• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.449-451
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• 2007

In the commercially managed timber lands, the information such as height, age, stand density, canopy closure and leaf area index need to be collected periodically. Stand volume is the most fundamental information in the valuation of timber, however, stand age information is the primary element of forest inventory and these two are highly correlated. Conventional method of collecting stand age information by field surveys such as ring count method is accurate; however, it is expensive, labor-intensive and time consuming. In the present study it was aimed to collect stand age information using modem techniques in a commercially managed timberland situated in Tennessee, USA. The Landsat Thematic Mapper (TM), Enhanced Thematic Mapper (ETM+) of three different periods, Shuttle Radar Topography Mission (SRTM), National elevation dataset (NED) and field inventory data were used. Normalized difference vegetation index (NDVI) and Tasselled Cap (TC) transformation techniques were applied on the TM and ETM+ data. The regression analysis was carried out to identify the correlation between stand age and NDVI, TC. In the present study about 2,469 datasets were analyzed. The $R^{2}$ value for stand age estimation was 0.713. The NDVI, TC2 and TC3 were found to produce accurate timber age information.

• Journal of Forest and Environmental Science
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• 제34권3호
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• pp.235-241
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• 2018

This study was conducted to find out the growth pattern of Pinus koraiensis plantation over 34 years, focusing on DBH, height, basal area and allometric change. Total increment (TI), mean annual increment (MAI) and correlation coefficient were calculated and compared with stand and dominants. Total increment and mean annual increment of both DBH and height of dominants were bigger than those of stand. The difference was apparently shown bigger in DBH than height. Unlike DBH and height the total increment and mean annual increment of basal area per hectare of dominants were distinctively smaller than those of stand. Furthermore MAI of dominant was increasing until age 42, while MAI of stand increased at early ages and then gradually decreased after culmination like MAIs of DBH and height. MAIs of basal area of dead trees at each measurement tended to increase until early age (18 years in this study), while it reached a peak and gradually decrease after that (21 years in this study). Correlation coefficient between DBH and height tended to decrease as both dominant and stand age and the difference between dominant and stand was not clearly shown over the measurement period. Correlation coefficients between DBH and crown width tended to decrease as the trees age and correlation coefficients of dominant were clearly shown smaller than that of stand. Correlation coefficients of height and crown width also was found to be similar to correlation coefficients between DBH and crown. Meanwhile correlation coefficient of height and crown width dropped more radically than coefficient of DBH and crown width as the trees age.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2004년도 Proceedings of ISRS 2004
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• pp.14-16
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• 2004

Although there have been wide range of studies to characterize forest stands based upon spectral information of satellite image, it was not fully understood the texture information of forest stand using high resolution data. The objective of this study is to evaluate several texture measures for characterizing forest stand structure, such as species composition, diameter at breast height(DBH), stand density, and age. High resolution IKONOS satellite imagery data were acquired in August 200 lover the forested area near Ulsan, Korea. Primary forest types were plantation pine, mixed forest, and natural deciduous forest of stand age ranging from 10 to 50 years old. Several GLCM-based texture measures were compared with forest stand characteristics. In overall, a texture measure (contrast) calculated using red band were better to differentiate species and age group than other texture measures and near infrared bands.

• 한국습지학회지
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• 제20권2호
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• pp.116-123
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• 2018

산림생태계에서 대기로의 토양의 이동은 토양 호흡이라는 과정을 통해 이루어진다. 본 연구에서는 임령이 다른 잣나무림을 대상으로 생육기 동안의 토양 호흡값과 토양 내 뿌리의 양, 미생물 개체군 생물량을 측정하여, 토양호흡량이 임령에 따라 어떻게 다르며, 뿌리와 미생물 개체군이 얼마나 기여할 것인지 알아보고자 하였다. 토양 온도와 토양 호흡은 임령과는 상관없이 유사한 패턴을 보여 7월까지는 증가하고 이후 감소하였다. 산림의 임령이 높을수록 토양 호흡량이 대체적으로 높았다. 토양 내 뿌리와 미생물을 조사한 결과, 임령이 높을수록 토양 내 존재하는 지름 2 mm 이하인 세근의 양이 많았으며 토양 미생물 개체군의 생물량이 많았다. 토양에서 뿌리를 제거하였을 때 70년 숲은 변화가 없었으나, 40년 숲에서는 토양 호흡값이 감소하였다. 본 연구결과로 볼 때, 산림의 연령이 높아질수록 토양 호흡량이 커지며, 식물 뿌리와 특히 토양 미생물이 토양 호흡값에 많은 기여를 하고 있는 것으로 생각해 볼 수 있다.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.94-97
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• 2006

Timber stand age information of timber in industrialized plantation forest is generally collected by field surveying which is labor-intensive, time-consuming, and very costly. It is also inconsistent in analyses perspective. As an alternative, The objective of this research is to present a practical solution for estimating timber age of loblolly pine plantation using Landsat thematic mapper (TM) images, shuttle radar topography mission (SRTM), and national elevation dataset (NED). A multivariate regression model was developed based upon satellite image-based information (i.e.normalized difference vegetation index (NDVI), tasseled cap (TC) transformation, and derived tree heights). A residual studentized technique was applied to remove potential outliers. After that, a refined age estimation model with a correlation coefficient R-square of 84.6% was obtained. Finally, the feasibility test of estimated model was performed by comparing estimated and measured stand ages of timber plantations using test datasets of plantation stands (2,032 stands). The result shows that the proposed method of this study can estimate loblolly pine stand age within an error of $2{\sim}3$ years in an effective and consistent way in terms of time and cost.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.165-169
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• 2008

This study attempts to analyze the relationship between forest volume and age based on 5th NFI data and spectral characteristics of satellite imagery using ASTER sensor in Korea. Forest stand volume and age had the negative correlation with the spectral reflectance in all of the band (Blue, Green, Red, SWIR). With increasing of stand volume and age, spectral reflectance decrease. The spectral reflectance of band1 showed the highest correlation between stand volume and spectral reflectance among the VNIR wavelength. The spectral reflectance band 1, 2 (visible wavelength) and stand age have high correlation compared to other bands. The correlation coefficients between forest volume and vegetation indices have low relationship. This result indicates that the reflectance of blue band may be important factor to improve the potential of optical remote sensing data to estimate forest volume and age.

