• Title/Summary/Keyword: Field Coverage

Search Result 414, Processing Time 0.028 seconds

Vegetation structure and distribution characteristics of Symplocos prunifolia, a rare evergreen broad-leaved tree in Korea

  • Kim, Yangji;Song, Kukman;Yim, Eunyoung;Seo, Yeonok;Choi, Hyungsoon;Choi, Byoungki
    • Journal of Ecology and Environment
    • /
    • v.44 no.4
    • /
    • pp.275-285
    • /
    • 2020
  • Background: In Korea, Symplocos prunifolia Siebold. & Zucc. is only found on Jeju Island. Conservation of the species is difficult because little is known about its distribution and natural habitat. The lack of research and survey data on the characteristics of native vegetation and distribution of this species means that there is insufficient information to guide the management and conservation of this species and related vegetation. Therefore, this study aims to identify the distribution and vegetation associated with S. prunifolia. Results: As a result of field investigations, it was confirmed that the native S. prunifolia communities were distributed in 4 areas located on the southern side of Mt. Halla and within the evergreen broad-leaved forest zones. Furthermore, these evergreen broad-leaved forest zones are themselves located in the warm temperate zone which are distributed along the valley sides at elevations between 318 and 461 m. S. prunifolia was only found on the south side of Mt. Halla, and mainly on south-facing slopes; however, small communities were found to be growing on northwest-facing slopes. It has been confirmed that S. prunifolia trees are rare but an important constituent species in the evergreen broad-leaved forest of Jeju. The mean importance percentage of S. prunifolia community was 48.84 for Castanopsis sieboldii, 17.79 for Quercus acuta, and 12.12 for Pinus thunbergii; S. prunifolia was the ninth most important species (2.6). Conclusions: S. prunifolia can be found growing along the natural streams of Jeju, where there is little anthropogenic influence and where the streams have caused soil disturbance through natural processes of erosion and deposition of sediments. Currently, the native area of S. prunifolia is about 3300 ㎡, which contains a confirmed population of 180 individual plants. As a result of these low population sizes, it places it in the category of an extremely endangered plant in Korea. In some native sites, the canopy of evergreen broad-leaved forest formed, but the frequency and coverage of species were not high. Negative factors that contributed to the low distribution of this species were factors such as lacking in shade tolerance, low fruiting rates, small native areas, and special habitats as well as requiring adequate stream disturbance. Presently, due to changes in climate, it is unclear whether this species will see an increase in its population and habitat area or whether it will remain as an endangered species within Korea. What is clear, however, is that the preservation of the present native habitats and population is extremely important if the population is to be maintained and expanded. It is also meaningful in terms of the stable conservation of biodiversity in Korea. Therefore, based on the results of this study, it is judged that a systematic evaluation for the preservation and conservation of the habitat and vegetation management method of S. prunifolia should be conducted.

Effects of Azolla Incorporation During Paddy Cultivation on Weed Control, Nitrogen Supply and Rice Yield (물개구리밥(Azolla)이 논 잡초 발생, 질소공급 및 쌀 수량에 미치는 영향)

  • Shin, Jong-Hee;Han, Chae-Min;Kwon, Jung-Bae;Won, Jong-Gun
    • KOREAN JOURNAL OF CROP SCIENCE
    • /
    • v.66 no.4
    • /
    • pp.271-278
    • /
    • 2021
  • Azolla is a genus of small aquatic ferns native to Asia, Africa, and America. Azolla is potentially significant as a nitrogen source in agriculture, particularly in conjunction with rice (Oryza sativa L.) cultivation. In addition, Azolla may either control weeds or act as a weed depending on management; therefore, we aimed to determine the effect of Azolla incorporation on weed (e.g., Monochoria vaginalis, Rotala indica, Aeschynomene indica, and Cyperus amuricus) control and its other benefits during rice cultivation. The effects of Azolla on weed emergence were evaluated based on plot area coverage by the Azolla mat, which appears as a green sheet over water, and the rate of weed emergence in paddy field. Weed occurrence was investigated 40 days after Azolla inoculation. Soil samples from the experimental plots were collected following harvest in 2014-2015, and analyzed. Moreover, rice growth, yield, and grain quality were measured. Azolla suppressed weed growth by 72%. Azolla mat incorporation in rice fields suppressed weed growth by over 60%. In addition, Azolla promoted nitrogen fixation. Compared with nitrogen management using chemical fertilizers, Azolla incorporation showed the potential for various positive effects, including the improvement of soil fertility by increasing total nitrogen, and organic matter content. Rice grown with Azolla maintained its yield without additional herbicide treatment. Moreover, the palatability of cooked rice was better when grown with Azolla.

