• Korean Journal of Ecology and Environment
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• v.48 no.2
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• pp.95-107
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• 2015

In order to identify long-term trends of water quality parameters in Lake Kyeongpo, Mann-Kendall test, Sen's slope estimator and linear regression were applied on data, with 15 parameters from three different sites and rainfall, monitored once in every two months from March to November during 1998~2013. Seasonal variation analysis only used Mann-Kendall test and Sen's slope estimator. Analysis result showed that salinity, transparency and nutrient variables (total phosphorus, dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen, ammonia nitrogen) were only parameters having statistically significant trend. In linear regression analysis, salinity (surface and bottom layer of all sites) and transparency (only at site 1), were figured out with statistically significant increasing trend, while in non-parametric statistical method, salinity and transparency in all sites (surface, middle, deep) were figured out with statistically significant increasing trend. Water quality parameters showing statistically significant decreasing trends were dissolved oxygen (surface layer of site 1 and bottom layer of sites 2 and 3), total phosphorus (sites 1 and 2), dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in the linear regression analysis and, dissolved oxygen (bottom layer of all sites), total phosphorus, dissolved inorganic phosphorus, total nitrogen, nitrate nitrogen and ammonia nitrogen in the non-parametric method. Seasonal trend analysis result showed that salinity, turbidity, transparency and suspended solids in spring, salinity, transparency, nitrate nitrogen and suspended solids in summer and temperature, salinity, transparency and suspended solids in fall were the variables depending on the season with increasing trends. In general, rainfall during the research period showed decreasing trend. The significant reduction trends of nutrients in Lake Kyeongpo were believed to be related to lagoon restoration and water management project run by Gangneung city and under-water wear removal, but further detailed studies are needed to know the exact causes.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.1
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• pp.135-146
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• 2015

This study was carried out to understand ecological characteristics of Korean goral such as home range, seasonal home range and habitat use and used for Korean goral restoration and conservation, through a pair of gorals in the north Gyeongbuk province of Korea. With data from GPS collars, we analyzed the behavioral characteristics of the endangered Korean gorals(n=2) in Uljin area from June 2013 to July 2014. As a result, their home range was $1.38{\pm}0.24km^2$ in MCP 95%, $0.81{\pm}0.09km^2$ in FK 95% and $0.15{\pm}0.16km^2$ in FK 50% (t=8.118, p>0.05). Seasonal home range for MCP 95% was $0.74{\pm}0.31km^2$ > (winter) > $0.71{\pm}0.27km^2$ (spring) > $0.61{\pm}0.06km^2$ (autumn) > $0.27{\pm}0.04km^2$ (summer) (F=2.135 p>0.05). It showed that home range in winter was the largest and that in summer was the smallest. Mean elevation of male for seasonal habitat use was $440.18{\pm}71.32m$ in summer and that of female was $727.25{\pm}99.98m$ in spring. The lowest altitude for male was $372.72{\pm}70.79$ and female was $664.60{\pm}139.71m$. It meant that there were seasonal change and thus annual and seasonal behavior characteristics for both sexes had different correlation according to elevation change. Although in this study the correlation with prey in habitat and the changes of habitat disturbance were not clearly investigated, We could understand goral home range and habitat use through research data.

• Korean Journal of Environment and Ecology
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• v.33 no.5
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• pp.497-505
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• 2019

