• Korean journal of applied entomology
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• v.50 no.2
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• pp.115-123
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• 2011

Although Guleopdo is small island of only $1.71\;km^2$, the endangered butterfly species, Argynnis nerippe, is abundant there. This study was carried out to estimate the abundance of A. nerippe in Guleopdo, using quadrate, mark-recapture, and line-transect methods. Although the study was insufficient, the population size was estimated at 4,467 to 6,700 larvae and approx. 1,000 adults. A. nerippe was the most abundant among butterfly species in Guleopdo, and it comprised 32% of the total butterflies. A total of 28 butterfly species were observed in this study, and 3 species of these species were migrating species. When the abundance of A. nerippe throughout the country during the period from 1938 to 2010 was studied, we found that it decreased abruptly in the 2000s. Presently, A. nerippe inhabits a few locations in the mid-northern region and western islands. The relatively high numbers of A. nerippe in Guleopdo was due to conservation of natural grasslands and grazing of livestock, which provides adequate habitat for this species.

• Ecology and Resilient Infrastructure
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• v.9 no.3
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• pp.194-205
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• 2022

Sandbars formed by sediment transportation and sedimentation are some of the most important habitats for specific wildlife and they provide an aesthetic landscape in streams. The purpose of this study was to understand the successional process of the colonization and development of early vegetation over time on sandbars exposed by the opening of a gate at a downstream weir. We selected the following four study sites in the Geumgang River, South Korea: three weir-upstream sites with different gate-opening times and a control site that was not affected by weir operation. Changes in the structural characteristics and spatial distribution of the riparian vegetation on the sandbars exposed after opening the gate at the weir were surveyed according to the different exposure periods of the sandbars at the study sites. The newly formed sandbars accounted for more than 33% of the area of the existing floodplain in the three weir-upstream sites of the Geumgang River after opening the gate at the weir. Nine main plant communities were distributed on the exposed sandbars. These communities were classified as annual mesophytic, perennial hydrophytic, perennial hygrophytic, subtree, and tree vegetation based on their species traits. As the duration of exposure of the sandbar increased, the area of the bare sandbar and the annual herbaceous and perennial hydrophytic communities decreased, and the areas occupied by perennial hygrophytic, subtree, and tree communities increased. Changes in vegetation on the sandbar were classified into three types of succession according to the condition of the aquatic habitat before the gate-opening and the degree of physical disturbance caused by the water flow after the gate-opening. The types of succession were: 1) succession starting from hydrophytes in the lentic aquatic zone, 2) succession starting from annual herbaceous hygrophytes in the lotic aquatic zone, and 3) willow-dominated succession in the disturbed channel side. Our results suggested that the dynamics of successional changes in vegetation should be considered during weir operation to ecologically manage the habitats and landscape of the fluvial landforms, including sandbars in streams.

• Journal of Korea Water Resources Association
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• v.56 no.9
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• pp.553-562
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• 2023

The Gobiobotia naktongensis is a species endemic to Korea, and it has recently been designated as a class I endangered species of freshwater fish. Naeseong Stream, one of the tributaries of the Nakdong River, where the Gobiobotia naktongensis was first discovered, provided an optimal habitat for the Gobiobotia naktongensis in the past with fine sand beds and riffle. Currently, due to the construction of Yeongju Dam and the excessive dredging of river channels by the local government, the riverbed armoring in the downstream area of the dam is undergoing rapid changes, and as a result, the habitat environment of the Gobiobotia naktongensis is deteriorating. In this study, the variations of the habitat suitability of the Gobiobotia naktongensis due to the change in the riverbed grain size of the Naeseong Stream were analyzed based on the WUA (weight usable area) using the physical habitat model, River2D. The study domain is the reach from Seoktap Bridge to Hoeryong Bridge downstream of Yeongju Dam. The change in riverbed grain size was analyzed using D50 acquired in 2010 and 2020, respectively. The substrate grain size of Naeseong Stream in 2020 was thicker than that in 2010, and the riverbed coarsening phenomenon was evident overall. As a result of the River2D analysis, the area in which the Gobiobotia naktongensis could inhabit was only about 0.75% in 2010 compared to the entire area of the flow, and even this decreased to 0.55% in 2020 due to riverbed armoring.