Comparison of Rice Growth and Yield in Different Direct Seeding Methods (벼 직파 유형별 생육 및 수량 비교 연구)

  • Park, K.H.;Park, S.T.
    • Journal of Practical Agriculture & Fisheries Research
    • /
    • v.19 no.1
    • /
    • pp.119-128
    • /
    • 2017
  • The field trial was performed to evaluate the rice growth and yield in different direct seeding methods. The required time for seed emergence was for 8~ 9days in the tested direct seeding methods and there was high in seedling establishment according to wet hill-seeding with iron-coated seeds> wet hill-seeding with soil coverage>water seeding with iron-coated seeds and water seeding with pregerminated seeds as the conventional treatment. The rice plant height was taller in wet hill-seeding methods than that of water seeding with broadcasting method but there was not significant difference in terms of statistical analysis at 75day after seeding except the water seeding with pregerminated seeds. The growth of tiller number in the rice plant was highest in water seeding with iron-coated seeds. The milled rice yield was highest in water seeding with iron-coated seed being with 6.4t/ha and percentage of head rice was the highest in wet hill-seeding and water seeding with iron-coated seeds.

Ecological Traits of Weed Flora with Different Soil Moisture in Remodeled Paddy Field of Nakdong River (낙동강 리모델링 농경지 수분함량별 잡초발생 특성 분석)

  • Hwang, Jae-Bok;Yun, Eul-Soo;Jung, Ki-Yeol;Park, Chang-Young;Choi, Young-Dae;Jeon, Seong-Ho;Oh, In-Seok
    • Weed & Turfgrass Science
    • /
    • v.2 no.1
    • /
    • pp.8-14
    • /
    • 2013
  • Collection of weeds were done in 3 remodeled paddy fields located in different districts with different soil moisture conditions such as Samolpo district (14.6%), Gimhae (9.8%) and Chilhyun (5.6%). Remodeled paddy fields composed of 62 plant species belonging to 23 families. Among 23 families, Compositae was the largest family with 11 species belonged to (17.7%) followed by Poaceae with 9 species (14.5%), Leguminosae with 8 species (12.9%), Cyperaceae with 7 species (11.3%), and Polygonaceae with 5 species (8.1%). Summed dominance ratio of each species based on number, coverage, frequency, and plant height in Samolpo district was Echinochloa oryzoides (100%) > Cyperus difformis (9.0%) > Bidens frondosa (5.3%) > Panicum dichotomiflorum (4.8%) > Eclipta prostrata (4.4%). In Gimhae; Digitaria ciliaris (100%) > Panicum dichotomiflorum (49.4%) > Echinochloa oryzoides (48.8%) > Persicaria hydropiper (27.1%) > Chenopodium ficifolium (10.2%), and in Chilhyun were Panicum dichotomiflorum (90.8%) > Digitaria ciliaris (66.7%) > Cyperus iria (8.6%) > Bidens frondosa (7.6%). Total dry weight of weeds recorded was 535.4 g $m^{-2}$, 316.1 g $m^{-2}$ and 346.2 g $m^{-2}$ in Samolpo, Gimhae and Chilhyun districts, respectively. Simpson's index was calculated to 0.09~0.28, which showed that weed occurrence in remodeled paddy fields with different soil moistures varied.

National survey for genetic counseling and demands for professional genetic counselor (유전상담과 전문 유전상담사 수요에 대한 전국적인 조사)