Winter hibernation in wildlife is a unique physiological mechanism for survival. For Asiatic black bears (ABBs, Ursus thibetanus ussuricus), hibernation is a very important but dangerous time for the cubs to be born. This study surveyed ABBs living in Mt. Jiri To examine the relationship between the temperature during hibernation and the hibernation days. The survey found that the average start and end dates of hibernation was December 7 and April 20, respectively. The average day of hibernation for females who gave birth was $167.8{\pm}22.6$ days. The average temperature of 5 days before hibernation was $0.6{\pm}4.1^{\circ}C$, the average temperature during hibernation was $1.3{\pm}2.43^{\circ}C$, and the average temperature of five days before the end of hibernation was $12.6{\pm}3.1^{\circ}C$. The hibernation days of the females that did not give birth to cubs and the males were $120.4{\pm}25.7$ days and $113.6{\pm}25.8$ days, respectively. The average temperatures of 5 days before hibernation was $2.1{\pm}4.2^{\circ}C$ and $-1.8{\pm}3.9^{\circ}C$, respectively. The average temperature during hibernation was $-0.2{\pm}1.6^{\circ}C$ and $-0.4{\pm}2.4^{\circ}C$. The average temperatures of five days before the end of hibernation were $7.8{\pm}3.6^{\circ}C$ and $7.8{\pm}4.4^{\circ}C$. These results indicate that females giving birth to cubs have higher hibernation days and average temperatures than the females that do not give birth and the males, which is due to the process of raising cubs during hibernation. The hibernating days and mean temperature for the groups in each lifecycle did not show any difference between the groups. This study is meaningful in that it disclosed the characteristics of hibernating intrinsic behaviors of ABBs. It observed the specific hibernation period and temperature of ABBs bears inhabiting in Mt. Jiri and examined the difference by sex, female(giving birth) and life cycle group according to temperature. The results of this study can be used to prevent the conflict between ABBs and humans in winter and spring and establish the preservation management plan.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.322-340
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• 2021

Due to climate change and its consequential spring temperature rise, flowering time of Robinia pseudoacacia has advanced and a simultaneous blooming phenomenon occurred in different regions in South Korea. These changes in flowering time became a major crisis in the domestic beekeeping industry and the demand for accurate prediction of flowering time for R. pseudoacacia is increasing. In this study, we developed and compared performance of four different models predicting flowering time of R. pseudoacacia for the entire country: a Single Model for the country (SM), Modified Single Model (MSM) using correction factors derived from SM, Group Model (GM) estimating parameters for each region, and Local Model (LM) estimating parameters for each site. To achieve this goal, the bloom date data observed at 26 points across the country for the past 12 years (2006-2017) and daily temperature data were used. As a result, bloom dates for the north central region, where spring temperature increase was more than two-fold higher than southern regions, have advanced and the differences compared with the southwest region decreased by 0.7098 days per year (p-value=0.0417). Model comparisons showed MSM and LM performed better than the other models, as shown by 24% and 15% lower RMSE than SM, respectively. Furthermore, validation with 16 additional sites for 4 years revealed co-krigging of LM showed better performance than expansion of MSM for the entire nation (RMSE: p-value=0.0118, Bias: p-value=0.0471). This study improved predictions of bloom dates for R. pseudoacacia and proposed methods for reliable expansion to the entire nation.

• Journal of Korean Society of Forest Science
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• v.110 no.3
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• pp.341-354
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• 2021

A large part of Gapyeong is occupied by Korean pine (Pinus koraiensis) and Japanese larch (Larix kaempferi) plantations. Abies holophylla stands are scattered throughout Gapyeong, but little information on their distribution is available. This study explored the potential of succession from planted species to native A. holophylla in plantations. Trees were inventoried and regeneration of A. holoplhylla and stand management history were examined in Korean pine, Japanese larch, and A. holophylla-dominated stands. The importance percentage of A. holophylla was the highest among species with a range of 36.1% to 79.1% in all stands and the density of A. holophylla in understory (DBH <2 cm or <1.3 m height) ranged from 50 to 5,820 trees ha^-1. Non-metric multidimensional scaling classified stands into four types, AN, AP, AM, and P. The AN type showed a reverse J-shape DBH distribution, which was similar to that in natural A. holophylla stands. Both AP and AM types included Korean pine plantations with A. holophylla seed trees within stands. For AP, A. holophylla competed with planted species in overstory and deciduous broadleaved species in understory. The AM type was once thinned from below, thus stem density in the mid DBH classes was lower than upper or lower DBH classes. The P type consisted of plantations without A. holophylla seed trees. However, understory regeneration of A. holophylla was abundant through seed supply from A. holophylla in adjacent stands. Plantations with A. holophylla seed trees within or in adjacent stands showed vigorous natural regeneration of A. holophylla, highlighting the potential for succession from planted species to native A. holophylla in the Gapyeong area. Further studies can help develop techniques to restore plantations to native species-dominated natural stands using ecological succession.

