• Korean Journal of Agricultural Science
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• v.50 no.2
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• pp.299-312
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• 2023

The paddy environment is classified as a wetland and occupies a very large proportion of the freshwater environment. It is also ecologically important as a habitat and spawning ground for many aquatic insects and amphibian larvae. However, due to climate change and indiscriminate spraying of pesticides, the rice field ecosystem is continuously threatened. In order to restore ecologically damaged rice paddies in the future, information on organisms living in the rice paddy ecosystem, which can serve as a restoration standard, is needed. The eDNA metabarcoding analysis method is a very effective means of accumulating information on many organisms living in the rice field ecosystem because it can indirectly identify the existence of taxa that are no longer found in the target ecosystem due to different adult life periods or metamorphosis. In this study, genes of four species of frogs and nine species of aquatic insects were also discovered, and some taxa were directly discovered in the field. A large number of taxa have been discovered only by DNA searches, and traditional survey methods have only been able to identify very limited taxa. This eDNA-based paddy field biosearch is expected to be very useful in the investigation of biodiversity in agricultural ecosystems due to its strong analytical resolution.

• Korean Journal of Environmental Agriculture
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• v.40 no.4
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• pp.295-312
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• 2021

BACKGROUND: Global warming is one of the most pressing environmental issues which concomitantly complicates global climate change. Methane emission is a balance between methanogenesis and methane consumption, both of which are driven by microbial actions in different ecosystems producing methane, one of the major greenhouse gases. Paddy fields are major sources of anthropogenic methane emissions and could be compounded by organic fertilization. METHODS AND RESULTS: Literature reviews were conducted to give an overview of the global warming conditions and to present the relationship of carbon and methane to greenhouse gas emissions, and the need to understand the underlying processes of methane emission. A more extensive review was done from studies on methane emission in paddy fields under organic fertilization with greater emphasis on long term amendments. Changes in paddy soils due to organic fertilization include alterations of the physicochemical properties and changes in biological components. There are diverse phylogenetic groups of methanogens and methane oxidizing bacteria involved in methane emission. Also, multiple factors influence methanogenesis and methane oxidation in rice paddy fields under organic fertilization and they should be greatly considered when developing mitigating steps in methane emission in paddy fields especially under long term organic fertilization. CONCLUSION(S): This review showed that organic fertilization, particularly for long term management practices, influenced both physicochemical and biological components of the paddy fields which could ultimately affect methanogenesis, methane oxidation, and methane emission. Understanding interrelated factors affecting methane emission helps create ways to mitigate their impact on global warming and climate change.

• Korean Journal of Environmental Biology
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• v.40 no.2
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• pp.138-147
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• 2022

Paddy fields are important habitats for maintaining the biodiversity of agricultural ecosystems. Recently, as the need for safe food and biodiversity conservation has increased, the rice cultivation methods have undergone changes. This study was conducted to investigate the fish fauna in Environmentally Friendly Paddy fields (EFP) and Conventional Paddy fields (CP), and compare the characteristics of Misgurnus anguillicaudatus and Aphyocypris chinensis populations in EFP and CP. A total of 2,703 fish were collected and classified into six families and 13 species. Our results showed that there was a difference in the proportion of fish populations in the two paddy fields, and the number of individuals in EFP was higher than in CP. The weight values of M. anguillicaudatus were higher in EFP than in CP, and the total length, body length, and weight values of A. chinensis were higher in EFP than in CP. Conditional factor(K) values also showed similar trends in EFP and CP. Our results indicate that the farming practices in paddy fields have a significant effect on the characteristics of M. anguillicaudatus and A. chinensis populations, and the results of this study can be used as basic data for securing biodiversity in future agricultural ecosystems.

• Korean Journal of Environmental Biology
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• v.35 no.4
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• pp.640-647
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• 2017

The need for an efficient sampling technique to collect aquatic organisms has risen with the increase of interest in rice paddy fields, which have been recognized as important ecosystems supporting biodiversity. In the present study, a submerged funnel trap used with the assistance of attracting agents (fish meal and chemical light) was designed as an easy, objective and quantitative tool for collecting aquatic organisms in the rice paddy fields. The preference for collecting aquatic organisms as a means for attracting agents was analyzed using a generalized linear mixed model. Also, based on the data of previous research, we compared the community composition of the aquatic macroinvertebrates, which were collected using the quadrat method, and newly designed submerged funnel traps, by analyzing non-metric multidimensional scaling. The results showed that the catching efficiency of 18 of the total 65 taxa was affected by the attracting agents. 12 taxa including Pomacea canaliculata, Hippeutis cantori, Austropeplea ollula, Erpobdella lineata, Ostracoda spp. Branchinella kugenumaensis, Hydaticus grammicus, Rhantus pulverosus, Chironomidae spp., Rana nigromaculata, Cobitidae spp. etc., favored fish meal and 6 taxa including Ischnura asiatica, Coenagrionidae spp. Sternolophus rufipes etc., were attracted by chemical light. The submerged funnel trap used as a measurement tool for biodiversity was less applicable than the quadrat method; however, it was more effective for the selective collection of specific taxa. We expect that this newly designed trap can be a simple and quantitative method for collecting aquatic organisms, and could be used for long term and extensive surveys in rice paddy fields in the future.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.237-247
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• 2023

