• Title/Summary/Keyword: Phenology

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Growth Simulation of Ilpumbyeo under Korean Environment Using ORYZA2000: III. Validation of Growth Simulation

  • Lee Chung-Kuen;Shin Jae-Hoon;Shin Jin-Chul;Kim Duk-Su;Choi Kyung-Jin
    • Proceedings of the Korean Society of Crop Science Conference
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    • 2004.04a
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    • pp.104-105
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    • 2004
  • [ $\bigcirc$ ] In the phenology model of ORYZA2000, the effect of photoperiod on the developmental rate was a little ignored because most crop parameters were measured with IRRI varieties which are insensitive to photoperiod, therefore it is very difficult to apply this phenology model directly to Korean varieties which are usually sensitive to photoperiod. $\bigcirc$ After introducing PPFAC and PPSE to improve the phenology model, the precision of heading date prediction was improved but not satisfied. $\bigcirc$ In the growth simulation using data from several regions, yield tended to be overestimated under high nitrogen applicated condition. $\bigcirc$ The precision of yield was much improved by introducing nitrogen use efficiency, but still different between regions because of different soil fertility or property of irrigation water between regions

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Prediction of Blooming Dates of Spring Flowers by Using Digital Temperature Forecasts and Phenology Models (동네예보와 생물계절모형을 이용한 봄꽃개화일 예측)

  • Kim, Jin-Hee;Lee, Eun-Jung;Yun, Jin I.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.15 no.1
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    • pp.40-49
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    • 2013
  • Current service system of the Korea Meteorological Administration (KMA) for blooming date forecasting in spring depends on regression equations derived from long term observations in both temperature and phenology at a given station. This regression based system does not allow a timely correction or update of forecasts that are highly sensitive to fluctuating weather conditions. Furthermore, the system cannot afford plant responses to climate extremes which were not observed before. Most of all, this method may not be applicable to locations other than that which the regression equations were derived from. This note suggests a way to replace the location restricted regression equations with a thermal time based phenology model to complement the KMA blooming forecast system. Necessary parameters such as reference temperature, chilling requirement and heating requirement were derived from phenology data for forsythia, azaleas and Japanese cherry at 29 KMA stations for the 1951-1980 period to optimize spring phenology prediction model for each species. Best fit models for each species were used to predict blooming dates and the results were compared with the observed dates to produce a correction grid across the whole nation. The models were driven by the KMA's daily temperature data at a 5km grid spacing and subsequently adjusted by the correction grid to produce the blooming date maps. Validation with the 1971-2012 period data showed the RMSE of 2-3 days for Japanese cherry, showing a feasibility of operational service; whereas higher RMSE values were observed with forsythia and azaleas.

Correlation Analysis between Phenology of Salix spp. and Meteorological Factors (버드나무류 (Salix spp.)의 계절학적 특성과 주요 기상요인 상관분석)

  • Kim, Seong-Bo;Kim, Ji Yoon;Im, Ran-Young;Do, Yuno;Park, Hee-Sun;Joo, Gea-Jae;Kim, Gu-Yeon
    • Journal of Environmental Science International
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    • v.22 no.12
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    • pp.1633-1641
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    • 2013
  • The objective of this study was to analyze correlation between phenological characteristics of Salix spp. and meteorological factors in the Upo wetlands. Phenology of Salix subfragilis Andersson and Salix chaenomeloides Kimura was monitored from 2007 to 2012. Meteorological variables were monitored by Korea Meteorological Administration (Hap-chon). Average date of flowering, fruiting, seed dispersion was 86, 113, 136 days for S. subfragilis and 112, 140, 164 days for S. chaenomeloides as Julian days. Flowering of S. subfragilis and S. chaenomeloides were correlated with daily mean air temp. in March (r=-0.92, r=-0.85, p<0.05). Fruiting of S. subfragilis was correlated with total precipitation between Jan and March of previous year (r=-0.90, p<0.01), however, the fruiting of S. chaenomeloides was highly correlated with max. temp. in Jan of previous year (r=0.99, p<0.01). Seed dispersion of both species is correlated with min. temp. in Feb. Phenology monitoring will contribute to understanding Salix spp. response against climate change.

Analyzing Relationship between Satellite-Based Plant Phenology and Temperature (위성영상을 기반으로 도출된 식물계절과 기온요인과의 상관관계 분석)

  • CHOI, Chul-Hyun;JUNG, Sung-Gwan;PARK, Kyung-Hun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.19 no.1
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    • pp.30-42
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    • 2016
  • Climate change are known to have had enormous impacts on plant phenology and thus to have damage on other species which are interacted within ecosystem. In Korea, however, it is difficult to analyze the relationship between climate and phenology due to the limitation of measurement data of plant phenological records. In this study, to be effective analysis of SOG(start of growing season), we used phenological transition dates by using satellite data. Then, we identified the most influential variable in variation of SOG throughout the relationship between SOG and temperature factors. As a result, there is a strong correlation between the SOG and April temperature, TSOGmin($3^{\circ}C$, 12days). This study is expected to be used for predicting plant phenological change using climate change scenario data.

