Introduction

Mt. Munsusan (1,205 m) is surrounded by mountains over 1,200 m - Mt. Seondal, Mt. Okseok, Mt. Guryong, Mt. Gakhwa - to the north and east of its summit, and mostly relatively low mountains below 700 m to its west and south with villages at their foot. It is placed at the midpoint between Mt. Taebaek and Mt. Sobaek regions when Baekdudaegan of South Korea is broken down into five regions. This mountain is facing Mt. Okseok with Jusilryeong as its boundary on the section leading to Mt. Sobaek - Mt. Galgot - Mt. Seondal - Bakdalyeong- Mt. Okseok (Okdolbong) - Doraegijae - Mt. Guryong - Mt. Taebaek located between the sections 5 and 6 presented in the Baekdudaegan Ecology Map (https://www.forest.go.kr/).

Floristic-geographically speaking, it belongs to the Korean region of the Sino-Japanese region and warm-temperate forest zone, and it falls under the cool temperate forest central zone among the eight zones divided according to the flora zone of Korea (Lee and Yim, 1978). According to the new flora structure in the southern part of the Korean Peninsula suggested by the Korean Forest (VI) Flora Region and Vegetation Climate of Korea (Korea National Arboretum, 2020), it is a warm temperate flora zone (Zone III) and Korean forests classified according to the vegetation climate area is part of deciduous broad-leaved forests (WI 45-85) in temperate northern vegetation climate.

Its climate displays a continental climate with large annual temperature variances owing to its geographical location of being in the mountainous inland of Gangwon Province. Its average annual temperature for the last five years (2016 - 2020) is 10.6℃ (10.3 ~ 11℃), with the highest temperature of 37.8℃ in 2018 and the lowest one of -21.7℃ confirmed in 2018. Its mean maximum temperature is 18.1℃, coupled with the average minimum temperature of 3.9℃, and its precipitation is 1,086.78 ㎜ (795.3 ~ 1297.3 ㎜) (Korea Meteorological Administration, 2020).

The geological map of the Korean Peninsula indicates most of the geology in this area is composed of Gyeonggi metamorphic rock complex, Mt. Sobaek metamorphic complex, Mt. Jiri metamorphic rock complex, and foliated granite, which are the rocks formed in the Archaeon-Proterozoic eon and the Mesozoic era. From the angle of the tectonic zone of the Korean Peninsula, it spans over the Yeongnam Massif and Mt. Taebaek Basin, and the present geological features were witnessed in the Yeongnam Massif during the Paleoproterozoic time of the Precambrian Period and in Mt. Taebaek Basin during the Ordovician-Cambrian Period (Ministry of Land, Infrastructure and Transport, 2016). Its soil is brown forest one, and its types are lithosols and red-yellow soil. Brown forest soil represents the forest soil of Korea, and humus decomposed from the organic matter on its topmost layer accumulates nearby the topsoil layer, rendering it with dark black color. For subsoil layer, its soil color gets brighter with the increase in mineral content. Soil in this mountain is mainly made up of loam and the average soil depth is 50 - 660 ㎝ (Ministry of Land, Infrastructure and Transport, 2016).

Most of the flora studies in this region are relevant to the formation of the Baekdudaegan National Arboretum. Consequently, there have been many researches that reported the area where this arboretum was built - Mt. Munsusan, Mt. Okseok, and Mt. Guryong - in an integrated fashion, rather than an intensive survey on Mt. Munsusan (Byeon et al., 2016; Chung et al., 2015; Kim and Yun, 2009; You et al., 2009). Accordingly, reported theses and report results so far demonstrate that no intensive investigation has been carried out on Mt. Munsusan, leading us to reach a decision to conduct a survey according to various routes by citing previous research data as it is. So we tried to come up with a list based on evidence samples by making a sample collection centering on field investigations. Any absence of sample during the process was supplemented through image data. The intention of our endeavor is to report on the vascular plants distributed in Mt. Munsusan, identify taxa requiring conservation, and use it as the basis data for the efficient management of Baekdudaegan plants going forward.

