Floristic study of bryophytes in a subtropical forest of Nabeup-ri at Aewol Gotjawal, Jejudo Island
Article information
Abstract
This study presents a survey of bryophytes in a subtropical forest of Nabeup-ri, known as Geumsan Park, located at Aewol Gotjawal in the northwestern part of Jejudo Island, Korea. A total of 63 taxa belonging to Bryophyta (22 families 37 genera 44 species), Marchantiophyta (7 families 11 genera 18 species), and Anthocerotophyta (1 family 1 genus 1 species) were determined, and the liverwort index was 30.2%. The predominant life form was the mat form. The rates of bryophytes dominating in mesic to hygric sites were higher than the bryophytes mainly observed in xeric habitats. These values indicate that such forests are widespread in this study area. Moreover, the rock was the substrate type, which plays a major role in providing micro-habitats for bryophytes. We suggest that more detailed studies of the bryophyte flora should be conducted on a regional scale to provide basic data for selecting indicator species of Gotjawal and evergreen broad-leaved forests on Jejudo Island.
Jejudo Island was formed by volcanic activities and has unique topological and geological features. In this unique volcanic terrain, forests established on lava flows are scattered around the island, known as “Gotjawal,” which is a newly coined compound word that comes from dialects spoken on Jejudo Island (Jeju Special Self-Governing Province, 2009; Yoon, 2014). It is difficult to access Gotjawal and use it for agricultural purposes, as the trees and vines are dense, rocks of various sizes are scattered randomly, and the depth of the soil is shallow in Gotjawal. Therefore, thus far it has only been used for grazing cattle, making charcoal or as a firewood source and is commonly recognized as useless land (Jeon et al., 2012; Jeong, 2012, 2015; Yoon, 2014). Recently, however, it has become known that Gotjawal is an area inhabited by various plants and animals where unique and various ecosystems are also sustained; the area serves as a natural waterway of the type necessary to create underground water, and it has high preservation value (Jeon et al., 2012; Kang et al., 2013; Yoon, 2014; Jeong, 2015). In addition, its cultural importance has also emerged. Therefore, scientific studies of Gotjawal have been conducted to examine geological, ecological, and cultural aspects (Jeong et al., 2013; Jeon et al., 2015). However, a floristic study of bryophytes has not been conducted, except for that at Dongbaek-dongsan of Seonheul Gotjawal by Yim et al. (2013).
The areal ranges and Gotjawal terrains have not yet been established (Jeon et al., 2015). According to Song (2000), Gotjawal can be divided into four major terrains, i.e., Gujwa- Seongsan, Jocheon-Hamdeok, Hangyeong-Andeok, and Aewol. Among them, the Aewol Gotjawal terrain ranges from the Nokome Oreum (833.8 m above sea level) to Nabeup-ri and the far eastern area (90 m above sea level) with a distance of 9.0 km (Song, 2003). This region, which is the highest place within Gotjawal, is the only place where the vertical vegetation ranges from the temperate forest to the subtropical forest, and it is an area of high biodiversity (Kim et al., 2009).
The subtropical forest of Nabeup-ri, which is located at the bottom of Aewol Gotjawal, is also known as Geumsan Park. The forest is the only remaining evergreen forest in Aewol Gotjawal and in the flatlands of the northwestern area of Jejudo Island. In addition, the original vegetation is highly conserved. For these reasons, this area is considered to be a very important region from an academic point of view. Moreover, it is designated and protected as Natural Monument No. 375 by the Cultural Heritage Administration of Korea (The Cultural Property Preservation Bureau, Korea, 1993; Song et al., 2009). The flora and vegetation of vascular plants in this area have been well studied. It has been reported that a total of 123 taxa inhabit in this area, and the plant communities are divided into five groups: the Quercus glauca community, Machilus thunbergii community, Celtis sinensis community, Pinus thunbergii community and agricultural land (Boo et al., 2006; Song et al., 2009). However, as stated above, bryophytes have not been studied to date. Therefore, it is necessary to establish a comprehensive flora including bryophytes to provide basic data for the selection of indicator species.
The purpose of this study was to establish a comprehensive flora of the subtropical forest of Nabeup-ri. Furthermore, this study aims to contribute to studies of the bryophyte flora of Gotjawal and the evergreen broad-leaved forests on Jejudo Island on a regional scale and to provide basic data for selecting relevant indicator species.
Materials and Methods
Study area
Field surveys were carried out in Subtropical Forest of Nabeup-ri where the dense evergreen broad-leaved forest is distributed with an area of approximately 0.034 km2 (Fig. 1).
The locations of the Aewol Gotjawal terrain and a subtropical forest of Nabeup-ri, Jejudo Island, Korea.
Identification, nomenclature and arrangement of taxa
The samples collected in the investigated area from July of 2011 to March of 2017 were identified at the species level by macroscopic morphology and microscopic features using relevant studies (Institute of Botany Chinese Academy of Sciences, 1972; Iwatsuki and Mizutani, 1972; Inoue, 1974, 1976, 1986; Choe, 1980; Noguchi, 1987, 1988, 1989, 1991, 1994; Hwang, 1991; Kim and Hwang, 1991; Gao et al., 1999; Makino, 2000; Iwatsuki, 2001; Li et al., 2001; Wu et al., 2002; Cao et al., 2003; Smith, 2004). The voucher specimens were deposited at the Warm-Temperate and Subtropical Forest Research Center in Korea (WTSFRC). Only one collection number for each taxon was cited to avoid repetition in the floristic list. The nomenclature and arrangement of the taxa follow the system proposed by Goffinet et al. (2009), Crandall-Stotler et al. (2009) and Renzaglia et al. (2008) for mosses, liverworts and hornworts, respectively.
