• Journal of Advanced Marine Engineering and Technology
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• v.38 no.2
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• pp.208-216
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• 2014

In case of any coastal ocean near the mouth of huge rivers, low salinity water can be formed due to its large amount of freshwater discharge. For the acoustic analysis on the low salinity environment, some oceanographic data of the East China Sea and the Atlantic Ocean were collected through KODC (Korea Oceanographic Data Center) and NODC (National Oceanographic Data Center) online service. In this paper, the T-S gradient diagram is introduced to show a relation between the gradients of temperature and salinity in view of acoustic surface channel formation. Existence of haline channel, quantitative contribution of gradients of salinity and temperature, effectiveness of the channel formation can be known by the T-S gradient diagram. After applying the collected data into the diagram, tropical regions of the Atlantic Ocean show strong haline channel due to its nearly invariant temperature and drastic change of salinity with depth. The averaged transmission loss in the channel is about 5.7 ~ 7.5 dB less than that out of the channel by the results of acoustic propagation model (RAM: Range independent Acoustic Model). On the other hand, the East China Sea and temperate region of the Atlantic ocean have weaker haline channel with less difference of the averaged transmission loss between in and out of the channel as 3.2 ~ 6.0 dB. Although data samples used in this study have limitation to represent the general physical structures of the three ocean regions, the T-S gradient diagram is shown to be useful and acoustic field affected by low salinity environment is investigated in this study.

• Ocean and Polar Research
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• v.26 no.3
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• pp.401-414
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• 2004

Temperature, salinity, alkalinity, pH, nutrient, chlorophyll, and iron were measured within the upper 250m water column around the Antarctic Polar Front in the Scotia Sea from late November to early December 2001. Temperature and salinity showed a rapid change across the Polar Front, and the temperature minimum layer existed only in the southern area of the Polar Front. Total $CO_2$ and nutrient concentrations were relatively high and increased rapidly with water depth in the southern area of the Polar Front, which was resulted from upwelling of the Antarctic deep water containing high concentrations of total $CO_2$ and nutrient. ${\Delta}C:{\Delta}N:{\Delat}P$ ratios measured in the norhem and southern areas of the Polar Front were 75:11.4:1 and 84:12.5:1, respectively, which were lower than the Redfield ratio. ${\Delta}Si:{\Delta}N$ ratio (3.65) measured in the southern area of the Polar Front was two times higher than that (1.95) in the northern area. These two ratios were higher than the ratio (1.0) measured in the temperate and tropical oceans. Chlorophyll concentrations were extremely high in the area of $59^{\circ}{\sim}60^{\circ}S$, which was attributed to favorable environmental conditions for phytoplankton growth in this area, such as sufficient iron, high water column stability, and high silicate concentration.

• Ocean and Polar Research
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• v.31 no.1
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• pp.63-70
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• 2009

Eutrophicated water fed through Mankyeong River and Dongjin River into the new Saemankeum Lakemight seriously affect the water quality and phytoplankton community in the lake. To obtain control reference data for the later studies on environmental changes due to the construction of the Saemankeum Sea Wall, we performed a monthly investigation on the physico-chemical properties of the water and phytoplankton community at 3 stations in the Mankyeong River Estuary over 14 months starting from September 1999. Water temperature ranged from $0.3{\sim}32.9^{\circ}C$ due to the typical seasonal variations in temperate on the coasts and salinity exhibited a wide annual range of $0.2{\sim}33.7$ psu along with regular and huge hourly variations according to tidal cycles. Inorganic nutrients were supplied from rivers to the monitoring station and the whole lake. The average concentration of total-N, $6.99\;mg{\cdot}l^{-1}$, was higher than the water quality for agricultural use with peak values occurring in winter. Species composition showed a seasonal succession pattern, where a high diversity was observedin summer and autumn and vice versa in winter. Hourly variations of water properties in the "Mankyeong bridge" Station were quite regular and well in accordance with the daily tidal cycles. The different degree of sea water intrusion during the flood tide at each of the 3 stations exhibited a different range and variation pattern of water temperature and salinity throughout a day. Hourly changes in species composition were in harmony with the daily tidal cycles, resulting in extremely variable spatio-temporal variation.