Materials and Methods

This undertaking took place through fifteen field surveys of Mt. Munsusan ranging over two years (2019 and 2020). The said mountain is in the western part of Bonghwa County, North Gyeongsang Province at 36°48' ~ 37°03' in north latitude and 128°41' ~ 128°49' in east longitude, and it is part of Mullya-myeon, Chunyang-myeon, and Bongseong-myeon. Our survey was conducted in several routes to encompass various habitats such as slopes, ridges, valleys, and forest roads of Mt. Munsusan (Table 1, Fig. 1).

Fig. 1.

The location of investigated area and survey routes in Mt. Munsusan.

All species verified from our investigation of various routes were collated or photographed. Such collected plants were then dried and made into specimens of plant pressing and kept in the KBA (Herbarium of the Baekdudaegan National Arboretum). For exact identification, this job was performed using the illustrated books of Cho et al. (2016), Korea National Arboretum (2004, 2019), Lee (1996, 2003, 2006), Lee and Lee (2015), Park (2009), Yoo (2013) and so on. Their scientific and common names followed those in the National Standard Plant List (http://www.nature.go.kr/) published by the Korea National Arboretum. The vascular plants that have completed identification are based on Engler's vascular plant taxonomy (Melchior, 1964) for classification and placement. Especially, major plants of this mountain were prepared with reference to Korean endemic species (Chung et al., 2017), rare species (Korea National Arboretum, 2008), floristic specific species (Kim et al., 2018), and naturalized species (Lee et al., 2011) and so forth.

Results

According to our survey on the distribution of vascular plants in Mt. Munsusan, 94 families, 310 genera, 496 species, 4 subspecies, 63 varieties, and 8 formas were found, comprising a total of 571 taxa (Table 2). It was confirmed that this finding corresponds to 34% of 1,684 taxa of vascular plants in North Gyeongsang Province (Korea National Arboretum, 2017) and 11.7% of 4,881 taxa of vascular plants existing on the Korean Peninsula (Korea National Arboretum, 2017; http:// www.nature.go.kr/kpni/). Also, the recent results of the flora of Mt. Hwangaksan area in Baekdudaegan showed similar results as Mt. Munsusan results, and just over 30 taxa Angiospermae was investigated in Mt. Munsusan (Son et al., 2021).

Compared with recent research outcomes and the total number of taxa provided in the previous studies undertaken in the identical surveyed area, 184 more than the 388 taxa presented in the result of Chung et al. (2015) as well as 130 more than the 442 taxa of Byeon et al. (2016) were examined in our research. The results of these two preceding studies included Mt. Munsusan and its nearby mountain areas - Mt. Oksok, Mt. Guryong - and facilities & exhibition gardens of the Baekdudaegan National Arboretum. Through our exercise, we conducted a variety of routes and seasonal surveys, allowing us to believe it offers the result of an intensive investigation, and we could obtain more precise outcome for vascular plants that are native to Mt. Munsusan.

Endemic species of Mt. Munsusan

Seventeen taxa of 11 families and 16 genera, including Salix koriyanagi Kimura, Clematis trichotoma Nakai, Corydalis maculata B. U. Oh & Y. S. Kim, Vicia chosenensis Ohwi, Cirsium setidens Nakai, Heloniopsis koreana Fuse, N. S. Lee & M. N. Tamura, Hemorocallis hakuunensis Nakai, and Carex okamotoi Ohwi are identified, taking up about 4.7% of Korea’s endemic plants (Chung et al., 2017, Table 3).

Besides Clematis trichotoma Nakai, Vicia chosenensis Ohwi, and Weigela subsessilis (Nakai) L. H. Bailey seen throughout the inland area of ​​North Gyeongsang Province, Peucedanum insolens Kitag, which is the southern limit species of the inland area of ​​the province, is verified (Jeong, 2019). First discovered in Mt. Deokwoo, Gangneung City, it was confirmed that P. insolens Kitag is a northern plant mainly distributed in Gangwon Province and grows wild around the valley of Mt. Munsusan. Its flowering period is July and August, and its leaves are similar to those of Astilbe chinensis (Maxim.) Franch. & Sav.. According to the Comprehensive Report on the Distribution of Rare and Endemic Plants (Korea National Arboretum, 2010), Lilium distichum Nakai ex Kamib., Rhododendron micranthum Turcz., Streptopus ovalis (Ohwi) F. T. Wang & Y. C. Tang and Weigela subsessilis (Nakai) L. H. Bailey, amongst the endemic species spread across Baekdudaegan region, are distributed in Mt. Munsusan.