Paddy fields not only provide a variety of ecosystem services but also serve as crucial habitats for biodiversity conservation. Recently, their ecological value and significance have been increasingly emphasized. Therefore, this study aimed to investigate the characteristics of soil seed banks and analyze their correlation with soil environmental factors in Conventional Paddy field (CP) and Organic Paddy field (OP) with different farming practices. Our results revealed that the vegetation in CP was simple, resulting in low plant diversity in the soil seed banks. On the other hand, the vegetation in OP was relatively diverse, leading to higher plant diversity in the soil seed banks. Additionally, distinct differences in soil environmental characteristics were observed between OP (K, Ca, Mg, Na, Fe, Mn, B↓) and CP (K, Ca, Mg, Na, Fe, Mn, B↑). These results suggest that variations in agricultural practices for rice cultivation have influenced the structure and diversity of vegetation and soil seed banks. Furthermore, these agricultural practices have had both direct and indirect effects on soil environmental factors. Our findings can serve as fundamental data for evaluating biodiversity conservation in agricultural ecosystems, ecosystem restoration, and ecological value assessment.

• Journal of Soil and Groundwater Environment
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• v.15 no.3
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• pp.15-26
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• 2010

The contaminated soils near abandoned mine area can threaten human's health and natural ecosystems through multiple pathways. Remediation of contaminated soil using physicochemical technologies are expensive and destructive of soil environments. On the other hand, environmentally friendly approach that maximize biological remediation, that is, phytoremediation, attracts attention as a low carbon green growth technology. This research is a field demonstration study, focused on the enhanced phytoremediation by bioaugmenting PGPR(Plant Growth Promoting Rhizobacteria)that is helpful on the growth of and heavy metal removal by Echinochloa frumentacea, at a Zn contaminated paddy soil near SamBo mine at Hwasung, Kyunggi. The results showed that the zinc removal by the plant with PSM(Phosphate Solubilizing Bacteria), a kind of PGPR, was three times higher than that by the control. The results are valuable as it is a result from the field-scale technology demonstration. The results also implies that application of PGPR can enhance heavy metal removal from contaminated soil in full scale phytoremediation using Echinochloa frumentacea.

• Korean Journal of Environmental Biology
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• v.37 no.1
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• pp.82-87
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• 2019

Global warming has a significant impact on diverse ecosystems including agroecosystem through; changing of phenology, physiology and distribution. Monitoring of biological responses emanating from global warming is required to understand the challenges of biological diversity conservation posed by climate change. The Korean government selected four butterfly species as indicators of climate change in agroecosystem: Papilio xuthus, Pieris rapae, Colias erate, and Eurema mandarina. The aim of this study was to investigate the different monitoring methods of the butterflies in Korea and suggest a suitable monitoring method to track the population trends of butterflies in the agroecosystem. Butterfly monitoring was conducted in eight sites throughout Korea from April to October, 2018 using three survey methods: point census at rice paddy area, point census at the border between rice paddy and hill and line transect along the rice paddy and hill. Each method took approximately 30 min. to count the butterflies. A total of 4,691 butterflies and 92 species were counted: The most dominant species was Pieris rapae with a total count of 1,205 individuals followed by Polygonia c-aureum, Zizeeria maha, Colias erate, Cupido argiades and Papilio xuthus. Among the three census methods, the total number of species and individuals when using line transect method was statistically higher than in the other methods. However, the numbers of the four butterflies indicators showed no difference throughout three census methods. Based on the number of species and the total individuals butterflies in agroecosystem, we advocate for the application of line transect method as it can find more butterflies in agroecosystem. In addition, we advised for the implementation of education programs on the line transect method in butterfly identification to participants of the national monitoring program.

