Back-trajectory analyses for evaluating the transboundary transport effect to the aerosol pollution in South Korea.

This study performed a back-trajectory analysis to determine the influence of transboundary transport on the extent of aerosol pollution in South Korea, based on 5-year PM2.5 measurements (2015-2019) in five cities covering South Korea. A transboundary transport case was selected if a back trajectory passed over a dedicated region (BOX 1 and BOX 2) in the Yellow Sea. First, we found that the frequency of transboundary transport largely increases in the high pollution case, and this pattern is almost consistent for all months and all five cities, indicating the importance of investigating the horizontal direction of air mass movement associated with PM2.5, which has been discussed extensively in previous studies. In this study, we also examined the altitude change and straight moving distance (defined as travel distance) of back trajectories regarding the extent of local PM2.5. Consequently, we found that back trajectories in high aerosol pollution showed much lower altitudes and shorter travel differences, implying a significant contribution of surface emissions and stagnant air conditions to severe aerosol pollution. As a result, the local PM2.5 level was not significantly enhanced when the air mass passed over the Yellow Sea if transboundary transport occurred at high altitudes with rapid movement (i.e., high altitude and long travel distance back-trajectory). Based on these results, we suggest utilizing the combined information of the horizontal direction, altitude variation, and length of back trajectories to better evaluate transboundary transport.

Mid-Term Strategic Plan for the Public Health and Medical Care Cooperation in the Korean Peninsula.

As extensive as the concept of and the resources required for 'Health for Korean Unification' are, and due to the limited access to information on the state of health and medical care in North Korea, discussion on 'Health for Korean Unification' has tended to be intermittent and lacked concrete action plans. In this article, we specifically distinguished areas of cooperation and selected five executable agenda that meet the goals of international development cooperation: 1) Health security; 2) Easing the burden of major diseases; 3) Resilient healthcare system; 4) R&D cooperation; 5) Sustainable cooperation system. Then we provided corresponding strategic priorities and operative directions, in consideration of future military and political sanctions against North Korea. The strategies we outline are sustainable, preemptive for problems that might affect lives of South and North Korean citizens, and satisfy the unmet needs of the North Korean health system. Throughout the process, we utilized a special platform, the 'Korean Peninsula Healthcare Cooperation Platform,' designed to enable continual communication across sectors engaged in public health and medical care. By doing so, we take the first step to actually carry out the 'Health for Korean Unification,' which tended to have remained on the discussion agenda.

Approximate Bayesian computation and ecological niche models elucidate the demographic history and current fragmented population distribution of a Korean endemic shrub.

Climatic fluctuations and geological events since the LGM are believed to have significantly impacted the population size, distribution, and mobility of many species that we observe today. In this paper, we determined the processes driving the phylogeographic structure of the Korean endemic white forsythia by combining the use of genome-wide SNPs and predicting paleoclimatic habitats during the LGM (21 kya), Early Holocene (10 kya), Mid-Holocene (6 kya), and Late Holocene (3 kya). Using a maximum of 1897 SNPs retrieved from 124 samples across nine wild populations, five environmental predictors, and the species' natural occurrence records, we aimed to infer the species' demographic history and reconstruct its possible paleodistributions with the use of approximate Bayesian computation and ecological niche models, respectively. Under this integrated framework, we found strong evidence for patterns of range shift and expansion, and population divergence events from the onset of the Holocene, resulting in the formation of its five distinct genetic units. The most highly supported model inferred that after the split of an ancestral population into the southern group and a larger central metapopulation lineage, the latter gave rise to the eastern and northern clusters, before finally dividing into two sub-central groups. While the use of molecular data allowed us to identify and refine the (phylo)genetic relationships of the species' lineages and populations, the use of ecological data helped us infer a past LGM refugium and the directions of post-glacial range dynamics. The time frames of these demographic events were shown to be congruent with climatic and geological events that affected the central Korean Peninsula during these periods. These findings gave us a better understanding of the consequences of past spatiotemporal factors that may have resulted in the current fragmented population distribution of this endangered plant.

Identification of Sympetrum depressiusculum Sélys, 1841 in South Korea (Odonata: Libellulidae) According to Morphology and Genetic Markers.