• Journal of Environmental Impact Assessment
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• v.27 no.6
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• pp.685-694
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• 2018

We measured ecological niche space (ENS) using carbon and nitrogen stable isotope ratios of benthic macroinvertebrates to estimate its applicability for large river assessment. In particular, we compared ENSs of selected macroinvertebrates between upper and lower area of Seungchon Weir in Yeongsan River to estimate the impact of weir on biological community. We also measured basic water quality and community indices including benthic macroinvertebrates index (BMI) to estimate their correlations with calculated ENS. ENS was calculated using the Bayesian Stable Isotope in R statistics (package "SIBER"). The results showed that seasonal variations in water quality and community indices were found, but there was no apparent tendency between upper and lower area of the Seungchon Weir in June (before rainy season) and August (after rainy season). However, ENS of benthic macroinvertebrates markedly decreased across the weir in both June and August regardless of changes in water quality. This means the physical change of the stream due to the weir cause decrease of ecological isotopic niche space of benthic macroinvertebrates regardless of water quality, suggesting physical modification by the weir can affect the interaction between habitat condition and macroinvertebrates. Therefore, the ecological isotopic niche space can be a useful supplementary indicator for the river ecosystem assessment.

• Korean Journal of Environment and Ecology
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• v.17 no.2
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• pp.133-143
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• 2003

The three wild populations including unrecorded two wild populations and Do-dong population, where designated as a Natural Monument NO 51, of Cotoneaster wilsonii in Ulnung Island were studied. The population at Yilmoldae, western coast of the island is in the threat by the visitors, while the population at Tonggumi is well conserved due to the geomorphologically difficult to access . The existing 25 to 50 maturing individuals are are potentially vital sources fer the island species recovery projects in the future. There are no statistical difference in the floral characteristics of the species such as both length and width of the petals, while statistical difference were shown from the leaf characteristics such as length, width and area of the leaves in the three studies areas.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.287-294
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• 2019

This study investigated longitudinal changes in riverbed materials properties and temporal alteration of river channel geomorphology in the Geum River basin, where two multipurpose dams(Yongdam Dam and Daecheong Dam) were built in upstream area. We carried out grain size distribution analyses and measured soil organic matter contents of riverbed materials taken at the upper and lower sites of the two large dams. We also estimated the channel width, bar area and vegetation encroachment using the oldest map and aerial photographs taken before and after the construction of the dams. The results can contribute to increasing understandings of dam induced habitat alteration in river ecosystem.

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.638-646
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• 2018

The purpose of this study was to investigate the long-term habitat morphological alteration resulting from a large dam and weirs in the Tamjin River. To achieve this, we carried out a hydrograph analysis and a substrate size distribution analysis. We also estimated the channel width, bar area and vegetation encroachment using aerial photographs taken before and after the construction of the dam and weirs. The result of the hydrological analysis showed that flooding downstream was greatly reduced with small peaks occurrence after the dam construction. Interestingly, normal hydrographs in the main channel appeared just after tributary conjunction. There was a similar pattern in the substrate size analysis. Despite coarsened substrate just downstream of the dam site, more sand appeared again after introduction of the tributary. However, there was an increase in the bar area downstream of the dam's channels with most bars covered with vegetation. The channel width increased at the upper area of weirs through impoundment, but decreased downstream because of vegetation encroachment. This study indicate that unregulated tributary plays an important role in restoring hydro-physical habitat conditions in mainstream channels below a large dam. However, numerous weirs could be a causal factor to accelerate habitat deterioration in the dam downstream channels.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.1788-1792
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• 2007

