• Korean Journal of Remote Sensing
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• v.38 no.5_1
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• pp.627-646
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• 2022

Recently, the seriousness of climate change-related problems caused by global warming is growing, and the average temperature is also rising. As a result, it is affecting the environment in which various temperature-sensitive creatures and creatures live, and changes in the ecosystem are also being detected. Seasons are one of the important factors influencing the types, distribution, and growth characteristics of creatures living in the area. Among the most popular and easily recognized plant seasonal phenomena among the indicators of the climate change impact evaluation, the blooming day of flower and the peak day of autumn leaves were modeled. The types of plants used in the modeling were forsythia and cherry trees, which can be seen as representative plants of spring, and maple and ginkgo, which can be seen as representative plants of autumn. Weather data used to perform modeling were temperature, precipitation, and solar radiation observed through the ASOS Observatory of the Korea Meteorological Administration. As satellite data, MODIS NDVI was used for modeling, and it has a correlation coefficient of about -0.2 for the flowering date and 0.3 for the autumn leaves peak date. As the model used, the model was established using multiple regression models, which are linear models, and Random Forest, which are nonlinear models. In addition, the predicted values estimated by each model were expressed as isopleth maps using spatial interpolation techniques to express the trend of plant seasonal changes from 2003 to 2020. It is believed that using NDVI with high spatio-temporal resolution in the future will increase the accuracy of plant phenology modeling.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.143-149
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• 2007

To certify predictability for the times of phenological stages from cumulative air temperature in springtime, the first times of budding, leafing, flower budding, flowering and deflowering for 14 woody plants were monitored and air temperature was measured from 2005 to 2006 at Namsan. Year day index (YDI) and Nuttonson's Index (Tn) were calculated from daily mean air temperature. Of the 14 woody species, mean coefficient of variation was 0.04 in Robinia pseudo-acacia and 0.09 in Alnus hirsuta. However, mean coefficient of variation was 0.30 in Forsythia koreana and Stephanandra incisa and 0.32 in Zanthoxylum schinifolium. Therefore, the times of each phenological stage could be predicted in the former two species but not in latter three species by two indices. Of the five phenological stages, mean coefficient of variation was the smallest at deflowering time and the largest at budding time. In five phenological stages, mean coefficient of variation of YDI was in the range of $0.11{\sim}0.21$ but that of Tn was in the range of $0.15{\sim}0.26$. Therefore, the former was a better index than the latter. Of the species-phenological stage pair, coefficient of variation of YDI was 0.01 in Acer pseudo-sieboldianum - flower budding and below 0.05 in 11 pairs, whereas the YDIs over 0.40 were 4 pairs comprising of Prunus leveilleana - budding (0.51). Coefficient of variation of Tn was 0.01 in A. hirsuta - budding and below 0.05 in 8 pairs. The Tns over 0.40 were 5 pairs comprising of F. koreana - flower budding (0.66).

• Journal of Ecology and Environment
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• v.43 no.2
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• pp.104-116
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• 2019

Background: The composition of wild bird populations in temperate zones greatly varies depending on phenological changes rather than other environmental factors. Particularly, wild birds appearing in wetlands fluctuate greatly due to the crossover of species arriving for breeding during the summer and for wintering. Therefore, to understand the changes to species composition related to phenology, we conducted this basic analysis of populations to further the cause of the protection of wetland-dependent wild birds. Methods: It is wrong to simply divide a wild bird population investigation into seasons. This study identifies species composition and indicator species that change along with seasons. Wetlands to be surveyed are protected by natural monuments and wetland inventory and are in a state close to nature. In order to identify as many species as possible in wetlands, a survey was conducted in both shallow and deep wetlands. The water depth varied in these areas, ranging from 0.2 to 2.0 m, allowing for both dabbling and diving ducks to inhabit the area. Surveys were conducted using line-transect and distance sampling methods and were conducted at intervals of 2 weeks. The survey was conducted under the following three categories: the eco-tone and emergent zone, the submergent zone, and the water surface. The survey was conducted along a wetland boundary by observing wild birds. A PC-ord program was used for clustering, and the SAS program was used to analyze the changes in species composition. The data strongly indicates that day length is the main factor for seasonal migration periods, despite the fact that climate change and increasing temperatures are often discussed. Results and conclusions: The indicator species for determining seasons include migrant birds such as Ardea cinerea, Alcedo atthis, Anas penelope, and Poiceps ruficollis, as well as resident birds such as Streptopelia orientalis and Emberiza elegans. Importantly, increases in local individual counts of these species may also serve as indicators. The survey results of seasonal fluctuations in temperate zones shows that spring (April to June), summer (July to September), autumn (October), and winter (November to March) are clearly distinguishable, even though spring and summer seasons tend to overlap, leading to the conclusion that additional research could more clearly identify fluctuation patterns in species composition and abundance in the study area.

