• Korean Journal of Remote Sensing
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• v.10 no.2
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• pp.63-82
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• 1994

Multitemporal analysis with remotely sensed data is complicated by numerous intervening factors, including atmospheric attenuation and occurrence of clouds that obscure the relationship between ground and satellite observed spectral measurements. A reconstruction system was developed to increase the discrimination capability for imagery that has been modified by residual dffects resulting from imperfect sensing of the target and by atmospheric attenuation of the signal. Utilizing temporal information based on an adaptive timporal filter, it recovers missing measurements resulting from cloud cover and sensor noise and enhances the imagery. The temporal filter effectively tracks a systematic trend in remote sensing data by using a polynomial model. The reconstruction system were applied to the AVHRR data collected over Korean Peninsula. The results show that missing measurements are typically recovered successfully and the temporal trend in vegetation change is exposed clearly in the reconstructed series.

• Korean Journal of Remote Sensing
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• v.35 no.6_3
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• pp.1285-1298
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• 2019

Drought is one of the factors that can cause wildfires. Drought is related to not only the occurrence of wildfires but also their frequency, extent and severity. In South Korea, most wildfires occur in dry seasons (i.e. spring and autumn), which are highly correlated to drought events. In this study, we examined the relationship between wildfire occurrence and drought factors, and developed satellite-based new drought indices for assessing wildfire risk over South Korea. Drought factors used in this study were high-resolution downscaled soil moisture, Normalized Different Water Index (NDWI), Normalized Multi-band Drought Index (NMDI), Normalized Different Drought Index (NDDI), Temperature Condition Index (TCI), Precipitation Condition Index (PCI) and Vegetation Condition Index (VCI). Drought indices were then proposed through weighted linear combination and one-class support vector machine (One-class SVM) using the drought factors. We found that most drought factors, in particular, soil moisture, NDWI, and PCI were linked well to wildfire occurrence. The validation results using wildfire cases in 2018 showed that all five linear combinations produced consistently good performance (> 88% in occurrence match). In particular, the combination of soil moisture and NDWI, and the combination of soil moisture, NDWI, and precipitation were found to be appropriate for representing wildfire risk.

• Journal of Wetlands Research
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• v.24 no.4
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• pp.354-366
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• 2022

To analyze the distribution of plant communities growing in river wetlands and the relationship between biotic and abiotic environmental factors, plant communities and environmental factors were investigated in river wetlands in the Boseong River. The Boseong River Wetland, the research site, consists of Hwapyeong Wetland, Bangujeong Wetland, and Seokgok Wetland. From June to September 2022, a plant community survey was conducted from the perspective of physiognomical vegetation, and the coverage of the emerging species followed the Braun-Blanquet scale. Plant species and the coverage of each species were recorded in the quadrant for plant community survey, and the cover of the quadrant, the total number of species, and the number of exotic species were measured as biological factors. As abiotic factors, altitude, orientation, inclination, soil texture, litter layer depth, dominant species diameter at breast height, and topography were recorded. In a total of 50 square plots, the most common Salix koreensis and Phragmites japonicus communities were found, and the community with the highest Shannon species diversity index was Phragmites japonicus-Echinochloa caudata community. As a result of ordination analysis by DCCA, the most significant clusters were separated according to topographic factors such as leeve, leeve slope, upper floodplain, lower floodplain, upper waterside, middle waterside, lower waterside, river island and opem water. As rare plants that need to be preserved in river wetlands, Hydrocharis dubia and Penthorum chinense were found in lower waterside, and it was found that the management of the river in the reservoir is necessary in line with the topographical distribution of ecosystem-disrupting plants, such as Paspalum distichum var. indutum.

• Korean Journal of Environment and Ecology
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• v.36 no.1
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• pp.72-86
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• 2022

This study was conducted to identify structural characteristics of the evergreen broad-leaved forests distributed in Hak-dong, Geojae island. For a survey, 52 sites were set up in areas with changes in the vegetation community or location environment where Cinnamomum yabunikkei, Neolitsea sericea, and Machilus thunbergii dominated or appeared in the canopy, sub-canopy, or shrub layer. The community classification with TWINSPAN identified the following communities: N. sericea-C. yabunikkei, C. yabunikkei-Camellia japonica, Ca. japonica, Quercus variabilis-Ca. japonica, Pinus thunbergii-Ca. japonica, Castanopsis sieboldii, P. thunbergii, and Platycarya strobilacea-Mallotus japonicus. Considering the result of the study that succession series of warm-temperate forest reflecting the latent natural vegetation is the transition of conifers and deciduous broad-leaved forest to evergreen broad-leaved forest, the communities predominated by the communities predominated by the communities predominated by P. thunbergii, Q. variabilis, and Pl. strobilacea are likely to transform into the evergreen forest predominated by N. sericea and C. yabunikkei. The sites where C. yabunikkei, N. sericea, and Castanopsis sieboldii are dominant in the canopy and sub-canopy layers are likely to maintain the status quo if there is no artificial disturbance. The relationship between the impact of the environmental factors and the vegetation distribution showed silt among the physical properties of the soil directly or indirectly affected it, which was judged to be due to the fact that it was located on a steep slope. The soil acidity (pH) was 5-5.84, electrical conductivity 0.047-0.139 dS/m, and organic matter content was 3.32-12.06%. Although there were differences by the colony, they were generally low.

