• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.6
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• pp.586-592
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• 1986

The marine bacterial flora of seawater at Masan Bay located in southern part of Korea was investigated to provide basic information about the origin of red tides in this area. The samples were collected at 5 sampling stations (see fig.1) established once a month from July 1985 to June 1986. The results are summerized as follows: 1. Two hundred and ninety one strains of marine bacteria among 299 strains isolated were identified from 156 samples(150 seawater samples and 6 mud samples) collected in the study area. 2. During the study period, the dissolved oxygen ranged from 2.1 to 6.3 ml/l; temperature of surface seawater ranged from 4.6 to $30.1^{\circ}C$; phosphate, silicate and nitrite ranged from 1.6 to 5.6 ${mu}g-at/l$, 327.27 to 3798.38 ${mu}g-at/l$, and 1.09 to 5.5 ${mu}g-at/l$, respectively. 3. Pseudomonas spp. were the most dominant bacterial species before red tides, Ancinetobacter spp. and Flavobacterium spp. during red tides, and Flavobacterium spp., Vibrio spp. and Acinetobacter spp. after red tides. 4. Viable counts marine bacterial flora ranged $10^4{\sim}10^8cell/ml$, and the most abundant viable counts of marine bacteria occured during red tides ($10^7{\sim}10^8cell/ml$).

• Korean Journal of Environment and Ecology
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• v.26 no.4
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• pp.593-603
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• 2012

This study was carried out to investigate the ecological succession sere and conservative value, and to provide the basic data for the planning of the Provincial Park Management in Seonamsagol(Valley), Jogyesan(Mt.) Provincial Park(altitude 884m), Suncheon City, Korea by analysing the structure of the plant community. Twenty plots(size is $20m{\times}20m$) were set up at an altitude of range from 315m to 480m. As a result of analysis of TWINSPAN which is one of the ordination technique, the plant communities were divided into four groups which are community I(Quercus variabilis community), community II(Q. serrata community), community III(Decideous broad-leaved plant community), and community IV(Carpinus tschonoskii community). The warmth index is $104^{\circ}C{\cdot}month$ based on the data of monthly mean temperature during the past thirty years(1981~2010), so we found out that the vegetation of the study site located in the South Temperate Climate Zone. We supposed that the ecological succession sere of the study site is in the early stage of developing from Q. serrata community to Carpinus tshonoskii community, however we should do a long-term monitoring to investigate the changes of the ecological succession each plant community, meanwhile Sasa borealis was dominant species in the shrub layer. The diameter at breast height of specimen tree is range from 20 to 55cm(average 36cm) and the height of that is range from 14 to 35m(average 23cm). The age of community I was 64 years old, that of community II was from 59 to 64 years old, that of community III was from 51 to 62 years old, and that of community IV was from 41 to 68 years old, thus the age of the study site is about from 38 to 72 years old. According to the index of Shnnon's diversity(unit: $400m^2$), community IV was ranged from 0.8452 to 1.2312, community III was ranged from 0.8044 to 1.1404, community II was ranged from 0.8221 to 0.9971, and community I was 0.8324.

• Korean Journal of Environment and Ecology
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• v.32 no.3
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• pp.342-350
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• 2018

The purpose of this study was to identify the environmental factors that affect the beginning and end of calling by Hyalessa fuscata and Cryptotympana atrata, which are dominant cicada species in the central urban areas of Korea. The study area was Banpo Apartments in Seoul. The research period included two months, being from the end of July to the end of August 2015. We analyzed the start and end time of cicada calling, and on average H. fuscata started calling at 5:21 am and C. atrata started at 7:40 am. The average end time of calling was 6:31 pm for H. fuscata and 7:51 pm for C. atrata. From the scatter plot and box plot results, H. fuscata started calling at 05:00 am, whereas C. atrata consistently stopped calling at 20:00 pm compared to H. fuscata. Multiple regression analysis of the start and end time of cicada calling showed that sunrise time was a factor affecting the start of H. fuscata calling. The end time of H. fuscata calling was affected by sunset time and total cloud cover. The starting time of C. atrata calling was mostly affected by temperature and sunrise time. The effect of temperature was greater than that of sunrise time. The end time of C. atrata calling was strongly affected by sunset time, whereas peak temperature was also shown to affect the end time. From the above results, sunrise and sunset are thought to be the critical factor affecting the start and end time of H. fuscata calling. Therefore, H. fuscata started calling with sunrise, and the end time was also affected by sunset. Temperature was the factor most affecting the start of C. atrata calling and sunset was identified as the factor affecting the end time. Therefore, the start time of C. atrata calling shows variation with daily temperature changes, and C. atrata stop calling simultaneously with sunset.