  • Chung, Yoon-Sok;Kim, Sook-Ryung;Choi, Ji-Young;Kim, Hyon-J.
    • Journal of Genetic Medicine
    • /
    • v.4 no.2
    • /
    • pp.167-178
    • /
    • 2007
  • Purpose : The necessity of professional non-MD genetic counselor has been recently emphasized in a medical field. By conducting a national survey on the demands for generic counseling and professional non-MD generic counselor, we can make a long-term master plan to execute the educational program for professional genetic counselors and indeed promote genetic counseling in Korean health care service in a systemic manner. Methods : The survey has been conducted from September 3rd to October 4th of 2007 in a way of e-mail, telephone interview, fax, and direct contacts. It's targets were senior researchers and professors in medical and non-medical institutions, policy makers, research institutions or foundations. The survey questions consist of 16 questionnaires. Results : As a result of survey, 102 of 650 people responded. 80% of respondents indicated that genetic counseling is needed as a health care service and 34% among them considered it as "the most needed". In addition, 77% of the respondents showed that, it is necessary to have a professional non-MD genetic counselor with a master degree or higher in the field of medical genetics and among them 29% thought it as "the most necessary". A 77% of respondents considered that the cost of genetic counseling should be covered by health insurance and among them, 29% answered "strongly agreed". A 56% of respondents chose the answer of "They have a plan to hire the professional non-MD genetic counselor" in their institution, and among them 71% selected "within 5 years" in terms of when to hire. Also, they tend to expect the role of the professional non-MD genetic counselor to be not only "genetic counselor" (60%), but also "researcher" (42%), "educator" (18%) and "clinical laboratory coordinator" (19%). Conclusion : The 102 of 650 people responded to the survey. Based upon the nationwide survey over the needs on genetic counseling in health care service and demands on the professional non-MD genetic counselor, systematic educational program for the genetic counseling, with reimbursement coverage for counseling service by health insurance should be emphasized in development of a master plan.

  • PDF

Comparison of Intensity-modulated Radiation Therapy (IMRT), Uniform Scanning Proton Therapy (USPT), and Intensity-modulated Proton Therapy (IMPT) for Prostate Cancer: A Treatment Planning Study (전립선 암 환자의 IMRT, USPT, 및 IMPT 기법에 따른 치료효과 비교)

  • Son, Kihong;Cho, Seungryong;Kim, Jin Sung;Han, Youngyih;Ju, Sang Gyu;Ahn, Sung Hwan;Shin, Eunhyuk;Shin, Jung Suk;Park, Won;Pyo, Hongryul;Choi, Doo Ho
    • Progress in Medical Physics
    • /
    • v.24 no.3
    • /
    • pp.154-161
    • /
    • 2013
  • This study assessed compared photon and proton treatment techniques, such as intensity modulated radiation therapy (IMRT), uniform scanning proton therapy (USPT), and intensity modulated proton therapy (IMPT), for a total of 10 prostate cancers. All treatment plans delivered 70 Gy to 95% of the planned target volume in 28 fractions. IMRT plans had 7 fields for the step and shoot technique, while USPT and IMPT plans employed two equally weighted, parallel-opposed lateral fields to deliver the prescribed dose to the planned target. Inverse planning was then incorporated to optimize IMPT. The homogeneity index (HI) and conformity index (CI) for the target and the normal tissue complication probability (NTCP) for organ at risk (OAR) were calculated. Although the mean HI and CI for target were not significantly different for each treatment techniques, the NTCP of the rectum was 2.233, 3.326, and 1.707 for IMRT, USPT, and IMPT, respectively. The NTCP of the bladder was 0.008, 0.003, and 0.002 respectively. The NTCP values at the rectum and bladder were significantly lower using IMPT. Our study shows that using proton therapy, particularly IMPT, to treat prostate cancer could be beneficial compared to 7-field IMRT with similar target coverage. Given these results, radiotherapy using protons, particularly optimized IMPT, is a worthwhile treatment option for prostate cancer.

Population Structure and Habitat Characteristics of Deutzia paniculata Nakai, as an Endemic Plant Species in Korea (한반도 특산식물 꼬리말발도리 개체군 구조 및 서식지 특성)

  • Jung, Ji-young;Pi, Jung-hun;Park, Jeong-geun;Jeong, Mi-jin;Kim, Eun-hye;Seo, Gang-Uk;Lee, Cheul-ho;Son, Sung-won
    • Korean Journal of Ecology and Environment
    • /
    • v.49 no.1
    • /
    • pp.31-41
    • /
    • 2016
  • Deutzia paniculata is an endemic species to the Korean Peninsula. Despite of importance for conservation, the population structure and habitat characteristics of D. paniculata have not been determined yet. We analyzed the ecological characteristics of the species based on the literature review and field survey. Field survey was conducted on May to October 2014 during which 11 quadrats of size $15{\times}15m$ were studied in six regions. Each of the quadrats were further divided into $5{\times}5m$ small quadrats and population characteristics were recorded. The population and habitat characteristics were analyzed, including species abundance (density and coverage), demographic attributes (flowering rates and fruiting plants), vegetation (structure, species composition), light availability (transmitted light and canopy openness) and soil characteristics (temperature and humidity). We found that D. paniculata mainly distributed in Gyeongsangdo (including Taebaek in Gangwondo) along a broad elevational range of 290~959 m (mean: 493 m) above sea level. In preferred habitat the species grows within the slope range of $7^{\circ}$ and $35^{\circ}$ with the average of $16^{\circ}$. D. paniculata was generally distributed on talus deposits and low adjacent slopes. The average number of individual plants per small quadrat was 12.5 with the mean density $0.5stems\;m^{-2}$. The vegetative reproduction was frequent in D. paniculata and mean flowering rate was as low as 15%. Altogether 138 taxa were found in whole observation area with the dominant tree species mainly spring ephemerals, such as Cornus controversa (importance value: 25.5%) and Fraxinus rhynchophylla (importance value: 15.8%). Although, C. controversa usually grows on steep slopes and F. rhynchophylla mostly distributed at high-altitudes, however, both species distributed in disturbed environments and among talus deposits. Thus based on our results, we concluded that D. paniculata is a disturbance-prone species, primarily existing in habitats subjected to natural disturbances, such as floods. The species occurs less at anthropogenically disturbed sites, thus there is no apparent threat to the populations and habitat of D. paniculata.

