67Traditional vs ISOPAM vegetation classification

■ INTRODUCTIONCountries around the world have constructed large-scale

vegetation databases for use in environmental conservation (Dengler et al. 2012). The Japanese government also col-lects vegetation data, accompanied by nationwide vegeta-tion mapping, and publishes it in a database (Japanese Min-istry of the Environment 2018). Plot data are collected as reference standards for vegetation map legends, but they can also be used for vegetation research. For example, Abe (2018) studied the habitats of near-threatened plants by analyzing data from this database at the order and alli-ance levels for environmental impact assessments. How-ever, the database is better to be classified into vegetation units at the community level to clarify the habitats of more conservation target species and for ecosystem protection.

Vegetation scientists traditionally analyze plant commu-nities using phytosociological tabular comparison (Braun-

Blanquet 1964; Müller-Dombois & Ellenberg 1974). This method compares data obtained from the field or a da-

Original article

Vegetation Science 38 : 67-80, 2021

Comparison of traditional and automated approaches in classifica-tion of Japanese coastal beach and dune vegetationSeiya ABE* Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry

Large-scale phytosociological survey data are gathered globally and used for environmental conservation. The Japanese government collects vegetation data accompanied by national vegetation mapping and publishes it in a database. However, classifying large-scale databases using traditional phytosociological table manipulation is time- and labor-intensive. Although the automated approach is expected to classify large-scale vegetation data rapidly, it is necessary to verify its consistency with the established classification system for practical use. Thus, I compared traditional classification and ISOPAM, a recently developed automated approach, for classifying Japanese coastal beach and dune vegetation for which community classification has already been es-tablished. The traditional table manipulation classified 42 herbaceous and 11 shrub communities, most of which corresponded to previously reported phytosociological vegetation units. ISOPAM automatically classi-fied the same dataset into 16 vegetation units using the default settings. These vegetation units corresponded well to major communities with many data obtained through traditional tabular comparison. Plant communi-ties with few data did not correspond to the ISOPAM classification, as they were integrated into major vegeta-tion units. ISOPAM was therefore considered a suitable method for automatically extracting large-scale vege-tation patterns using a large dataset. However, rare communities and outliers with few data might be difficult to detect with an unsupervised classification such as ISOPAM. Therefore, a high-quality labeled database needs to be developed as training data based on past phytosociological findings to classify large-scale data effi-ciently.

Key words: coastal beach and dune plant communities, community classification, ISOPAM, national vegeta-tion database, phytosociology

tabase to previously described vegetation units, such as as-sociations. However, it requires considerable time and ex-pert knowledge, especially for large datasets. In contrast, automatic classification methods require minimum labor and time without the need for specialist judgment. Schmidtlein et al. (2010) recently introduced a novel brute-force approach to vegetation classification named ISOPAM by combining Isomap dimensional reduction (Tenenbaum et al. 2000) and partitioning around medoids (PAM) cluster partitioning (Kaufman & Rousseeuw 1990). The ISO-PAM algorithm automatically extracts indicator species from fidelity to groups of sites and obtains a hierarchical classification result by repeating nonhierarchical partition-ing. Černý et al. (2015) classified an extensive vegetation database of Korean forests and successfully identified the primary environmental gradient in the Korean peninsu-la. Peterka et al. (2017) classified large datasets of Euro-pean fen vegetation and identified alliance-level vegetation units. These studies suggest that ISOPAM automatically produces classification results from large datasets similar to

*Central Research Institute of Electric Power Industry, Abiko 1646, Abiko-shi, Chiba 270-1194, JapanE-mail: abe@criepi.denken.or.jpThe Society of Vegetation Science ♦ Received September 18, 2020╱ Accepted March 1, 2021

Vegetation Science Vol. 38, No. 1, 202168

the communities obtained from traditional tabular compari-son. However, it has not been investigated whether com-munity units such as associations defined by the traditional phytosociology approach correspond to those obtained by the automatic classification approach. It is necessary to verify the consistency with the conventional established community system for practical application.