• The Korean Journal of Malacology
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• v.22 no.1 s.35
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• pp.63-86
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• 2006

A list of species of bivalve mollusks, their local distributions and relative abundance in Yeongil Bay were analysed. Species richness ranging from 1 to 37 species was low (less than 10) in some stations at the entrance and in the central part of the bay. Fifteen species (Acila insignis, Nucula tenuis, Yoldia notabilis, Mytilus galloprovincialis, Arca boucardi, Axinopsida subquadrata, Felaniella usta, Mactra chinensis, Raeta pulchella, Nitidotellina hokkaidoensis, Theora fragilis, Alvenius ojianus, Callithaca adamsi, Ruditapes philippinarum and Laternula anatina) were most frequently encountered, and seven of them were most abundant numerically (per sample): Th. fragilis in the inner bay, A. insignis, N. tenuis, and A. ojianus in the outer bay, and C. adamsi, A. subquadrata, R. puichella in both parts. Local distributions of common species were described and presented in plotted data, and three distribution patterns were recognized. Biogeographical analysis shows that a majority of species (55%) belongs to the subtropical group, tropical-subtropical species (16%) play a relatively significant role, and the percentage of boreal (temperate) and boreal-arctic species is 18% which characterizes the whole fauna as subtropical. Zonal-biogeographical composition and number of species in families in Yeongil Bay are compared with those of some Japanese (Wakasa and Mutsu) and Russian (Peter the Great, Possjet and Amursky) bays of the East Sea. The absence of a number of typical warm-water embaymental mollusks in Yeongil Bay found in the north further East Sea and Japan, and the similar zonal-biogeographical structure of the inner and outer bay faunas are explained by active water exchange due to the openness of the bay, relatively low summer temperatures, and presence of upwelled cold waters.

• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.1
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• pp.1-10
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• 2014

This study was carried out to investigate the range of distribution and vegetation structure of habitats of genus Cymbidium which is distributed in Jeju Island, Korea. This genus is distributed in tropical and subtropical Asia and North Australia. In Korea, there are six species [i. e. C. goeringii (Rchb. f.) Rchb. f., C. kanran Makino, C. lancifolium Blume var. aspdistrifolium (Fukuy.) S. S. Ying., C. macrorhizum Lindl., C. nagifolium Masam. and C. ensifolium L.], which were also distributed in Jeju Island. The habitats of this genus ranged between 16 meter and 574 meter above sea level in Jeju Island. C. macrorhizum had the broadest altitudinal range (16-574 meter above sea level), whereas C. ensifolium, C. nagifolium and C. lancifolium var. aspidistrifolium had the narrow altitudinal range. According to the classification analysis by TWINSPAN, the plant communities were divided into five groups of Castanopsis sieboldii community, Castanopsis sieboldii-Pinus thunbergii community, Pinus thunbergii-Quercus acutissima community, Pinus thunbergii community and Quercus glauca- Aphananthe aspera community. Three species, C. kanran, C. nagifolium, and C. ensifolium inhabited Castanopsis sieboldii community and C. lancifolium var. aspdistrifolium inhabited Castanopsis sieboldii-Pinus thunbergii community. C. macrorhizum inhabited Pinus thunbergii community, Pinus thunbergii-Quercus acutissima community and Quercus glauca-Aphananthe aspera community. C. goeringii inhabitated Castanopsis sieboldii-Pinus thunbergii community and Pinus thunbergii-Quercus acutissima community. The populations of the genus Cymbidium have been extremely decreased due to illegal collection in Jeju Island. Especially, the distribution range of C. kanran, C. nagifolium, and C. ensifolium was narrow and limited to evergreen broad-leaved forests, therefore, conservation plans are needed for the protection of these species.

• Korean Journal of Environment and Ecology
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• v.30 no.3
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• pp.386-398
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• 2016

