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It is essential to maintain the health of forests so that they are protected against a diverse range of stressors and show improved resilience. An area-based forest health map is required for efficient forest management on a national scale however, most national forest inventories are based on in-situ observations. This study examined methodologies to establish an area-based map on tree vitality grade using field survey data, particularly that containing information on several trees at one point. The forest health monitoring dataset of the Republic of Korea was used in combination with 37 satellite-based environmental predictors. Four methods were considered: Multinomial logistic regression (MLR), random forest classification (RF), indicator kriging (IK), and multi-model ensemble (MME) approaches using species distribution models. The MLR and RF produced biased results, whereby almost all regions were classified as first grade; the spatialization results of these methods were considered inappropriate for forest management. The maps produced using the IK and MME methods improved the distinctions between the distributions of five grades compared to the previous two methodologies however, the MME method produced better results, reliably reflecting topographical and climatic characteristics. Comparisons with the vegetation condition index and bioclimate vulnerability index also emphasized the usefulness of the MME. This study is particularly relevant to the national forest managers who struggle to find the most effective forest monitoring and management strategies. Suggestions to improve spatialization of field survey data are further discussed.
Yuyoung Choi; Hye Chung; Chul-Hee Lim; Jun-Hee Lee; Won Choi; Seong Jeon. Multi-Model Approaches to the Spatialization of Tree Vitality Surveys: Constructing a National Tree Vitality Map. Forests 2021, 12, 1009 .
AMA StyleYuyoung Choi, Hye Chung, Chul-Hee Lim, Jun-Hee Lee, Won Choi, Seong Jeon. Multi-Model Approaches to the Spatialization of Tree Vitality Surveys: Constructing a National Tree Vitality Map. Forests. 2021; 12 (8):1009.
Chicago/Turabian StyleYuyoung Choi; Hye Chung; Chul-Hee Lim; Jun-Hee Lee; Won Choi; Seong Jeon. 2021. "Multi-Model Approaches to the Spatialization of Tree Vitality Surveys: Constructing a National Tree Vitality Map." Forests 12, no. 8: 1009.
Analysis of the correlation between vegetation greenness and climate variable trends is important in the study of vegetation greenness. Our study used Normalized Difference Vegetation Index-3rd generation data from the Advanced Very High-Resolution Radiometer - Global Inventory Modeling and Mapping Studies (AVHRR-GIMMS NDVI3g), land cover data from the Climate Change Initiative (CCI-LC), and climate data from the Climatic Research Unit global time series (CRU TS) of climate variables (temperature and precipitation, solar radiation) over the past 33 years. First, we estimated the overall trends for vegetation greenness and climate variables over five time periods. Second, we subjected the data to correlation, regression, and residual analyses to detect correlations between vegetation greenness and different climate variables. Third, we extracted trends and correlation results by primary land cover types for each climate zone. Our study was focused at the global scale, and findings indicate that the largest decreasing trend of vegetation greenness and grasslands occurred in the mid-latitude regions of the Northern Hemisphere and in parts of South America, Africa, Saudi Arabia, and south and northeast Asia. In particular, the cold climatic zones of forest (36.6%), cropland (36.6%), and grassland (14.1%) suffered significant decline in vegetation greenness. Anthropogenic activities are mainly responsible for declining vegetation greenness particularly in northern Africa, central and western Asia. However, residual analysis shows an increase in vegetation greenness in some parts of western Europe, southern Australia, and the northern part of South America. The study also identified temperature and precipitation as the main factors responsible for controlling vegetation growth. Hot-spot areas with the largest temperature increases were found in the Amazon, Central America, southern Greenland, east Africa, south-east Asia, and other areas. However, temperatures decreased in the western part of South America, Angola, the Philippines, Indonesia, and Papua New Guinea. Precipitation decreased the most from March to May over most parts of the world with high correlation (r = 0.88) in Russia Canada, northeast Asia, and central Africa. In general, climate factors were the principal drivers of the variation in vegetation greenness globally in recent years.