In South Korea, both Sympetrum depressiusculum Sélys, 1841 (Odonata: Libellulidae), which is distributed throughout Europe and from Russia to the Korean Peninsula, and Sympetrum frequens Sélys, 1883, which is endemic to Japan, are recorded. However, the identity of South Korean populations and the validity of listing the two species have not yet been settled. In this study, we collected seventy-four individuals of Sympetrum species from South Korea (five localities), Russia, The Netherlands, and Japan. These samples were examined for morphology and sequenced for partial COI, 16S rRNA, and a nuclear internal spacer (ITS) region, after which these molecular data were combined with available public data from Russia, Japan, and The Netherlands. Major morphological characters that have been used to distinguish the two species and phylogenetic, network, and structure analyses all consistently suggest that South Korean populations form a single species. Consequently, it could be valid to treat South Korean populations as one species, S. depressiusculum, by applying the senior name. Nevertheless, the validity of maintaining each as an independent species in other countries may need additional study considering that our samples were focused more on South Korea and limited for Europe, Russia, and Japan.

Additional record of Tuponia Reuter (Heteroptera, Miridae, Phylinae) from Korea, with a new synonym and discussion on distribution.

Background: The genus Tuponia Reuter, 1875 belongs to the subfamily Phylinae and comprises 91 species worldwide. Before this study, only T.koreana Kim & Jung had been recorded from the Korean Peninsula. New information: Two species of Tuponia Reuter, 1910 are recognised from the Korean Peninsula including the first record of T.mongolica Drapolyuk, 1980. T.koreana Kim & Jung, 2021 is proposed as a junior synonym of T.chinensis Zheng & Li, 1992. The species is identified, based on the dorsal habitus and male and female genitalic structures. A brief discussion of the distribution of Korean Tuponia species also is presented.

Molecular investigation on diversity of the land snail genus Aegista (Gastropoda, Camaenidae) in South Korea.

Aegista Albers, 1850 is a large genus of the land snail family Camaenidae Pilsbry, 1895 and distributed in south, southeast and east Asian countries (from India and Nepal to Korea and Japan). Fourteen species and subspecies of Aegista are known from South Korea. They were described, based only on shell morphology during 1887-1943 and our knowledge on diversity of Korean Aegista has seldom been updated since then. In this study, we provide the report on the first molecular investigation of diversity of Aegista in South Korea, which unmasked some of overlooked diversity of this group.

Foraging Strategy of Black-faced Spoonbill During Breeding Period in Rice Fields of Korea.

Rice fields are important habitats for a variety of water birds, and their importance is increasing with the destruction of natural wetlands. This study was conducted to understand the foraging strategy of the black-faced spoonbill, an internationally endangered species, in rice fields. To achieve this objective, the feeding success rate of black-faced spoonbills in rice fields was analyzed considering the species' feeding behavior, environmental factors, and external factors. The number of sweeps per minute and number of steps per minute were evaluated as features of feeding behavior; rice field type, water level, and rice height as environmental factors; and the size of a flock and number of other species in the fields when black-faced spoonbills were feeding as external factors. The feeding success rate of the black-faced spoonbills increased as they were feeding while moving at a fast pace in a rice field with a water level of 10 cm or below, rice height of 15 cm, and without herons (competitor species). These factors may be an effective strategy to increase the probability of food acquisition by black-faced spoonbills in rice fields. Therefore, to allow black-faced spoonbills during breeding season to use the rice fields for feeding, it is necessary to maintain a water level of 15 cm or less before transplanting rice. Moreover, the use of pesticides must be minimized to increase abundance of the food resources in rice fields.

Phylogenetic relationship, biogeography, and conservation genetics of endangered Fraxinus chiisanensis (Oleaceae), endemic to South Korea.

Endemic plants are important for understanding phylogenetic relationships, biogeographical history, and genetic variation because of their restricted distribution and their role in conserving biodiversity. Here, we investigated the phylogenetic relationships of the Korean endemic Fraxinus chiisanensis by reconstructing the molecular phylogeny of Fraxinus based on two nuclear DNA (nrITS and phantastica) and two chloroplast DNA (psbA-trnH and rpl32-trnL) regions. Within our fossil-calibrated phylogenetic framework, we also inferred the biogeographical history of F. chiisanensis. To provide a scientific basis for the conservation of F. chiisanensis, we determined the levels of genetic diversity and genetic differentiation in this species. Combining information from nuclear and chloroplast DNA sequence data, our molecular phylogenetic analyses identified F. chiisanensis as a genetically distinct unit from its sister group, Fraxinus platypoda from Japan. Our molecular dating analyses using nuclear and chloroplast DNA data sets show F. chiisanensis diverged from its sister F. platypoda in the Early or Middle Miocene and differentiated in the Late Miocene on the Korean Peninsula. Our results suggest that the divergence of F. chiisanensis was associated with the submergence of the East China Sea land bridge and enhanced monsoons in East Asia. When compared to F. platypoda, F. chiisanensis exhibits low genetic diversity within populations and high genetic differentiation among populations. These results help us to understand the evolutionary history of F. chiisanensis and to develop a conservation strategy for this species.

