheongyang and Boryeong regions in Chungnam. The total dry weights in Cheongyang and Boryeong regions were 122.36 kg/tree and 137.68 kg/tree while the aboveground biomass for these two regions were 72.23 Mg/ha and 143.27 Mg/ha, respectively. Total(above-and belowground) biomass were 91.77 Mg/ha and 178.98 Mg/ha, respectively. Net primary production of above-and belowground biomass in Cheongyang and Boryeong regions were 8.69 Mg/ha, 10.03 Mg/ha, 16.00 Mg/ha and 18.66 Mg/ha, respectively. Stem density (g/$cm^3$) was 0.457 and 0.421 while the above and total biomass expansion factors were 1.394~1.662 and 1.324~1.639, respectively. These results suggested that stand density and site quality could be influenced on the biomass and net primary production of the two regions. In addition, the results of this study could be very useful to calculate carbon sequestrations by applying stem density values and biomass expansion factors for Pinus densiflora in these two regions.

• Journal of agriculture & life science
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• v.43 no.1
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• pp.1-8
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• 2009

This study was conducted to examine the biomass, allometric equations, net primary production, above and total biomass expansion factors and stem density values for 27 years old Korean pine(Pinus koraiensis Siebold et Zuccarini) plantation at the Gangneung National Forest. After considering of the diameter distributions in the $20m{\times}20m$ plot measurement, a total of 5 representative sample trees were destructively sampled to measure green weights and dry weights of the four(root, stem, branch and foliage) protions of Korean pine trees. According to the results of this study, total dry weights were 117.6 kg/tree and 59.9 ton/ha. Aboveground biomass and total (above and belowground) biomass for this species were 59.9 and 82.4 ton/ha, respectively. Ratios of root to aboveground biomass were 0.38. Net primary production of aboveground biomass and belowground biomass were 9.4 and 11.3 ton/ha, respectively. Stem density was $0.49g/cm^{3}$. Above and total biomass expansion factors were 1.78 and 2.19, repectively. This information could be very useful to calculate carbon sequestrations by applying stem desity values and biomass expansion factors for Korean pine species.

• Korean Journal of Environment and Ecology
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• v.21 no.6
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• pp.554-558
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• 2007

Current biomass stock of forest has been calculated by using biomass expansion factors (BEFs) that convert timber volumes to dry weight and stem density. The objective of this study was to estimate stem density values and to develop BEFs that are dependent on tree age classes for Quercus acuta stands in Jeonnam Wando-gun. Sample trees on the three different age classes were harvested to obtain each components biomass with stem analysis. Stem density values as tree age classes were ranged from 0.557 to 0.636. Aboveground BEFs were ranged from 1.168 to 1.324. BEFs were increased with increasing age classes. There was a significant difference between BEFs and stem density values with tree age classes. These results suggest that the reliability of the national carbon stock inventory could be improved by applying age classes BEFs, which are formulated on the basis of representative for Quercus acuta.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.1-8
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• 2006

This study was conducted to develope allometric equations and to estimate biomass, stem density, and biomass expansion factor for the three stand age classes (I-II, III-IV, and V-VI) of Japanese larch (Larix leptolepis) in Gapyeong area. Total dry weight (kg/tree) and aboveground biomass (ton/ha) were 57.8 and 71.1 for I-II class, 185.4 and 195.6 for III-IV class, and 1047.9 and 180.6 for V-VI class, respectively. Total above and belowground biomass (ton/ha) was 96.3 for I-II class, 265.7 for III-IV class, and 244.5 for V-VI class. The proportion (%) of stem to total biomass increased with stand age class and was 53.9 for I-II class, 55.7 for III-IV class, and 57.7 for V-VI class, respectively, while that of foliage decreased and was 7.1 for I-II class, 4.5 for III-IV class, 2.3 for V-VI class. Ratios of root to aboveground biomass were 0.35 for all age classes. Stem density ($g/cm^3$) differed between I-II class and III-VI class. Aboveground and total biomass expansion factors were 1.31-1.44 and 1.26-1.94. Our results showed that differences in stand density with stand age classes might influence allometric equation, stem density and ratios of aboveground biomass to stem biomass and total biomass to stem biomass (biomass expansion factors).

• Journal of Korean Society of Forest Science
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• v.105 no.3
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• pp.275-283
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• 2016

The objective of this study was to examine carbon dynamics with biomass, soil $CO_2$ efflux, litter and root decomposition after tree density control in young Pinus densiflora stands. The stands were established with 50% thinning, clear-cut, and control stands with three pseudo-replicated plots and a bare soil plot in 8-year-old Pinus densiflora nursery field. Monthly measurements were conducted from March 2012 to February 2014 and aboveground biomass and coarse-roots were estimated by derived allometric equations. Average diameter growth at root collar in control and thinned was 0.89 cm and 1.48 cm per year, respectively, and the diameter growth of control stand was significantly higher than that of thinned stands (p<0.05). Total biomass was estimated to 5.17, $4.85kg\;C\;m^{-2}$ per year in control and thinned, respectively. Annual soil $CO_2$ efflux in control, thinned, clear cut, and bare soil was 3.71, 3.90, 4.17, $4.56kg\;CO_2\;m^{-2}\;yr^{-1}$, respectively and removing trees significantly increased soil $CO_2$ efflux (p<0.05). Net Ecosystem Production (NEP) was 1.57, 1.36, -0.67, $-1.25kg\;C\;m^{-2}\;yr^{-1}$ in control, thinned, clear cut and bare soil in the young Pinus densiflora stands. NEP was significantly decreased by removing trees. Thinning increased diameter at root collar and carbon of individual tree and recovered 86% of carbon removed by thinning after one-year. In addition, soil $CO_2$ efflux increased and NEP increased by thinning. Results of this study, tree density control such as thinning increased the carbon storage and growth of the young Pinus densiflora stands.

• 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.