Munkhnasan Lamchin; Sonam Wangyel Wang; Chul-Hee Lim; Altansukh Ochir; Ukrainskiy Pavel; Belay Manju Gebru; Yuyoung Choi; Seong Woo Jeon; Woo-Kyun Lee. Understanding global spatio-temporal trends and the relationship between vegetation greenness and climate factors by land cover during 1982–2014. Global Ecology and Conservation 2020, 24, e01299 .
AMA StyleMunkhnasan Lamchin, Sonam Wangyel Wang, Chul-Hee Lim, Altansukh Ochir, Ukrainskiy Pavel, Belay Manju Gebru, Yuyoung Choi, Seong Woo Jeon, Woo-Kyun Lee. Understanding global spatio-temporal trends and the relationship between vegetation greenness and climate factors by land cover during 1982–2014. Global Ecology and Conservation. 2020; 24 ():e01299.
Chicago/Turabian StyleMunkhnasan Lamchin; Sonam Wangyel Wang; Chul-Hee Lim; Altansukh Ochir; Ukrainskiy Pavel; Belay Manju Gebru; Yuyoung Choi; Seong Woo Jeon; Woo-Kyun Lee. 2020. "Understanding global spatio-temporal trends and the relationship between vegetation greenness and climate factors by land cover during 1982–2014." Global Ecology and Conservation 24, no. : e01299.
Habitat changes in temperate forests are more vulnerable to climate change than tropical or boreal forests. This study assessed forest habitat suitability and diversity to determine the impact of climate change on the Korean Peninsula. We used the MaxEnt (Maximum Entropy) species distribution model, three key climate indices, and two representative climate change scenarios, using short and long-term data. Two of the three key climate indices related to temperature were more capricious than the precipitation-related index in the future. In the baseline prediction, both statistical and qualitative validation using the actual vegetation map showed excellent results. Regarding forest habitat suitability, northward migration and substantial increase were definitely distinctive in warm temperate evergreen forest. On the other hand, subalpine forest areas decreased significantly due to climate change; the suitable area for Representative Concentration Pathways (RCP) 8.5 2070s decreased by more than half. With regard to forest habitat diversity, regions with high diversity declined due to climate change. In the RCP 8.5 scenario, areas where all three forest types are suitable no longer appeared; however, in the case of RCP 4.5 2050s, suitable areas for two forest types increased, which implies climate change is not only negative in terms of diversity. As this negative prediction of future change is discouraging, active mitigation and adaptation are required to prevent these changes. The sustainability of future ecosystems is still dependent on our efforts.
Chul-Hee Lim; Somin Yoo; Yuyoung Choi; Seong Woo Jeon; Yowhan Son; Woo-Kyun Lee. Assessing Climate Change Impact on Forest Habitat Suitability and Diversity in the Korean Peninsula. Forests 2018, 9, 259 .
AMA StyleChul-Hee Lim, Somin Yoo, Yuyoung Choi, Seong Woo Jeon, Yowhan Son, Woo-Kyun Lee. Assessing Climate Change Impact on Forest Habitat Suitability and Diversity in the Korean Peninsula. Forests. 2018; 9 (5):259.
Chicago/Turabian StyleChul-Hee Lim; Somin Yoo; Yuyoung Choi; Seong Woo Jeon; Yowhan Son; Woo-Kyun Lee. 2018. "Assessing Climate Change Impact on Forest Habitat Suitability and Diversity in the Korean Peninsula." Forests 9, no. 5: 259.