The complete mitochondrial genome of the Amur soft-shelled turtle (Pelodiscus maackii Brandt, 1858), from South Korea.

In this study, we use a specimen from wild-caught individual to determine the complete mitochondrial genome of the Amur soft-shelled turtle (Pelodiscus maackii). The complete mitogenome of P. maackii has 16,258 bp in length and consists of 13 protein-coding genes (PCGs), 22 tRNAs, two rRNAs, and one control region. The arrangement of genes of P. maackii is identical with previously reported mitogenomes in the family Trionychoidea. According to our result, the ML tree for the phylogenetic reconstruction revealed that the individuals used in present study is closely related with the previously reported sequences of P. sinensis (AY962573 and MG431983) in p-distance 0.7% and 2.5%.

Interannual variability of heat waves over the Korean Peninsula based on integrated approach.

Heat waves can provide detrimental impacts on human society and the environmental system, and thus have received substantial attention in scientific research. Since heat waves are relevant to a wide range of stakeholders, definitions for heat wave events vary in terms of threshold values, durations, and utilized variables. While there is a value in this diversity of perspectives, the various definitions often complicate the assessment of heat wave risk, thereby underscoring the improved utility of a unified definition. In this study, we examine the interannual variability of heat wave patterns by using a proposed copula-based framework. From five observed temperature-related variables, this study first evaluates the individual changes of fifteen previously published heat wave indices focused on heat wave events across the Korean Peninsula for the last 49 years (1973-2021). We then extract the integrated signals to understand the overall trend patterns using the multiple heat wave indices. Results indicate that different heat wave definitions present distinctive attributes (e.g., in the magnitude of temporal changes) depending on the locations, implying that the diversity of heat wave definitions leads to potentially inconsistent conclusions. Using the integrated analysis, we identify that the expected heat wave day has increased across the majority of the regions in the Korean Peninsula. To be specific, substantial increases are shown in North Korea, while rapid increases in heat wave events have been observed after the year 2010 over South Korea. Finally, through the sensitivity analysis, we demonstrate the importance of choosing the heat wave definition in the integrated analysis.

Predicting rice yield at pixel scale through synthetic use of crop and deep learning models with satellite data in South and North Korea.

Prediction of rice yields at pixel scale rather than county scale can benefit crop management and scientific understanding because it is useful for monitoring how crop yields respond to various agricultural systems and environmental factors. In this study, we propose a methodology for the early prediction of rice yield at pixel scale combining a crop model and a deep learning model for different agricultural systems throughout South and North Korea. Initially, satellite-integrated crop models were applied to obtain a pixel-scale reference rice yield. Then, the pixel-scale reference rice yields were used as target labels in the deep learning model to leverage the advantages of crop models. Models of five different deep learning network architectures were employed to help determine the hybrid structure of long-short term memory (LSTM) and one-dimensional convolutional neural network (1D-CNN) layers by predicting the optimal model about two months ahead of harvest time. The suggested model showed good performance [R2 = 0.859, Nash-Sutcliffe model efficiency = 0.858, root mean squared error = 0.605 Mg ha-1], with specific spatial patterns of rice yields for South and North Korea. Analysis of the relative importance of the input variables showed the water-related index and maximum temperature in North Korea and the vegetation indices and geographic variables in South Korea to be crucial for predicting rice yields. The proposed approach successfully predicted and diagnosed rice yield at the pixel scale for inaccessible locations where reliable ground measurements are not available, especially North Korea.

Driven to the edge: Species distribution modeling of a Clawed Salamander (Hynobiidae: Onychodactylus koreanus) predicts range shifts and drastic decrease of suitable habitats in response to climate change.

Climate change is one of the major threats to global amphibian diversity, and consequently, the species distribution is expected to shift considerably in the future. Therefore, predicting such shifts is important to guide conservation and management plans. Here, we used eight independent environmental variables and four representative concentration pathways (RCPs) to model the current and future habitat suitability of the Korean clawed salamander (Onychodactylus koreanus) and then defined the dispersal limits of the species using cost distance analysis. The current habitat suitability model generated using the maximum entropy algorithm was highly consistent with the known distribution of the species and had good predictive performance. Projections onto years 2050 and 2070 predicted a drastic decrease of habitat suitability across all RCPs, with up to 90.1% decrease of suitable area and 98.0% decrease of optimal area predicted from binary presence grids. The models also predicted a northeastward shift of habitat suitability toward high-elevation areas and a persistence of suitability along the central ridge of the Baekdudaegan Range. This area is likely to become a climatic refugium for the species in the future, and it should be considered as an area of conservation priority. Therefore, we urge further ecological studies and population monitoring to be conducted across the range of O. koreanus. The vulnerability to rapid climate change is also shared by other congeneric species, and assessing the impacts of climate change on these other species is needed to better conserve this unique lineage of salamanders.

