• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.83-91
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• 2012

Crown density, which is defined as the proportion of the forest floor concealed by tree crown, is important and useful information in various fields. Previous methods of measuring crown density have estimated crown density by interpreting aerial photographs or through a ground survey. These are time-consuming, labor-intensive, expensive and inconsistent approaches, as they involve a great deal of subjectivity and rely on the experience of the interpreter. In this study, the crown density of a forest in Korea was estimated using KOMPSAT-2 high-resolution satellite images. Using the image segmentation technique and stand information of the digital forest map, the forest area was divided into zones. The crown density for each segment was determined using the discriminant analysis method and the forest ratio method. The results showed that the accuracy of the discriminant analysis method was about 60%, while the accuracy of the forest ratio method was about 85%. The probability of extraction of candidate to update was verified by comparing the result with the digital forest map.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.391-396
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• 2010

To analyze the characteristics of canopy fuel in Pinus densiflora stand, which is essential to assess the crown fire hazard, allometric equations for estimation of crown fuel biomass were developed by subjectively categorized crown fuel component and crown bulk density was analyzed by available fuel component categories. Ten trees were destructively sampled at Pinus densiflora stand in Mt. Palgong in Daegu and their crown fuels were weighed separately for each fuel category by size classes and by living and dead. Regression equations that estimate crown fuel load by diameter at breast height(D) or additional total height(H) were derived. The adjusted coefficient of determination values were the highest (${R^2}_{adj}$=0.835-0.996) and standard error of estimate were the lowest (SEE=0.074-0.638) in the allometric equation lnWt=${\alpha}+{\beta}lnD+{\gamma}lnH$ in average. However, in needles and small branches categories, the differences in ${R^2}_{adj}$ and SEE between equations were not significant. Crown bulk density (CBD), which was calculated by crown fuel load divided by crown volume, was 0.067 kg/$m^3$ in average when only needles were considered as available crown fuel and 0.097 kg/$m^3$ when needles and branches (0-0.5 cm diameter) were considered. The increments of CBD of needles and small branches were little even when diameter at breast height increased.

• Korean Journal of Environment and Ecology
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• v.35 no.4
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• pp.398-407
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• 2021

This study intended to identify causes of poor tree vigor in the Hanbando coastal forest by investigating its geographical environment, climate condition, soil physicochemical characteristics, and growth condition of Pinus thunbergii. It divided the forest into an area with poor tree vigor or dead standing trees and a control area with good tree vigor and examined them separately. The survey showed that stand density was significantly higher in the area with poor tree vigor. In contrast, the crown width in the area with good tree vigor was wider. The number of dead standing trees and the stand density showed a negative correlation. The stand density and diameter at breast height (DBH), tree height, crown height, and crown width also showed a negative correlation. The result indicated that, as the tree's stand density increases, the crowns of individual trees overlapped and the lower branches died. Then crown height and crown width decreased, and the number of leaves and photosynthesis was reduced, leading to lower tree height and weaker growth of breast diameter. As a result, tree vigor weakened, and combined with environmental pressures from the lack of moisture and nutrients in coastal soil and salty wind, P. thunbergii in coastal areas is expected to die massively. Although the causes of dead standing trees and poor tree vigor of P. thunbergii in the Hanbando coastal forest are complicated, poor management of adequate tree density in response to the growth of P. thunbergii is the primary cause. The secondary cause is external environmental pressures, including unfavorable soil conditions and salty and strong wind that obstruct the growth of P. thunbergii.

• Korean journal of applied entomology
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• v.48 no.4
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• pp.447-451
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• 2009

Locust gall midge (LGM), Obolodiplosis robiniae (Haldeman) (Diptera: Cecidomyiidae), is a cecidomyiid insect forming roll-up galls on leaves of Robinia pseudoacacia Linnaeus (Fabaceae). LGM, known as native to North America, was reported from Korea and Japan in 2002. LGM was observed weekly or biweekly to clarify their voltinism and distribution within the crown of the host tree in two sites of Osan and Siheung in Korea from May to August, 2007. Density of LGM was investigated based on the number of larvae per leaf. Two generations of LGM were observed in Siheung site whereas three generations in Osan site during the present study. The result indicated that LGM had at maximum three generations per year. The density of LGM in Osan was higher in the upper crown of the host trees than middle or lower part. In Siheung, LGMs were distributed more on the exterior of the lower crown than the interior. The average number of larvae per gall was $3.3{\pm}0.1$ and $2.8{\pm}0.1$ individuals per leaf in Osan and Siheung, respectively.