When compared with the survey finding of Chung et al. (2015), seven taxa; Lonicera subsessilis Rehder, Pseudostellaria coreana (Nakai) Ohwi, Saussurea macrolepis (Nakai) Kitam., Saussurea uchiyamana Nakai, Salvia chanroenica Nakai, Lysimachia coreana Nakai, and Thalictrum actaeifolium var. brevistylum Nakai, along with five taxa; Thalictrum actaeifolium var. brevistylum Nakai, Philadelphus schrenkii Rupr., Eleutherococcus divaricatus var. chiisanensis (Nakai) C. H. Kim & B. Y. Sun, Saussurea macrolepis (Nakai) Kitam, and Saussurea uchiyamana Nakai are not verified. Thalictrum actaefolium var. brevistylum Nakai found in the central southern area of the Peninsula, out of the above unidentified taxa, is thought to be the misidentification of Thalictrum filamentosum var. tenerum (Huth) Ohwi, and other remaining taxa are believed to require further confirmation through a supplementary investigation on the research path of the preceding study. Among our surveyed taxa, newly identified endemic plants compared with the previous survey result are eight taxa, including Populus tomentiglandulosa T. B. Lee, a planting tree, Aconitum pseudolaeve Nakai, Corydalis maculata B. U. Oh & Y. S. Kim, Ostericum praeteritum Kitag., Peucedanum insolens Kitag., Paulownia coreana Uyeki, Hemerocallis hakuunensis Nakai, and Carex erythrobasis H.Lév. & Vaniot.

Rare species of Mt. Munsusan

Rare plants designated by the Korea Forest Service are 12 taxa in 9 families and 12 genera, and critically endangered (CR), endangered species (EN), and data-deficient species (DD) were not investigated. Concerning vulnerable (VU) species, Cimicifuga heracleifolia var. bifida Nakai, Paeonia japonica (Makino) Miyabe & Takeda, and Rhododendron micranthum Turcz. are confirmed, while nine taxa of Eranthis stellata Maxim., Viola albida Palib., and Parasenecio firmus (Kom.) Y. L. Chen for least concerned (LC) species, are investigated during our exercise (Table 4).

If compared with the survey outcome of Chung et al. (2015), five taxa of Panax ginseng C. A. Mey., Salvia chanryoenica Nakai, Epilobium angustifolium L., Lysimachia coreana Nakai, and Bupleurum L. are not identified, while the survey outcome of Byeon et al. (2016), nine taxa of Taxus cuspidata Siebold & Zucc., Eleutherococcus senticosus (Rupr. & Maxim.) Maxim., Aristolochia contorta Bunge, Syringa wolfii C. K. Schneid., Trigonotis icumae (Maxim.) Makino, Salvia chanryoenica Nakai, Trillium camschatcense Ker Gawl., Eleutherococcus divaricatus var. chiisanensis (Nakai) C. H. Kim & B. Y. Sun, and Lloydia serotina (L.) Rchb. are unaccounted for, too. Among such unidentified taxa, Panax ginseng C.A. Mey. is thought to be investigated in the cultivation area in this previous research, and Lloydia serotina (L.) Rchb. is believed to be the misidentification of Lloydia triflora (Ledeb.) Baker due to its distribution(Table 4, △^w). Our judgment is that additional confirmation would be necessary for other remaining taxa through a supplementary investigation on the research path of the preceding study. Amongst the taxa that we examined, newly identified rare plants compared with the previous survey result are the one taxa of Arisaema heterophyllum Blume.

It was found in Mt. Munsusan’s neighborhood that the local national forest management office’s annual intensive management of the forest stand of Pinus densiflora f. erecta Uyeki is producing the fragmentation of the population of Rhododendron micranthum Turcz.. On the other hand, many plant colonies could be confirmed along the valley, such as Eranthis stellata Maxim., Parasenecio firmus (Kom.) Y. L. Chen, Paeonia japonica (Makino) Miyabe & Takeda, and Rodgersia podophylla A. Gray, which prefer wet conditions rather than the dry environment.