한강 "수변구역"에서 비점오염물질의 공공수역 유입을 억제하기 위한 다양한 방법들 중에서 보편적이고 자연친화적인 방법은 다양한 생물의 서식공간이며, 동시에 본류로 유입되는 과정에서 수질을 정화시키는 수질개선 공간인 수변완충구역, 또는 지대를 설정하여 관리하는 것이다. 그러나 이러한 수변완충지대 효과 분석 및 설정에 관한 연구는 국내에서 아직 수행되지 않았다. 본 연구의 목적은 수변구역의 자정능력을 높이는 것은 물론 그 밖의 하천 연안에서 비점오염물질의 차단과 처리능력을 증진시키고 수변 생태계의 서식처 보전 및 복원을 위해서 수변완충지대의 수질정화 기술개발과 생물다양성을 창출하는 수변완충지대 조성 기법을 개발하는데 있다. 본 연구에서는 기존 수변완충지의 추가적인 조성과 보완, 시험완충지 생태구조 및 기능 기초조사, 시험완충지 오염부하 저감효과의 실험 및 분석, 수변완충지대 설치 구상 등의 연구를 수행하여 수변완충지대 조성 시 설정 폭을 산정할 수 있게 하였다. 수행 지역은 한강수계 지역으로 남한강 수변인 경기도 양평군 병산리에서 실시하였으며, 잔디와 갈대, 갯버들, 혼합지역, 자연그대로의 상태(대조지역)의 5 구역으로 구분하였고, 거리별, 깊이별 샘플을 채취하여 유입수에 대한 오염물질 제거효율을 도출하고, 이를 이용하여 수변완충지대의 설계 시 필요한 유역의 폭, 면적, 길이 등과 같은 설계인자를 도출할 수 있도록 하였다.

• Korean Journal of Environment and Ecology
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• v.21 no.4
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• pp.366-373
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• 2007

This study researched the number of individuals of Roe deer (Capreolus pygarus tianschanicus Satunin), which inhabit Mt. Halla (Hallasan) National Park and its neighboring areas ranging about $270km^2$ areas. The research was done from November(late fall), 1998 to March(early spring), 2001, and additional research was carried out from November 2006 to January 2007. As a result of this, we identified a total of 1,444 deer, and found out the fact that there lived 5.33 deer per $km^2$. By region, we identified a maximum of 270 deer at Donnaeko hiking path and a minimum of 12 deer at the adjacent areas to the second Sanrok-road. The frequency of Roe deer group sighting was higher at the edge of Hallasan National Park than any other surveyed region. Thus, it is estimated that the distribution of Roe deer of Hallasan is more influenced by the quantity and quality of food than human-made interference during wintry season.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.499-503
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• 2010

본 연구결과 채집된 어류는 총 9과 36종 4,669개체였다. 과(family)로는 잉어과(Cyprinidae) 어류가 24종으로 전체 채집된 어종의 66.7%로 가장 많이 출현하였다. 고유종은 쉬리(Coreoleuciscus splendidus) 등 20종으로 55.6%를 차지하여 높은 출현율을 보였다. 멸종위기야생동물(endangered species)로 감돌고기(Pseudopungtungia nigra) 외 2종이 출현하였다. 구성비가 가장 높은 종은 참갈겨니(Zacco koreanus)로 34.0%를 차지하여 우점종으로 나타났고, 다음은 피라미(Z. platypus)로 22.6%, 쉬리는 13.3% 순으로 나타났다. 쉬리의 산란기는 4월~6월로 나타났으며, 주산란성기는 5월 이었다. 유속, 수심 및 하상에 대한 쉬리의 HSI는 유속 0.4~0.6 m/sec, 수심 0.3~0.5 m, 하상재료 가는자갈 굵은자갈로 나타났다. 생태유량을 모의한 결과, 하류로 내려갈수록 유량이 증가되어 쉬리가 살 수 있는 가용면적이 커지는 것으로 나타났다.