• 한국환경복원기술학회지
• /
• 제16권5호
• /
• pp.59-69
• /
• 2013

Global warming also has effects on the phenology. The limitation of phenology study is an acquisition of phenology data. Satellite images analysis can make up limitation of monitering data. This study is to analyze spatial distribution and characteristics of phenology changes using MODIS images. Research data collected images of 16 day intervals of 11 years from year 2001 to 2010. The data analyzed 228 images of 11 years. It can figure out changes of phenology by analyzing enhanced vegetation index of MODIS image. We made a comparison between changes of phenology and flowering of cherry blossoms. As a results, Startup of season spatially was getting late from southern area to north area. Startup of Phenology was foreshortened 13 days during 11 years, and change ratios of cherry blooming was getting more faster from 0.18 dat to 0.22 day per year during that same period.

• 대한원격탐사학회지
• /
• 제40권2호
• /
• pp.179-190
• /
• 2024

This study aims to compare supervised classification methods with phenology-based approaches, specifically pixel-based and segment-based methods, for accurate crop mapping in agricultural landscapes. We utilized Sentinel-2A imagery, which provides multispectral data for accurate crop mapping. 31 normalized difference vegetation index (NDVI) images were calculated from the Sentinel-2A data. Next, we employed phenology-based approaches to extract valuable information from the NDVI time series. A set of 10 phenology metrics was extracted from the NDVI data. For the supervised classification, we employed the maximum likelihood (MaxLike) algorithm. For the phenology-based approaches, we implemented both pixel-based and segment-based methods. The results indicate that phenology-based approaches outperformed the MaxLike algorithm in regions with frequent rainfall and cloudy conditions. The segment-based phenology approach demonstrated the highest kappa coefficient of 0.85, indicating a high level of agreement with the ground truth data. The pixel-based phenology approach also achieved a commendable kappa coefficient of 0.81, indicating its effectiveness in accurately classifying the crop types. On the other hand, the supervised classification method (MaxLike) yielded a lower kappa coefficient of 0.74. Our study suggests that segment-based phenology mapping is a suitable approach for regions like South Korea, where continuous cloud-free satellite images are scarce. However, establishing precise classification thresholds remains challenging due to the lack of adequately sampled NDVI data. Despite this limitation, the phenology-based approach demonstrates its potential in crop classification, particularly in regions with varying weather patterns.

• 한국농림기상학회지
• /
• 제24권4호
• /
• pp.318-329
• /
• 2022

본 연구를 통해 설계된 테스트베드 지역의 식물계절 관측과 적설 탐지는 반복 이미지 학습 및 정량적 RGB 분석을 통해 정확도 높은 산림 식물계절 및 적설 관측 기반을 마련하였다. 무인카메라 기반 식물계절 및 적설 탐지 기술 개발은 복잡한 산악지형이라는 특수한 환경에서 다양한 고도의 환경 데이터를 실시간 수집하는 체계를 구축함으로써 산림환경 연구를 위한 기초 데이터를 수집하는 계기가 되었다. 첨단기술을 활용한 주요 산악지역의 식물계절 변화 탐지 연구는 산림청에서 제공하는 개화 및 개엽 예측 정보의 검증과 산림휴양쾌적지수 고도화 등에 활용 가능하며, 향후 농림위성의 NDVI 등 영상 이미지의 검⋅보정용 자료로써 활용 가치가 매우 높다. 무인카메라 활용 기술은 산림 식물계절 및 적설 탐지뿐만 아니라 산림재해 감시 및 산림관리 등 다양한 산림분야에서도 활용될 수 있을 것으로 기대된다.

• 한국농림기상학회지
• /
• 제14권1호
• /
• pp.11-18
• /
• 2012

월별 기후통계량의 조화해석에 의해 생성한 일 기온 자료가 생물계절모형의 입력자료로서 적합한지 여부를 평가하여 농림업 부문 기후시나리오 응용정보 제작 상오류를 제거하기 위해 본 연구를 수행하였다. 서울관측소의 1971-2000 평년 월별 일 최고기온과 최저기온 평균값으로부터 조화해석에 의해 365일 간 기온자료를 생성하였다. 이것을 널리 검증된 온도시간 기반의 벚꽃 개화모형에 입력하여 휴면, 발아, 개화 등 주요 식물계절을 추정하였다. 같은 기간 중 실측기온자료에 의해 모형을 구동시켜 얻은 결과와 비교한 바, 연차변이를 전혀 반영하지 못하는 것은 물론, 휴면해제 25일 단축, 강제 휴면기간 57일 연장, 발아 14일 지연, 개화 13일 지연등 평균값도 크게 달라 식물계절을 크게 왜곡시키는 것으로 판단되었다. 대안으로서 확률추정기법에 의해 일기상자료를 생성하고 이를 이용하여 모형을 구동한 결과 실측결과에 비해 휴면해제 6일 단축, 강제휴면기간 10일 단축, 발아 3일 지연, 개화 2일 지연 등으로 조화해석자료 사용에 비해 크게 개선되었음을 확인하였다. 연차변이양상 역시 실측기온에 의한 모의결과와 크게 다르지 않아, 향후 이 자료를 농업부문 전자기후도 제작에 적용하면 기후변화 적응정책 수립을 실용수준에서 지원할 수 있을 것으로 보인다.