• Journal of Korean Society of Forest Science
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• v.100 no.3
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• pp.402-407
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• 2011

The objectives of this study were to analyze the crown vertical structure, crown bulk density, and to develop regression models for predicting crown fuel load using the data from 10 destructively sampled Pinus densiflora trees in Bonghwa, Gyeongbuk. The fuel loads were observed higher in the middle portion of the vertical distribution of crown followed by the lower portion and upper portion of Pinus densiflora, respectively. Approximately 25% crown fuel load was found in the needle while 33% was observed in the branches with <1 cm diameter with a total of 58% available fuel loads. The average crown bulk density was $0.45kg/m^3$, and $0.27kg/m^3$ of this was available in the needles and branches with <1 cm diameters. The resulting models in linear equations were able to account for 84% and 88% of the observed variation, while the allometric equations with diameter at breast height as the single predictor showed better results to account for 90% and 95% of the observed variation in the available crown fuel loads and total crown fuel loads, respectively. The suggested equations in this study could provide quantitative fuel load attributes for crown fire behavior models and fire management of red pine stands in Bonghwa areas.

• Korean journal of applied entomology
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• v.42 no.3
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• pp.233-240
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• 2003

The effect of density suppression of Amblyseius fallacis (Garman) against Panonychus citri (McGregor) on citrus tree introduced with some different ratio was investigated. When it was introduced with over 16:1 (Panonychus citri: A. fallacis) ratio, Panonychus citri was suppressed very effectively. And in case of introduced once or two times with 20: 1 ratio when the density of Panonychus citri was reached 0.5 and 1.0 per leaf, the density of A. fallacis was formed highly, but the suppression effect against Panonychus citri was not effective. Also, the density changes of P. citri and A. fallacis on the citrus tree released with 10: 1 ratio (P. citri: A. fallacis) when the density of P. citri was reached about 0.1 per leaf in plastic film house were investigated. In case of released twice at the interval of 10 days, the density of A. fallacis was high and P. citri was suppressed so effectively over two month. On the inside of canopy of the citrus tree planted in plastic film house, the air temperature was much lower than on the outside of canopy, while relative humidity was much higher.

• Journal of Forest and Environmental Science
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• v.16 no.1
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• pp.34-41
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• 2000

This study investigated tree vigor of damaged forest by Thecodiplosis japonensis Uchida et Inouye. In damaged forest by pine gall midge, the investigation result of damaged rate section (severe, moderate, light) indicated that severe stand showed higher value of electric resistance ($k{\Omega}$) than that of light stand, the investigation result of tree density section(crowed, middle, little) indicated that crowed stand showed higher value of electric resistance than that of little stand (the value of electric resistance at which low reading show high vigor tree and high reading low vigor tree). The crown width and DBH (diameter of breast height) of external factors showed lower value of electric resistance than that of small size. The results of comparative between Crown area and value of electric resistance in each stand were $13.4m^2$ in severe stand, $10.9m^2$ in moderate stand and $7.9m^2$ in light stand. Therefore, the tree which have big crown showed low value of electric resistance (below $15k{\Omega}$)that has high possible of survial.

• Journal of Korean Society of Forest Science
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• v.107 no.4
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• pp.412-421
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• 2018

The objective of this study was to analyze the effects of forest management activities on canopy fuel characteristics for Pinus densiflora stands in South Korea. We used 1,085 managed stands data and 349 unmanaged stands data of the National Forest Inventory for this study, and it was estimated by using the Weibull function for the growth of stand and canopy fuel characteristics. Comparing the canopy fuel characteristics for the managed stands and unmanaged stands shows that the average canopy fuel load is about 14% higher than that of managed stands, and the canopy bulk density is also approximately 16% higher. The results of comparing growth projections for 40 years, 50 years and 60 years with the Weibull function are as follows: Over time, managed stands was predicted the maximum number of medium and large class diameter, while unmanaged stands was predicted maximum number of small and medium class diameter. From a fire fuel perspective, unmanaged stands are predicted to be of the type small class diameter and high density, which is a good condition for crown fire. In addition, Canopy fuel load, Canopy bulk density is relatively higher than managed stands, indicating that the possibility of high crown fire hazard.

• Journal of Korean Society of Forest Science
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• v.99 no.1
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• pp.52-56
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• 2010

Crown fuel characteristics such as crown bulk density, crown base height, and fuel moisture content of Japanese red pine were analyzed. Ten trees in Mt. Palgong at Daegu, were destructively sampled and their crown fuels were weighed separately for each fuel category. Fuel content of live and dead crown component were 53%, and 15.3%, respectively. Foliar moisture content was 56%. Needles and twigs with diameter less than 1cm diameter accounted for 16.2%, 55% of total and crown fuel load. Average crown bulk density of Japanese red pine was 0.24 kg/$m^3$, effective crown fuel bulk density was 0.1325 kg/$m^3$.

• 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.