The distribution and population status of Quercus myrsinifolia (Fagaceae) on the Korean peninsula

The distribution and population status of Quercus myrsinifolia (Fagaceae) on the Korean peninsula

Jung-Hyun Lee

, Dong-Hyuk Lee

, Hyeok-Jae Choi

, Yoshihisa Suyama

, Toshiaki Kondo

, Yuji Isagi

and Byoung-Hee Choi

*

1

Department of Biological Sciences, Inha University, Incheon 402-751, Republic of Korea

2

Department of Biology, Changwon National University, Changwon 641-773, Republic of Korea

3

Graduate School of Agricultural Science, Tohoku University, Naruko-onsen, Osaki, Miyagi 989-6711, Japan

4

Graduate School for International Development and Cooperation, Hiroshima University, Higashi-Hiroshima 739-8529, Japan

5

Division of Forest and Biomaterials Science, Graduate School of Agriculture, Kyoto University, Kyoto 606-8502, Japan (Received 17 July 2014; Accepted 12 August 2014)

한반도 가시나무(참나무과)의 분포 및 자생지 현황

이정현^1,5·이동혁¹·최혁재²·Yoshihisa Suyama³·Toshiaki Kondo⁴·Yuji Isagi⁵·최병희¹*

1

인하대학교 자연과학대학 생명과학과,

창원대학교 자연과학대학 생물학과,

3

Graduate School of Agricultural Science, Tohoku University,

4

Graduate School for International Development and Cooperation, Hiroshima University,

5

Division of Forest and Biomaterials Science, Kyoto University

ABSTRACT: Most evergreen Quercus species are typical, dominant members of Korean evergreen forests. How- ever, little is known about the distribution status of Q. myrsinifolia Blume there. To enhance our knowledge about their natural range in Korea, we conducted field surveys based on specimen records and an extensive lit- erature search. We also determined their exact number as a first step in planning their conservation. The results indicated that these trees are strictly limited to Jin Island, and 169 mature individuals were the maximum num- ber and occurred in only three subpopulations on that island. Previous misidentifications and perhaps misla- beled locations for plant specimens were the main reasons for earlier confusion about distribution. We believe that these results can provide guidance when making specific recommendations for management interventions.

These discoveries also demonstrate the value in having reliable information about plant specimens in general.

We also speculated about what makes this species particularly vulnerable to local extinction.

Keywords: Conservation, Jin Island, Korean Peninsula, mature individuals, Quercus myrsinifolia, restricted distribution

적 요: 상록성 참나무류는 한반도 상록활엽수림을 구성하는 주요 수종으로 알려져 있다. 그러나 가시나무

(Quercus myrsinifolia Blume) 의 한반도 분포지와 자생현황은 명확히 밝혀져 있지 않다. 본 연구에서는 문헌 조사와 표본에 근거한 현지조사를 토대로 가시나무의 자생지를 밝혀 한반도 내 분포를 명확히 하고자 하였 다. 또한 보존대책의 첫 단계로 자생 개체수 전수 조사를 실시 하였다. 조사결과, 한반도 내에서 가시나무는 전남 진도에 단 3개의 아집단으로 구성된 169개의 성체만이 제한적으로 자라는 것으로 확인되었다. 본 연구 를 통해 오동정과 식물표본의 채집지 오기재가 종의 분포에 대한 혼란을 야기하는 주된 원인임을 알 수 있

*Author for correspondence: [email protected] http://www.pltaxa.or.kr

Copyright © 2014 the Korean Society of Plant Taxonomists

또한 식물표본의 정확한 데이터 기재의 필요성을 확인할 수 있다. 한편 본 논문에서는 한반도에서 이 종의 분포가 진도에만 제한되게 된 원인에 대해 논의 하였다.

주요어: 가시나무, 보전, 성체, 제한적 분포, 진도, 한반도

Approximately 2,000 islands are found in a narrow zone along the southern and southwestern coastal areas of the Korean Peninsula (Yang, 2013). This region is covered by forests dominated by evergreen, broad-leaved trees (Lee and Choi, 2010). The evergreen Quercus species (subgenus, Cyclobalanopsis) are major components in those forest canopies. On the Korean Peninsula, Cyclobalanopsis comprises five species: Quercus acuta Thunb., Q. salicina Blume, Q.

glauca Thunb., Q. myrsinifolia Blume, and Q. gilva Blume (Chang, 2007). Most of them are key factors that distinguish the climatic boundaries of these mixed mountainous forests (Lee and Choi, 2010). They are also of high economic importance because of their wood, bark (cork), fruit, and benefits to local ecosystems (Petit et al., 2013).

