• Korean Journal of Ecology and Environment
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• v.48 no.3
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• pp.195-202
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• 2015

We identified research trends for freshwater exotic species in South Korea using text mining methods in conjunction with bibliometric analysis. We searched scientific and common names of freshwater exotic species as searching keywords including 1 mammal species, 3 amphibian-reptile species, 11 fish species, 2 aquatic plant species. A total of 245 articles including research articles and abstracts of conference proceedings published by 56 academic societies and institutes were collected from scientific article databases. The search keywords used were the common names for the exotic species. The $20^{th}$ century (1900's) saw the number of articles increase; however, during the early $21^{st}$ century (2000's) the number of published articles decreased slowly. The number of articles focusing on physiological and embryological research was significantly greater than taxonomic and ecological studies. Rainbow trout and Nile tilapia were the main research topic, specifically physiological and embryological research associated with the aquaculture of these species. Ecological studies were only conducted on the distribution and effect of large-mouth bass and nutria. The ecological risk associated with freshwater exotic species has been expressed yet the scientific information might be insufficient to remove doubt about ecological issues as expressed by interested by individuals and policy makers due to bias in research topics with respect to freshwater exotic species. The research topics of freshwater exotic species would have to diversify to effectively manage freshwater exotic species.

• Korean Journal of Ecology and Environment
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• v.54 no.4
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• pp.363-373
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• 2021

An ecological niche is defined as the specific role of a species influenced by time, space, and other resources. By investigating overlaps between ecological niches of different species, we could estimate the degrees of interspecific competition. Such studies often use geographic information systems (GIS) to discover niche overlaps between species. In this study, we used GIS to estimate the spatial niches of two Korean frog species(Pelophylax nigromaculatus and P. chosenicus). This enabled us to predict their geographic distributions in order to identify their coexistence regions and distribution patterns. The results confirmed that altitude was an important variable for predicting their distribution, with a correlation with their climatic range. Spatial distributions of the two frog species were highly overlapped, as the distribution range for P. nigromaculatus included most of the range of P. chosenicus, showing a sympatric distribution pattern. Within the coexisting regions, however, the presence sites for the two species did not overlap, implying weak competition. To confirm the principal factors influencing their competitive relationship and reasons for their sympatric distribution pattern, we need more detailed in-depth studies on the diverse environmental variables within the regions where the two species coexist. By doing so, we would be able to identify various mechanisms for avoiding competition in sympatric frog species.

• Journal of Environmental Health Sciences
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• v.45 no.2
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• pp.192-202
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• 2019

Objectives: According to the central limit theorem, the samples in population might be considered to follow normal distribution if a large number of samples are available. Once we assume that toxicity dataset follow normal distribution, we can treat and process data statistically to calculate genus or species mean value with standard deviation. However, little is known and only limited studies are conducted to investigate whether toxicity dataset follows normal distribution or not. Therefore, the purpose of study is to evaluate the generally accepted normality hypothesis of aquatic toxicity dataset Methods: We selected the 8 chemicals, which consist of 4 organic and 4 inorganic chemical compounds considering data availability for the development of species sensitivity distribution. Toxicity data were collected at the US EPA ECOTOX Knowledgebase by simple search with target chemicals. Toxicity data were re-arranged to a proper format based on the endpoint and test duration, where we conducted normality test according to the Shapiro-Wilk test. Also we investigated the degree of normality by simple log transformation of toxicity data Results: Despite of the central limit theorem, only one large dataset (n>25) follow normal distribution out of 25 large dataset. By log transforming, more 7 large dataset show normality. As a result of normality test on small dataset (n<25), log transformation of toxicity value generally increases normality. Both organic and inorganic chemicals show normality growth for 26 species and 30 species, respectively. Those 56 species shows normality growth by log transformation in the taxonomic groups such as amphibian (1), crustacean (21), fish (22), insect (5), rotifer (2), and worm (5). In contrast, mollusca shows normality decrease at 1 species out of 23 that originally show normality. Conclusions: The normality of large toxicity dataset was not always satisfactory to the central limit theorem. Normality of those data could be improved through log transformation. Therefore, care should be taken when using toxicity data to induce, for example, mean value for risk assessment.

• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.575-581
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• 2018

The relationship between the body size of species and the environment has been an active research subject for many years. Until recently, studies had focused on the relationship between the body size and environment based on the ecogeographic rule for various animal groups. In this study, we examined the relationship between body size of Hyla japonica and the habitat environment in Jeju island located at the southernmost part of the Korean peninsula. We collected H. japonica from three breeding sites, Cheonji, Bonggae, and Aewol, and measured SVL, BW, and HW of the species. We also measured the altitude, longitude, latitude, annual mean temperature, and annual mean precipitation of each site to analyze the relationship between the body size and the habitat environment. The analysis results showed that there was the clear difference of the body size according to the habitat and the body size in Aewol was significantly bigger than others, while the body size in Cheonji was the smallest. The altitude was the most important environmental variable and showed a positive correlation with body size. The body size of H. japonica increased as the altitude increased, and this results were consistent with Bergmann's rule, one of the biological laws related to body size. In conclusion, the environment could affect the body size of H. japonica, and the body size has a certain direction according to the environment.

• Korean Journal of Heritage: History & Science
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• v.44 no.1
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• pp.122-137
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• 2011

The purpose of this study was to present the characteristics of tree growth and the status of the ecosystem in Yeongdeok Docheon-ri Docheon forest, which was designated as Natural Monument No. 514. Results showed that most of the soil properties were generally within desirable levels except for some properties. The forest was composed of 503 trees. Major trees included Zelkova serrata, Celtis sinensis, Cornus walteri, Diospyros lotus, Hemiptelea davidii, and Evodia daniellii. In particular, trees such as Zelkova serrata, Celtis sinensis, and Cornus walteri showed D.B.H ranging from 10cm to 70cm. These trees appeared to be major tree species since the beginning of Docheon forest's existence. The wild birds observed from the site were from 18 families, 20 species, and 95 individuals. Also were found 1 mammal species, 1 reptile species, and 1 amphibian species. A dead Aix galericulata (designated Natural Monument No. 327) was found in the forest. The annual tree diameter growth of the sample trees was 2.3mm per year on average. The average age of the overstory trees was approximately 101 years, and the oldest tree was estimated to be 300~400 years old.

• Journal of Korean Society of Forest Science
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• v.108 no.2
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• pp.241-258
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• 2019

The aim of this study was to analyze the factors that affect the habitat of fishes and amphibians in a mountain stream that is part of an experimental forest at Kongju National University, Gongju, Chungcheongnam, Korea, and examine the differences in the presence of fishes and amphibians in the stream before and after construction of an erosion control dam. The results showed that the factors that affect the presence of fishes are pH, electrical conductivity (EC), dissolved oxygen (DO), flow velocity, and step-pool number, and that the factors that affect the presence of amphibians are monthly rainfall, pH, EC, DO, and crown density. Of these factors, pH, EC, flow velocity, and monthly rainfall were significantly different before and after dam construction; however, the differences among the other three factors from dam construction, except EC, might not have been enough to affect the presence of fishes and amphibians. Our results suggest that the difference in the frequency of fishes and amphibians surveyed before and after dam construction in the upper and lower stream sections were not statistically significant. One exception to this was the presence of amphibians in the lower stream section during and after dam construction, which could have been the result of a large amount of sediment produced by excavation that led to high EC.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.25 no.2
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• pp.23-38
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• 2022

This study investigates the characteristics and physical habitat requirements for each Bufo gargarizans life history through a literature survey. After deriving variables for each component of Bufo gargarizans, in order to reduce regional deviations from eight previously studied literature research areas for deriving the criteria for variables, a total of 12 natural habitats of Bufo gargarizanss are selected as spatial ranges by selecting four additional sites such as Umyeonsan Ecological Park in Seoul, Wonheungibangjuk in Cheongju in the central region, Changnyeong Isan Reservoir in the southern region, and Mangwonji in Daegu. This study presents Bufo gargarizans SI, a species endemic to Korea, whose population is rapidly declining due to large-scale housing site development and road development, and develops a Bufo gargarizans HSI model accordingly to improve the function of the damaged Bufo gargarizans habitat and to present an objective basis for site selection of alternative habitat. At the same time, it provides basic data for adaptive management and follow-up monitoring. The three basic habitat requirements of amphibians, the physical habitat requirements of Bufo gargarizans, synthesized with shelter, food, and water, and the characteristics of each life history, are classified into five components by adding space and threats through literature research and expert advice. Variables are proposed by synthesizing and comparing the general characteristics of amphibians, among the previously studied single species of amphibians, the components of HSI of goldfrogs and Bufo gargarizans, and the ecological and physical environmental characteristics of Bufo gargarizans. Afterwards, through consultation with an amphibian expert, a total of 10 variables are finally presented by adjacent forest area(ha), the distance between spawning area and the nearest forest land(m), the soil, the distance from the wetland(m), the forest layered structure, the low grassland space, the permanent wetland area(ha), shoreline slope(%), PH, presence of predators, distance from road(m), presence or absence of obstacles. n order to derive the final criteria for each of the 10 variables, the criteria(alternative) for each variable are presented through geographic information analysis of the site survey area and field surveys of the previously studied literature research area. After a focus group interview(FGI) of 30 people related to the Bufo gargarizans colony in Cheongju, a questionnaire and in-depth interviews with three amphibians experts are conducted to verify and supplement the criteria for each final variable. Based on the finally developed Bufo gargarizans HSI, the Bufo gargarizans habitat model is presented through the SI graph model and the drawing centering on the Bufo gargarizans spawning area