Many researchers have proposed phytosociological asso-ciations and their upper units for coastal beach and dune plant communities and revealed the character and differen-tial species of the vegetation units (Ohba et al. 1973; Mi­yawaki & Suzuki 1976; Itow & Kawasato 1980). These vegetation units can be easily identified by traditional phy-tosociological tabular comparison referring to previous re-ports. Thus, they are suitable to confirm whether the auto-mated approach can extract community units similar to the traditional approach. Besides, the automatic classification approach requires considering weight between the upper and lower layers in multi-layered communities such as for-ests, while there is no need for single-layered plant com-munities such as beach and dune vegetation. Natural dune areas are rapidly decreasing because of tsunami disasters and embankment construction and urgently need conserva-tion. The recent distribution of coastal beach and dune communities needs to be classified on a national scale to set conservation targets. I therefore tested automatic classifi-cation to identify coastal beach and dune plant communities and evaluated its applicability to constructing vegetation systems by comparing it to traditional phytosociological tabular comparisons.

■ METHODSData collection

I collected phytosociological relevés from Japanese na-tional vegetation survey data (http://gis.biodic.go.jp/webgis/sc-016.html, accessed March 2019), which could provide information on predefined categories corresponding to the legends of actual vegetation maps. I selected 695 records defined as dune vegetation in the broad category, including not only dune scrub and grassland but also vegetation on cobbles, pebbles, and shingle beaches. All these relevés were collected from September 2000 to October 2017 in the field on almost all coasts of Japan in the range of latitude 45°31′3.6″ in the north and latitude 24°2′58″ in the south, and geographical coordinates were included in the Japanese Geodetic Datum 2000. However, these records contain incorrect and outdated local species names because of in-sufficient plant name confirmation. Thus, I revised all species names to standard names by referring to the Japa-nese scientific botanical name index, Y-list (http://ylist.

info/, accessed May 2019).

Data analysis I divided the collected records into the following three

datasets based on physiognomy, species characteristics, and habitat: (1) herbaceous beach and dune communities, (2) other herbaceous coastal communities, and (3) beach and dune scrub communities. I applied traditional phytosocio-logical tabular comparison (Braun-Blanquet 1964; Müller-Dombois & Ellenberg 1974) to these datasets and referred to published phytosociological reports and classification systems to define basic classification units, such as associa-tions. Classified plant communities were organized into three separate constancy tables. To compare traditional and automatic classification methods, I applied the ISO-PAM algorithm to the same datasets without prior physiog-nomical division. The ISOPAM algorithm first calculated dissimilarities between input objects (e.g., relevés) for Iso-map nonlinear dimension reduction. I therefore selected the default Bray-Curtis distance measures. Braun-blan-quet’s dominant value was used as an ordinal scale to cal-culate the distance between survey points, but the non-nu-merical + value was converted to the median percentage coverage of 0.1. Hierarchical partitioning levels were set automatically and not limited to a specific value. I ar-ranged the ISOPAM calculations into a constancy table similar to the table from the traditional tabular compari-son. Differential species groups were rearranged by ap-plying the phytosociological abundance criteria based on the species groups extracted by fidelity during the ISOPAM calculation. Subsequently, I compared vegetation types obtained with ISOPAM and manual phytosociological tabu-lar methods. I used Fisher’s exact to test statistically sig-nificant associations between vegetation units classified by ISOPAM and traditional tabular comparison. It is a statis-tical test for analyzing categorized data when the sample size is small, and the chi-square test is inappropriate. All statistical analyzes were performed using R 3.6.0 and pack-age isopam 0.9-13.

■ RESULTSTraditional phytosociological classification

Table 1 shows the synoptic table of beach and dune her-baceous plant communities classified using phytosociologi-cal tabular comparison. Twenty-three communities were extracted by referring to previously published phytosocio-logical classification systems (Miyawaki et al. 1994) and some other reports (Ohba et al. 1973; Miyawaki & Suzuki 1976; Itow & Kawasato 1980). The Spinifex littoreus community (Ba) was characterized by Spinifex littoreus,

69Traditional vs ISOPAM vegetation classification

Table 1. Synoptic table of beach and dune herbaceous communities in Japanese coastal regions. Roman numerals indicate constancy classes (I: 0-20%, II: 20-40%, III: 40-60%, IV: 60-80%, V: 80-100%) and superscript numerals show ranges of dominance classes. Species with less than 34 spots (less than 5% of all stands) are omitted.

