Update on Distribution and Conservation Status of Amphibians in the Democratic People's Republic of Korea: Conclusions Based on Field Surveys, Environmental Modelling, Molecular Analyses and Call Properties

Abstract

Simple Summary In this study, we used field and literature surveys, call recordings, photographs, landscape models and molecular tools to estimate the presence, range and status of amphibians in the Democratic People's Republic of Korea. We found 18 native species and the suspected presence of Karsenia koreana and two Onychodactylus species. We also determined northern range boundaries for Rana uenoi and Dryophytes japonicus with molecular tools. Based on distribution and modelling, we can expect the contact zone between species within the Rana and Onychodactylus genera to be located along the Changbai Massif, a high mountain range. The species richness was higher in the lowlands and at lower latitudes, with up to 11 species, while species richness in northern areas was half that value. Following the categories and criteria of The IUCN Red List of species, ecological models and known threats, we recommended ten species to be listed as threatened at the national level. The ecology of species in the DPR Korea is understudied, although species reliant on agricultural wetlands (e.g., rice paddies) are not as threatened as species living in forested areas due to the enduring presence of extensive agricultural landscapes. Determining the range, status, ecology and behaviour of species from areas where surveys and samplings are uncommon or difficult to conduct is a challenge, such as in the Democratic People's Republic of Korea (DPR Korea). Here, we used genetic samples, field surveys, call recordings, photographic identification and a literature review to estimate the presence, range and status of amphibians in the DPR Korea. From our combined results and based on the IUCN Red List categories and criteria, we were able to estimate the national threat levels for most species. Our results demonstrated the presence of 18 native species and the suspected presence of Karsenia koreana and two Onychodactylus species. We reported the first record for Rana uenoi in the vicinity of Pyongyang using molecular tools and similarly confirmed the presence of Dryophytes japonicus at the same location. Based on distribution and modelling, we can expect the contact zone between species within the Rana and Onychodactylus genera to be located along the Changbai Massif, a mountain range that marks a shift in ecoregions and acts as a barrier to dispersion. The species richness was higher in the lowlands and at lower latitudes, with such areas populated by up to 11 species, while more northern regions were characterised by species richness of about half of that value. The combination of ecological models and known threats resulted in the recommendation of ten species as threatened at the national level following the IUCN Red List categories and criteria. This high number of threatened species was anticipated based on the high threat level to amphibians in bordering nations and globally. While the ecology of species in the DPR Korea is still understudied, we argue that species relying on agricultural wetlands such as rice paddies are not under imminent threat due to the enduring presence of extensive agricultural landscapes with low rates of chemical use and mechanisation. The maintenance of such landscapes is a clear benefit to amphibian species, in contrast to more industrialised agricultural landscapes in neighbouring nations. In comparison, the status of species dependent on forested habitats is unclear and threat levels are likely to be higher because of deforestation, as in neighbouring nations.