• Korean Journal of Environment and Ecology
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• v.36 no.6
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• pp.662-675
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• 2022

This study was intended to investigate and analyze the current status of the plant community structure in order to provide basic data for the systematic conservation and management of the Buxus sinica area appearing on the ridgeline connecting the Gyeokjabong(Mt.) and Keungiljae, on Bogildo Island. In consideration of location characteristics such as density, topography, and direction of B. sinica appearing in the shrub layers, a total of 26 sites were set as the survey area for representative vegetation communities or areas with changes in topography. According to DCA and TWINSPAN, it was classified into 6 communities, namely Carpinus turczaninovii-Deciduous broad-leaved, C. turczaninovii, C. turczaninovii-B. sinica, C. turczaninovii-Evergreen broad-leaved, Q. acuta, and D. trifidus-Q. acuta. The community dominated by C. turczaninovii maintains the status quo for the present moment, however, Q. acuta will dominate the surrounding area in the long term, so Q. acuta has high succesion potential. In the case of the Q. acuta and D. trifidus-Q. acuta communities, Q. acuta, known as the climax species of warm-temperate forests, will maintain dominant status. In a case of B. sinica, the community dominated by C. turczaninovii will remain in good status due to the topographical conditions, but the community dominated by Q. acuta growth difficulties are expected due to the high coverage. In the relationship between environmental factors and vegetation distribution, analysis showed that only soil pH affect vegetation distribution. Furthermore, the soil acidity (pH) was 3.78-5.30, the electrical conductivity was 0.186-0.543 dS/m, and the organic matter content was 2.25-2.89%.

• Korean Journal of Environment and Ecology
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• v.32 no.1
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• pp.105-117
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• 2018

This study conducted health assessment and multivariate vegetation analysis using the riparian vegetation index in 30 sites of the Geumgang mainstream and Mihocheon to obtain practical data on the river management of the Geumgang. The result showed that the number of plant communities was 54. The flora was 75 families, 185 genera, 243 species, 2 subspecies, 21 varieties, 2 varieties, and 268 taxa. The riparian vegetation index was 38.3 (3.3; G-D1 ~ 66.7; G-U2, G-U4, and G-M3), and the health of the rivers in this area was evaluated as normal (grade C). The health of rivers was the highest in the upper stream of Geumgang mainstream and lowest in the downstream of Geumgang mainstream. The relationship between riparian vegetation index and chlorophyll-a content was low. The riparian vegetation was divided into five groups of Digitaria ciliaris colony group, Salix gracilistyla colony group, Erigeron annuus colony group, the group dominated by Humulus japonicus, Salix koreensis, Miscanthus sacchariflorus, and Phragmites japonica colonies, and the group dominated by Conyza canadensis and Echinochloa crusgalli var. echinata colonies. They had the similar health conditions. The CCA analysis showed that the environmental factors affecting the distribution of vegetation were physical factors such as vegetation area, artificial structure area, waterway area, branch width, channel width, and bank height and the biological factors such as the number of species. As such, it is necessary to maintain the health condition through continuous monitoring where the health condition is high and to apply active measures such as ecological restoration where the health condition is low.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.708-721
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• 2019

This study was conducted to understand the plant community structure characteristics of warm-temperate forest in Geoje Island. Survey sites were set up on ridges, valleys, and slopes where evergreen broad-leaved trees predominated or distributed in canopy, sub-canopy, or shrub layers at Chunjangsan(Mt.). Thirty-one sites were located in the areas, such as vegetation community, ridges, valleys, and slopes, to observe vegetation structure and location changes. The community classification with TWINSPAN identified six groups: Neolitsea sericea-Platycarya strobilacea, N. sericea-Styrax japonicus, N. sericea-Euonymus oxyphyllus, Pinus thunbergii-N. sericea, N. sericea-Quercus serrata, and Q. variabilis-P. strobilacea. Considering the results of previous studies that reported that the successional pattern of the warm temperate forests progressed from deciduous to evergreen forests, the regions predominated by deciduous communities such as P. thunbergii, Q. serrata, P. strobilacea, Zelkova serrata, and Q. variabilis, is likely to transform into the evergreen forest predominated by N. sericea. The relationship between the impact of the environmental factors and the vegetation distribution showed that slope, Na +, K +, electrical conductivity, and clay among physical properties had direct or indirect effects on vegetation distribution.