Community type Ba Bb Bc Bd Be Bf Bg Bh Bi Bj Bk Bl Bm Bn Bo Bp Bq Br Bs Bt Bu Bv BwNumber of releve 11 31 1 5 4 10 10 74 22 11 1 17 43 56 19 4 3 3 3 28 46 14 8

Differential species of Ixerido-Thuareion involutaeThuarea involuta Kuroiwazasa II +-1 II +-3 ･ I 4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Bidens pilosa var. radiata Obananosendangusa II +-3 I + ･ I + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Scaevola taccada Kusatobera + 1 + +-1 1 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Spinifex littoreus communitySpinifex littoreus Tsukiige V 2-5 r + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Pandanus odoratissimus Adan III + + + ･ I + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Volkameria inermis Ibotakusagi I 2-3 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Lepturus repens Haishiba I + r + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Vigna marina-Ipomoea pes-caprae communityIpomoea pes-caprae Gumbaihirugao II +-2 V +-5 ･ III +-1 1 + ･ ･ ･ ･ ･ ･ ･ ･ r +-1 + 1 ･ ･ ･ ･ ･ ･ ･ ･Vigna marina Hamaazuki II +-2 II 1-5 ･ I 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Melanthera robusta communityMelanthera robusta Ohamaguruma ･ r + 1 4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Cassytha filiformis communityCassytha filiformis Sunazuru II +-1 r 2 ･ V 3-5 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Chamaesyce atoto Sunajitaigeki + + + + ･ IV +-2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Panicum repens communityPanicum repens Haikibi + + + +-2 ･ ･ 4 1-5 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Canavalia lineata-Crinum asiaticum var. japonicum communityCrinum asiaticum var. japonicum Hamaomoto I +-1 + + 1 1 ･ ･ IV +-4 ･ r +-1 ･ + 1 ･ ･ r + + +-1 + + ･ ･ ･ ･ ･ ･ ･ ･Canavalia lineata Hamanatamame ･ + +-3 ･ ･ ･ III 2-5 ･ ･ ･ + 2 ･ I +-1 ･ r + ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Imperata cylindrica var. koenigii communityImperata cylindrica var. koenigii Chigaya + + + +-2 ･ ･ 2 1 I 1-4 V 3-5 r 1-2 I + + 3 ･ + 5 r 2 + +-2 I +-1 ･ ･ ･ ･ r 1 r 2-5 ･ ･

Differential species of Caricion kobomugiCarex kobomugi Kobomugi ･ + +-1 ･ ･ 1 + ･ ･ IV +-5 IV +-5 IV +-3 1 1 III +-3 II +-5 V +-5 ･ 3 + ･ 1 1 ･ V +-4 ･ II +-3 ･

Differential species of Ischaemum anthephoroides communityIschaemum anthephoroides Kekamonohashi ･ I +-2 ･ ･ 1 1 ･ + + V +-5 III +-2 II 1-2 ･ I +-1 I +-2 r + ･ 2 +-2 ･ ･ ･ I +-1 + +-3 ･ ･

Differential species of Zoysia macrostachya communityZoysia macrostachya Onishiba ･ ･ ･ ･ ･ ･ ･ II +-1 V +-5 + 1 ･ ･ + +-1 + +-1 + + ･ ･ ･ ･ I +-1 + +-4 ･ ･

Differential species of Melanthera prostrata communityMelanthera prostrata Nekonoshita + 1 r + ･ I + ･ + 2 ･ + +-1 I +-2 V 1-5 ･ ･ + +-3 + + ･ ･ ･ ･ ･ ･ r +-1 ･ ･

Differential species of Fimbristylis sericea communityFimbristylis sericea Birodotentsuki ･ ･ ･ ･ ･ ･ + 1 ･ ･ ･ 1 1 ･ ･ r + ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Lathyrus japonicus communityLathyrus japonicus Hamaendo ･ ･ ･ ･ 1 1 II 1-2 I +-2 I +-1 II +-2 I +-1 ･ V +-5 + +-2 + +-1 ･ 2 + 3 2-3 2 +-1 1 3 II +-2 III +-3 III +-3 V +-3