Trees of Q. myrsinifolia have long been regarded as widely distributed, frequently overlapping areas populated with Q.

acuta and Q. salicina, which are typical members of evergreen forests on the Korean Peninsula (Lee, 1996; Lee, 2006; Lee et al., 2009). However, several reports have indicated that they are in fact rare (Lee, 1980; Kim and Kim, 2011) or do not exist in that region (Choi, 2001). Although their status remains uncertain in Korea, their distribution has been thoroughly examined elsewhere, such as in Japan and China, because of the economic and conservation value of the Quercus species (e.g., Ohashi et al., 2006; Ito et al., 2007). Furthermore, researchers have evaluated the impact of future climatic changes on land use patterns (e.g., Nakao et al., 2011).

The biodiversity of warm-temperate evergreen forests is threatened by anthropogenic pressures, primarily via disturbances that cause habitat destruction due to urbanization, firewood production, and over-collection of desirable plants (Choi, 2001;

Lee and Choi, 2006). These effects are even more severe within island ecosystems (Chung et al., 2014). Unfortunately, debate continues about attempts to preserve Korean populations, perhaps because these trees occur more frequently in other regions, such as China and Japan (Chang et al., 2005) and, also, because some believe that their local extinction has arisen from natural causes (Chang et al., 2001).

Nevertheless, regardless of their conservation value or the reason of their potential demise, the first, most fundamental step when initiating preservation efforts for any organism is to identify the species or populations that are either in decline or

facing the risk of extinction so that one can recognize their status. Although such information may provide clues for making specific recommendations for management interventions, conflicting data can present incorrect knowledge about plant distributions. Here, we report the current distribution and population status of Q. myrsinifolia on the Korean Peninsula, based on objective and quantifiable data that identify threats and assess the risks to various species.

Moreover, we distinguish between naturally sourced threats and human disturbances in order to explain what makes this species particularly vulnerable to local extinction on Korean Peninsula.

Materials and Methods

Study species

Quercus myrsinifolia Blume is distinguished from other species by having leaves with regularly serrate margins and abaxially whitish farinose green (Lee, 2012). Trees are wind- pollinated, with a seed-dispersal mechanism that is animal- cached (Choi, 2001), and can attain a height of 15 m and a diameter at breast height (DBH) of 0.6 m (Lee, 2012). These evergreen broad-leaved trees cover a large range across the warm-temperate regions of southern to eastern Asia (i.e., northern Thailand, Laos, Vietnam, Taiwan, China, Korea, and Japan; Chang, 2007). Especially in eastern China and southern Japan, these plants are an important component in the canopies of evergreen or mixed evergreen/deciduous broad-leaved forests, usually exhibiting widely variable ecological preferences (Wu, 1980; Liu et al., 2008).

Methods

The research data for this study were drawn from three main

sources: 1) specimen records, 2) literature searches, and 3) field

surveys. We first collected specimen information from the

following Herbaria: Inha University (IUI), Hannam University

(HNHM), Seoul National University (SNU and SNUA), Korea

National Arboretum (KH), Chonbuk National University (JNU),

and the Warm-temperate and Subtropical Forest Research Center

(WTFRC). This information was supplemented with image

data from the Korea Biodiversity Information System

(www.nature.go.kr). We then updated this information through

re-identifications performed by Jung-Hyun Lee, a taxonomist

specializing in evergreen Quercus who is the first author on this paper. Collection information was excluded if it had originally been obtained for trees that did not originate via natural regeneration (clearly stated on the specimen label), e.g., stock planted at botanical gardens and arboretums. Literature searches and field surveys were conducted based on evidence of individual specimens (Lee et al., 1973; Kim and Jang, 1989;

Cho and Gwak, 1996; Lee, 2012).

Finally, we identified a key region (Jin Island) and thoroughly canvassed the area to obtain individual numbers of Q. myrsinifolia at Mt. Cheomchal between 10 and 12 May 2013 (Fig. 1). We also surveyed other sites considered suitable around that mountain, but found no Q. myrsinifolia at those sites (i.e., Temp. Ssanggyesa → Neopjeokbawi; Dumokje

→ Observatory; Dumokje → Mt. Deoksin). To ensure accurate record-keeping, we marked each tree with a red, numbered label (ca. 2 cm × 4 cm), and mapped its location with GPSMAP 60CSx (Garmin) and GPS Pathfinder ProXT (Trimble Navigation Ltd.) (Fig. 2). If the trees could be distinguished from each other at ground level, even within closely spaced patches (for example, ca. 3 m × 3 m narrow plot), each stem was considered a separate trunk. Trees with DBH measurements of at least 10 cm were recorded as adults. This was because we have observed in the field that inflorescences

- aments or catkins - are commonly found on trees taller than 5 m. However, no relationship between DBH and age has yet been definitively established for Q. myrsinifolia.

