• 환경생물
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• 제39권4호
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• pp.536-541
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• 2021

Pantala flavescens is a dominant Odonata species in the rice fields in Korea. To determine the effects of different temperatures on its larval growth and emergence, field and laboratory experiments were conducted. Larval growth was also monitored in mono-cropping and double-cropping rice fields. The growth of larvae was monitored every week by measuring the head width. In the field experiment, no difference was found in larval growth and emergence between the control temperature and +1.9℃ of the control temperature. The larval growth was greater at 23℃ than at 20℃ laboratory temperatures, and no emergence was recorded at either temperature after eight weeks of monitoring. There was a quadratic relationship between larval growth and temperature in an incubator at five temperature regimes of 15, 20, 25, 30, and 35℃. Midseason water drainage caused the extinction of the existing individuals and newly hatched larvae dominated after re-watering in the rice fields. Larval size was greater in double-cropping fields than in mono-cropping fields in late July but the tendency was reversed in early August. The results of this study suggest that temperature warming will directly promote the larval growth of P. flavescens and indirectly influence seasonal growth via changes in water management in rice fields.

• 한국환경농학회지
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• 제32권4호
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• pp.294-303
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• 2013

본 연구는 수학적 모델(Lotka-Volterra 방정식)을 이용하여 기후변화가 논습지를 이용하는 조류 개체군의 크기와 구조에 미치는 영향에 대해 분석 및 예측하였다. 특히 논습지를 이용하는 조류 개체군 동태에 영향을 주는 기후변화에 대해, 1) 계절 내 최고 및 최저 기온의 변화와 2) 계절 길이의 변화를 조합하여 11가지 가능한 기후변화시나리오를 모델시뮬레이션에 이용하였다. 본 연구의 수학모델은 기온 변화, 즉 계절이 바뀜에 따라 월동, 이동, 그리고 번식조류가 일정한 시기에 그리고 일정한 분포패턴으로 논습지를 취식 및 서식지로 이용하고 있음을 보였다. 기후변화 시나리오의 결과, 기온변화의 폭이 커질 수록 조류 개체군 동태의 변이는 증가하였으며, 계절의 길이 변화, 특히 계절이 짧아진 경우에 논습지를 이용하는 기간도 크게 짧아져 전체적으로 개체군 동태를 감소시켰다. 전체적으로 한 계절 내의 기온변화가 발생하고, 다른 계절은 평년 기온을 유지할 경우에는, 해당 계절의 조류 개체군 동태만 기온변화에 영향을 받았다. 더욱이 계절의 길이 변화는 계절 내 기온 변화보다 더 뚜렷한 개체군 동태의 변화를 유도하였다.

• The Korean Journal of Ecology
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• 제20권5호
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• pp.375-384
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• 1997

The effects of three different irrigating water qualities(clean water, life sewage and animal sewage) on the pattern of arthropod communities in the rice fields were investigated at Banwol, Kyonggi-do, mid-western part of Korea from 1994 to 1996. The total density of arthropod was highest in the rice field which was irrigated with clean water(clean water field), and the arthropod community was mainly composed of aphids and collembolans. Each functional group was found in the order of 'pests>non-pests>natural enemies' in its density. The dominant taxa in the pest group were aphids, planthoppers(Delphacidae), leafhoppers(Cicadelidae) and rice water weevil(L. oryzophilus). In the non-pest group collembolans, non-biting midges and dipterans were main arthropods, and in the natural enemy group Araneae was the dominant taxon. In the early growth stage of rice plant the dominant functional group was pests, and in the mid growth stage both the pest and the natural enemy group became dominant. But in the late growth stage none of the functional group was dominant over the other functional groups. The densities of spiders were much more higher in the clean water field than in the other fields. And through all the growth stages of rice plants the density of spiders in clean water field kept increase in contrast to the others. The species composition of spiders in the life sewage field was similar to that in the animal sewage field, but in the clean water field it was different from the other two fields.