Differential species of Carex pumila communityCarex pumila Koboshiba + + + +-1 ･ ･ 1 + ･ II + I +-2 + + + 1 ･ I +-1 V +-5 ･ ･ ･ ･ ･ ･ I +-3 II +-2 II +-1 I +

Differential species of Calystegia soldanella communityCyperus rotundus Hamasuge ･ ･ ･ ･ ･ ･ ･ r 4 r 2 ･ ･ ･ ･ ･ II +-4 ･ ･ ･ ･ ･ ･ ･ ･Bidens pilosa var. pilosa Kosendangusa ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + + ･ ･ II + ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Ammophila breviligulata communityAmmophila breviligulata Ohamagaya ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 4 3-5 ･ ･ ･ r 2 ･ ･ ･

Differential species of Senecio pseudoarnica communitySenecio pseudoarnica Ezooguruma ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 3 1-4 ･ ･ ･ r +-2 ･ ･

Differential species of Heliotropium japonicum communityHeliotropium japonicum Sunabikiso ･ ･ ･ ･ ･ ･ ･ + +-2 r + ･ ･ ･ ･ r + ･ ･ ･ 3 2-4 ･ I + r + ･ ･

Differential species of Mertensia maritima subsp. asiatica communityMertensia maritima subsp. asiatica Hamabenkeiso ･ ･ ･ ･ ･ ･ ･ ･ r + ･ ･ ･ r + ･ ･ ･ ･ 1 + 3 3 ･ ･ ･ ･Honckenya peploides var. major Hamahakobe ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 1 ･ r 1-3 ･ ･

Differential species of Honkenyo majoris-Elymetalia mollisLeymus mollis Tenkigusa ･ ･ ･ ･ ･ ･ ･ + +-1 II +-3 + + ･ I +-1 + + + +-1 ･ ･ ･ ･ ･ V 1-5 V +-5 V 1-5 V 1-3

Artemisia stelleriana Shiroyomogi ･ ･ ･ ･ ･ ･ ･ ･ r + ･ ･ + + ･ + +-1 ･ ･ ･ ･ ･ I +-1 I +-3 II +-2 I +

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Pandanus odoratissimus, Volkameria inermis, and Lepturus repens and corresponded to the Glehnio-Spinificetum lit-torei Ohba, Miyawaki et Tx. 1973 association (Ohba et al. 1973). The Vigna marina-Ipomoea pes-caprae communi-ty (Bb) was characterized by Ipomoea pes-caprae and Vig-na marina, and corresponds to the Vigno-Ipomoeetum pe-dis-caprae Miyawaki et K. Suzuki 1976 association (Miyawaki & Suzuki 1976). The Melanthera robusta community (Bc) was characterized by Melanthera robusta and has been reported in Hinomisaki, Wakayama prefecture (Suzuki 1984a). The Cassytha filiformis community (Bd) was characterized by Cassytha filiformis and Chamaesyce atoto. These four communities were grouped into the Ix-erido-Thuareion involutae Ohba 1973 alliance, which is characterized by Thuarea involuta, Bidens pilosa var. radi-ata, and Scaevola taccada. The Panicum repens commu-nity (Be) was characterized by Panicum repens. The Can-aval ia l ineata-Crinum asiat icum var. japonicum community (Bf) was characterized by Crinum asiaticum var. japonicum and Canavalia lineata and corresponded to the Vitici-Crinetum japonici Nakanishi 1980 association (Nakanishi 1980). The Imperata cylindrica var. koenigii community (Bg) was characterized by the dominance of Imperata cylindrica var. koenigii.

The Ischaemum anthephoroides community (Bh) was characterized by Ischaemum anthephoroides and corre-sponded to the Ischaemetum anthephoroidis association group (Ohba et al. 1973). The Zoysia macrostachya com-munity (Bi) was characterized by Zoysia macrostachya and corresponded to the Zoysietum macrostachyae association

Table 1. Continued.Community type Ba Bb Bc Bd Be Bf Bg Bh Bi Bj Bk Bl Bm Bn Bo Bp Bq Br Bs Bt Bu Bv BwNumber of releve 11 31 1 5 4 10 10 74 22 11 1 17 43 56 19 4 3 3 3 28 46 14 8