• Journal of Korean Society of Forest Science
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• v.102 no.3
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• pp.446-454
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• 2013

The present study investigated the biological agents and environmental conditions of the habitats of the Kirengeshoma koreana, a class 2 endangered species class according to the South Korean Ministry of Environment (MOE), elucidated the structural characteristics of the forest stands in the habitats with the importance value and the diversity index, conducted comparative analysis of the factors, and explored their relationship with environmental factors. According to the results of direction analysis of natural habitats of the Kirengeshoma koreana, the direction was distributed to the north or the northeast, and the slope amounted to $15-40^{\circ}$, thus demonstrating that the slope has little effect. In addition, the results showed that the distribution of Kirengeshoma koreana populations dramatically increased starting in areas at least 600 m above the sea level and that the relative light intensity was 3.79% on an average. Most populations were native to gorges and crevices between rocks so that they mainly tended to inhabit areas that could see soil loss in times of precipitation. In addition, a considerable number of the populations were close to hiking trails as well, thus leading to concerns about their artificial destruction. The soil of layer a in the main growth space of the Kirengeshoma koreana was analyzed and turned out to be strongly acidic, measuring pH 4.45-4.89 (average: 4.68). All investigation sections were typical natural broad-leaved tree areas, and, judging from the fact that the Kirengeshoma koreana was most likely to appear in colonies of the Mongolian oak tree (Quercus mongolica Fisch. ex Ledeb.), the Mongolian oak tree seems to be the species of tree that has the greatest effect on the inhabitation of the Kirengeshoma koreana.

• Korean Journal of Environment and Ecology
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• v.24 no.6
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• pp.657-679
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• 2010

Mushroom fruiting was investigated in pine and oak dominated forest stands in Songni National Park located in central Korea for six years from 2003 to 2008, in order to understand the relationship between mushroom diversity and the environmental factors, precipitation, temperature, soil moisture and vegetation. The most frequent fruiting families were those of ectomycorrhizal mushrooms, Tricholomataceae, Amanitaceae, Russulaceae, Cortinariaceae, and Boletaceae. The frequency of mushroom fruiting varied from 94 to 167 species per year, with July and August having the highest(13~90 species). Mushroom fruiting was positively correlated to precipitation(r=0.897), using Palmer Drought Severity Index for the long term period and Standard Precipitation Index for short term period. Soil moisture content also affected mushroom fruiting, with Lactarius chrysorrheus and Russula virescens fruiting only at soil moisture content higher than 20%. Positive correlation between mushroom fruiting and temperature was also noted(r=0.77), with optimum rates at $21{\sim}25^{\circ}C$. Tricholoma flayayirens, Amanita gymnopus, Lactarius piperatus, Inocybe asteropora and Xerocomus chrysenteron were able to fruit at temperatures higher than $25^{\circ}C$. However, Laccaria amethystea, Amanita virosa and Russula mariae fruited at relatively wide temperature range. The influence of vegetation on mushroom fruiting was likewise noted, with 38 species, including Suillus bovinus and Boletopsis leucomelas being specific to pine dominated stands, while 42 species, including Polyporus arcularius and Hericium erinaceum were specific to oak dominated stands. On the other hand, around 50 species, including Laccaria laccata and Lycoperdon parlatum, were able to fruit in both types of vegetation. In conclusion, mushroom fruiting greatly varies with changes in precipitation, soil moisture, temperature and vegetation.

• Korean Journal of Remote Sensing
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• v.38 no.1
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• pp.57-72
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• 2022

In this paper, we aimed to examine the flowering dates of cherry blossom and the peak dates of maple leaves in South Korea, by the combination of temperature observation data from ASOS (Automated Surface Observing System) and NDVI (Normalized Difference Vegetation Index) from MODIS (Moderate Resolution Imaging Spectroradiometer). The more recent years, the faster the flowering dates and the slower the peak dates. This is because of the impacts of climate change with the increase of air temperature in South Korea. By reflecting the climate change, our statistical models could reasonably predict the plant phenology with the CC (Correlation Coefficient) of 0.870 and the MAE (Mean Absolute Error) of 3.3 days for the flowering dates of cherry blossom, and the CC of 0.805 and the MAE of 3.8 for the peak dates of maple leaves. We could suppose a linear relationship between the plant phenology DOY (day of year) and the environmental factors like temperature and NDVI, which should be inspected in more detail. We found that the flowering date of cherry blossom was closely related to the monthly mean temperature of February and March, and the peak date of maple leaves was much associated with the accumulated temperature. Amore sophisticated future work will be required to examine the plant phenology using higher-resolution satellite images and additional meteorological variables like the diurnal temperature range sensitive to plant phenology. Using meteorological grid can help produce the spatially continuous raster maps for plant phenology.