Distribution of Carex nakasimae Ohwi, a Korean endemic sedge (Cyperaceae)
Article information
Abstract
Carex nakasimae Ohwi (Cyperaceae) is an endemic species on the Korean peninsula. This study reports a new locality of the species, updating the distribution map. A new population of the species was found during field surveys in 2014 in a small swamp in Haman-gun, Gyeongsangnam-do province, located in the southeastern part of the Korean peninsula. In the flowering and fruiting periods of the species, the population is associated with ca. 91 vascular plant taxa from 40 families. To conserve the endemic species, maintaining the habitat is critical. Furthermore, taxonomic and phylogenetic positions of the species should be clarified to establish biological conservation strategies for the rare, endemic C. nakasimae.
Carex L. (Cyperaceae) is the most species rich genus in the Korean peninsula although the number of species recognized differs (157–ca.180) depending on the literature cited (Oh, 2007; Park et al., 2016). The genus is the most diverse in the temperate zone with more than 2,000 species worldwide and is often a dominant or co-dominant in various habitats such as deciduous or mixed forests, grasslands and wetlands (Ball and Reznicek, 2002; Global Carex Group, 2015). Out of approximately 180 taxa in Korea, around 10 are endemic, including C. nakasimae Ohwi (Park et al., 2016; Chung et al., 2017).
Carex nakasimae (Hwa-san-sa-cho) is an endemic, rare species described in 1944 from Hwaseong-si city (Gyeonggi-do province), a small city in middle of the Korean peninsula (Figs. 1, 2A) (Ohwi, 1944; Son et al., 2017). Since its description, the species has been barely recognized, possibly due to its rarity and lack of available data. Lee (2003) included the species in the Korean floristic diversity and mentioned that the type specimens was last. Son et al. (2017) designated a lectotype, choosing an isotype in National Museum of Nature and Science herbarium (Fig. 1). Park et al. (2016) placed the species in section Physocarpae Drejer ex L. H. Bailey as did Ohwi (1944) with four other Korean native taxa and considers C. vesicaria L. as the most similar species morphologically.
Isotype of Carex nakasimae Ohwi designated by Son et al. (2017).
Distribution of Carex nakasimae. A. Distribution in the Korean peninsula. Black star (★) type locality, black circles (●) specimens examined. B. Distribution in Haman-gun, Gyeongsangnam-do. Black circle (●) specimens examined, black triangle (▲) new locality.
Carex nakasimae has long rhizomes, 2–3 terminal male spikes, and 2–3 lateral female spikes characterized by lanceolate perigynia with long, bifid, and curved beaks (1–2.5 mm) (Table 1, Figs. 1, 3D) (Lee, 2003; Park et al., 2016). Ohwi (1944) pointed out that the species was distinguished from C. vesiacria by narrow perigynia with bifid, curved beaks. Upo-neup wetland, a large wetland in Gyeongsangnam-do, is the only well-known habitat of the species (Park et al., 2016). This wetland is a nature conservation area composed of four swamps and is number 934 on the Ramsar List (Kim et al., 2011; https://rsis.ramsar.org/ris/934).
Diagnostic morphological characters of Carex nakasimae and C. vesicaria.
New population in Haman-gun, Gyeongsangnam-do. A. Habitat in April 2016. B. Habitat in June 2016. C. Population in May 2019, red arrows indicate C. nakasimae individuals. D. C. nakasimae inflorescences with mature perigynia in May 2019.
During field work in 2014, a new population of Carex nakasimae was found in a small swamp in Haman-gun, Gyeongsangnam-do province (Figs. 2B, 3). The swamp is about 2,328 m2 and branched from Haman-cheon creek, connected with Nakdong-gang river. Nakdon-gang river, the longest river in South Korea, runs 506 km from the Taebaek Mountains to the South Sea or Korean Strait and passes Uponeup wetland as well (Kim et al., 2011).
To understand the ecological features of the population’s habitat, associated species were surveyed from 2014 until 2019 during flowering and fruiting times of C. nakasimae. This study updates the distribution of C. nakasimae and reports a new population with the floristic composition of its habitat.
Materials and Methods
Habitat survey
In the new population of C. nakasimae, associated vascular plant taxa were surveyed and collected in 2015, 2016, and 2019 during flowering and fruiting periods of the species (Fig. 2B). The resulting list of vascular plants follows the nomenclature of The Genera of Vascular Plants of Korea (Park, 2007). Identifications of the taxa were made based on Lee (2003), Park et al. (2016), and Hoshino et al. (2011). Scientific and Korean names of taxa follow the biodiversity portal (https://species.nibr.go.kr/index.do) provided by Korea National Institute of Biological Resources. Biological resources subject to overseas export approval, endemic, introduced, climatesensitive biological indicator species, planted species, and floristic degrees of the species were also determined according to the portal. All voucher specimens and images are deposited at the Department of Division of Biological Science, Chonnam National University herbarium (CNU).
Specimen examination
To make a distribution map, C. nakasimae specimens at the Korean National Arboretum herbarium (KH) and National Institute of Biological Resources herbarium (KB) were examined. The KH houses Carex specimens collected through ‘Research on unidentified native plant name in Korea’ and ‘a taxonomic review of Cyperaceae in Korea’ projects. In addition, the KB stores voucher specimens for various biodiversity research projects such as ‘National Ecosystem Survey’ and ‘the survey of new and unrecorded taxa in vascular plants’. The identifications of all the specimens were evaluated, and 18 verified specimens were utilized for determining the distribution of the species.