To understand the vegetation structure in the ridgeline area of Nakdong-jeongmaek, six primary areas in Nakdong-jeongmaek were selected and their vegetation distribution was surveyed considering the environmental conditions and artificial influences. According to the results of community classification based on TWINSPAN, the vegetation in the surveyed region was categorized into 9 groups: Betula costata-Quercus mongolica community, Q. mongolica community, Pinus densiflora-Q. mongolica community, P. densiflora community, Deciduous oaks-P. densiflora community, Deciduous oaks community, P. thunbergii community, P. koraiensis-P. rigida community, and Chamaecyparis obtusa-Alnus firma community. In Baekbyeongsan(Mt.) located in Taebaek-si of Gangwon-do, Betula costata-Quercus mongolica community was found, reflecting the environmental characteristics of northern temperate climate. P. thunbergii community appeared in Gudeoksan(Mt.) of Busan metropolitan city, which is near the coast. Since Gudeoksan(Mt.) is near to the downtown and its altitude above the sea is relatively low, people visit the area often. Therefore, C. obtusa and P. thunbergii have been planted for producing forest trees and implementing anti-erosion afforestation. In the other primary survey areas, Q. mongolica-dominant communities, P. densiflora-dominant communities, and deciduous oak-dominant communities, which are representative forest vegetation types of Jeongmaeks in South Korea, were mainly distributed, showing no significant difference compared to the forest vegetation types of other Jeongmaeks. Since the Nakdong-jeongmaek from south to north, it shows clear characteristics of vegetation changes between the northern temperate climate and the warm temperate climate of the south.

• Korean Journal of Agricultural and Forest Meteorology
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• v.7 no.3
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• pp.201-210
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• 2005

This study was conducted to prepare efficient and systematic measures for nature conservation and management in Beomseom Islet, and to provide for basic data to investigate the process of vegetation change in the future. The vegetation of Beomseom Islet was classified to six vegetation type; i.e., Miscanthus sinensis community, Pinus thunbergii community, Iythophyte vegetation, evergreen broad leaf community, shrub community, and Pseudosasa japonica community. The size of each vegetation type was 40,230 $m^2$ ($23.3\%$) for shrub community, 39,366 $m^2$($22.8\%$) for Iythophyte vegetation, 30,012 $m^2$ ($17.4\%$) fur Pinus thunbergii community, 29,853 $m^2$ ($17.3\%$) for Miscanthus sinensis community, 5,564 $m^2$ ($3.2\%$) for evergreen broad leaf community, and 3,325 $m^2$ ($1.9\%$) for Pseudosasa japonica community. The area of non-vegetated sea cliff Bone that composed of bare rocks is 24,246 $m^2$($14.1\%$). We estimated that these distribution patterns of vegetation were the result of various environmental factors such as the steepness of slope and shallowness of soil as well as the cultivation of exotic plants causing disruption of native vegetation.

• Journal of Environmental Science International
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• v.25 no.1
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• pp.57-65
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• 2016

This study's purpose was to provide basic data for the monitoring of ecological changes caused by change of vegetation structure of Abies koreana forest in a study site susceptible to climatic change in Yeongsil area of Hallasan Mountain, Jeju Island. Surveys revealed this: in Yeongsil area of Hallasan Mountain, per 1 ha of A. koreana forests, total number 1,781, and A. koreana number 989, accounting for 55.5% of the total number of trees. 190 A. koreana or 19.2% were found to be dead. For the number of individual trees by DBH, trees standing 5 cm - 10 cm tall formed the largest portion at 39.9%, and in the case of other trees except A. koreana, the number of individual trees below 5 cm accounted for 23.5% of the total number of trees. The survey of importance by height revealed this: at the top level, the importance of A. koreana was the highest at 106.23, but the sum of importance of temperate deciduous broad-leaved trees (Prunus maximowiczii, Quercus mongolica, and Taxus cuspidata) was higher at 142.84 than that of A. koreana. The analysis of species diversity revealed 0.645 species diversity for the tree layer and 0.817 for the shrub layer; for evenness, 0.549 for the tree layer and 0.664 for the shrub layer; for dominance value; 0.451 for the tree layer and 0.336 for the shrub layer. The analysis of tree vitality revealed that for the A. koreana forests in Yeongsil, the composition ratio of A. koreana by type is AS type>AL type>DS type>DB type, and that of the other trees is AL type>AS type>AF type>AB type. Compared with the forests in other areas, the A. koreana forests in the Yeongsil area have a very high occurrence rate of dead trees, and a high importance of trees is shown in the deciduous broad-leaved tree forests. Compared with the A. koreana forests in the Jindallaebat area, with the same level above sea, the vegetation structures are fast changing. Also, due to dryness and other non-physical environmental changes caused by a lack of rainwater and dry winds in winter, dead trees are fast increasing in number. Environmental changes such as climate change diversely affect the maintenance of A. koreana in individual areas, and if environmental changes are fast and continue long, of the A. koreana forest areas in the Hallasan Mountain, the A. koreana forests in the Yeongsil area will decrease fastest in number and will experience changes in the vegetation structure. Thus, it is necessary to survey the vegetation changes in A. koreana forests, which are distributed in all directions but are centered on Hallasan Mountain, and to thus conduct long-term monitoring and research.