• 한국환경과학회지
• /
• 제22권12호
• /
• pp.1633-1641
• /
• 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.

• 한국지리정보학회지
• /
• 제19권1호
• /
• pp.30-42
• /
• 2016

기후변화는 식물계절주기에 큰 영향을 미쳤으며, 이로 인해 유기적인 상호관계 하에 있는 생태계 내 다른 생물들까지도 피해를 받는다는 것이 밝혀졌다. 그러나 국내의 경우 식물계절 조사 자료의 구축이 미흡하여 기후와 식물계절간 관계와 관련된 연구를 수행하는데 있어 어려움이 있다. 이에 본 연구에서는 위성영상을 이용한 식물계절 분석방법을 사용하여 효율적으로 국내 산림의 생육개시일을 도출하였다. 또한 생육개시일-기온요인간 상관관계를 분석하여 생육개시일 변동에 가장 영향력이 큰 변수를 도출해보고자 하였다. 분석결과, 국내 산림지역의 생육개시일은 4월 평균기온 그리고 TSOGmin($3^{\circ}C$, 12일)과 가장 상관성이 큰 것으로 나타났다. 이러한 결과는 추후 미래의 기후변화 시나리오 자료를 통해 식물계절 변화를 예측할 수 있는 유용한 자료로 사용될 수 있을 것으로 판단된다.

• 한국작물학회지
• /
• 제44권2호
• /
• pp.149-153
• /
• 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.

• 대한원격탐사학회지
• /
• 제40권1호
• /
• pp.57-69
• /
• 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.

• Journal of Ecology and Environment
• /
• 제47권3호
• /
• pp.134-145
• /
• 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.

• 한국농림기상학회지
• /
• 제16권3호
• /
• pp.213-218
• /
• 2014

대기 이산화탄소 농도 증가가 상수리나무 잎의 생물계절현상에 미치는 영향을 알아보고자 본 연구를 수행하였다. 상부개방형온실을 이용하여 대기 이산화탄소 농도를 높여 처리하였다. 대기 이산화탄소 처리 농도의 설정은 현재 농도, 현재 농도의 1.4배, 현재 농도의 1.8배 등 3 처리구로 하였고, 온실효과에 대한 검정을 위하여 상부개방형온실 외부에 비교구를 설치하였다. 잎의 생물계절현상은 2013년에 동아 파열, 개엽, 단풍, 낙엽에 대하여 각 생물계절현상이 나타나는 일자와 적산온도를 조사하였고, 2014년에는 봄철 계절현상인 동아 파열과 개엽에 대하여 각가의 일자와 적산온도를 조사하였다. 동아 내의 탄수화물 함량 분석을 위하여 2014년 3월에 각 처리구별로 동아를 채취하여 분석하였다. 봄철의 생물계절현상이 연도간에 차이가 나타났는데, 2013년도에는 동아 파열과 개엽 시기가 이산화탄소 처리 농도가 증가함에 따라 빨라지는 것으로 나타났다. 봄철 기온이 높았던 2014년도에는 동아 파열 및 개엽 시기 모두 처리구간에 차이가 나타나지 않았다. 단풍과 낙엽 등 가을철의 생물계절현상은 이산화탄소 처리 농도가 증가함에 따라서 늦어지는 것으로 나타났다. 동아 내의 탄수화물 함량 분석 결과 이산화탄소 처리 농도가 증가함에 따라서 전분, 총 비구조 탄수화물, 총 수용성 당류의 함량이 증가하는 것으로 나타났다. 대기 이산화탄소 농도의 상승은 상수리나무의 개엽을 빠르게 하고 낙엽을 늦추어 전체적인 생육기간을 연장시키게 될 것이다. 봄철의 이른 개엽은 동해피해의 가능성을 높이나, 개엽 시기는 온도에 의한 영향을 크게 받으며, 전년도 이산화탄소 농도 증가에 의하여 동아 내의 전분, 수용성 당 등 탄수화물 함량이 증가되기 때문에 봄철의 동해피해 가능성은 낮을 것으로 판단된다.