• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.573-580
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• 2017

The oxicity assesment of Phenanthrene (PHE) has been investigated by using the rate (r) of survival and population growth in rotifer Brachionus plicatilis. The survival rate was determined after 24 h of exposure to PHE. The survival rate of PHE had no effect at a maximum of $300mg\;L^{-1}$. The r was determined after 72 h of exposure to PHE. It was observed that r in the controls (absence PHE) was greater than 0.5, but that it suddenly decreased with an increased concentration of PHE. PHE reduced r in a dose-dependent manner and a significant reduction occurred at a concentration of greater than $37.5mg\;L^{-1}$. The $EC_{50}$ value of r in PHE exposure was $63.7mg\;L^{-1}$. The no-observed-effect-concentration (NOEC) of r in PHE exposure was $18.8mg\;L^{-1}$. The lowest-observed-effect-concentration (LOEC) of r in the PHE exposure was $37.5mg\;L^{-1}$. From the results, the concentration of PHE (greater than $37.5mg\;L^{-1}$) has a toxic effect on the r of B. plicatilis in natural ecosystems. These results(including NOEC, LOEC and $EC_{50}$) might be useful for the Polycyclic aromatic hydrocarbons(PAHs) toxicity assessment in marine ecosystems.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.138-147
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• 2022

Paddy fields are important habitats for maintaining the biodiversity of agricultural ecosystems. Recently, as the need for safe food and biodiversity conservation has increased, the rice cultivation methods have undergone changes. This study was conducted to investigate the fish fauna in Environmentally Friendly Paddy fields (EFP) and Conventional Paddy fields (CP), and compare the characteristics of Misgurnus anguillicaudatus and Aphyocypris chinensis populations in EFP and CP. A total of 2,703 fish were collected and classified into six families and 13 species. Our results showed that there was a difference in the proportion of fish populations in the two paddy fields, and the number of individuals in EFP was higher than in CP. The weight values of M. anguillicaudatus were higher in EFP than in CP, and the total length, body length, and weight values of A. chinensis were higher in EFP than in CP. Conditional factor(K) values also showed similar trends in EFP and CP. Our results indicate that the farming practices in paddy fields have a significant effect on the characteristics of M. anguillicaudatus and A. chinensis populations, and the results of this study can be used as basic data for securing biodiversity in future agricultural ecosystems.

• Korean journal of applied entomology
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• v.32 no.1
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• pp.30-41
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• 1993

In the present investigation, some multivariate discriminant analyses were done for each population of the native honeybee workers (Apis cerana), which were selected for 15 different localities in spring and 16 in summer form Korea. when the comparison of both seasons for different populations and regardless of seasons were conducted, all the classification results revealed that the differences were significantly prominent. And the length of fore tibia(FTL) was the best contributed character among the 47 morphometric characters used in the analysis.

• Korean Journal of Environment and Ecology
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• v.22 no.5
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• pp.530-535
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• 2008

This study was carried out to analyze the vegetation and soil characteristic, and ordination of Wasabia japonica population at Ulleung-Do. The Wasabia japonica population is distributed in altitudes of 440m to 570m at Seo-Myon and also in altitudes of 340m near Nari-valley. In the study sites, soil organic matter, nitrogen, available phosphorous, exchangeable potassium, exchangeable calcium, exchangeable magnesium concentration, cation exchange capacity, and soil pH were 15.01%, 0.48%, 44.19ppm, 2.00(me/100g), 7.19(me/100g), 4.44(me/100g), 22.55(me/100g), and 6.17, respectively. The Rumohra standishii dominant population was mainly found in high in soil nitrogen, organic matter, CEC, and exchangeable calcium concentration in comparison with Boehmeria spicata dominant population. The Boehmeria spicata dominant population was mainly found in high in soil pH.