• Ocean and Polar Research
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• v.33 no.spc3
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• pp.349-358
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• 2011

In order to ascertain latitudinal variation of lipid contents and compositions in copepods, we collected warm water copepod species (Euchaeta sp. and Pleuromamma spp.) from four different regions from low (sub-tropical) to mid (temperate) latitudes in the Northwest Pacific Ocean. Total lipid contents of Pleuromamma spp. were about 11 $ug{\cdot}ind^{-1}$ with little latitudinal variation, whereas Euchaeta sp. showed slightly higher lipid content (20 $ug{\cdot}ind^{-1}$) than Pleuromamma spp. with latitudinal gradient (low at subtropic and high at temperate). Wax esters, known as the major storage lipid classes, were found to be the dominant lipid classes (accounting for more than 35% of total lipids) in Euchaeta sp., whereas in Pleuromamma spp., phospholipids, known as cellular membrane components, were the dominant lipid classes. However, the exception was specimens from warm pool region exhibiting dominance in storage of lipids as a form of triacylglycerols. Among fatty acids, polyunsaturated fatty acids (PUFA), especially docosahexaenoic acid (DHA : 22:6(n-3)) (about 35% of total fatty acids), were most abundant in Euchaeta sp., while saturated fatty acids (SAFA), specially hexadecanoic acid (16:0) (about 30% of total fatty acids), were most abundant in Pleuromamma spp.. Among the neutral fraction of lipids, phytol, originated from the side chain of chlorophyll, was found in all samples which generally indicate active copepods feeding on algae. While only trace amounts of short-chain fatty alcohols were found in Pleuromamma spp., significant amounts of fatty alcohols were found in Euchaeta sp.. Particularly, significant amounts of long chain monounsaturated fatty alcohols (20:1 and 22:1), generally found in cold water species, were found in Euchaeta sp. from low latitudes. The latitudinal variation of trophic lipid markers in these copepods could be significantly related with in-situ food availability and species-specific diet preference. The result of this study suggests that the lipid contents and compositions in copepods may not only indicate their nutritional condition and feeding ecology but also provide insight into species-specific living strategies under different environmental conditions (i.e. water temperature, food availability).

• Journal of Ecology and Environment
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• v.43 no.4
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• pp.438-453
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• 2019

Background: To investigate the trends of succession occurring at the Pinus thunbergii forests on the lowlands of Jeju Island, we quantified the species compositions and the importance values by vegetation layers of Braun-Blanquet method on the Pinus thunbergii forests. We used multivariate analysis technique to know the correlations between the vegetation group types and the location environmental factors; we used the location environment factors such as altitudes above sea level, tidal winds (distance from the coast), annual average temperatures, and forest gaps to know the vegetation distribution patterns. Results: According to the results on the lowland of Jeju Island, the understory vegetation of the lowland Pinus thunbergii forests was dominated by tall evergreen broad-leaved trees such as Machilus thunbergii, Neolitsea sericea, and Cinnamomum japonicum showing a vegetation group structure of the mid-succession, and the distribution patterns of vegetation were determined by the altitudes above sea level, the tidal winds on the distance from the coast, the annual average temperatures, and the forest gaps. We could discriminate the secondary succession characteristics of the Pinus thunbergii forests on the lowland and highland of Jeju Island of South Korea. Conclusions: In the lowland of Jeju Island, the secondary succession will progress to the form of Pinus thunbergii (early successional species)→Machilus thunbergii, Litsea japonica (mid-successional species)→Machilus thunbergii (late-successional species) sequence in the temperate areas with strong tidal winds. In the highland of Jeju Island, the succession will progress to the form of Pinus thunbergii (early successional species)→Neolitsea sericea, Eurya japonica (mid-successional species)→Castanopsis sieboldii (late-successional species) sequence in the areas where tidal winds are weak and temperatures are relatively low. However, local differences between lowland and highland of Jeju Island will be caused by the micro-environmental factors resulting from the topographic differences and the supply of tree seeds. From the characteristics of succession study, we could properly predict and manage the Pinus thunbergii forest ecosystem on lowland and highland of Jeju Island.