• Korean Journal of Agricultural Science
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• v.10 no.1
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• pp.9-21
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• 1983

The structures of oak stands were studied in relation to their productivity. Three plots classified by the site quality following to altitude, were selected on the oak stand located at Naryongri Eunsanmyun Buyeogun. The site qualities of the stand studied were generally estimated to be moderate in respect to some soil physical and chemical properties. Quercus variabilis was dominant species in the vegetation composition of the stand studied. The crown densities of the stand were varied from 65.4% in plot I to 78.2% in plot III and the parts, occupied with oak trees, ranged from 44.4% in plot I to 65.9% in plot III in the density. In the contrast to crown density, the growing stocks of oak trees ranged from $3.937m^3$ in plot I (73.4% of plot total) to $2.075m^3$ in plot III (84.3% of plot total). The occupied ratios, measured by crown class, exhibited dissimilarity between crown projection area and volume, and also the ratios brought into different patterns by plot. Highly significant correlations were proved between crown projection areas and volumes of individual oak trees by plot, but not proved in the relations by crown class. The cumulative growth, current annual increment and mean annual increment displayed various patterns by plot and by crown class in the heights, D. B. H. s and volumes of oak trees. The maximum values of current annual increment of height were generally recorded in 10 to 20 years, earlier than those of D. B. H. The mean annual increment of height, D. B. H. and volume maintained similar levels after about 10 years and fluctuated irregularly. The crown projection area and volume following to thinning decreased in the order of the thinning methods of grade A < grade B < crown thinning$90m^3/ha$ in about 40 years in the productivity of volume of the oak stand studied.

• Korean Journal of Weed Science
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• v.13 no.1
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• pp.36-43
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• 1993

Differences in community space of weed and rice were investigated among five types of rice (Oryza sativa L.) cultivation. The five types employed were three transplanting cultivations such as conventional hand transplanting, machine transplanting with 30-day-old seedling, and machine transplanting with 10-day-old seedling and two direct-seedlings such as flood direct-seeded rice by pregerminated seed and dry direct-seeded rice by dry seed. The greatest competition between rice and weeds as determined by growth rate of rice was found in between 10 and 11 weeks after transplanting (WAT) and/or seeding, irrespective of cultivation types. Competition injury due to weeds was greater in transplanting with 10-day-old seedling than with 30-day-old seedling. The greatest injury in growth of rice was found in direct-seeded cultivation. In transplanting cultivations space occupation by rice in lower than 80 cm height level was low as compared with that by weeds. Plant heights of dominant weeds such as E. crus-galli and E. kuroguwai were shorter by heading date, but taller after the heading date than those of rice. In direct-seeding community space was mainly occupied by the weeds. The pattern of community structure and competition injury caused by weeds showed a similar tendency obtained on the basis of species distribution, number, and dry weight of the occurred weeds.

• Korean Journal of Ecology and Environment
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• v.49 no.4
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• pp.279-288
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• 2016

Stable Isotope Analysis(SIA) of carbon and nitrogen is useful tool for the understanding functional roles of target organisms in biological interactions in the food web. Recently, mixing model based on SIA is frequently used to determine which of the potential food sources predominantly assimilated by consumers, however, application of model is often limited and difficult for non-expert users of software. In the present study, we suggest easy manual of R software and package SIAR with example data regarding selective feeding of crustaceans dominated freshwater zooplankton community. We collected SIA data from the experimental mesocosms set up at the littoral area of eutrophic Chodae Reservoir, and analyzed the dominant crustacean species main food sources among small sized particulate organic matters (POM, <$50{\mu}m$), large sized POM (>$50{\mu}m$), and attached POM using mixing model. From the results obtained by SIAR model, Daphnia galeata and Ostracoda mainly consumed small sized POM while Simocephalus vetulus consumed both small and large sized POM simultaneously. Copepods collected from the reservoir showed no preferences on various food items, but in the mesocosm tanks, main food sources for the copepods was attached POM rather than planktonic preys including rotifers. The results have suggested that their roles as grazers in food web of eutrophicated reservoirs are different, and S. vetulus is more efficient grazer on wide range of food items such as large colony of phytoplankton and cyanobacteria during water bloom period.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.1
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• pp.45-55
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• 1998