A Study on Vascular Plants, Distribution Status and Management Plans of the Cactus Habitat (No. 429 Natural Monument) in Wolryung-ri, Jeju Island (제주 월령리 선인장군락지(천연기념물 제429호)의 관속식물상, 분포실태, 관리방안에 관한 연구)

  • Lee, Cheol-Ho;Jang, Gye-Hyun;Ryu, Tae-Bok;Choi, Byoung-Ki
    • Journal of the Korean Institute of Traditional Landscape Architecture
    • /
    • v.36 no.1
    • /
    • pp.55-66
    • /
    • 2018
  • The cactus habitat in Jeju Island has a phytogeographically specific distribution in the East Asian region, and forms a unique landscape as the only native cactus (Opuntia ficus-indica (L.) Mill.) habitat in Korea. However, there has been no detailed investigation on the distribution of cacti in the habitat and no investigation on the diversity of the mixed composition of plants in the habitats and their correlation with the distribution of cactus populations. This study attempted to investigate the diversity of vascular plants in the Wollyeong-ri cactus habitat and record the actual distribution and trends of cactus distribution. In addition to the distribution characteristics of cacti, we also discuss the characteristics of species reflecting the characteristics of the habitat among the mixed population of plant species, as well as the biological and environmental factors that threaten the maintenance of cactus populations or require management for preservation of cacti. Considering the phenological character, we conducted the field surveys for flora identification six times between June 2015 and September 2017. The Engler classification system was used for the arrangement sequence and names of plants, and the Korean Plant Names Index was adopted for the Korean name of the species. The study results showed that the Wolryung-ri cactus habitat in Jeju Island has the characteristic physiognomy of an area dominated by cactus. For the vascular plants, a total of 125 taxa were identified, including 53 families, 104 genera, 109 species, 15 varieties and 1 forma. Endangered plants specified by the Ministry of Environment were not found. Two species, Cyrtomium falcatum and Asplenium incisum, were identified as the ferns, and no gymnosperms were found. In addition, 123 taxa of angiosperms, 91 taxa of dicotyledones and 32 taxa of monocotyledons were identified. The distributions of cacti were confirmed in 289 meshes corresponding to 59.3% of the total 487 meshes in the cactus protected area, which showed various coverage distributions ranging from 5% to 95%. Most of the meshes where no cacti were found are coastal areas with exposed basalt rocks where the soil depth has not developed or extremely restricted due to repeated waves, or areas where artificial facilities, grasslands, and observation paths have been constructed. On the other hand, there were 71 lattice points in 14.5% of the total area where the cactus showed 70% or higher dominance. Cacti are randomly distributed in these areas. They have adapted to the microhabitat environment and are found to be opportunistically distributed along the growable locations. Considering that the reproduction of cacti in the habitat is mostly dependent on parthenogenesis, the present distribution seems to reflect the potentially distributable regions of cacti in the habitat. Based on the results of field surveys, a management plan for conservation and protection of the protected areas has been proposed.