Analysis of Korean Peninsula Earthquake Network Based on Event Shuffling and Network Shuffling.

In this work, a Korean peninsula earthquake network, constructed via event-sequential linking known as the Abe-Suzuki method, was investigated in terms of network properties. A significance test for these network properties was performed via comparisons with those of two random networks, constructed from two approaches, that is, EVENT (SEQUENCE) SHUFFLING and NETWORK (MATRIX) SHUFFLING. The Abe-Suzuki earthquake network has a clear difference from the two random networks. However, the two shuffled networks exhibited completely different functions, and even some network properties for one shuffled datum are significantly high and those of the other shuffled data are low compared to actual data. For most cases, the event-shuffled network showed a functional similarity to the real network, but with different exponents/parameters. This result strongly claims that the Korean peninsula earthquake network has a spatiotemporal causal relation. Additionally, the Korean peninsula network properties are mostly similar to those found in previous studies on the US and Japan. Further, the Korean earthquake network showed strong linearity in a specific range of spatial resolution, that is, 0.20°~0.80°, implying that macroscopic properties of the Korean earthquake network are highly regular in this range of resolution.

Decaying Post-Seismic Deformation Observed on the Korean Peninsula Following the 2011 Tohoku-Oki Earthquake.

We investigated decaying post-seismic deformation observed on the Korean Peninsula associated with the 2011 Mw 9.0 Tohoku-Oki earthquake using Global Navigation Satellite System (GNSS). The GNSS velocity vectors were estimated in five periods from 2005 to 2019. A co-seismic offset of the Korean Peninsula caused by the 2011 earthquake was inversely proportional to epicentral distances. According to the temporal variations of two components (magnitude and direction) of the GNSS velocity vector with the epicentral distance, the difference between the eastern and western regions for the two components becomes smaller over time. For approximately nine years after the 2011 event, the direction for the crustal movement in South Korea showed a recovery pattern returning to the pre-earthquake motion. In addition, the recovery patterns of the crustal movement were observed differently with the regional geologic structure (e.g., the crustal thickness) and each period. Our estimates of the decay in post-seismic deformation of the Korean Peninsula suggest that post-seismic relaxation will be complete within 5-20 years after the 2011 earthquake. The results suggest that the crustal movement on the Korean Peninsula is gradually recovering to its pre-earthquake motion.

Revision of Gymnomitriaceae (Marchantiophyta) in the Korean Peninsula.

This paper provides a revision of Gymnomitrion and Marsupella in the Korean Peninsula based on a study of the collections housed in the herbaria of Jeonbuk National University (JNU) and the Botanical Garden-Institute in Vladivostok (VBGI). In total, 12 species were recorded (six in Gymnomitrion and seven in Marsupella), including four taxa whose identity was not confirmed with the available materials and suspected to be recorded wrongly. Each confirmed species is annotated by morphological descriptions based on available Korean material, data on ecology, distribution, specimens examined as well as illustrations.

Integrating continental mainland and islands in temperate East Asia: liverworts and hornworts of the Korean Peninsula.

The liverwort and hornwort flora of the Korean Peninsula possesses some unique traits arising from the geographic position of the Peninsula, where the mainland flora meets insular flora. This flora is still not exhaustively studied, due not only to political reasons, but also because much less attention has been paid than to adjacent lands by hepaticologists. A checklist presented is based on a study of ca. 15,500 specimens collected by the authors and a review of relevant literature. This study provides the checklist of liverworts and hornworts known from Korea and the geographical distribution of each species within the peninsula. The liverworts and hornworts in Korean flora include 346 taxa (326 species, 16 subspecies and four varieties) in 112 genera and 50 families. Since 2007, 75 taxa of liverworts and four taxa of hornworts are reported as new to the Korean Peninsula, with a number of the new records arising following application of new taxonomic concepts that have become apparent over the last few decades. While compiling the checklist, 42 species, previously reported to Korea, are excluded from the Korean liverwort flora.

The complete mitochondrial genome information of Rana uenoi (Amphibia, Anura, Ranidae) and the phylogenetic implication.