Phytoplankton community and primary productivity have been investigated in a fall season in the southern coastal waters of the last Sea, Korea. A strong thermocline formed at the 20\~60\;m$ layer and a cold water mass also existed in the bottom around Yong-il Bay. The offshore of the surveyed area was likely to be influenced by relatively warmer water, whereas the inshore represented Higher primary productivity with lower water temperature and lower salinity. A total of 133 species of phytoplankton occurred, representing 107 spp. of diatom, 23 spp. of dinoflagellate 3 spp. of silicoflagellate. Skeletonema costatum and Asterionellepsis glacialis were most predominant with more than $30\%$ dominance ratio, while Leptocylindrus danicus was also dominant at all transect lines. Standing crops of phytoplankton ranged from $2.7{\times}10^3\;to\;141.6{\times}10^3\;cell^{\ell-1}$. Chlorophyll a concentration varied with stations and layers, but the $30\~50$ m layer showed maximun with about $1.18{\mu}g{\ell}^{-1}$ rather than at the surface layer. It is believed that the maximun in standing crops and chlorophyll of phytoplankton formed at the $20\~50$ m layer above the thermocline during the survey. Phytoplankton primary productivity ranged from 0.32 to 3.04 mgC $m^{-3}\;hr^{-1}$, showing higher at the inshore than at the offshore. The range of integrated primary productivity was $263.3\~1085.5 mgC\;m^{-2}\;day^{-1}$ for the euphotic layer. Photosysthesis rates varied with the range from 0.76 to 8.04 mgC mgChl $\alpha^{-1}\;hr^{-1}$. Phytoplankton photosynthesis at the inshore was saturated at lower irradiance ($15\~35\%$ of surface) and showed higher efficiency, Thus, it revealed that the phytoplankton community probably adapted to the middle of euphotic layer because the depth of mixing layer became thinner due to the formation of thermocline.

• Journal of The Geomorphological Association of Korea
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• v.20 no.1
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• pp.11-20
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• 2013

The pollen analysis was performed targeting the valley plain alluvium of Jangjae-ri, Asan area in order to clarify the climate and vegetation environment of the Last glacial maximum and the Late glacial in terms of Gokgyo River Watershed In Asan-City, Korea. The sample collection point gets included in the current deciduous broadleaf forest zone (south cool temperate zone). The results are as follows. (1) The vegetation environment of about 19,300-14,100yrB.P. at the investigation area is mainly classified into YJ-I period and YJ-II period while YJ-Ia period is classified once again into YJ-Ia period and YJ-Ib period. YJ-Ia period (19,300-17,500yrB.P.) is correlated with the Last Glacial Maximum while the vegetation at the time has relatively a little wide distribution area of grassland compared to the forest and the forest vegetation of this time period is the mixed conifer and deciduous broad-leaved forest. YJ-Ib period (15,400-14,750yrB.P.) is correlated with the Late glacial (or the Last Glacial Maximum) and the distribution area of grassland became wider compared to the forest. While the forest vegetation of this time period is the mixed conifer and deciduous broad-leaved forest, a difference exists in terms of the dominant tree species. YJ-II period (about 14,650-14,100yrB.P.) is correlated with the Last glacial while the distribution area of grassland became even wider than the forest compared to the YJ-Ib in case of the vegetation at the time and the forest vegetation of this time period is the coniferous forest. (2) Both YJ-I period and YJ-II period were relatively cold and dry compared the End of Late Glacial (about 12,000-10,000yrB.P.)~Early Holocene (10,000-8,500yrB.P.), Also, YJ-II period was relatively colder than the YJ-I period and the YJ-Ib period was relatively more humid than the YJ-Ia period.

• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.6
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• pp.669-676
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• 2017

To understand the relationship between environmental factors and phytoplankton community structures and why early outbreaks of Cochlodinium polykrikoides occur in the inner bay of Korea, short-term investigations were conducted at 17 stations in the eastern part of the South Sea of Korea, with sessions every two weeks from July 7 to August 24, 2016. The water temperature increased from $22.3^{\circ}C$ in the first survey to $28.4^{\circ}C$ in the fourth survey, which was a rise of about $6.01^{\circ}C$. Salinity was relatively high at Stns. 8 13 in the inner bay. In the first survey, rainfall of about 150 mm was observed, so nutrients were supplied at a high level and a high concentrate of Chl. a was observed. Cryptophyta (Crpytomonas spp.) represented 58.3 % of the community, followed by Bacillariophyta at 33.8 %. In particular, at Stn. 5, Dinophyta Prorocentrum spp. accounted for a very high percentage, 32.2 %. In the second survey, low phytoplankton populations were observed, and Bacillariophyta (Chaetoceros spp.) accounted for 61.0 %. At Stn. 4, Skeletonema spp. showed high populations but did not appear at other stations even at a low density. In the third and fourth surveys, phytoplankton populations were very low. Bacillariophyta represented 78.0 % in the third study and 73.3 % in the fourth. Interestingly, although the appearance of C. polykrikoides was investigated at the beginning of the red tide in the coastal area, they were not observed inshore, implying that the likelihood of inflow by the germination of resting cysts was low for the inner bay during this study period. In addition, environmental characteristics such as salinity and nutrient presence were significantly different between sampling stations due to the existence of a semi-closed bay in the southern sea, resulting in dominant phytoplankton species and community composition differing in these short-term investigations.

• Journal of Ecology and Environment
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• v.42 no.4
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• pp.210-218
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• 2018

Background: Soil respiration (Rs) is a major factor of the absorption and accumulation of carbon through photosynthesis in the ecosystem carbon cycle. This directly affects the amount of net ecosystem productivity, which affects the stability and sustainability of the ecosystem. Understanding the characteristics of Rs is indispensable to scientifically understand the carbon cycle of ecosystems. It is very important to study Rs characteristics through analysis of environmental factors closely related to Rs. Rs is affected by various environmental factors, such as temperature, precipitation, soil moisture, litter supply, organic matter content, dominant plant species, and soil disturbance. This study was conducted to analyze the effects of micro-topographical differences on Rs in forest vegetation by measuring the Rs on the ridge and southern slope sites of the broadly established Quercus mongolica forest in the central Korean area. Method: Rs, Ts, and soil moisture data were collected at the southern slope and ridge of the Q. mongolica forest in the Mt. Jeombong area in order to investigate the effects of topographical differences on Rs. Rs was collected by the closed chamber method, and data collection was performed from May 2011 to October 2013, except Winter seasons from November to April or May. For collecting the raw data of Rs in the field, acrylic collars were placed at the ridge and southern slope of the forest. The accumulated surface litter and the soil organic matter content (SOMC) were measured to a 5 cm depth. Based on these data, the Rs characteristics of the slope and ridge were analyzed. Results: Rs showed a distinct seasonal variation pattern in both the ridge and southern slope sites. In addition, Rs showed a distinct seasonal variation with high and low Ts changes. The average Rs measurements for the two sites, except for the Winter periods that were not measured, were $550.1\;mg\;CO_2m^{-2}h^{-1}$ at the ridge site and $289.4\;mg\;CO_2m^{-2}h^{-1}$ at the southern slope, a difference of 52.6%. There was no significant difference in the Rs difference between slopes except for the first half of 2013, and both sites showed a tendency to increase exponentially as Ts increased. In addition, although the correlation is low, the difference in Rs between sites tended to increase as Ts increased. SMC showed a large fluctuation at the southern slope site relative to the ridge site, as while it was very low in 2013, it was high in 2011 and 2012. The accumulated litter of the soil surface and the SOMC at the depth range of 0~5 cm were $874g\;m^{-2}$ and 23.3% at the ridge site, and $396g\;m^{-2}$ and 19.9% at the southern slope site. Conclusions: In this study, Rs was measured for the ridge and southern slope sites, which have two different results where the surface litter layer is disturbed by strong winds. The southern slope site shows that the litter layer formed in autumn due to strong winds almost disappeared, and while in the ridge site, it became thick due to the transfer of litter from the southern slope site. The mean Rs was about two times higher in the ridge site compared to that in the southern slope site. The Rs difference seems to be due to the difference in the amount of litter accumulated on the soil surface. As a result, the litter layer supplied to the soil surface is disturbed due to the micro-topographical difference, as the slope and the change of the community structure due to the plant season cause heterogeneity of the litter layer development, which in turn affects SMC and Rs. Therefore, it is necessary to introduce and understand these micro-topographical features and mechanisms when quantifying and analyzing the Rs of an ecosystem.