• Journal of Korean Society of Forest Science
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• v.97 no.1
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• pp.113-117
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• 2008

This study was conducted to clarify the differences in habitat characteristics and rodent populations between before and after damaged tree removals at forest fired areas in coniferous forest, Samcheok, Gangwon Province, Korea. The understory coverage and the number of shrub stem were increased by forest succession. Number of snags and downed CWD (coarse woody debris) were decreased after damaged tree removals. Population density of Apodemus agrarius was increased after damaged tree removal. However, population density of total rodents, Apodemus peninsulae and Eothenomys regulus were decreased. Changes in habitat structures may be influenced in rodent species composition. Especially, that would be negative effect on forestdwelling rodents.

• Korean Journal of Environmental Biology
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• v.25 no.4
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• pp.363-369
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• 2007

To understand property of distribution restricted at northern slope of Corylopsis coreana, we investigated process of sedentary formation from seed germination to seedling and its micrometeorological factors in Cheongsogol, Suncheon in Korea. The germination tests were carried out in-situ and manipulated condition, respectively. Air and soil temperatures, relative humidity, soil water contents and PPFD were measured in southern and northern slopes for four seasons. The seeds did not shown difference in germination to azimuth slope. However, seedling in the northern slope should have taken advantage on the sedentary stage of seedlings because there was low temperature and high humidity during the spring. At the southern slope, the seedlings seemed to have a disadvantage on high temperature and low humidity in spring season. Accordingly, the formation of Corylopsis coreana population is influenced by microclimatic factors, especially in low temperature and high humidity at the sedentary stage of the germinated seedlings.

• Korean Journal of Ecology and Environment
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• v.37 no.3 s.108
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• pp.304-312
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• 2004

The transient dynamics of three-trophic populations (prey, predator, and super predator) using ratio-dependent models responding to environmental impacts is analyzed. Environmental factors were divided into two parts: periodic factor (e.g., temperature) and general noise. Periodic factor was addressed as a frequency and bias, while general noise was expressed as a Gaussian distribution. Temperature bias ${\varepsilon}$, temperature frequency ${\Omega}$, and Gaussian noise amplitude ${\`{O}}$ accordingly revealed diverse status of population dynamics in three-trophic food chain, including extinction of species. The model showed stable limit cycles and strange attractors in the long-time behavior depending upon various values of the parameters. The dynamic behavior of the system appeared to be sensitive to changes in environmental input. The parameters of environmental input play an important role in determining extinction time of super predator and predator populations.

• Korean Journal of Environment and Ecology
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• v.34 no.1
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• pp.18-26
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• 2020

Echinosophora koreensis (Nakai) Nakai an endemic plant with limited distribution in some parts of the Korean Peninsula, is designated as "Endangered" species on the IUCN Red List. The species is under the threat of deterioration in nature due to various environmental changes causing loss of natural habitats. We investigated the distribution pattern and population structure of E. koreensis to serve as a basic reference for identifying the dynamics and persistence of natural populations of this species in the future. To determine the characteristics of the E. koreensis population, we laid two to three large plots sized 20m×30m on the ridgeline as the reference in Yanggu, Chuncheon, and Hongcheon and laid four to seven small quadrats sized 1m×1m on the transect. A total of 530 plots were laid, 10 each at 2m interval, to measure the number of the stems, the number of fruiting, height, and other factors. The collected distribution information was compared with the existing IUCN assessed categories by applying IUCN Red List ver 3.1 Criteria B. The average population density of the three surveyed areas was 3.47 stem/㎡; the density of each area was 3.95 stems/㎡ in Yanggu, 3.37 stems/㎡ in Chuncheon, and 2.87 stems/㎡ in Hongcheon. The number of fruiting per stem was 0.0038, indicating only 7 fruits out of 1,837 stems and that vegetative reproduction is likely to be more dominant than sexual reproduction. The distribution tendency of population density in the small plots in three surveyed areas showed that the density of E. koreensis tended to decrease toward the center of the forest with low crown openness and around the mountain ridge with high crown openness. It indicated that the quantity of light could be a very important factor for the growth of individuals of this species. The analysis of the heights of individuals present in the surveyed plots showed a range of 2.3 ~ 68.5cm and an average of 20.1cm. An analysis on the stage-structure of the E. koreensis population based on the sieve height found that the appearance frequency decreased with increasing height above 15 ~ 20cm and that the percentage of individuals lower than 10cm, which were presumed to be seedlings, was severely low, indicating a necessity of study on the population sustainability based on the monitored data. The occupied area calculated with the collected species distribution information was 200㎢, indicating the EN category according to the IUCN Red List Reference B.