In agriculture, balancing water use and retention is an issue dealt with in most regions and for many crops. In this study, we suggest agricultural water equilibrium (AWE) as a new concept that can facilitate a spatially explicit management of agricultural water. This concept is based on the principle of supply and demand of agricultural water, where the virtual water content of crops (VWC) can be defined as the demand, and cropland water budget (CWB) as the supply. For assessing the AWE of the Korean Peninsula, we quantified the CWB based on the hydrological cycle and the VWC of rice, a key crop in the Peninsula. Five factors, namely crop yield, growing season evapotranspiration, annual evapotranspiration, runoff, and annual precipitation, were used to assess the AWE, of which the first four were estimated using the spatially explicit large-scale crop model, Geographical Information System (GIS)-based Environmental Policy Integrated Climate (GEPIC). The CWB and VWC were calculated for a period of three decades, and the AWE was computed by deducting the VWC from the CWB. Our results show a latitudinal difference across the Korean Peninsula. On analyzing the AWE of the major river basins, we found most basins in North Korea showed very low values inferring unsustainable overconsumption of water. The latitudinal difference in AWE is a reflectance of the latitudinal changes in the VWC and CWB. This can be explained by decoupling the demand and supply of agricultural water. Although the AWE values presented in this study were not absolute, the values were sufficient to explain the latitudinal change, and the demand and supply of agricultural water, and establish the usefulness of the indicator.
Chul-Hee Lim; Yuyoung Choi; Moonil Kim; Soo Lee; Christian Folberth; Woo-Kyun Lee. Spatially Explicit Assessment of Agricultural Water Equilibrium in the Korean Peninsula. Sustainability 2018, 10, 201 .
AMA StyleChul-Hee Lim, Yuyoung Choi, Moonil Kim, Soo Lee, Christian Folberth, Woo-Kyun Lee. Spatially Explicit Assessment of Agricultural Water Equilibrium in the Korean Peninsula. Sustainability. 2018; 10 (1):201.
Chicago/Turabian StyleChul-Hee Lim; Yuyoung Choi; Moonil Kim; Soo Lee; Christian Folberth; Woo-Kyun Lee. 2018. "Spatially Explicit Assessment of Agricultural Water Equilibrium in the Korean Peninsula." Sustainability 10, no. 1: 201.
Deforestation in North Korea is becoming the epitome of the environmental change occurring in the Korean Peninsula. This study estimates the agro-environmental variables of North Korea’s croplands and analyzes the impact of deforestation using the GEPIC (GIS-based EPIC (Environmental Policy Integrated Climate)) model and time-series land cover maps. To identify the changes in agricultural quality under deforestation, wind erosion, water erosion, organic carbon loss, and runoff were selected as the agro-environmental variables having an impact on cropland stability and productivity. Land cover maps spanning the past three decades showed that 75% of the forests were converted to croplands and that 69% of all converted croplands were originally forests, confirming the significant correlation between deforestation and cropland expansion in North Korea. Despite limitations in the verification data, we conducted qualitative and quantitative validation of the estimated variables and confirmed that our results were reasonable. Over the past 30 years, agro-environmental variables showed no clear time-series changes resulting from climate change, but changes due to spatial differences were seen. Negative changes in organic carbon loss, water erosion, and runoff were observed, regardless of the crop type. On newly-converted agricultural lands, runoff is 1.5 times higher and water-driven erosion and soil organic loss are more than twice as high compared to older croplands. The results showed that the agro-environment affected by deforestation had an impact on cropland stability and productivity.
Chul-Hee Lim; Yuyoung Choi; Moonil Kim; Seong Woo Jeon; Woo-Kyun Lee. Impact of Deforestation on Agro-Environmental Variables in Cropland, North Korea. Sustainability 2017, 9, 1354 .
AMA StyleChul-Hee Lim, Yuyoung Choi, Moonil Kim, Seong Woo Jeon, Woo-Kyun Lee. Impact of Deforestation on Agro-Environmental Variables in Cropland, North Korea. Sustainability. 2017; 9 (8):1354.
Chicago/Turabian StyleChul-Hee Lim; Yuyoung Choi; Moonil Kim; Seong Woo Jeon; Woo-Kyun Lee. 2017. "Impact of Deforestation on Agro-Environmental Variables in Cropland, North Korea." Sustainability 9, no. 8: 1354.