• Journal of Ecology and Environment
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• 제31권3호
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• pp.213-223
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• 2008

The increasing area of abandoned rice fields could provide new opportunities for wetland restoration in Asia. However, it is unknown how quickly or completely abandoned rice fields will recover from agricultural disturbances. We assessed water quality and plant community succession in abandoned rice fields with different hydrology in a mountain valley to understand the effects of hydrological regime on recovery. Water level, soil redox potential, water quality, plant composition, and primary production were measured. The sites, coded as D6, N13, and N16, had been recovering for 6, 13, and 16 years by 2006. N13 and N16 have been recovering naturally whereas D6 has been drained with a nearby dike and was tilled in 2001. The typical hydroperiods of D6, N13, and N16 were no surface water, permanently flooded, and seasonally flooded, respectively. The major change in vegetation structure of both D6 and N13 was the replacement of herbaceous species by woody species. Drawdown accelerated this change because Salix koreensis grew better in damp conditions than in flooded conditions. Phragmites japonica reduced plot-level plant species richness. The removal efficiency of $NH_4-N$, $NO_3-N$, and $PO_4-P$ from water varied seasonally, ranging between -78.8 to 44.3%, 0 to 97.5%, and -26.0 to 44.4%, respectively. In summary, abandoned rice fields quickly became suitable habitat for native wetland plant species and improved regional water quality. Variation among our sites indicates that it is likely possible to manage abandoned rice fields, mostly through controlling hydrology, to achieve site-specific restoration goals.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.266-266
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• 2017

In recent years, adoption of the System of Rice Intensification (SRI) is spreading in most Asian countries, and more recently in Cambodia is one of the Asian countries with high adoptions of SRI. We conducted on-farm experiment to investigate the effects of SRI on rice growth and yield in the farmers' fields in rainfed region of southern Cambodia. The study was undertaken in rainfed lowland fields of Popel commune ($11^{\circ}$ 04' 67" N, $104^{\circ}$ 40' 79" E) of Tram Kak District in Takeo Province during the wet seasons in 2012, 2013, and 2015. A total of 32 on-farm experiments were conducted during the wet seasons for three years of 2012 (11 fields), 2013 (8 fields), and 2015 (13 fields). Across the three years of study, SRI produced significantly greater plant biomass and grain yield than Non-SRI. The yield increase was mostly ascribed for the increased number of grains per land area, which was due to the increased number of spikelets per panicle rather than the number of panicles per land area. With no significant difference between SRI and Non-SRI with respect to seedling age, the greater number of grains per panicle was accounted for by the reduced planting density and increased amount of manure application in SRI than Non-SRI fields. It was found that the greater manure application has increased soil nitrogen content in SRI and Non-SRI fields. While SRI did not increase the number of panicles per land area, it did increase the number of panicles per hill.

• 농촌지도와개발
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• 제27권2호
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• pp.75-87
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• 2020

The purpose of this study is to investigate the location characteristics of the rice paddy fields and to predict shrinking areas of them. The study area is in South Korea nationwide, and a 300×300m raster level is adopted as a spatial analysis unit. The binary logit model and spatial simulation model are employed for the analyses. As a result, population, industry, climate and nature, and accessibility play a significant role in determining rice paddy fields' locations. It is predicted that the shrinking rate will be high in Gangwon-do, Gyeongsangbuk-do, and Gyeongsangnam-do until 2027. The hot spots are intensively shaped in the inland of Gangwon-do, eastern parts of Gyeonggi-do, and the borders of Gyeongsangnam-do and Jeollabuk-do between Charyeong and Sobaek mountain ranges. Using Gimcheon-si as an example, the study suggests fundamental policy implications for taking advantage of the simulation results from the lens of local agriculture. Several policy measures are proposed for improving management strategies for the rice paddy fields in the long run.

• Asian-Australasian Journal of Animal Sciences
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• 제22권2호
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• pp.216-224
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• 2009

In Japan, since rice consumption has been decreasing with the westernization of Japanese eating habits, surplus paddy fields have been increasing. If these surplus paddy fields can be utilized for forage rice production as feed for animal production and excretions (feces and urine) from animal production can be applied to the paddy fields as manure, then the problems of surplus paddy fields and excretions from animal production may be solved, and the environment kept sustainable. The objectives of the present study were to apply a bio-economic model to dairy and forage rice integration systems in Japan and to examine the merit of introducing whole crop rice silage (WCRS), as well as economic and environmental effects of various economic and management options in the systems. Five simulations were conducted using this model. The use of WCRS as a home-grown feed increased environmental loads and decreased economic benefit because of the higher amount of purchased feed, when compared to the use of typical crops such as maize, alfalfa and timothy silage (simulation 1). Higher economic benefits from higher forage rice yields and higher milk production of a dairy cow were obtained (simulations 2, 3). There were no economic and environmental incentives for utilizing crude protein (CP) rich WCRS, because an increase in the CP content in WCRS led to the use of more chemical fertilizers, resulting in high production costs and nitrogen outputs (simulation 4). When evaluated under the situation of a fixed herd size, increasing forage rice yields decreased the total benefit of the production, in spite of the fact that the amount of subsidies per unit of land increased (simulation 5). It was indicated that excess subsidy support may not promote yield of forage rice. It was, however, observed in most cases that dairy and forage rice integration systems could not be economically established without subsidies.