Floristic regional indicator plants of Mt. Munsusan

Floristic regional indicator plants verified in Mt. Munsusan are 49 families, 90 genera, and 114 taxa. Grade IV is 8 taxa, including Woodsia macrochlaena Mett. ex Kuhn, Anemone reflexa Steph. ex Willd., and Rodgersia podophylla A. Gray; Grade III is 27 taxa, like Betula costata Trautv., Eranthis stellata Maxim., Spiraea fritschiana C. K. Schneid., and Vicia chosenensis Ohwi. There are 46 taxa, such as Huperzia miyoshiana (Makino) Ching, Paeonia japonica (Makino) Miyabe & Takeda, and Ajuga spectabilis Nakai for Grade II; and 33 taxa for Grade I, such as Onoclea sensibilis var. interrupta Maxim., Clematis patens C. Morren & Decne. In total, 94 taxa were identified, accounting for 20.1% of the plants surveyed (Table 5, Appendix 1).

The floristic regional indicator plants designated by the Ministry of Environment (Ministry of Environment, 2018) are divided into five grades (I ~ V) according to the distribution range of the plants and 1,476 taxa are designated as such as a result. Thus, they are adopted to determine the characteristics and the priorities for preservation. Grade II, where 33 taxa were investigated, especially, is distributed in five South Korean floristic region but appears in mountainous areas over 1,000 m so it generally contains many plants that are seen around Baekdudaegan. A number of plants verified in high- altitude areas, like Huperzia miyoshiana (Makino) Ching, Prunus maximowiczii Rupr., Geranium koreanum Kom., Streptopus ovalis (Ohwi) F. T. Wang & Y. C. Tang, and Carex okamotoi Ohwi were observed and surveyed at the area we investigated.

Naturalized species of Mt. Munsusan

Naturalized species affirmed in Mt. Munsusan, it turned out, are 25 taxa in 9 families, 24 genera, such as Phytolacca americana L., Robinia pseudoacacia L., Ambrosia artemisiifolia L., Aster pilosus Willd., Carduus crispus L., and Erigeron annuus (L.) Pers. (Table 6). Consequently, the mountain’s naturalization rate is 4.8% [number of naturalized species investigated / total number of emerged species × 100], and its urbanization index is 7.7% [number of naturalized species investigated / total number of naturalized species in South Korea (321 taxa) × 100]. This figure is higher than the average urbanization index of 6.84% for forest-type and urban-type national parks in Korea (Jang et al., 2019). It was confirmed that a number of naturalized plants were discovered in the vicinity of Mt. Munsusan roads, where there is frequent vehicle traffic. Mt. Munsusan seems to be affected by the forestation for the continuous management of Pinus densiflora f. erecta Uyeki, forming a large-sized colony, and planted Larix kaempferi (Lamb.) Carrière, combined with artificial factors originating from mountaineering and trekking users of Oe-ssi-beo-sun Trail Course 9 placed adjacent to the Baekdudaegan National Arboretum.

In comparison with the survey result of Chung et al. (2015), ten taxa, such as Coreopsis lanceolata L. and Coreopsis tinctoria Nutt., which are planted extensively as horticultural plants, and Chenopodium album L., Dactylis glomerata L., and Capsella bursa-pastoris (L.) L. W. Medicus, alongside the three taxa of Rumex obtusifolius L., Dactylis glomerata L., and Festuca arundicanea Shreb. were unidentified relative to the result of Byeon et al. (2016). We learned that most of such unidentified taxa are planted as horticultural species, pioneer species that entered bare or grassland first, or plants used for cover to stabilize the ground and slope after forest roads were opened. Given that fourteen more taxa were surveyed compared to latest researches, in particular, the number of naturalized plants is expected to increase gradually going forth.

Out of the investigated naturalized species, it was discovered that ecologically-disturbing plants with a high degree of harm to the ecosystem (Notice of Ecosystem Disturbance Designation, Ministry of Environment, No. 2020-61) are two taxa - Ambrosia artemisiifolia L. and Aster pilosus Willd. They are the species that invade the forest, spread rapidly and propagate, taking away the home of native plants. As they can harm the native species of Mt. Munsusan as such, continuous monitoring and removal are desired. So attempts have been made to observe their spread in the forest through sustained monitoring in the areas where they are identified, in parallel with preparing a plan by drawing on a guidebook for eliminating the species disturbing the ecosystem to stem their proliferation. The Guidebook on How to Remove the Plants Disturbing Ecosystems (Ministry of Environment, Wonju Regional Environment Office, 2016) states that the best method is to remove the root of Aster pilosus Willd. before its flower blooms because it is a perennial plant growing year round. As for Ambrosia artemisiifolia L., the best way, likewise, is to eliminate this plant before its flower blossoms as it is an annual species growing all year round. Since a lot of seeds are formed and germinate while it is in the ground, this species needs to be continuously removed for 4-5 years. Because it moves along the wind or waterway, it needs to be displaced starting from the upstream.