Floristic Composition, Structure, and Dynamics of Koelreuteria paniculata Communities in Daegu City (대구시 자생 모감주나무군락의 종조성, 구조 및 동태)

  • Kim, Jun-Soo;Cho, Joon-Hee;Kim, Hak-Yun;Cho, Hyun-Je
    • Journal of Korean Society of Forest Science
    • /
    • v.108 no.2
    • /
    • pp.168-176
    • /
    • 2019
  • To understand the floristic composition, vegetation structure, and population dynamics of Koelreuteria paniculata communities, which are native to Daegu, South Korea, a field survey was conducted in July 2018 using phytosociological and complete enumeration methods. Based on information on vegetation and trees of >5 cm diameter at breast height collected during the field survey, we classified the community types by species composition and analyzed their vegetation strata, relative importance value (MIV), life forms, species diversity, and population structure. The community was divided into the following three types: Ulmus parvifolia-Vitex negundo var. incisa subcommunity, Securinega suffruticosa subcommunity, and Clematis apiifolia community. The vegetation unit system was organized into one community group, two communities, and two subcommunities. Vegetation coverage of the tree layer was >85%, while the herbaceous layer was <10%. MIV of K. paniculata appeared to be extremely high within all vegetation strata, with 94.3 of the tree layer, 81.6 of the subtree layer, 75.5 of the shrub layer, and 60.0 of the herbaceous layer. The species diversity (H') was significantly different among the community types, and the C. apiifolia community (2.062) was approximately four times higher than the S. suffruticosa subcommunity (0.547). The overall representative life form types were "$MM-R_5-D_4{\cdot}D_2-e$,", but there were some differences in the disseminule form among the community types. The population structure of K. paniculata showed the reverse J-shaped distribution with a high density of young individuals and low density of larger individuals among all three community types, and because no plant species within the lower vegetation could replace K. paniculata, it was considered to be a sustainable population.

Depositional Environment and Formation Ages of Eurimji Lake Sediments in Jaechon City, Korea (제천 의림지 호저퇴적물 퇴적환경과 형성시기 고찰)

  • 김주용;양동윤;이진영;김정호;이상헌
    • The Korean Journal of Quaternary Research
    • /
    • v.14 no.1
    • /
    • pp.7-31
    • /
    • 2000
  • Quaternary Geological and geophysical investigation was performed at the Eurimji reservoir of Jaechon City in order to interprete depositional environment and genesis of lake sediments. For this purpose, echo sounding, bottom sampling and columnar sampling by drilling on board and GPR survey were employed for a proper field investigation. Laboratory tests cover grain size population analysis, pollen analysis and $^{14}C$ datings for the lake sediments. The some parts of lake bottom sediments anthropogenically tubated and filled several times to date, indicating several mounds on the bottom surface which is difficult to explain by bottom current. Majority of natural sediments were accumulated both as rolling and suspended loads during seasonal flooding regime, when flash flow and current flow are relatively strong not only at bridge area of the western part of Eurimji, connected to stream valley, but at the several conduit or sewage system surrounding the lake. Most of uniform suspend sediments are accumulated at the lake center and lower bank area. Some parts of bottom sediments indicate the existence of turbid flow and mudflow probably due to piezometric overflowing from the lake bottom, the existence of which are proved by CM patterns of the lake bottom sediments. The columnar samples of the lake sediments in ER-1 and ER-3-1 boreholes indicate good condition without any human tubation. The grain size character of borehole samples shows poorly sorted population, predominantly composed of fine sand and muds, varying skewness and kurtosis, which indicate multi-processed lake deposits, very similar to lake bottom sediments. Borehole columnar section, echo sounding and GPR survey profilings, as well as processed data, indicate that organic mud layers of Eurimji lake deposits are deeper and thicker towards lower bank area, especially west of profile line-9. In addition the columnar sediments indicate plant coverage of the Eurimji area were divided into two pollen zones. Arboreal pollen ( AP) is predominant in the lower pollen zone, whreas non-aboreal pollen(NAP) is rich in the upper pollen zone. Both of the pollen zones are related to the vegetation coverage frequently found in coniferous and deciduous broad-leaved trees(mixed forest) surrounded by mountains and hilly areas and prevailing by aquatic or aquatic margin under the wet temperate climate. The $^{14}C$ age of the dark gray organic muds, ER1-12 sample, is 950$\pm$40 years B.P. As the sediments are anthropogenetically undisturbed, it is assumed that the reliability of age is high. Three $^{14}C$ ages of the dark gray organic muds, including ER3-1-8, ER3-1-10, ER3-1-11 samples, are 600$\pm$30 years B.P., 650$\pm$30 years B.P., 800$\pm$40 years B.P. in the descending order of stratigraphic columnar section. Based on the interpretation of depositional environments and formation ages, it is proved that Eurimji reservoir were constructed at least 950$\pm$40 years B.P., the calibrated ages of which ranges from 827 years, B.P. to 866 years B.P. Ancient people utilize the natural environment of the stream valley to meet the need of water irrigation for agriculture in the local valley center and old alluvium fan area.

  • PDF