• Journal of Environmental Impact Assessment
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• v.31 no.1
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• pp.75-81
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• 2022

The purpose of this study is to propose the angle-limit of the escape ramp by analyzing the frog behavior characteristics according to the inclination angle of the waterway escape ramp installed in the concrete U-bench plume pipe channel. Forthe experiment, an escape test device was manufactured with the same shape and number of materials applied in the field. And Rana coreana living in paddy wetlands were sel selected. The main behaviors of frogs on the slope were 'jumping', 'crawling' and 'slipping', and afterrecording the behavioralresults according to the inclination angle, statistical analysis was conducted using the chi-square test method. As a result of the analysis, there was no statistically significant difference between 30° and 40°. This result is an evidence for expanding the standard of inclination angle 30° suggested in the 'Guidelines for Installation and Management of Ecological Pathways' to a maximum of 40°. However, further research is required in that the escape ramp targets not only Korean frogs but also various small wild animals. However, considering that various wild animals are affected by artificial canals, additional studies using various target wild animals are needed.

• Korean Journal of Agricultural Science
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• v.50 no.2
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• pp.257-270
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• 2023

The paddy environment is classified as a wetland and occupies a very large proportion of the freshwater environment. It is also ecologically important as a habitat and spawning ground for many aquatic insects and amphibian larvae. However, due to climate change and indiscriminate spraying of pesticides, the rice field ecosystem is continuously threatened. In order to restore ecologically damaged rice paddies in the future, information on organisms living in the rice paddy ecosystem, which can serve as a restoration standard, is needed. The eDNA metabarcoding analysis method is a very effective means of accumulating information on many organisms living in the rice field ecosystem because it can indirectly identify the existence of taxa that are no longer found in the target ecosystem due to different adult life periods or metamorphosis. In this study, genes of four species of frogs and nine species of aquatic insects were also discovered, and some taxa were directly discovered in the field. A large number of taxa have been discovered only by DNA searches, and traditional survey methods have only been able to identify very limited taxa. This eDNA-based paddy field biosearch is expected to be very useful in the investigation of biodiversity in agricultural ecosystems due to its strong analytical resolution.

• Korean Journal of Environment and Ecology
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• v.30 no.1
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• pp.48-57
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• 2016

The distribution of fish (Cobitidae and Cyprinidae) and amphibians together with related environmental factors were surveyed at 30 randomly selected rice-fields (15 flooded unmanaged rice fields (FUR) and 15 unflooded managed rice fields (UMR)) near the Yedang reservoir in Korea, eight times from May to August in 2012. The total number of species captured from the entire survey area was 13 species with 8 families of fish and 5 species of amphibians. The number of species of Cyprinidae fish captured in FUR was higher than that in UMR. Upon the comparative analysis on the distribution of fish and amphibians in FUR and UMR, it was found that the number of Cyprinidae fish captured in FUR was significantly higher than that in UMR while the number of Cobitidae fish captured in UMR was higher than that in FUR. According to the analysis on the environmental factors that affect the distribution of fish, Cyprinidae fish tend to appear in rice-fields, that were flooded in winter, near the Yedang reservoir while Cobitidae fish tend to appear in rice fields that draws its water supply from forest reservoir and have a good water drainage system. In case of amphibians, the number of tadpoles captured in UMR was higher than that in FUR. Rana catesbeiana was dominant in FUR and Rana nigromaculata was dominant in UMR. Upon the analysis on the environmental factors that affect the distribution of tadpoles, it was found that Rana catesbeiana tadpoles tend to appear in rice fields, that were flooded in winter, near Yedang reservoir while Rana nigromaculata tadpoles tend to appear near mountains and far from the Yedang reservoir.