Useful resource species of Mt. Munsusan

On the basis of the classification of resource species according to their uses grouped by the Korea Forest Service (Korea Forest Service, 2014), 554 taxa or 97%, excluding species with no use, were counted as useful plants. In addition, a single plant can be used for multiple purposes so the sum of the proportions may exceed 100%. In terms of purpose, 391 taxa (68.5%) were the plants that can be consumed as food, 359 taxa (62.8%) for medicinal use, and 301 taxa (52.6%) for ornamental use. In all, over 50% of the surveyed flora can be utilized for edible, medicinal and ornamental purposes. Not only that, 241 taxa for feed/composting (42%), 217 taxa for industrial use (37.9%), 203 taxa for ecological restoration (35.3%), and 17 taxa for fragrance (3.1%) were identified, in this sequence (Table 7).

In particular, many species with high potential for use in various fields were investigated, as can be seen in our survey finding that plants which can be used for all of the seven purposes include 6 taxa, such as Akebia quinata (Houtt.) Decne., Rosa multiflora Thunb., and Viola mandshurica W. Becker; 36 taxa for the six purposes; 82 taxa for the five purposes; 122 taxa for the four purposes; 141 taxa for the three purposes; 122 taxa for the two purposes; and 48 taxa for the one purpose (Appendix 1). Therefore, this outcome can be capitalized on as the basic data for establishing a continued research and usage system since this discovery may lead not only to seed collection for rare and endemic species but also to plant nursery and further to the field of industrialization of wild plants.

In the list put forward in the Plant List of Mt. Munsusan (Appendix 1), edible (E) and medicinal (M) species requiring caution when they are for food intake are illustrated by additionally indicating them with (P). Table 7 is the sum of E+E(P) and M+M(P).

Discussion

Mt. Munsusan, our survey area, is at the foot of Mt. Okseok (Okdolbong), the main ridge of Baekdudaegan, and situated at the Baekdudaegan National Arboretum established for the plant research of Chuk-seo-sa Temple, Du-nae Mineral Spring, and Baekdudaegan. Investigating the vascular plants growing in this mountain and identifying and reporting the distribution of its major plants is designed for the systematic conservation and protection of Baekdudaegan, and it is a step for understanding the Baekdudaegan Reserve and its surrounding region. Our judgment is that it can supplement the result of the flora survey centering on the core location of ​​Baekdudaegan, namely, Marugeum, and it is valuable as the data informing the plants distributed in Mt. Sobaek area.

Furthermore, Mt. Munsusan is located where there is a colony of Pinus densiflora f. erecta Uyeki, serving as an important geographical location for gaining the foundational data to study and comprehend the plant resources of Baekdudaegan. Based the result of our plant survey, the distribution of various rare and endemic species was confirmed, above all else, so we believe it is an area suitable for a research aimed at learning about the changes in plant distribution and draw up management plans for the species in urgent need of conservation, through making ongoing surveys and long-term monitoring etc. At the same time, the outcome of such undertaking can be leveraged as the evidence for claiming Korea's biological sovereignty after the adoption of the Nagoya Protocol on Access to Genetic Resources and the Fair and Equitable Sharing of Benefits Arising from their Utilization to the Convention on Biological Diversity (ABS).

Human activities and their by-products, including the increase in naturalized plants, is the largest cont3ributor to ecosystem disturbance. Should such activities go on, we gather it is necessary to carry out a monitoring on Betula ermanii Cham., the arboreal species observed at an altitude of 1,000 m or higher near the summit of Mt. Munsusan and emerging in individual unit, for there is concern about the reduction in its vertical distribution range from climate change. Continuous monitoring and attention are called for to sustain the value of forest resources and genetic resources, which should be protected and conserved for future generations, including here, Mt. Munsusan, where various vascular plants have been reported.

Appendix