• 대한물리의학회지
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• 제9권1호
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• pp.101-106
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• 2014

PURPOSE: This study was to provide reference data and examine stroke and healty older differences in sit-to-stand test. This study were to determine utility of the 5 repetition sit to stand for discriminating between fallers and non-fallers, identifying an appropriate cutoff score to delineate between the groups. METHODS: Ninety-five participants were recruited. Seventy-two individuals with stroke and twenty-three healthy older agreed to participate in the study. Falls were recorded using a self-administered questionnaire. The 5 repetition sit to stand test measured the time taken to complete t repetitions of the sit to stand maneuver. The time from the initial seated position to the final seated position after completing five stands was the test measure. A cutoff score regarding 5 repetition sit to stand performance in fallers vs. non-fallers, stroke patients vs. healthy older and <60 vs. $$\geq_-$$ age groups was determined using and ROC curve. RESULTS: Cutoff score of 9.9 seconds were found to be discriminatory between healthy older and subjects with stroke. Cutoff score of 15.5 seconds were found to be discriminatory between fallers and non-fallers. Cutoff score of 18.3 seconds were found to be discriminatory between <60 and $$\geq_-$$ age groups. CONCLUSION: The 5-repetition sit-to stand test is quick, easily administered measure useful for gross determination of fall risk in people with stroke.

• 한국산림과학회지
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• 제98권3호
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• pp.225-230
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• 2009

본 연구에서는 Operations research 기법 중의 하나인 동적계획법을 이용하여 잣나무 임분의 총 수확량을 최대로 하기 위한 간벌 pathway를 검토해 보았다. 강원도 춘천시 강촌 모델림의 잣나무 임분 III영급을 대상으로 간벌 강도를 무간벌, 30% 및 50%의 간벌 수준을 적용하였으며, 임령 35년과 55년에서 총 2회의 간벌을 가정 하였고 벌기령을 70년으로 하였다. 임분 재적은 산림조사 자료의 분석을 통해 추정된 생장방정식을 이용하여 계산하였다. 동적계획법을 적용한 결과 총 9개의 pathway중 1차 간벌은 30%수준 그리고 2차 간벌은 50% 수준에서 시행하는 pathway가 총 수확량을 최대로 하는 것으로 나타났다.

• ALGAE
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• 제37권1호
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• pp.63-74
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• 2022

Perennial stipitate kelps are globally distributed and individual species can inhabit broad latitudinal ranges, expressing notably longevous persistence. Despite the foundational role kelps provide to their communities, little is known about the variability in persistence of the stipitate kelps at local spatial scales. We studied the population persistence of Eisenia arborea, a heat- and wave force-tolerant perennial stipitate kelp with a distributional range extending from British Columbia to south of the range limit of all other northeast Pacific kelps, in Baja California Sur, Mexico. Persistence characteristics for E. arborea among sites were compared and used to test the hypothesis that stand persistence varied at local spatial scales around Isla Natividad, a Pacific island off the Baja California peninsula with documented spatiotemporal environmental heterogeneity. Collected individuals around the island were "aged" using the previously validated age estimation technique of counting annual cortical dark rings. After detecting no significant differences among sites in the covariation between estimated ages for collected individuals and stipe length, we utilized in-situ population-level stipe length measurements to more rapidly predict age structures within six stands around the island. Predicted age structures, and associated stand densities, revealed persistence characteristics and density varied at local scales and a strong positive relationship existed between stand density and stand mean and maximum ages. We speculate that stands responded differently to deterministic influences (e.g., the 2014-2016 marine heatwave and / or competition with Macrocystis) resulting in heterogenous local persistence of this foundation species.

• 농업생명과학연구
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• 제45권5호
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• pp.33-39
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• 2011

본 연구는 강원지역 1영급 금강소나무를 대상으로 천연임분과 인공임분간의 직경별 뿌리의 분포 특성을 알아보기 위해 실시하였다. 직경별 뿌리분포는 두 임분 모두 0.5-2.0 mm 직경급의 뿌리가 가장 많았고, 10.0-20.0 mm 직경급의 뿌리가 가장 적었다. 두 임분간 직경별 뿌리발달에서 5.0 mm 이하의 직경급은 인공임분이 천연임분보다 우수하였지만, 5.0 mm 이상의 직경급 발달은 천연임분이 더 우수하였다. 토양층위별 뿌리의 직경별 발달은 천연임분이 인공임분보다 다양한 토양층위에 고르게 분포하였으며, 인공임분은 5.0 mm 이하의 직경급이 토심 10 cm, 토양 수평층위 20 cm 범위 내에 편중되어 발달하였다. 따라서 임분 성립방법의 차이는 뿌리발달의 현저한 구조적 차이를 나타낼 수 있으며, 이러한 결과는 인공조림시 올바른 식재방법과 조림지침을 제공하는데 중요한 기초자료로 사용될 수 있을 것이다.