Life forms and substrates
The life forms of bryophytes in the study area were estimated using work by Mägdefrau (1982), and they are also given in the floristic list for each taxon. The records of substrates for each taxon are included in this list.
Number of bryophyte taxa and liverwort index
We compared the number of taxa and the liverwort index of the subtropical forest of Nabeup-ri with those of other localities based on related studies [i.e., Deogyusan Mt. (Choi et al., 2010; Yoon et al., 2011), Taebaeksan Mt. (Papp, 2008), Gwanaksan Mt. (Hong, 1960a), Soyosan Mt. (Hong, 1960b), and Dongbaek-dongsan (Yim et al., 2013)]. The liverwort index, based on the finding that liverworts and hornworts tend to prefer more humid conditions than mosses, was calculated as follows (Nakanishi, 2001):
Results and Discussion
Number of bryophyte taxa and liverwort index
In this study, a total of 63 species belonging to Bryophyta (22 families 36 genera 44 species), Marchantiophyta (7 families 11 genera 18 species), and Anthocerotophyta (1 family 1 genus 1 species) were determined (Appendix 1). We expect that this study will provide the basic data for selecting indicator species of Gotjawal and the evergreen broad-leaved forests on Jejudo Island.
The results of a comparison of the number of taxa indicated that the subtropical forest of Nabeup-ri contained a rich diversity of bryophytes considering the area size (Table 1). Song et al. (2009) considered that the vascular flora of this area does not show high species richness. Nevertheless, this forest was evaluated as a well-conserved area based on a multi-criteria evaluation Matrix (Song et al., 2009), as the area has been well managed by local residents due to cultural influences and has been designated and protected as the natural monument. We agree with the evaluation Song et al. (2009) and consider that the result for the number of taxa is related to the well-conserved forest.
Comparison of the bryophyte species richness levels and liverwort indexes of the subtropical forest of Nabeup-ri and other localities.
The liverwort index is based on the finding that liverworts and hornworts tend to prefer more humid conditions than mosses. Therefore, it can be used to compare air humidity levels among different sites (Nakanishi, 2001). The liverwort index of the subtropical forest of Nabeup-ri was 30.2%, a value that indicates that the air humidity of the investigated area was relatively low compared to that of Deogyusan Mt. but was higher than that of Taebaeksan Mt., Dongbaek-dongsan, Gwanaksan Mt., and Soyosan Mt. (Table 1). We also suggest that more detailed studies of the bryophyte flora of Korea should be conducted on the regional scale.
Remarkable species
The distributions of Philonotis turneriana (Schwägr.) Mitt. (큰물가이끼) and Homomallium connexum (Cardot) Broth. (쌍끝양털이끼) were newly recorded from Jejudo Island through this study. Species for which the distributions in Korea are not known (except for Jeju-do) thus far, Eurhynchium savatieri Schimp. ex Besch. (가는부리이끼), Taxiphyllum cuspidifolium (Cardot) Z. Iwats. (뾰족캬라잎이끼), and Plagiochila furcifolia Mitt. (비자날개이끼), were also found in this study area. However, it is difficult to recognize these bryophytes as endemic species on Jejudo Island and assess the rarity or conservation status of bryophytes in this study area because, in the case of Korea, bryophyte flora are unexplored and have been studied by few researchers, aiming mainly at Jejudo Island. Therefore, we suggest that comprehensive research on the bryophyte flora of Korea should be conducted continuously.
Life forms
We estimated the life form of each taxon in the study area, as presented in Fig. 2. The predominant life form was the mat form (25 species, 39.7%) followed by the weft (17 species, 27%), tall turf (9 species, 14.3%), fan and cushion (4 species, 6.3% each), and short turf and tail (2 species, 3.2% each) forms. We analyzed the results based on the relationship between the adaptive strategy and life form of bryophytes according to Kürschner (2004), Uyar et al. (2007), and Glime (2017). As a result, the rate of pleurocarpous bryophytes (the mat, weft, fan, and tail life forms) dominating in mesic to hygric sites amounted to 76.2%, whereas acrocarpous bryophytes (the tall turf, short turf, and cushion life forms), mainly observed in xeric habitats, amounted to 23.8% (Appendix 1, Fig. 2). These values indicate that such forests are widespread in the study area.
Life form spectrum of the bryophytes in the study area.
It is meaningful that the rates of pleurocarpous bryophytes are higher in this area than in Dongbaek-dongsan (70.6%), identical to the liverwort index (Yim et al., 2013). These values indicate that the subtropical forest of Nabeup-ri at Aewol Gotjawal is relatively more humid than Dongbaek-dongsan at Seonheul Gotjawal.
Distribution pattern
We estimated the substrates for each taxon to investigate the distribution pattern. The numbers of taxa according to the substrate are presented in Table 2. Upon an investigation of the substrates, the bryophytes on rocks were most diverse, at 40 taxa, followed by those on bark (33 taxa), decayed trees (10 taxa), and soil (4 taxa). The results appear to stem from the fact that volcanic rock masses of various sizes lay scattered over the study area, offering numerous micro-habitats for bryophytes due to one of the characteristics of Gotjawal: it is a place where rocks of various sizes are scattered randomly.
The numbers of taxa according to the substrate in the study area.
Acknowledgements
This study was supported by Research Fellowship Program of the National Institute of Forest Science in 2017. We wish to express our sincere thanks to two anonymous referees and the editorial boards of Korean Journal of Plant Taxonomy for their invaluable comments to improve the manuscript.
Notes
Conflict of Interest
Authors declare that there is no conflict of interest.