Differential species of Sonchus brachyotus-Leymus mollis communitySonchus brachyotus Hachijona ･ ･ ･ ･ ･ ･ ･ r + ･ ･ ･ ･ ･ r + ･ ･ ･ ･ ･ ･ r 1 V +-2 I +

Differential species of Carex macrocephala-Leymus mollis communityCarex macrocephala Ezonokobomugi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + + V +-3

Species of Glehnietea littoralisCalystegia soldanella Hamahirugao I + + +-2 ･ I 1 3 + III +-2 II +-1 IV +-3 V +-3 IV + ･ IV +-5 IV +-4 IV +-5 V 2-5 1 + ･ 3 +-1 2 1-2 IV +-3 III +-4 II +-3 I 1

Ixeris repens Hamanigana ･ + +-2 ･ ･ ･ ･ + + III +-2 III +-2 II + ･ II +-2 II +-3 III +-2 I 1-3 1 + ･ 1 + ･ IV +-3 II +-3 II +-2 IV +-3

Glehnia littoralis Hamabofu + + ･ ･ I + 1 + + + + + II +-2 I +-3 III +-1 ･ I +-2 II +-2 II +-3 I + ･ ･ 1 + ･ II +-2 I +-1 I + IV +-1

Linaria japonica Unran ･ ･ ･ ･ ･ ･ ･ I +-3 I +-1 II +-1 ･ + 1 r +-2 I +-2 ･ ･ ･ 2 + ･ I +-1 I +-2 II + II +-1

Species of Viticetea rotundifoliaeVitex rotundifolia Hamago ･ II +-1 ･ II +-1 ･ III +-3 + + I +-2 r + III +-2 ･ I + + +-2 + + + + ･ ･ ･ ･ r 3 r + ･ ･

CompanionsOenothera laciniata Komatsuyoigusa II + II +-1 ･ ･ 2 +-1 + + III +-2 II +-2 III +-3 + + 1 1 I +-2 II +-2 II +-2 II +-2 ･ ･ ･ ･ II +-1 + +-1 ･ ･Digitaria ciliaris Mehishiba ･ r + ･ ･ ･ II +-2 + + + +-1 I + II + ･ II +-1 II +-1 I +-2 II +-2 1 + ･ ･ ･ r 1 + + ･ ･Rosa rugosa Hamanasu ･ ･ ･ ･ ･ ･ I + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ r + + +-3 ･ I 1

Artemisia capillaris Kawarayomogi ･ ･ ･ ･ ･ ･ + 2 I +-4 ･ II +-2 ･ + 2 ･ r +-1 + + ･ ･ ･ ･ r 2 + 1 ･ ･Salsola komarovii Okahijiki ･ ･ ･ ･ ･ ･ ･ + +-1 r + + + ･ + + I +-2 I +-2 I +-1 ･ ･ ･ ･ + +-2 I + ･ I +

Rosa luciae Terihanoibara + + ･ ･ ･ 1 + II +-2 I 1 r +-2 ･ + + ･ + 1 ･ + +-2 ･ ･ ･ ･ ･ + + r 1 ･ ･Cynodon dactylon Gyogishiba ･ + +-2 ･ ･ ･ II + ･ I +-2 r + ･ ･ + 2 + +-2 + +-2 I +-1 ･ ･ ･ ･ + +-1 + +-1 ･ ･Oenothera biennis Mematsuyoigusa ･ ･ ･ ･ ･ ･ ･ + + r + + + ･ ･ I +-1 + + ･ ･ ･ ･ ･ ･ I +-1 I + ･Artemisia indica var. maximowiczii Yomogi ･ r 1 ･ ･ ･ I + I +-1 r +-1 ･ ･ ･ ･ r + + + I +-1 ･ ･ ･ ･ r + + +-1 + + ･