• Korean Journal of Agricultural and Forest Meteorology
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• v.15 no.1
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• pp.50-58
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• 2013

This study was carried out to evaluate the geospatial characteristics of blooming date migration in three major spring flowers across North and South Korea as influenced by climate change. A thermal time-based phenology model driven by daily maximum and minimum temperature was adjusted for the key parameters (i.e., reference temperature, chilling requirement, heating requirement) used for predicting blooming of forsythia, azaleas, and Japanese cherry. The model was run by the RCP 8.5 projected temperature outlook over the Korean Peninsula and produced the mean booming dates for the three climatological normal years in the future (2011-2040, 2041-2070, and 2071-2100) at a 12.5 km grid spacing. Comparison against the observed blooming date patterns in the baseline climate (1971-2000) showed that there will be a substantial acceleration in blooming dates of the three species, resulting in cherry booming in February and flowers of azaleas and forsythia found at the top of mountain Baikdu by the 2071-2100 period. Flowering dates of the three species in the near future (2011-2040) may be accelerated by 3-5 days at minimum and 10-11 days at maximum compared with that in the baseline period (1971-2000). Those values corresponding to the middle future (2041-2070) can be from a minimum of 9-11 days to a maximum of 23-24 days. Blooming date of Japanese cherry can be accelerated by 26 days on average for the far future (2071-2100). The acceleration seems more prominent at islands and coastal plain areas than over inland mountainous areas.

• Korean Journal of Agricultural and Forest Meteorology
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• v.11 no.2
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• pp.61-71
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• 2009

Most deciduous trees in temperate zone are dormant during the winter to overcome cold and dry environment. Dormancy of deciduous fruit trees is usually separated into a period of rest by physiological conditions and a period of quiescence by unfavorable environmental conditions. Inconsistent and fewer budburst in pear orchards has been reported recently in South Korea and Japan and the insufficient chilling due to warmer winters is suspected to play a role. An accurate prediction of the flowering time under the climate change scenarios may be critical to the planning of adaptation strategy for the pear industry in the future. However, existing methods for the prediction of budburst depend on the spring temperature, neglecting potential effects of warmer winters on the rest release and subsequent budburst. We adapted a dormancy clock model which uses daily temperature data to calculate the thermal time for simulating winter phenology of deciduous trees and tested the feasibility of this model in predicting budburst and flowering of Niitaka pear, one of the favorite cultivars in Korea. In order to derive the model parameter values suitable for Niitaka, the mean time for the rest release was estimated by observing budburst of field collected twigs in a controlled environment. The thermal time (in chill-days) was calculated and accumulated by a predefined temperature range from fall harvest until the chilling requirement (maximum accumulated chill-days in a negative number) is met. The chilling requirement is then offset by anti-chill days (in positive numbers) until the accumulated chill-days become null, which is assumed to be the budburst date. Calculations were repeated with arbitrary threshold temperatures from $4^{\circ}C$ to $10^{\circ}C$ (at an interval of 0.1), and a set of threshold temperature and chilling requirement was selected when the estimated budburst date coincides with the field observation. A heating requirement (in accumulation of anti-chill days since budburst) for flowering was also determined from an experiment based on historical observations. The dormancy clock model optimized with the selected parameter values was used to predict flowering of Niitaka pear grown in Suwon for the recent 9 years. The predicted dates for full bloom were within the range of the observed dates with 1.9 days of root mean square error.

• Korean Journal of Ecology and Environment
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• v.49 no.2
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• pp.110-123
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• 2016

In order to obtain scientific information for the conservation of Utricularia japonica Makino, rare plant species, we investigated life history, phenology, growth and distribution in the east coastal region of Korea. Seven habitats of U. japonica were confirmed in this study. Turion of U. japonica rests overwinter at the bottom and ripens at the water surface and then usually germinate and sprout when the water warms in spring. A single shoot grown from turion divided into several shoots. Shoot decomposition started in October and formed a new turion at the end of the decomposed shoot. Flowering period was from early July to late October. Percentage of flowering ramets was significantly low as 6.3%. U. japonica showed the fastest growth rate from April to July, the maximum growth in August and the highest biomass in October. U. japonica tended to be concentrated in larger ramets in the water depth of 50 cm~150 cm in Cheonjin lake. The main factors affecting the growth of U. japonica were water temperature and turbidity. The establishment and growth of U. japonica in Cheonjin lake were determined by responses to water temperature with seasonal change and to light conditions caused by the different plants. These conditions affect the temporal and spatial distribution of U. japonica and population change. The findings of this study would be helpful to provide the basic information needed for the conservation and restoration of U. japonica.

