• Korean Journal of Ecology and Environment
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• v.45 no.1
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• pp.123-128
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• 2012

We aimed to estimate the accumulated degree days required for the development of $Cloeon$ $dipterum$ (Ephemeroptera: Baetidae) in an experimental tub under field conditions from August 7 to October 10 in 2011. After 4 days in a tub setting, a dead female adult was found on the water surface at which oviposition had presumably occurred. Adults emerged from 39 days to 61 days after the oviposition date. The total number of emerged adults was 229, and the sex ratio (number of females : total population) was 0.45, although not statistically significant ($p$ >0.05). The males generally emerged earlier than females. Assuming that the basal temperature ($T_b$) value is $0^{\circ}C$, we estimated the number of accumulated degree days required for the development of $C.$ $dipterum$ to be $1,221.8{\pm}116.0$ DD (mean${\pm}$SD). Since the annual number of accumulated degree days in the reference wetland was measured to be 5,650.0 DD, we estimated that $C.$ $dipterum$ is multivoltine, with a maximum of 4 cohorts in 1 year in natural habitats.

• Journal of Forest and Environmental Science
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• v.32 no.4
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• pp.353-366
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• 2016

The effect of different environmental conditions and altitudes on the growth and reproductive characteristics in 12 teak plantations at 4 different blocks (Cauvery canal bank, Topslip and Parambikulam (Tamil Nadu), Nilambur and Wayanad (Kerala) of Southern India was investigated. The annual rainfall and mean monthly temperature of the study areas varied significantly from 1390 to 3188 mm and 16 to $38^{\circ}C$ respectively. The teak plantations in Cauvery canal bank which grow in continuous moisture condition (8-10 months) retain the leaf for longer period due to moisture resulting continuous supply of photosynthates leads to fast and outstanding growth. The girth at breast height (GBH) of 34-years-old tree in canal area was similar to that of 40 to 49-years-old trees in other locations, indicating that teak plantations with regular watering and silvicultural practices may be harvested at the age of 30 years. The leaf fall, flowering and fruiting showed significant variations in different teak plantations due to environmental factors and altitudes. It was found that increase of rainfall enhances number of flowers in the inflorescence in teak. Tholpatty (block-IV) showed more flowering in a inflorescence (3,734-3,744) compared to other plantations (1,678-3,307). Flowering in Nilambur and Wayanad coincided with heavy rainfall resulting low fruitset (1.1-2.3%) probably heavy rainfall ensuing restriction of pollinators for effective pollination. On the other hand, flowering in Cauvery canal bank (Block-I) was not coincided with high rainfall exhibited high fruitset (2-3%). About 66 to 76% of the fruits in different plantations were empty, and it is one of the main reasons for poor germination in teak. The seeds of Topslip and Parambikulam (Block-II) showed higher seed weight, maximum seed filling and good germination indicating that the environmental factors and altitude play significant role in fruit setting and seed filling in teak. In addition, the teak plantations in Topslip and Parambikulam showed good growth suggesting that plantations in the altitude range of approximately 550-700 m may be suitable for converting into seed production areas for production of quality seeds.

• Korean Journal of Environmental Biology
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• v.34 no.4
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• pp.240-245
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• 2016

This study was conducted to predict the changes of potential distribution for invasive alien plant, Amaranthus viridis in Korea. The habitats of A. viridis were roadside, bare ground, farm area, and pasture, where the interference by human was severe. We used maximum entropy modeling (MaxEnt) for analyzing the environmental influences on A. viridis distribution and projecting on two different representative concentration pathways (RCP) scenarios, RCP 4.5 and RCP 8.5. The results of our study indicated annual mean temperature, elevation and precipitation of coldest month had higher contribution for A. viridis potential distribution. Projected potential distribution of A. viridis will be increased by 110% on RCP 4.5, 470% on RCP 8.5.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.2
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• pp.79-88
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• 2015

Preparations need to be made for Korean pine(Pinus koraiensis) in anticipation of climate change because Korean pine is an endemic species of South Korea and the source of timber and pine nut. Therefore, climate change adaptation policy has been established to conduct an impact assessment on the distribution of Korean pine. Our objective was to predict the distribution of Korean pine while taking into account uncertainty and afforestation conditions. We used the 5th forest types map, a forest site map and BIOCLIM variables. The climate scenarios are RCP 4.5 and RCP 8.5 for uncertainty and the climate models are 5 regional climate models (HadGEM3RA, RegCM4, SNURCM, GRIMs, WRF). The base period for this study is 1971 to 2000. The target periods are the mid-21st century (2021-2050) and the end of the 21st century (2071-2100). This study used the MaxEnt model, and 50% of the presences were randomly set as training data. The remaining 50% were used as test data, and 10 cross-validated replicates were run. The selected variables were the annual mean temperature (Bio1), the precipitation of the wettest month (Bio13) and the precipitation of the driest month (Bio14). The test data's ROC curve of Korean pine was 0.689. The distribution of Korean pine in the mid-21st century decreased from 11.9% to 37.8% on RCP 4.5 and RCP 8.5. The area of Korean pine at an artificial plantation occupied from 32.1% to 45.4% on both RCPs. The areas at the end of the 21st century declined by 53.9% on RCP 4.5 and by 86.0% on RCP 8.5. The area of Korean pine at an artificial plantation occupied 23.8% on RCP 4.5 and 7.2% on RCP 8.5. Private forests showed more of a decrease than national forests for all subsequent periods. Our results may contribute to the establishment of climate change adaptation policies for considering various adaptation options.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.8 no.2
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• pp.70-77
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• 2003