• 한국환경복원기술학회지
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• 제12권1호
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• pp.52-66
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• 2009

The increase of rice productivity, the decrease of rice demand, aging farmers, and the market-opening of rice along with the domestic and international conditions changes have been led to the increase of the abandoned rice paddy fields. Such abandoned rice paddy fields have been left in many areas and most of them have become wetlands. The purpose of this study is methodology of selection to the wetland for development in the abandoned rice paddy fields along with surroundings. The selection of habitat suitability index assessment study to conservation and restoration was done through hydrology, wild animals habitation, wetland vegetation, outside disturbance, and natural purification capacity assessment. In addition, the same method was applied to assessment items and standards for both the restoration site selection and the type of restoration. Both assessment items and standards were applied to the sites, drawn on the maps, and overlayer for the comprehensive map, and then the wetland suitability index was applied to the suitable site. The development technique was applied to 10 sites near the Banwol Stream watershed in Gunpo, Gyeonggi province. The selection of conservation, restoration, and the optimal sites can lead to not only the biodiveristy increase in agricultural or semi natural areas but also to the establishment of ecological networks in national level.

• 한국농림기상학회지
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• 제19권4호
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• pp.293-303
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• 2017

이 연구의 목적은 가뭄이 쌀 생산성에 미치는 효과를 추정하는데 있다. 가뭄 효과를 추정하기 위해서 우리는 기상변수와 수리답 비율 등이 쌀 생산성에 미치는 효과를 패널 회귀분석 모형을 통해 추정하였다. 분석결과 가뭄이 쌀 생산량에 미치는 영향은 통계적으로 유의한 것으로 나타났다. 또한, 전체 논면적에서 수리답 면적 비율이 1% 확대될수록 쌀 생산량은 0.025~0.035%씩 증가하는 것으로 나타났다. 하지만, 한발대비 수리답 면적 비중의 교차항이 쌀 단수에 미치는 영향은 매우 작은 것으로 추정되었다. 이는 한발대비 수리답이 가뭄 피해를 줄이는 데에는 효과가 거의 없음을 의미한다. 또한 추세항과 연도별 더미를 추가하였을 경우, 한발대비 수리답 면적 비중이 쌀 단수에 미치는 영향과 한발대비 수리답의 가뭄 피해 억제 효과는 통계적으로 유의하지 않은 것으로 추정되었다. 이는 수리안전답 조차도 표준강수지수(SPI6)가 -2.5이하로 떨어지는 심각한 가뭄의 피해를 줄이는 데에는 큰 효과가 없음을 의미할 수 있다. 따라서 50년 이상 노후화된 시설이 전체 약 74%에 육박하는 농업용 수리시설의 경우, 기후변화로 인한 가뭄의 빈도와 강도 증가에 더욱 취약할 것으로 예상된다.

• 한국환경농학회지
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• 제33권4호
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• pp.334-343
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• 2014

본 연구는 봄철 논습지에 도래하는 도요 물떼새류의 도래패턴과 서식지 이용 특성을 파악하고자 수행되었다. 조사는 한국 중서부지역에 위치한 아산만 일대의 농경지에서 2014년 4월 21일부터 5월 30일까지 2~3일 간격으로 총 18회 수행 되었다. 조사 기간 동안 관찰된 도요 물떼새류는 총 15종 7,852개체였다. 대상 종들의 시기별 도래 특성은 본답에 물을 대기 시작하는 4월 중반부터 관찰되었고 5월 초까지 지속적으로 종수와 개체수가 증가하는 경향이 나타났으며 5월 후반으로 가면서 종수와 개체수는 감소하였다. 농경지의 물리적 구조에 따른 서식지 이용 특성은 종별 차이가 나타났으며, 대부분의 종에서 본답과 논둑은 수로나 농로에 비해 선호성이 높게 나타났다. 본답의 미소서식지 선호성은 지역 농업인의 농업 관리에 의해 다양하게 나타났으며, 도요 물떼새류의 종별 서식지의 선호성 차이가 명확히 나타났다. 대부분 종은 무논의 본답 형태에서 관찰되었고, 써레질 후 5 cm 이하로 물을 얕게 댄 형태인 본답의 이용이 가장 높았다. 반면 물을 대지 않은 건답의 형태인 수확 후 추경한 형태는 이용을 하지 않았다. 결론적으로 봄철 논습지는 도요 물떼새류에게 중간 기착지로서 중요한 기능을 하는 것으로 나타났다.