• Journal of Plant Biotechnology
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• v.45 no.4
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• pp.400-408
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• 2018

Biodiversity has continued to degrade in the $21^{st}$ century due to global warming occasioned by destruction of the environment around the world.. The Nagoya protocol places Korea in a unique position to effectively develop and protect its domestic genetic resources. Microalgae under study in this research contains large amount of antioxidant substances such as beta carotene and astaxanthin, that can be used as biological resource owing to the large amounts of biomass that can be secured through photosynthesis. However, it is difficult to preserve it since cryopreservation method used for long-term preservation is yet to be developed. A basic study for long term cryopreservation was carried out on Nizschia frustulum and Nitzschia amabilis which belong to marine diatoms. As cryoprotectants (CPAs), glycerol, DMSO, and methanol which penetrate into cells were prepared at 5%, 10%, and 15% concentrations each, in case of methanol, it was tested at concentrations of 5%, 10% and 12% by its nature. Two kinds of microalgae, N. frustulum and N. amabilis, were diluted with $10^2$, $10^3$ and $10^4cells\;ml^{-1}$, respectively. The highest survival rate was shown at12% concentration of methanol, and the figures were $6.94{\pm}0.31%$ in N. frustulum and $8.85{\pm}0.16%$ in N. amabilis. As a result of 3 weeks cultivation of thawed microalgae after freezing, the result is shows that N. frustulum increased about 10 times faster and N. amabilis increased about 12 times the original concentration.

• Korean Journal of Environment and Ecology
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• v.33 no.4
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• pp.440-446
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• 2019

This study examined the growth and fruiting characteristics and the acorns biomass allometric equation of Quercus acuta to provide reference data related to the growth and seed supply during the restoration of evergreen forest in the warm temperate zone in Wando Island, Korea. For the growth survey, we selected and cut three sample trees having a mean diameter at breast height (DBH) to investigate the growth analysis through a stem analysis. We then developed the allometric equation (Y=aX+b) of DBH and tree height growth characteristic (Y) according to the average tree age (X) of sampled trees and estimated the DBH and tree height according to the age of Quercus acuta. For the fruiting survey, we selected and cut three sample trees with full fruit in August when, they are at the early mature fruiting stage, for the analysis. To develop the acorns/tree biomass allometric equation of Quercus acuta, we selected and cut ten sample trees of evenly divided diameters. The acorns biomass allometric equation ($Y=aX^b$) was derived by analyzing the biomass (Y) and the growth characteristics (X), such as the DBH, tree height, crown width, and crown height. The allometric equations of average tree age according to DBH and tree height were Y=0506X-2.064 ($R^2=0.999$) and Y=0.321X+0689 ($R^2=0.992$), respectively. The developed allometric equations estimated that the DBH were 3.0cm, 8.1cm, 13.1cm and 18.2cm while the tree heights were 3.9m, 7.1m, 10.3m, and 13.5m when the tree ages were 10, 20, 30, and 40 years, respectively. The analysis results of fruiting characteristics showed that the length, the diameter, the number of fruits, and the number of acorns per fruiting branch had the statistically significant difference and tended to decrease from the upper part to the lower part of crown downward. The total number of acorns was 1,312 acorns/tree in the upper part, 115 acorns/tree in the middle part, and 5 acorns/tree in the lower part of the crown. The allometric equation for the amount of acorns with DBH as an independent variable was $Y=0.003X^{4.260}$ with the coefficient of determination at 0.896. Although the coefficient of determination of the allometric equation using only DBH as the independent variable was lower than that using DBH and tree height ($D^2H$), it would be more practical to consider only DBH as the independent variable because of measurement errors.

• Korean Journal of Environment and Ecology
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• v.34 no.6
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• pp.515-529
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• 2020