Results and Discussion
In the new population of Carex nakasimae, about 91 taxa in 70 genera and 40 families grow during the flowering and fruiting periods of the species (Appendix 1). Cyperaceae is the most dominant with about eight taxa, and Fabaceae and Polygonaceae follow with seven taxa each. For such a small swamp, the site includes important vascular plants from floristic and environmental points of view; it is big enough to provide dynamic micro-habitats. There are nine biological resources subject to overseas export approval taxa and one climate-sensitive Biological Indicator Species designated by Korea Ministry of Environment. Furthermore, two Korean endemic species grow in the swamp: C. nakasimae and Hemerocallis hakuunensis Nakai. Both endemic species are not common and only occur in southern parts of the Korean Peninsula.
In the habitat, tall trees such as Salix chaenomeloides Kimura and S. koreensis Andersson shade on some areas in the swamp. However, some areas are more open and have shallow streams where C. nakasimae grows, as it prefers sunny, wet sites. The C. nakasimae population is in northwest side of swamp, which can only be accessed from the southeastern and northeastern sides, making hard to find it. Although many swamps in Haman-gun have been disturbed by wastewater from pig breeding and agricultural activities, this swamp might have avoided such disturbances.
Currently the distribution of C. nakasimae is restricted to a southeastern province, Gyeongsangnam-do, in Korea although the type locality of C. nakasimae is in a middle region of Korea (Gyeonggi-do province) (Fig. 2A). Park et al. (2016) notes a C. nakasimae collection made in Seoul (Mok-dong) with voucher specimen information (Park s.n., without date, KH). However, we failed to locate the voucher specimen at KH, and none of the specimens found are from Gyeonggi-do province. It is suspected that the type locality and other possible habitats in Gyeonggi-do and Seoul have been destroyed by urbanization (Park et al., 2016). All the habitats of C. nakasimae are wet such as swamps, wetlands, or lakesides. Nakdon-gang river seems to play a very important role for the plant distribution, assisting dispersal and establishment.
The phylogenetic position of C. nakasimae has not been studied although Ohwi (1944) and Park et al. (2016) place the species in Carex section Physocarpae Drejer ex L. H. Bailey. Among five Korean species in the section (C. rhynchophysa C. A. Mey, C. vesicaria L., C. nakasimae, C. rostrata var. borealis (Hartms.) Kük, and C. dickinsii Franch. & Sav.), C. vesicaria assembles with C. nakasimae (Park et al., 2016). C. vesicaria is broadly distributed in Asia, Europe, and North America in wet places (Ball and Reznicek. 2002; Dai et al., 2010). The treatment of the species in Carex section Vesicariae (Heuffel) J. Carey (Reznicek and Ford, 2002; Hoshino et al., 2011) suggests taxonomic research on the entirety of the two sections Physocarpae and Vesicariae is required. Phylogenetic work on Carex section Vesicariae proposes sub-sectional systems (Shekhovtsov et al., 2012), but the study does not include C. nakasimae. The taxonomic and phylogenetic positions of C. nakasimae need to be clarified.
Carex nakasimae is endemic to the Korea peninsula (Park et al., 2016), but it has been under-reported. The species is not included in recent Korea endemic vascular plant diversity studies such as Chung et al. (2017). To establish biological conservation strategies for the species, further research on ecological, taxonomic, and phylogenetic features of C. nakasimae should be conducted. In addition, the new habitat in Haman-gun, Gyeongsangnam-do should be well conserved and maintained for the conservation of the Korean rare, endemic taxa (C. nakasimae and Hemerocallis hakuunensis) in nature.
Specimens examined. KOREA. Gyeongsangnam-do: Changnyeong-gun, Ibang-myeon, Okcheon-ri, Uponeup (swamp), 6 Jun 2013, J.-H. Kim 13-38 (KB); 27 May 2012, J.-H. Kim Carex-Kim199 (KB); 1 Jun 2011, Y. Cho WR-20110601-002 (KH); 1 Jun 2013, Y. H. Cho 1207 (KH); 6 Jun 2013, Y. Cho et al. Uk_v2013038 (KH); Daehap-myeon, Jumae-ri, Uponeup (swamp), 17 May 2009, J.-H. Kim 139 (KB); Yueo-myeon, Sejin-ri, Uponeup (swamp), 28 Jun 2012, H. J. Choi Changnyeong-gun (Uponeup)-120628-001 (KH); Haman-gun, Daesan-myeon, Seochon-ri, 14 Jun 2014, J.-H. Kim 141057 (KB); Gaya-eup, Sanseo-ri, 31 May 2015, K.-S. Chung 1207 (CNU, KH); 22 May 2016, T. Hoshino et al. OKAY-24745 (OKAY); Miryang-si, Samnangjin-eup, Samnang-ri, Milyanggang (river), 11 May 2018, J.-S. Kim MR0082 (KB); Yangsan-si, Wondong-myeon, Yongdang-ri, Wondong (wetland), J-H. Kim 13-36 (KB).
Acknowledgements
The present research was partially supported by Korean Native Cyperaceae diversity project (Korea National Arboretum). Staff members at Korean National Arboretum herbarium (KH) and Korea National Institute of Biological Resources herbarium (KB) provided assistants for specimen examination; and Dr. Dong Chan Son at the Korean National Arboretum kindly provides the isotype image. We appreciate consistent effort of CEOs (dongdongnagu) to conserve the biodiverse swamp.
Notes
Conflict of Interest
The authors declare that there are no conflicts of interest.