• The Korean Journal of Pesticide Science
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• v.9 no.1
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• pp.60-69
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• 2005

The herbicide molinate has been detected with high frequency in the main river during the growing season in Korea. To elucidate the exposure of molinate in agricultural environment, the persistence and the degradation characteristics of molinate were investigated in paddy ecosystems. The half-lives of molinate were 4.1 days with soil aquatic system, and 4.2 days in only aquatic system. Initial dissipation rate of molinate in water was greater with soil aquatic system than that of only aquatic system. Photolysis of molinate was occurred about 31.0% of molinate treated in pure water, when irradiated at 5,530 $J/cm^2$ by the xenon lamp, but its hydrolysis was stable. For the accelerated photolysis of molinate in aqueous solution, several photosensitizers were screened, showing that the hydroperoxide($H_2O_2$) and acetone were prominent among the chemical tested. When hydroperoxide and zinkoxide(ZnO) were used as photosensitizer, their photolysis were accelerated greater than 98% and 58% in aqueous solution, respectively. Elution rate of molinate as granular formulations in aqueous system was more than 90% in 30 hour at $35^{\circ}C$. Molinate concentration pattern in paddy water was rapidly decrease from treatment till 7 days in paddy rice field and its half-lives were 3.7 days($Y=1.9258{\times}e^{-0.1865X}$(r=-0.9402)).

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.233-233
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• 2017

Algal communities are important to maintain the aquatic ecosystems function. Algae have short life cycles, they respond quickly to environmental change and their diversity and density can indicate and the quality of their habitat. The bloom forms before the rice seedings have emerged, it may present a physical barrier that prevents the seedlings from penetrating the floodwater. Wind may also move the algal bloom, pushing the young plants beneath the surface. Another harmful action develops when the water dries up and the algae form a layer at the bottom of the field. The layer envelops the seedlings, which are not yet deeply rooted, and drag them to the surface when the water is let in again. Soil utilization pattern can be the mail facter affecting soil physico-chemical properties, especially in soil phosphorus (P). Solid content of the algae culture solution increased with the increase in the nitrogen rather the phosphors concentration. Phosphoric acid was treated with conventional treatments (100-0%, before transplanting time-tillering stage), 50-50%, 0-100%, and un-treated. The herbicide was treated on the 7 DAT (day after transplanting). Green algae samples were collected 20 DAT. Total phosphoric acid was the highest at 0.06 in 50-50% treatment in 20 DAT. The amount of green algae was about twice (9.8 mg/20ml) that of un-treated. Total number of green algae was 54 species(Green algae 35 species, Euglena 9 species, Stone wheel 10 species). Among the phosphoric acid treatment methods, the number of occurrences of green algae were the highest with 39 species in 0-100%, followed by 50-50%, 28 species, conventional treatments, 22 species, non-treatment, 18 species, respectively. Rice Yield was not significantly different by phosphoric treatment time, but slightly higher than un-treated. The maximal algal biomass was observed about 2weeks or 1 month after transplanting; the subsequent decrease of the biomass was related to the consumption by grazers and to a deficient light under the rice canopy. Maximal algal growth was observed just before tillering. To estimate the suitable method of phosphorus application in puddled-soil drill seeding of rice, available phosphorus appearance of algal water bloom, and rice yield were investigated in paddy soil of rice-barley double cropping system.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.40-59
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• 2018

This review summarizes the history of freshwater zooplankton research in Korean Society of Limnology and necessary future topics that are remain poorly investigated in South Korea based on main research topics of published articles focusing on lakes, reservoirs, rivers and wetland ecosystems. In Korea, a total 450 freshwater zooplankton species have been reported (85 species of cladocera, ca. 230 species of rotifera since 1939, and 138 species of copepoda), and they cover 10% of total zooplankton species list. In the present paper, we provide recent species list of zooplankton found in Korea and their taxonomic keys. Over periods of 45 years, there are 25 published papers for zooplankton biota in lentic ecosystems in Korean Journal of Ecology and Environment (KJEE). The ecology of zooplankton communities in rivers has focused on the mechanisms involved in regulating their abundance, diversity and spatio-temporal patterns of genus Bosmina and rotifers (genus Brachionus and Keratella) that are most frequently found from Korea. On the other hand, the studies on zooplankton in wetland has focused on Alona, Chydorus and Ceriodaphnia with special emphasis on their relationships with aquatic macrophytes. Even though studies on the freshwater ecosystem in Korea have a long history, a few of studies on zooplankton biota were conducted at rice paddy, Dumbeong and wetlands. During the last two decades, experimental advances in freshwater zooplankton ecology and understanding of structure and function of this biota were made from a series of articles mainly in journal of KJEE. For future studies, quantitative, experimental and interdisciplinary approaches would be key words to understand zooplankton ecology and their roles in aquatic ecosystems under changing environments, and we have suggested necessary zooplankton research fields and future directions.