Results and Discussion

The two main findings from our study were that: (i) on the Korean Peninsula, Quercus myrsinifolia grows naturally only on Jin Island, where 169 mature individuals occur in three subpopulations (Fig. 1); and (ii) this restricted appearance may not have declined through severe anthropogenic disturbances, because no evidence exists for these trees to be growing naturally elsewhere in Korea apart from Jin Island. It is difficult to explain why this species is distributed within only certain regions, but it is also possible that a few other populations may still inhabit smaller public and private sites unknown to us.

However, we believe our extensive investigation is adequate for clearly delineating the range of Q. myrsinifolia on the Korean Peninsula.

Misidentifications were the major cause for confusion about

distributions. For example, all the specimens recorded

previously on Jeju Island were re-identified in our study as

being Q. salicina and Q. glauca instead. Thus, it was essential

that we correctly identify trees of Q. myrsinifolia (Fig. 2) in

Fig. 1. Location of natural Quercus myrsinifolia habitats along Korean Peninsula: a, The location map on Jin Island. b, Details of locations for

individuals from 3 subpopulations.

the field and in herbaria. In total, we found eight sites - Mt.

Jiri, Mt. Bonghwa, Hyangiram, Mt. Baegun, Mt. Yudal, Isl.

Heuksan, Isl. Goha, and Jin Island - where Q. myrsiniolia, trees had been labeled as growing naturally. For specimens reportedly observed at Mt. Jiri, Mt. Bonghwa, and Hyangiram on Dolsan Island, we concluded that those records were from non-native sources (i.e., planting), because those three areas are not suitable environments for supporting the natural growth of Q. myrsinifolia due to inadequate climatic conditions (Mt.

Jiri), use as an urban park (Mt. Bonghwa), or re-forestation via artificial means (Hyangiram).

It is also possible that collected specimens have been wrongly processed in the past, leading to errors in validating sites having Q. myrsinifolia. For example, although Mt. Baegun is a natural forest, it is not an appropriate environment for this particular species. Because the survival of evergreen, broad- leaved trees is highly and positively correlated with the mean temperature during the coldest month (Koo et al., 2001), we suggest that specimens thought to have been collected from Mt. Baegun were instead mislabeled, based on climatic conditions there. In contrast, one might expect those trees to inhabit more suitable sites at Mt. Yudal or on Isl. Heuksan and Isl. Goha, but this was not supported by our literature search.

Although it is not always an easy task to resolve such conflicts, Isl. Goha is fortunately a very small area (ca. 1.78 km

), which enabled us to survey it thoroughly on 09 May 2013. In doing so, we confirmed that Q. myrsinifolia does not occur on Isl.

Goha. Because these evergreen oaks frequently dominate

landscapes elsewhere (Liu et al., 2008), it would be difficult to miss seeing them if they, indeed, were growing on sites that were being surveyed. Thus, we believe that incorrect information for specimens, especially from sampling dates that are close together, might have been confused when collectors were preparing materials for herbaria (see also Appendix).

We found only one site on the Korean Peninsula - Mt.

Cheomchal, Jin Island - where we had expected Q. myrsinifolia to occur naturally, and counted 169 mature individuals in only three subpopulations. This situation is considered to be relatively satisfactory overall because the area has been conserved for evergreen broad-leaved forests. However, although numerous seedlings and saplings were also observed, a portion of that habitat is now under cultivation.

We do not believe that populations of Q. myrsinifolia are declining, or that they are limited to Jin Island because of anthropogenic disturbances. Based on specimen evidence from the 1950s for Jin Island (KBNA200409081075), we assume that, historically, individuals of that species were introduced there either through an episode of exceptional long-distance dispersal, sometimes even from a non-native source (Kondo et al., 2012), or because of a major contraction of its geographic range that left remnants stranded in isolated patches within suitable habitats (Lee et al., 2013).

Specimen evidence typically forms the basis for threat

identifications and endangerment assessments, especially with

concern to plants. Therefore, we have delineated the current

distribution and population status for Q. myrsinifolia. Our

Fig. 2. Photographs of Quercus myrsinifolia on Jin Island: a, leaves with inflorescences - aments or catkins. b, The stems separated from a

trunk. c, habitat deforested for cultivation. d, The bottom part of a trunk.

findings may provide a better foundation for specific recommendations toward management interventions as well as demonstrating the value of having accurate, basic data.

Acknowledgement

This work was supported by a grant from the National Research Foundation of Korea (NRF), funded by the Korea government (MEST) (No. 2012R1A2A2A01011428).

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