Relationship between Plastochrone and Development Indices Estimated by a Nonparametric Rice Phenology Model

  • Lee, Byun-Woo;Nam, Taeg-Su;Yim, Young-Seon
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.44 no.2
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    • pp.149-153
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    • 1999
  • Prediction of rice developmental stage is necessary for proper crop management and a prerequisite for growth simulation as well. The objectives of the present study were to find out the relationship between the plastochrone index(PI) and the developmental index(DVI) estimated by non-parametric phenology model which simulates the duration from seedling emergence(DVI=0) to heading(DVI=l) by employing daily mean air temperature and daylength as predictor variables, and to confirm the correspondency of developmental indice to panicle developmental stages based on this relationship. Four japonica rice cultivars, Kwanakbyeo, Sangpungbyeo, Dongjinbyeo, and Palgumbyeo which range from very early to very late in maturity, were grown by sowing directly in dry paddy field five times at an interval of two weeks. Data for seedling emergence, leaf appearance, differentiation stage of primary rachis branch and heading were collected. The non-parametric phenology model predicted well the duration from seedling emergence to heading with errors of less than three days in all sowings and cultivars. PI was calculated for every leaf appearance and related to the developmental index estimated for corresponding PI. The stepwise polynomial analysis produced highly significant square-rooted cubic or biquadratic equations depending on cultivars, and highly significant square-rooted biquadratic equation for pooled data across cultivars without any considerable reduction in accuracy compared to that for each cultivar. To confirm the applicability of this equation in predicting the panicle developmental stage, DVI at differentiation stage of primary rachis branch primordium was calculated by substituting PI with 82 corresponding to this stage, and the duration reaching this DVI from seedling emergence was estimated. The estimated duration revealed a good agreement with that observed in all sowings and cultivars. The deviations between the estimated and the observed were not greater than three days, and significant difference in accuracy was not found for predicting this developmental stage between those equations derived for each cultivar and for pooled data across all cultivars tested.

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The Efficiency of Long Short-Term Memory (LSTM) in Phenology-Based Crop Classification

  • Ehsan Rahimi;Chuleui Jung
    • Korean Journal of Remote Sensing
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    • v.40 no.1
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    • pp.57-69
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    • 2024
  • Crop classification plays a vitalrole in monitoring agricultural landscapes and enhancing food production. In this study, we explore the effectiveness of Long Short-Term Memory (LSTM) models for crop classification, focusing on distinguishing between apple and rice crops. The aim wasto overcome the challenges associatedwith finding phenology-based classification thresholds by utilizing LSTM to capture the entire Normalized Difference Vegetation Index (NDVI)trend. Our methodology involvestraining the LSTM model using a reference site and applying it to three separate three test sites. Firstly, we generated 25 NDVI imagesfrom the Sentinel-2A data. Aftersegmenting study areas, we calculated the mean NDVI values for each segment. For the reference area, employed a training approach utilizing the NDVI trend line. This trend line served as the basis for training our crop classification model. Following the training phase, we applied the trained model to three separate test sites. The results demonstrated a high overall accuracy of 0.92 and a kappa coefficient of 0.85 for the reference site. The overall accuracies for the test sites were also favorable, ranging from 0.88 to 0.92, indicating successful classification outcomes. We also found that certain phenological metrics can be less effective in crop classification therefore limitations of relying solely on phenological map thresholds and emphasizes the challenges in detecting phenology in real-time, particularly in the early stages of crops. Our study demonstrates the potential of LSTM models in crop classification tasks, showcasing their ability to capture temporal dependencies and analyze timeseriesremote sensing data.While limitations exist in capturing specific phenological events, the integration of alternative approaches holds promise for enhancing classification accuracy. By leveraging advanced techniques and considering the specific challenges of agricultural landscapes, we can continue to refine crop classification models and support agricultural management practices.

Flowering and fruiting phenology of herbs, climbers, shrubs, and trees in the deciduous dipterocarp forest of Northern Thailand

  • Janejaree Inuthai
    • Journal of Ecology and Environment
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    • v.47 no.3
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    • pp.134-145
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    • 2023
  • Background: The flowering and fruiting periods play an important role in biological processes. The deciduous dipterocarp forest is an important forest type in Thailand, however the phenological studies are still limited, particularly in different plant life forms. Thus, the present study focused on the flowering and fruiting phenology of herbs, climbers, shrubs, and trees in the deciduous dipterocarp forest at Lampang province of Northern Thailand. Field visits were made to record plant life forms and observe reproductive phenological events at monthly intervals from November 2018 to October 2019 and September to December 2020. Results: The phenological observations were based on 126 species of 45 families and 102 genera. Flowering and fruiting periods showed similar patterns in herbaceous plants, climbers, and shrubs. Most of these species produced flowers and fruits from the end of the rainy season (October) to the winter season (November-January). Whereas most of flowering and fruiting trees were found from the summer season (March-April) to the beginning of the rainy season (May-June). Most of the dry-fruited species occurred during the dry period (winter and summer seasons), while the majority of fleshy-fruited species dominated in the wet period (rainy season). The statistical analysis supported the phenological patterns of flowering and fruiting in the present study. There were significant negative correlations between the number of flowering and fruiting species and temperature. The number of flowering and fruiting species is significantly impacted by the interaction between seasons and plant life forms. Conclusions: Plant life form seems to be the important factor that affects the different phenological patterns in the studied plants. The abiotic and biotic factors play major roles in reproductive phenology. However, long-term study and in-depth phenological observations are necessary for better understanding.