Sustainable agriculture in the era of climate change needs to find solutions for the retention and proper utilization of water. This study proposes an ensemble approach for identifying the virtual water content (VWC) of main crops on the Korean Peninsula in past and future climates. Ensemble results with low uncertainty were obtained using three regional climate models, five potential evapotranspiration methods, and the Environmental Policy Integrated Climate (EPIC) crop model. The productivity results of major crops (rice and maize) under climate change are likely to increase more than in the past based on the ensemble results. The ensemble VWC is calculated using three types of crop yields and fifteen consumptive amounts of water use in the past and the future. While the ensemble VWC of rice and maize was 1.18 m3 kg−1 and 0.58 m3 kg−1, respectively, in the past, the future amounts were estimated at 0.76 m3 kg−1 and 0.48 m3 kg−1, respectively. The yields of both crops showed a decline in future projections, indicating that this change could have a positive impact on future water demand. The positive changes in crop productivity and water consumption due to climate change suggest that adaptation to climate change can be an opportunity for enhancing sustainability as well as for minimizing agricultural damage.
Chul-Hee Lim; Seung Hee Kim; Yuyoung Choi; Menas C. Kafatos; Woo-Kyun Lee. Estimation of the Virtual Water Content of Main Crops on the Korean Peninsula Using Multiple Regional Climate Models and Evapotranspiration Methods. Sustainability 2017, 9, 1172 .
AMA StyleChul-Hee Lim, Seung Hee Kim, Yuyoung Choi, Menas C. Kafatos, Woo-Kyun Lee. Estimation of the Virtual Water Content of Main Crops on the Korean Peninsula Using Multiple Regional Climate Models and Evapotranspiration Methods. Sustainability. 2017; 9 (7):1172.
Chicago/Turabian StyleChul-Hee Lim; Seung Hee Kim; Yuyoung Choi; Menas C. Kafatos; Woo-Kyun Lee. 2017. "Estimation of the Virtual Water Content of Main Crops on the Korean Peninsula Using Multiple Regional Climate Models and Evapotranspiration Methods." Sustainability 9, no. 7: 1172.
Biodiversity is rapidly declining globally and efforts are needed to mitigate this continually increasing loss of species. Clustering of areas with similar habitats can be used to prioritize protected areas and distribute resources for the conservation of species, selection of representative sample areas for research, and evaluation of impacts due to environmental changes. In this study, Northeast Asia (NEA) was classified into 27 bioclimatic zones using statistical techniques, and it was re-clustered into 14 groups to identify the environmental characteristics of these zones. In particular, we added land cover variables into the clustering to reflect not only simple climate but also social factors influencing biological habitats. In total, 53 bioclimatic variables were constructed, and principal components were generated using correlation analysis and principal component analysis (PCA). The iterative self-organizing data analysis technique algorithm (ISODATA) was used to cluster the principal components and land cover variable. The constructed bioclimatic zones were assigned codes and descriptive names based on aridity, seasonality, and naturality, and their environmental characteristics were identified. This study is significant in that it improved the understanding of biological habitats of NEA and established a basis for monitoring the distribution of species and for efficient and systematic management of biodiversity.
Yuyoung Choi; Chul-Hee Lim; Jieun Ryu; Seong Woo Jeon. Bioclimatic Classification of Northeast Asia Reflecting Social Factors: Development and Characterization. Sustainability 2017, 9, 1137 .
AMA StyleYuyoung Choi, Chul-Hee Lim, Jieun Ryu, Seong Woo Jeon. Bioclimatic Classification of Northeast Asia Reflecting Social Factors: Development and Characterization. Sustainability. 2017; 9 (7):1137.
Chicago/Turabian StyleYuyoung Choi; Chul-Hee Lim; Jieun Ryu; Seong Woo Jeon. 2017. "Bioclimatic Classification of Northeast Asia Reflecting Social Factors: Development and Characterization." Sustainability 9, no. 7: 1137.