group (Ohba et al. 1973). The Melanthera prostrata com-munity (Bj) was characterized by Melanthera prostrata, which is a differential species of the following three associations: Wedelio-Ischaemetum anthephoroidis Ohba, Miyawaki et Tx. 1973, Wedelio prostrate-Zoysietum mac-rostachyae Ohba, Miyawaki et Tx. 1973, and Wedelio-Car-icetum kobomugi Ohba, Miyawaki et Tx. 1973 (Miyawaki et al. 1994). The Fimbristylis sericea community (Bk) was characterized by Fimbristylis sericea and corresponded to the Ixerido-Fimbristylidetum sericeae Ohba, Miyawaki et Tx. 1973 association (Ohba et al. 1973). The Lathyrus japonicus community (Bl) was characterized by Lathyrus japonicus and has been reported in southwestern Japan as a Calystegia soldanelia-Lathyrus japonicus community, which grows near the shoreline on shingle beaches (Naka-nishi 1981, 1984). The Carex pumila community (Bm) was characterized by Carex pumila and corresponded to the Caricetum pumilae Shimizu et Nagata 1980 association (Miyawaki et al. 1986). Communities Bh-Bm were grouped into the Caricion kobomugi Ohba, Miyawaki et Tx. 1973 alliance, which is characterized by Carex kobo-mugi. The Carex kobomugi community (Bn) was also grouped into this alliance but lacked character or differen-tial species. This community corresponded to the Carice-tum kobomugi association group (Ohba et al. 1973).

The Calystegia soldanelia community (Bo) was charac-terized by the dominance of Calystegia soldanelia but lacked the character and differential species of other com-munities and alliances. The Ammophila breviligulata community (Bp) was characterized by Ammophila brevilig-

71Traditional vs ISOPAM vegetation classification

ulata, which is native to the North American East Coast and Great Lakes Region (Seabloom & Wiedemann 1994) and is an invasive alien species in Japan (Sasaki 2007). The Se-necio pseudoarnica community (Bq) was characterized by Senecio pseudoarnica, a character species of the Senecioni pseudo-arnicae-Elymion mollis Ohba, Miyawaki et Tx. 1973 alliance (Ohba et al. 1973; Miyawaki et al. 1994). This community has also been reported in Hokkaido (Suzu-ki 1988). The Heliotropium japonicum community (Br) was characterized by Heliotropium japonicum and corre-sponded to the Messerschmidio-Elymetum mollis Ohba, Miyawaki et Tx. 1973 association (Ohba et al. 1973). The Mertensia maritima subsp. asiatica community (Bs) was characterized by Mertensia maritima subsp. asiatica, Honckenya peploides var. major and corresponded to the Mertensio asiaticae-Elymetum mollis Ohba, Miyawaki et Tx. 1973 association.

The Carex kobomugi-Leymus mollis community (Bt) was characterized by the co-occurrence of Carex kobomugi, an alliance-level character species, and Leymus mollis, an order-level character species. The Leymus mollis commu-nity (Bu) was also characterized by Leymus mollis but lacked the character and differential species of the other communities that belong to the same upper unit. The Son-chus brachyotus-Leymus mollis community (Bv) was char-acterized by Sonchus brachyotus and corresponded to the Soncho brachyotus-Elymetum mollis Tx. 1966 association (Tüxen 1966). Finally, the Carex macrocephala-Leymus mollis community (Bw) was characterized by Carex macro-cephala and corresponded to the Glehnio littoralis-Carice-tum macrocephalae Ohba, Miyawaki et Tx. 1973 associa-tion (Ohba et al. 1973). The last four communities were grouped in the Honckenyo majoris-Elymetalia mollis Ohba, Miyawaki et Tx. 1973 order.

Table 2 is the synoptic table of herbaceous coastal plant communities, excluding beach and dune perennial herb communities, classified via phytosociological tabular com-parison. Nineteen communities were identified. The Salsola komarovii community (Ra) was characterized by Salsola komarovii and corresponded to the Calystegio sol-danellae-Salsoletum komarovii Ohba, Miyawaki et Tx. 1973 association (Ohba et al. 1973). The Atriplex patens community (Rb) was characterized by Atriplex patens and corresponded to the Polygono polyneuron-Atriplicetum gmelinii Ohba, Miyawaki et Tx. 1973 (Ohba et al. 1973) association. The Tetragonia tetragonioides community (Rc) was characterized by Tetragonia tetragonioides and corresponded to the Tetragonietum tetragonoides Ohba et Sugawara 1979 association (Ohba & Sugawara 1979a). The Limonium tetragonum community (Rd) was character-ized by Limonium tetragonum and corresponded to the Li-

monietum tetragoni Miyawaki et Ohba 1969 association (Miyawaki & Ohba 1969). The Zoysia sinica var. nippon-ica community (Re) was characterized by Zoysia sinica var. nipponica and corresponded to the Zoysietum sinicae nip-ponicae Miyawaki et Ohba 1969 association (Miyawaki & Ohba 1969). The Cladium jamaicense subsp. chinense community (Rf) was characterized by Cladium jamaicense subsp. chinense and corresponded to the Cladietum chinen-sis Ohba et Sugawara 1980 association (Ohba & Sugawara 1980).