• Korean Journal of Environment and Ecology
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• v.23 no.2
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• pp.116-126
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• 2009

This study was carried out focused an ecological characteristics and habitat management of Abeliophyllum distichum subpopulations in the Byeonsanbando National Park, Korea. Among three subpopulations of the target species in the studied area, Gamaso region are known as translocation site due to the dam construction while the wild populations which is located at both the lower terrain of the Buandaem bank and Chongnim-ni, which is designated as Natural Monument No 370, is threat due to an intensive site management likes clearance of scrub amongst the Abeliophyllum plants. Vascular plant taxa in the studied sites were summarized as 182 taxa; 65 families, 143 genera, 164 species, 17 varieties and 1 form, and Gamaso area, the lower terrain of the Buandaem and Cheongnim-ni areas are summarized as 75, 102 and 89 taxa, respectively. The plant species likes persimmon tree, paulownia tree and wild mulberry tree are dominant species in the Gamaso subpopulation, while Quercus variabilis is dominant at the lower terrain of the Buandaem. The intensive site management was applied to the Cheongnim-ni subpopulation, one of the original wild habitats of the species. The population dymanics was varied; the one or two sprouting number of stems was over 87% both at Gamaso area and the lower terrain of the Buandam, while the Cheongnim-ni subpopulation recorded as 74.8%. Also three sprouting number recorded as 16% and as 9.2% for sprouting on numbers of four to eleven. The invaded species likes Chenopodium album, Rumex obtusifolius, Phytolacca americana, Pharbitis nil, Solanum lyratum, Erigeron canadensis and Erigeron annuus, were found at the wild habitat of the species, and those invaded species grow faster than Abeliophyllum plants. Among three habitats of the target species in the studied area, the habitat which in located at the lower terrain of the Buandam and Gamaso region are known as translocated due to the dam construction, and wild subpopulation at Chongnim-ni, which is designated as Natural Monument No 370, is under threatened due to an intensive site management likes clearance of scrub amongst the Abeliophyllumplants. It is one of the evidence that Cuscuta japonica at the population indicated an intensive site management likes clearance of scrub is not proper habitat management protocol. Thus, further researches should be followed to determine the effect of canopy removal and other disturbance factors as management techniques.

• Journal of Wetlands Research
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• v.10 no.2
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• pp.165-172
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• 2008

In order to clarify the factors that diminish the population size of Scirpus planicumis in Han River Esturay Wetland Conservation Area of South Korea, I analysed the autoecological traits of competitive hydrophytes over the species, compared the performance ability of Scirpus planicum group inhabited between in soil-accumulated site and in soil-unaccumulated site, and suggested the management strategy of restoration of this plant based on the field survey. Scirpus planicumis had lower competitive ability than other hydrophyte such as Phragmites australis, Zonia latifolia, Typha augustifola. in terms of dry matter production, height, and reproductive regime. S. planicumis group in soil-accumulated site had lower tuber production, lower vegetative and reproductive production than that of in soil-unaccumulated site, and plant height was shorter in soil-accumulated than in soil-unaccumulated condition. Tuber was appeared in lower soil depth within 15cm in laboratory condition. These results indicated that soil-accumulated condition is the dominant factor caused the decreasing of population size of S. planicumis. It was urgently suggested that constructing a water ways to removed accumulated soil layer is need to restore the population size of S. planiculmus in this wetland.