• 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.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.3
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• pp.186-190
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• 2013

Soil respiration in forest ecosystems play an important role in global carbon cycle. This study was carried out to determine the annual variation of soil $CO_2$ efflux for 4 years in a broadleaved deciduous forest of the Geumsan (Mt.) Long-Term Ecological Research (GLTER) site in Southern Korea. The soil $CO_2$ efflux in the GLTER site showed annual variations with the fluctuations of annual mean soil temperature, but not with those of soil water content. The annual mean soil $CO_2$ efflux except for winter season was 0.32 g $CO_2\;m^{-2}h^{-1}$ for 2008, 0.40 g $CO_2\;m^{-2}h^{-1}$ for 2009, 0.41 g $CO_2\;m^{-2}h^{-1}$ for 2007, and 0.54 g $CO_2\;m^{-2}h^{-1}$ for 2010. The lowest soil $CO_2$ effluxin 2008 was associated with the lowest soil temperature ($2.0^{\circ}C$) in comparison with those of other years ($13.0-13.5^{\circ}C$). The exponential relationships between monthly soil $CO_2$ efflux and the corresponding soil temperature at the soil depth of 20 cm were significant ($R^2$ = 0.31-0.75, P < 0.05). The results indicate that the annual variation of soil $CO_2$ efflux was attributed to the variations of soil temperature rather than soil water content in the GLTER site.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.2
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• pp.242-251
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• 2010

In comparison with other terrestrial ecosystems, rice paddies are unique because they provide the primary food source for over 50% of the world's population, and act as major sources of global methane. The present paper summerizes a long-term field study that combine carbon isotopes, and canopy-scale flux measurements in an irrigated rice paddy, in conjugation with continuous monitoring of environmental, and vegetational factors. Both $CO_2$, and methane fluxes were largely influenced by soil temperature, and moisture conditions, especially across drainage events. Soil-entrapped $CO_2$, and methane showed a gradually increasing trend throughout growing season, but rapidly decreased upon flood water drainage. These variations in flux were well correlated with changes in concentration, and isotope ratio of soil $CO_2$, and methane, and of atmospheric $CO_2$, and methane within, and above the canopy. The isotopic signature of the gas exchange process varied markedly in response to change in contribution of soil respiration, belowground storage, fraction of $CO_2$ recycled, magnitude, and direction of $CO_2$ exchange, transport mechanism, and fraction of methane oxidized. Our results clearly demonstrate that stable isotope analysis can be a useful tool to study underlying mechanisms of gas exchange processes under natural conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.4
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• pp.380-389
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• 1994

Larvae of the freshwater shrimp, Macrobrachium nipponense(De Haan) were reared in the laboratory under constant conditions ($25^{\circ}C,\;7\%0$ S), and their feeding rate, oxygen consumption, ammonia nitrogen excretion, and growth were measured at regular intervals during development from hatching to post larval stage. Growth was measured as dry weight, carbon, nitrogen, hydrogen, protein and lipid. All these physiological and biochemical traits revealed significant changes from instar to instar. Average feeding rate was high in intermolt stage of the molt cycle and it showed a bell-shaped pattern. Respiration(R) increased from hatching to post larval stage. Excretion(U) increased in intermolt phase of larvae and it showed a bell-shaped variation pattern, in all larval instars with a maximum near the middle of the molt cycle. Regression equations describing rates of feeding, growth, respiration and ammonia excretion as functions of time during individual larval molt cycles were inserted in a simulation model, in order to analyse time-dependent patterns of variation as well as in bioenergetic efficiencies. Carbon was initially increased and nitrogen showed a tendency to increase in premolt phase during individual molt cycles. Protein remained clearly the predominant biochemical constituent in larval biomass.