We determined the complete mitochondrial genome of Rana uenoi (Anura: Ranidae) for the first time. The whole sequences were 17,370 bp and included 13 protein-coding genes, 2 ribosomal RNA genes, and 22 transfer RNA genes. The gene arrangement was completely identical to those observed from other Ranidae species. We used 11 protein-coding genes to examine the phylogenetic placement of this species in the genus Rana. Rana dybowskii was the closest sister species to R. uenoi. The clade of R. uenoi and R. dybowskii formed a cluster with Rana huarensis, which had a sister relationship with the group of Rana amurensis, Rana coreana, and Rana kunyuensis.

Plastic debris ingestion by seabirds on the Korean Peninsula.

Plastic ingestion studies in seabirds that analyse the frequency of occurrence and the characteristics of the plastics ingested by each species provide valuable information for marine environmental assessments by quantifying the impacts of marine debris on seabirds. We investigated the frequency of plastic ingestion from a sample of 387 individuals of 11 seabird species on the Korean Peninsula. We found evidence of plastic ingestion in red-breasted mergansers (Mergus serrator) (33.3%), Pacific loons (Gavia pacifica) (10.0%), Swinhoe's storm petrels (Hydrobates monorhis) (93.7%), black-tailed gulls (Larus crassirostris) (12.9%) and ancient murrelets (Synthliboramphus antiquus) (0.9%). In particular, it was observed that Swinhoe's storm petrels had the highest frequency of plastic ingestion, both in terms of the number of affected individuals, and the accumulated mass of plastic debris ingested. The majority of seabirds examined in our study had ingested microplastics, comprised predominantly of user plastics. This is the first report quantifying plastic ingestion in seabirds on the Korean Peninsula and in the broader area of the East Asian Seas.

Disentangling the Impacts of Speciation, Sympatry and the Island Effect on the Morphology of Seven Hynobius sp. Salamanders.

Closely related individuals from different areas can see their morphologies change based on differences between clades, but also ecological variables such as the island effect or sympatry. This is the case of salamanders, which have adapted to a broad range of ecological niches, ranging from underground dwellers in xeric landscape to tropical arboreal habitats. On the Korean Peninsula, salamanders from the Hynobius clade are widespread on the mainland and islands, with several partially sympatric clades and candidate species. Currently, seven lineages have been identified based on mtDNA, four of them matching named species and three others for which the species status remains untested. While the morphology of Korean Hynobius is known to be variable between genetically segregated clades, we hypothesise that (1) the candidate species are morphologically different, and that (2) the island effect and (3) the sympatric status have significant impacts on the morphology of individuals within the genus. Here we measured 329 Hynobius salamanders from all seven clades, in areas of sympatry and allopatry, and on islands and on the mainland (Graphical Abstract A). We determined that the island effect had a significant impact on the morphology of the genus, with mainland individuals generally displaying a broader range of morphology than islandic individuals (Graphical Abstract B). We also determined that sympatry had an impact on morphology, with the sizes of individuals from clades in sympatric areas diverging from each other (Graphical Abstract C). Finally, we demonstrated that all seven clades have significantly different morphologies, and we described the three candidate species that had already been isolated based on mtDNA and microsatellite data: Hynobius notialis sp. nov., Hynobius geojeensis sp. nov. and Hynobius perplicatus sp. nov. We conclude that looking at morphology alone would be misleading about the true diversity of Hynobius species, and species in general, because of the island and patry effects.

Phylogeographic study of the Bufo gargarizans species complex, with emphasis on Northeast Asia.

We conduct a phylogeographic and population genetic study of the Asiatic toad (Bufo gargarizans) to understand its evolutionary history, and the influence of geology and climate. A total of 292 individuals from 94 locations were genotyped for two mitochondrial loci (cytb, ND2) and five nuclear introns (Sox9-2, Rho-3, CCNB2-3, UCH-2, and DBI-2), and we performed a suite of phylogenetic, population genetic, and divergence dating analyses. The phylogenetic trees constructed using mitochondrial loci inferred B. gargarizans being divided into two major groups: China mainland and Northeast Asia (Northeast China, Russia, and Korean Peninsula). As with previous studies of this species, we recover population genetic structure not tied to geographic region. Additionally, we discover a new genetic clade restricted to Northeast Asia that points towards the Korean Peninsula being a glacial refugium during the Pleistocene. The weak phylogeographic pattern of B. gargarizans is likely the result of multiple biological, anthropogenic, and historical factors - robust dispersal abilities as a consequence of physiological adaptations, human translocation, geologic activity, and glacial cycles of the Pleistocene. We highlight the complex geologic and climatic history of Northeast Asia and encourage further research to understand its impact on the biodiversity in the region.