• Korean Journal of Remote Sensing
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• v.27 no.4
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• pp.457-466
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• 2011

The objectives of this study are to produce level 3 type LULC map and analysis of phenological features of North Korea, ISODATA clustering of the 88scenes of MVC of MODIS NDVI in 2008 and 8scenes in 2009 was carried out. Analysis of phenological phases based mapping method was conducted, In level 2 type map, the confusion matrix was summarized and Kappa coefficient was calculated. Total of 27 typical habitat types that represent the dominant species or vegetation density that cover land surface of North Korea in 2008 were made. The total of 27 classes includes the 17 forest biotopes, 7 different croplands, 2 built up types and one water body. Dormancy phase of winter (${\sigma}^2$ = 0.348) and green up phase in spring (${\sigma}^2$ = 0.347) displays phenological dynamics when much vegetation growth changes take place. Overall accuracy is (851/955) 85.85% and Kappa coefficient is 0.84. Phenological phase based mapping method was possible to minimize classification error when analyzing the inaccessible land of North Korea.

• Korean journal of applied entomology
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• v.53 no.3
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• pp.311-315
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• 2014

Lantern fly(Lycorma delicatula) is a major invasive pest that causes withering symptom of agricultural crops by sucking tree sap and sooty mold symptom by producing honeydew. This study was conducted to investigate the occurrence pattern of lantern fly in grape orchards in Gyeonggi area and the effect of winter temperature on L. delicatula egg survival during 2010 to 2013. In Gyeonggi areas, overwintered L. delicatula eggs began to hatch from early May and nymphs peaked in mid May. Adults emerged from late July and laid eggs until early November. The survival of L. delicatula eggs during overwintering was largely affected by winter temperatures. The relationship between the number of days below a threshold temperature (x) in January and the survival rate of overwintering L. delicatula eggs (y) was using linear regression model. The best model selected by the lowest RSS (residual sum of square) between predicted and actual survival was y = -1.0486 x + 94.496 ($R^2=0.7067$) with $-11^{\circ}C$ of threshold temperature. These results should be helpful to conduct L. delicatula management programs, since the results provided relivable prediction for the winter survival of L. delicatula eggs and the phenology of egg hatch in the spring.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.553-563
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• 2006

This study aims to produce land-cover maps of Korean peninsula using multi-temporal MODIS (Moderate Resolution Imaging Spectroradiometer) imagery. To solve the low spatial resolution of MODIS data and enhance classification accuracy, Linear Spectral Mixture Analysis (LSMA) was employed. LSMA allowed to determine the fraction of each surface type in a pixel and develop vegetation, soil and water fraction images. To eliminate clouds, MVC (Maximum Value Composite) was utilized for vegetation fraction and MinVC (Minimum Value Composite) for soil fraction image respectively. With these images, using ISODATA unsupervised classifier, southern part of Korean peninsula was classified to low and mid level land-cover classes. The results showed that vegetation and soil fraction images reflected phenological characteristics of Korean peninsula. Paddy fields and forest could be easily detected in spring and summer data of the entire peninsula and arable land in North Korea. Secondly, in low level land-cover classification, overall accuracy was 79.94% and Kappa value was 0.70. Classification accuracy of forest (88.12%) and paddy field (85.45%) was higher than that of barren land (60.71%) and grassland (57.14%). In midlevel classification, forest class was sub-divided into deciduous and conifers and field class was sub-divided into paddy and field classes. In mid level, overall accuracy was 82.02% and Kappa value was 0.6986. Classification accuracy of deciduous (86.96%) and paddy (85.38%) were higher than that of conifers (62.50%) and field (77.08%).

• Korean Journal of Environment and Ecology
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• v.32 no.6
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• pp.582-590
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• 2018

Although there are many studies of the effect of climate change on the breeding phenology and community diversity of amphibians, the studies of variations in reproductive population size of individual species according to climate change are still lacking. We examined the effect of climate change on the reproductive population size of Rana huanrenensis and Hynobius leechii, which bred in mountain valleys, by surveying the reproductive population of the two species between 2005 and 2012 and analyzing the correlation between the variation of the outdoor population and the surrounding climate change factors, obtained from a meteorological observatory located at 5.6 km from the study site. The size of the reproductive population of the two species commonly fluctuated with aan pproximately 3.5-year cycle. That of H. leechii, in particular, decreased significantly over eight years. The air temperature tended to more closely relate with the reproductive population size of R. huanrenensis as was the case of the precipitation with that of H. leechii. The yearly mean highest temperature and spring mean temperature variation consistently decreased over the eight years, and the latter was related with the significantly decreased size of H. leechii reproductive population. These results showed that recent climate change directly could affect the reproductive population size of amphibians, particularly H. leechii, which breeds in mountain valleys.