Constructed wetlands undergo biological and physical changes such as an increase in the proportion of arid plants due to the natural succession process after formation. It can adversely affect not only the purification function but also the habitat of species. As such, this study aims to identify environmental factors affecting biodiversity and propose management plans based on the monitoring results of physical environmental changes and the emergence of species in seven constructed wetlands selected based on the water depth and surrounding conditions among the lands purchased by the Nakdong River basin. We examined the environmental conditions and emergence of the Odonata, which is a wetland-dependent species, to predict the trend of changes in biodiversity and abundance. The results showed that the open water area decreased as the emergent plants spread to the deep water in 2015 compared to 2012 when they were initially restored to a depth of 0.2 to 1 m. While a total of 54 dragonfly species were observed, the habitat diversity, such as vegetation, water surface, and grassland, remained similar to the initial formation of the wetlands despite the expansion of the emergent plants. On the other hand, the number of Agrionidae species, which prefer areas with fewer aquatic plants, decreased between 2012 and 2015 due to the diminished water surface. The p-values of the differences in the number of species and population between wetlands by year were 2.568e-09 and 1.162e-08, respectively, indicating the statistically significant differences. The decrease in open water surface was found to have the greatest effect on the biodiversity and habitat density of dragonflies. The time-series survey of constructed wetlands confirmed that the spread of Phragmites communis, P. japonica, Typha orientalis, etc., caused a decrease in species diversity. It suggests that environmental management to maintain the open water surface area is necessary.

• Korean Journal of Ecology and Environment
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• v.54 no.1
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• pp.49-60
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• 2021

We examined the flow characteristics by direct runoff and base flow in a headwater stream during observed 59 rainfall events of flood season (June~September) from 2017 to 2020 yrs. Total precipitation ranged from 5.0 to 400.8 mm, total runoff ranged from 0.1 to 176.5 mm, and runoff ratio ranged from 0.1 to 242.9% during the rainfall events. From hydrograph separation, flow duration in base flow (139.3 days) was tended to be longer than direct runoff (78.3 days), while the contribution of direct runoff in total runoff (54.2%) was greater than base flow (45.8%). The total amount and peak flow of direct runoff and base flow had the highest correlation (p<0.05) with total precipitation and duration of rain among rainfall and soil moisture conditions. Dominant rainfall events for the total amount and peak flow of base flow were generated under 5.0~200.4 and 10.5~110.5 mm in total precipitation. However, when direct runoff occurred as dominant rainfall events, total amount and peak flow were increased by 267.4~400.8 and 169.0~400.8 mm in total precipitation. Therefore, the unique aspects of our study design permitted us to draw inferences about flow characteristic analysis with the contribution of base flow and/or direct runoff in the total runoff in a headwater stream. Furthermore, it will be useful for the long-term strategy of effective water management for integrated surface-groundwater in the forested headwater stream.

• Korean Journal of Environmental Biology
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• v.39 no.2
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• pp.184-194
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• 2021

Since the construction of a dike in 1983, the water quality in the Bunam Lake has continued to deteriorate due to algal bloom caused by agricultural nutrient loading. Therefore, we evaluated the change in water quality and phytoplankton ecological characteristics in Bunam Lake and Cheonsu Bay, Korea. Water temperature, salinity, dissolved oxygen, chemical oxygen demand (COD), chlorophyll, and phytoplankton community were surveyed in April during the dry season and in July during the rainy reason. As a result, during the dry period, phytoplankton proliferated greatly and stagnated in the Bunam Lake while a very high population of cyanobacteria Oscillatoria spp. (8.61×10⁷ cells L^-1) was recorded. Most of the nutrients, except, nitrate and nitrite, were consumed due to the large growth of phytoplankton. However, during the rainy period, concentrations of ammonia, phosphate, silicate, nitrate, and nitrite, were very high towards the upper station due to the inflow of fresh water. Cyanobacteria Oscillatoria and Microcystis spp. were dominant in the Bunam Lake during the rainy period. Even in the Cheonsu Bay, cyanobacteria dominated due to the effect of discharge and diatoms, such as, Chaetoceros spp. and Eucampia zodiacus, which also proliferated significantly due to increased levels of nutrients. Since the eutrophication index was above 1 in Bunam Lake, it was classified as eutrophic water and the Cheonsu Bay was classified as eutrophic water only during the rainy season. In addition, a stagnant seawater-derived hypoxia water mass was observed at a depth of8m in the Bunam Lake adjacent to the tide embankment and the COD concentration reached 206 mg L^-1 in the bottom layer at B3. Based on this result, it is considered that the water quality will continue to deteriorate if organic matters settle due to continuous inflow of nutrients and growth of organisms while the bottom water mass is stagnant.