From March 1998 to August 2000, the phenological and morphometric changes of Zostera marina L. were examined at the Duksan Port in the eastern coast of Korea. Morphometric characteristics, phenological stage, shoot density, biomass of Z. marina population and environmental parameters were also measured. Nutrient levels in water column varied over the season. Morphometric characteristics of vegetative shoot changed with season; shoot heights ranged from 54.2 cm (March) to 100.0 cm (October). Reproductive shoots appeared from mid-March to early September of which the height was ranged from 97.8 cm (March) to 213.0 cm (July). The flowering phase started at 12$^{\circ}C$ and the fruit development was resulted up to 21$^{\circ}C$. The seed maturing was developed at 22$^{\circ}C$-$25^{\circ}C$. Shoot density and biomass in permanent quadrate (0.25 m$^2$) were significantly different among seasons ranging from 38 to 136 shoots (mean 80.3$\pm$6.5) for shoot density, and 190 g dry wt m$^{-2}$ in October 1998 to 922 g dry wt m$^{-2}$ in June 1998 for biomass respectively. Relationships between shoot morphometrics and physico-chemical parameters were not significantly correlated. Seasonal changes in water temperature seemed responsible for the replacement of reproductive phases and the annual changes of shoot morphometrics in Z. marina populations.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.5
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• pp.659-663
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• 1999

Gametogenesis, reproductive cycle, condition factor, and meat weight rate of the surf clam, Tresus Keenae were studied by histological observations and morphometric data based on the samples which have been collected from the south coast of Korea, from January 1995 to February 1996. The annual ranges of the mean seawater temperature and specific gravity in habitat of the surf clam were $4.9\~24.9^{\circ}C$ and 1.0210$\~$1.0266, respectively. Monthly changes in the condition factor showed in a wide range from 0.2381 to 0.2827, began to increase in January and reached the first maximum (0.2827) in April. And then the value rapidly decreased in June, thereafter, reached the second peak (0.2812) in August. The condition factor of this species showed the two peaks, and gonadal development reached sexually mature and ripe conditions during the period of these two peaks. The meat weight rate ranged from $38.0\%$ to $46.4\%$, and its change showed a similar tendency with the condition factor. The reproductive cycle of this species can be divided into five successive stages: in both sex, multiplicative (December to January, July to August), growing (January to February, September to October), mature (February to April, September to November), spawning (April to June, September to November), and degenerative and resting stage (May to July, November to January).

• Korean Journal of Environmental Biology
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• v.36 no.4
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• pp.672-679
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• 2018

This study was conducted to predict the potential distribution and risk of invasive alien plant, Amaranthus patulus, in an agricultural area of South Korea. We collected 254 presence localities of A. patulus using field survey and literature search and stimulated the potential distribution area of A. patulus using maximum entropy modeling (MaxEnt) with six climatic variables. Two different kinds of agricultural risk index, raster risk index and regional risk index, were estimated. The 'raster risk index' was calculated by multiplying the potential distribution by the field area in $1{\times}1km$ and 'regional risk index' was calculated by multiplying the potential distribution by field area proportion in the total field of South Korea. The predicted potential distribution of A. patulus was almost matched with actual presence data. The annual mean temperature had the highest contribution for distribution modeling of A. patulus. Area under curve (AUC) value of the model was 0.711. The highest regions were Gwangju for potential distribution, Jeju for 'raster risk index' and Gyeongbuk for 'regional risk index'. This different ranks among the index showed the importance about the development of various risk index for evaluating invasive plant risk.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.17 no.2
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• pp.92-100
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• 1984