• Journal of Wetlands Research
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• v.6 no.1
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• pp.117-132
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• 2004

Despite its significance in understanding ecological structure and biogeochemical element cycles, there have been few studies on the microbial mineralization of organic matter and mineralization pathway in the intertidal flat of Korea. We measured anaerobic mineralization of organic matter and sulfate reduction rate, and evaluated the significance of sulfate reduction in total anaerobic carbon respiration at the southern part of Ganghwa Island. Depth-integrated carbon mineralization rate down to 6 cm depth ranged from 41.9 to $89.4mmol\;m^{-2}d^{-1}$, which accounted for approximately 216 tons of organic matter mineralization in entire intertidal flat area of Ganghwa($300km^2$). The results indicated that capacity for the organic matter mineralization in the Ganghwa tidal flat is comparable to highly productive salt marsh environments. Mineralization rates in the sediment amended with acetate were 2~5 times higher than in unamended sediment. The results implied that microbial mineralization was limited by the availability of organic substrates, and the organic matter mineralization capacity seems to be higher than estimated at ambient organic substrate level. Depth-integrated sulfate reduction rates within 6 cm depth of the sediment ranged from 20.7 to $45.1mmol\;SO{_4}^{2-}m^{-2}d^{-1}$, and sulfate reduction was mostly responsible for organic matter remineralization. It should be noticed that the increase of $H_2S$ in the sulfate reduction dominated tidal flat may result in the decrease of biological diversity.

• ALGAE
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• v.30 no.2
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• pp.121-137
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• 2015

Studies on carbon flux in the oceans have been highlighted in recent years due to increasing awareness about climate change, but the coastal ecosystem remains one of the unexplored fields in this regard. In this study, the dynamics of carbon flux in a vegetative coastal ecosystem were examined by an evaluation of net and gross ecosystem production (NEP and GEP) and $CO_2$ exchange rates (net ecosystem exchange, NEE). To estimate NEP and GEP, community production and respiration were measured along different habitat types (eelgrass and macroalgal beds, shallow and deep sedimentary, and deep rocky shore) at Gwangyang Bay, Korea from 20 June to 20 July 2007. Vegetative areas showed significantly higher ecosystem production than the other habitat types. Specifically, eelgrass beds had the highest daily GEP ($6.97{\pm}0.02g\;C\;m^{-2}\;d^{-1}$), with a large amount of biomass and high productivity of eelgrass, whereas the outer macroalgal vegetation had the lowest GEP ($0.97{\pm}0.04g\;C\;m^{-2}\;d^{-1}$). In addition, macroalgal vegetation showed the highest daily NEP ($3.31{\pm}0.45g\;C\;m^{-2}\;d^{-1}$) due to its highest P : R ratio (2.33). Furthermore, the eelgrass beds acted as a $CO_2$ sink through the air-seawater interface according to NEE data, with a carbon sink rate of $0.63mg\;C\;m^{-2}\;d^{-1}$. Overall, ecosystem production was found to be extremely high in the vegetated systems (eelgrass and macroalgal beds), which occupy a relatively small area compared to the unvegetated systems according to our conceptual diagram of a carbon-flux box model. These results indicate that the vegetative ecosystems showed significantly high capturing efficiency of inorganic carbon through coastal primary production.

• Journal of Climate Change Research
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• v.4 no.2
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• pp.77-93
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• 2013

Global warming accelerates both carbon (C) input through increased forest productivity and heterotrophic C emission in forest soils, and a future trend in soil C dynamics is uncertain. In this study, the Korean forest soil carbon model (KFSC model) was applied to 1,467,458 ha of Pinus densiflora forests in Korea to predict future C dynamics under RCP 8.5 climate change scenario (RCP scenario). Korea was divided into 16 administrative regions, and P. densiflora forests in each region were classified into six classes by their stand ages : 1 to 10 (I), 11 to 20 (II), 21 to 30 (III), 31 to 40 (IV), 41 to 50 (V), and 51 to 80-year-old (VI+). The forest of each stand age class in a region was treated as a simulation unit, then future net primary production (NPP), soil respiration (SR) and forest soil C stock of each simulation unit were predicted from the 2012 to 2100 under RCP scenario and constant temperature scenario (CT scenario). As a result, NPP decreased in the initial stage of simulation then increased while SR increased in the initial stage of simulation then decreased in both scenarios. The mean NPP and SR under RCP scenario was 20.2% and 20.0% higher than that under CT scenario, respectively. When the initial age class was I, IV, V or VI+, predicted soil C stock under CT scenario was higher than that under RCP scenario, however, the countertrend was observed when the initial age class was II or III. Also, forests having a lower site index showed a lower soil C stock. It suggested that the impact of temperature on NPP was higher when the forests grow faster. Soil C stock under RCP scenario decreased at the end of simulation, and it might be derived from exponentially increased SR under the higher temperature condition. Thus, the difference in soil C stock under two scenarios will be much larger in the further future.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.193-193
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• 2017