Reproductive Phenology of Gracilaria verrucosa (Rhodophyta) in Cheongsapo near Pusan, Korea

  • Kim Young Sik;Choi Han Gil;Kim Hyung Geun;Nam Ki Wan;Sohn Chul Hyun
    • Fisheries and Aquatic Sciences
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    • v.1 no.1
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    • pp.147-151
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    • 1998
  • The reproductive phenology of Gracilaria verrucosa was studied in Cheongsapo near Pusan, Korea. Among the life history phases, tetrasporic plants occurred dominantly in varying degrees of abundance throughout the year except from July to September. Cystocarpic plants increased rapidly during summer, and then recorded maximum abundance in July. Whereas, seasonal peaks of spermatangial plants were observed in April and September. However, they were less than cystocarpic plants in abundance. Vegetative plants dominated from December to May for long period, with a occurrence peak in February. Even though fertile plants in both gametophytes and tetrasporophytes occurred throughout the year, their seasonal abundance suggests that the positive correlation between reproduction and water temperature is basically found in the reproductive pattern of Gracilaria verrucosa. The distributional aspect of life history phases appears to be related with differences of their longevity, fecundity or survivorship.

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Trends in the effects of climate change on terrestrial ecosystems in the Republic of Korea

  • Choi, Sei-Woong;Kong, Woo-Seok;Hwang, Ga-Young;Koo, Kyung Ah
    • Journal of Ecology and Environment
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    • v.45 no.3
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    • pp.117-129
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    • 2021
  • In this review, we aimed to synthesize the current knowledge on the observed and projected effects of climate change on the ecosystems of Korea (i.e., the Republic of Korea (ROK) or South Korea), as well as the main causes of vulnerability and options for adaptation in these ecosystems based on a range of ecological and biogeographical data. To this end, we compiled a set of peer-reviewed papers published since 2014. We found that publication of climate-related studies on plants has decreased in the field of plant phenology and physiology, whereas such publication has rapidly increased in plant and animal community ecology, reflecting the range shifts and abundance change that are occurring under climate change. Plant phenology studies showed that climate change has increased growing seasons by advancing the timing of flowering and budburst while delaying the timing of leafing out. Community ecology studies indicated that the future ranges of cold-adapted plants and animals could shrink or shift toward northern and high-elevation areas, whereas the ranges of warm-adapted organisms could expand and/or shift toward the areas that the aforementioned cold-adapted biota previously occupied. This review provides useful information and new insights that will improve understanding of climate change effects on the ecosystems of Korea. Moreover, it will serve as a reference for policy-makers seeking to establish future sectoral adaptation options for protection against climate change.

Feasibility of Stochastic Weather Data as an Input to Plant Phenology Models (식물계절모형 입력자료로서 확률추정 기상자료의 이용 가능성)

  • Kim, Dae-Jun;Chung, U-Ran;Yun, Jin-I.
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.14 no.1
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    • pp.11-18
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    • 2012
  • Daily temperature data produced by harmonic analysis of monthly climate summary have been used as an input to plant phenology model. This study was carried out to evaluate the performance of the harmonic based daily temperature data in prediction of major phenological developments and to apply the results in improving decision support for agricultural production in relation to the climate change scenarios. Daily maximum and minimum temperature data for a climatological normal year (Jan. 1 to Dec. 31, 1971-2000) were produced by harmonic analysis of the monthly climate means for Seoul weather station. The data were used as inputs to a thermal time - based phenology model to predict dormancy, budburst, and flowering of Japanese cherry in Seoul. Daily temperature measurements at Seoul station from 1971 to 2000 were used to run the same model and the results were compared with the harmonic data case. Leaving no information on annual variation aside, the harmonic based simulation showed 25 days earlier release from endodormancy, 57 days longer period for maximum cold tolerance, delayed budburst and flowering by 14 and 13 days, respectively, compared with the simulation based on the observed data. As an alternative to the harmonic data, 30 years daily temperature data were generated by a stochastic process (SIMMETEO + WGEN) using climatic summary of Seoul station for 1971-2000. When these data were used to simulate major phenology of Japanese cherry for 30 years, deviations from the results using observed data were much less than the harmonic data case: 6 days earlier dormancy release, 10 days reduction in maximum cold tolerance period, only 3 and 2 days delay in budburst and flowering, respectively. Inter-annual variation in phenological developments was also in accordance with the observed data. If stochastically generated temperature data could be used in agroclimatic mapping and zoning, more reliable and practical aids will be available to climate change adaptation policy or decision makers.