The seasonal variation of catch and the fishing ground formation of anchovy caught by gill net are studied by using the data for 14 years, 1969 to 1982, published by the Fisheries Research and Development Agency of Korea. The main fishing season of anchovy by gill net can be devised into two seasons: spring and autumn. The former begins early in spring, marks peak in May with the monthly mean catch of 3,000 $\frac{M}{T}$ and ends in summer. The latter begins early in autumn, marks peak in October with the monthly mean catch of 1,500$\frac{M}{T}$ and ends in winter. The fishing ground begins to be formed in the southern waters of Korea with the begining of spring fishing season, and it is extended all over the south-eastern waters from spring to summer and it is converged to the coastal areas from autumn to winter. From the calculation of correlationship between adjacent fishing sections, the fishing ground can be devided into three areas; the northern area of $37^{\circ}N$, the southern area of $35^{\circ}N$ and the area between $35^{\circ}N\;and\;37^{\circ}N$. In the northern area of $37^{\circ}N$, monthly centers of the fishing ground are located in the adjacent aea area of Sockcho-Jumunjin district in the whole year, and its annual mean variance shows about 8 miles in the latitudinal direction and 10 miles in the longitudinal direction. In the area between $35^{\circ}N\;and\;37^{\circ}N$, monthly centers are located in the adjacent sea area of Kijang-Kuryongpo district, and the variance shows about 10 miles in the longitudinal direction and 20 miles in the latitudinal direction. In the southern area of $35^{\circ}N$, monthly centers are located in the open sea in spring and summer, and are conversed to the coastal area in autumn and winter, and the variance shows 8 miles in the latitudinal direction and 35 miles in the longitudinal direction. Water temperature and salinity at the fishing ground where the anchovy gill net was effectively operated are estimated from 14 to $20^{\circ}C$ and from 33.0 to $34.0\%0$ respectively.

• Korean Journal of Environmental Agriculture
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• v.33 no.4
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• pp.327-333
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• 2014

BACKGROUND: Rabbiteye blueberry(Vaccinium ashei) is one of the most widely grown blueberry types in the world, together with Northern and Southern highbush blueberry(Vaccinium corymbosum). Rabbiteye blueberry have higher soil adaptability and fruit productivity but less cold tolerance to low temperature than highbush blueberry. The objective of this study is to investigate freezing tolerance of floral buds and establish a cultivation zone for rabbiteye blueberry cultivars. METHODS AND RESULTS: Bearing branches which have similar thickness and same number of floral buds were collected in the early January at the blueberry germplasm preservation plot located in Namhae Sub-station, National Institute of Horticultural and Herbal Science in Gyeongsangnamdo. Cold response of bearing branches were investigated by electrolyte leakage and freezing tolerance of floral buds were determined by ovary browning ratio of 50%($LT_{50}$). Cultivation zone was established based on mean annual extreme minimum temperature for 30 years, from 1981 to 2010. The electrolyte leakage of bearing branches in rabbiteye blueberry increased as temperature decreased and was lowest in 'Brightwell' but highest in 'Bluegem' when they were kept in $-5^{\circ}C$. Besides, the electrolyte leakage increased in 'Brightblue', 'Brightwell', 'Climax', 'Delite', 'Gardenblue', 'Southland' and 'Woodard' in $-20^{\circ}C$. Freezing tolerance($LT_{50}$) was lowest in 'Bluegem' and 'Homebell'($-13.3^{\circ}C$), and highest in 'Tifblue'($-25^{\circ}C$) among different rabbiteye blueberry cultivars. $LT_{50}$ of 'Southland' was from -15.0 to $-16.7^{\circ}C$, that of 'Delite', 'Brightwell',' Austin' and 'Climax' was $-18.3^{\circ}C$, and that of 'Bluebelle', 'Woodard' and 'Powderblue' was $-20^{\circ}C$. CONCLUSION: This study indicate that The hardiness zones of rabbiteye blueberry were classified into Six cultivation zones and cultivation zones of most cultivars were the south of Jeollanam-do and Gyeongdangnam-do, except for 'Tifblue.'

• Journal of Korean Society of Forest Science
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• v.106 no.2
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• pp.249-257
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• 2017

This study was conducted to analyze the relationship between tree-ring growth of Pinus densiflora and climate factors based on national forest inventory(NFI) data. Annual tree-ring growth data of P. densiflora collected by the $5^{th}$ NFI were first organized to analyze yearly growth patterns of the species. Yearly growing degree days and standard precipitation index based on daily mean temperature and precipitation data from 1951 to 2010 were calculated. Using the information, yearly temperature effect index(TEI) and precipitation effect index(PEI) were estimated to analyze the effect of climate conditions on the tree-ring growth of the species. A tree-ring growth estimation equation appropriate for P. densiflora was then developed by using the TEI and PEI as independent variables. The tree-ring growth estimation equation was finally applied to the climate change scenarios of RCP 4.5 and RCP 8.5 for predicting the changes in tree-ring growth of P. densiflora from 2011 to 2100. The results indicate that tree-ring growth of P. densiflora is predicted to be decreased over time when the tree-ring growth estimation equation is applied to the climate change scenarios of RCP 4.5 and RCP 8.5. It is predicted that the decrease of tree-ring growth over time is relatively small when RCP 4.5 is applied. On the other hand, the steep decrease of tree-ring growth was found in the application of RCP 8.5, especially after the year of 2050. The results of this study are expected to provide valuable information necessary for estimating local growth characteristics of P. densiflora and for predicting changes in tree-ring growth patterns caused by climates change.