The black heart in potato is a physiological disorder that occurs when potatoes suffer from breathing problems. When storing potatoes at a low temperature around $0^{\circ}C$, there is a high possibility that the respiration rate of potato will rise and black heart will occur. Also, respiration can occur easily and briefly in a state where high temperature and ventilation is insufficient. Recently, as black heart has been occurred continuously and severely in South Korea, here we tried to identify the causes of black heart in potato and to develop the control strategy of this disorder. Firstly, we analyzed the influence on the black heart on the basis of preservation containers (breathable plastic box, burlap bag, paper box, sealed plastic box). After harvesting the potato which is cv. Superior, it preserved for 6 months under conditions of temperature $3.5^{\circ}C{\pm}0.2$ and humidity 85%, after then we surveyed the incidence of emergence rate, rate of weight loss and occurrence rate of black heart. Secondly, in order to investigate the time point of black heart initiation under the oxygen concentration condition of 1% or less, The potatoes were used for this experiment stored for 6 months in a aerated plastic box under conditions of temperature $3.5^{\circ}C{\pm}0.2$ and humidity 85% under sufficient oxygen condition. After stored for 6 month, those were stored at $15^{\circ}C$ and below 1% of oxygen for 25 days, and then the incidence of black heart was surveyed. Thirdly, to investigate the effects of the number of days after harvest on the occurrence of black heart, it was examined the occurrence of black heart stored on 40 days and 100 days after harvesting under sealed condition and vacuum condition. The temperature condition of potato storage was stored was at $4^{\circ}C$ and $25^{\circ}C$ in humidity 85%. As a result of investigating the occurrence of black heart depending on the storage containers, all of the potatoes stored in the sealed plastic box had been occurred black heart. However, black heart of the potatoes in the other treatments did not. Potato preserved under the condition of below 1% of oxygen was found to occur 32% black heart after 25 days of storage. The potatoes corresponding to the required number of days after harvesting were stored for 31 days and the black heart was examined on the occurred. As a result, the potatoes which were 40 days after the harvest did not have black heart under sealed condition and vacuum condition. But potatoes harvested 100 days after harvesting had a black heart incidence of 95.7% under sealed condition at $4^{\circ}C$. The potato placed in the vacuum condition and a sealed state at $25^{\circ}C$ was transformed into anaerobic respiration, the inner tissue of tuber collapsed. Therefore, it is considered that black heart is caused by the breathing trouble in the central part when the oxygen is almost consumed after the aerobic respiration which gradually consumes the oxygen. We conclude that the black heart occurred in the central part where exchange of oxygen and carbon dioxide is the slowest is sensitive to respiration disorder. It is thought that research to investigate black heart generation time according to storage conditions and post-harvest state of potatoes is further necessary.

• Korean Journal of Agricultural Science
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• v.36 no.2
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• pp.147-158
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• 2009

This study was conducted to investigate the effect of 1-MCP, market temperature and combination treatment of freshing agent with 1-MCP on fruit quality of 'Hong Bak' peach (Prunus persica Batsch). The 1-MCP treatment at the rate of 1000ppb showed the best results in delaying the firmness loss and skin color development during shelf life without any detrimental effects on fruit quality. Moreover, positive effects of 1-MCP on fruit quality parameters were more significant in the fruits stored at $30^{\circ}C$ of high temperature shelf life than those of $20^{\circ}C$. The combination treatment of carbon ceramic with 1-MCP showed a beneficial effects including a prevention of firmness loss and maintaining external appearance during the five days of room temperature storage of 'Hong Bak' peach.

• The Korean Journal of Ecology
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• v.27 no.4
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• pp.245-256
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• 2004

The simple biosphere model 2 (SiB2), which is one of the land surface models, simulates the exchange of momentum, energy and mass such as water vapor and carbon dioxide between atmosphere and biosphere, and includes the biochemical sub-model for representation of stomatal conductance and photosynthetical activities. Throughout the SiB2 simulation, the significant information not only to understand of water and carbon budget but also to make an analysis of interaction such as feed-back and-forward between environment and vegetation is given. Using revised SiB2-Paddy, one sample study which is the evaluation of the runoff in Chaophraya river basin according to land use/cover change is presented in this review. Hence, SiB2 is available in order to ecological studied, if revised SiB2 for realistic simulation about soil respiration, computing leaf area index, vegetation competition and soil moisture is improved.