The Zoysia japonica community (Rg) was characterized by Zoysia japonica, a character species of the Zoysion ja-ponicae Suz.-Tok et Abe 1959 ex. Suganuma 1970 alli-ance. The Cynodon dactylon var. nipponica community (Rh) was characterized by Cynodon dactylon var. nipponi-ca. The Cynodon dactylon community (Ri) was character-ized by Cynodon dactylon and has been reported on the coastline of central and southwestern Honshu (Suzuki 1981, 1982, 1983, 1984b, 1985). The Zoysia pacifica community (Rj) was characterized by Zoysia pacifica and has been reported in Yakusima (Suzuki 1980). The Setar-ia viridis var. pachystachys community (Rk) was character-ized by Setaria viridis var. pachystachys and Sagina maxi-ma and corresponded to the Setario pachystachyos-Saginetum maximae Miyawaki et al. 1980 association. The Phyla nodiflora community (Rl) was characterized by Phyla nodiflora and has been reported in Omaezaki, Shi-zuoka prefecture (Miyawaki et al. 1986). The Fimbristylis pacifica community (Rm) was characterized by Fimbristylis pacifica. The Oenothera laciniata community (Rn) was characterized by Oenothera laciniata, Xanthium orientale subsp. orientale, and Elymus tsukushiensis var. transiens.

The Silene gallica var. quinquevulnera community (Ro) was characterized by Silene gallica var. quinquevulnera, Aira elegans, and Viola mandshurica. The Sphagneticola calendulacea community (Rp) was characterized by Sphag-neticola calendulacea. The Cirsium maritimum commu-nity (Rq) was characterized by Cirsium maritimum, Dian-thus japonica, and Raphanus sativus var. hortensis f. raphanistroides and corresponded to the Cirsietum maritimi Ohba et Sugawara 1979 association (Ohba & Sugawara 1979b). The Euphorbia jolkinii community (Rr) was characterized by Euphorbia jolkinii and Boehmeria arenic-ola and corresponded to the Euphorbietum jolkinii Ohba et Sugawara 1979 association (Ohba & Sugawara 1979b). The Ipomoea indica community (Rs) was characterized by Ipomoea indica, Pueraria lobata, Boehmeria nivea var. concolor f. nipononivea, and Arundo donax. Similar com-munities have been reported in the Nansei Islands (Muraka-mi 1991).

Table 3 shows the synoptic table of beach and dune scrub

Vegetation Science Vol. 38, No. 1, 202172

Table 2. Synoptic table of other coastal herbaceous communities in Japanese coastal regions. Roman numerals indicate constancy classes (Ⅰ: 0-20%, Ⅱ: 20-40%, Ⅲ: 40-60%, Ⅳ: 60-80%, Ⅴ: 80-100%) and superscript numerals show ranges of dominance classes. Species with less than 34 spots (less than 5% of all stands) are omitted.

Community type Ra Rb Rc Rd Re Rf Rg Rh Ri Rj Rk Rl Rm Rn Ro Rp Rq Rr RsNumber of releve 8 1 1 2 2 1 1 2 3 1 6 1 1 1 2 1 2 2 2

Differential species of Salsola komarovii communitySalsola komarovii Okahijiki Ⅴ 1-3 ･ ･ 1 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Atriplex patens communityAtriplex patens Hosobahamaakaza Ⅰ 2 1 2 ･ ･ 1 + ･ ･ ･ ･ ･ Ⅰ + ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Tetragonia tetragonoides communityTetragonia tetragonoides Tsuruna Ⅱ +-1 ･ 1 5 ･ ･ ･ ･ ･ ･ ･ Ⅲ + ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Limonium tetragonum communityLimonium tetragonum Hamasaji ･ ･ ･ 2 2-4 1 2 ･ ･ ･ ･ 1 1 ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Zoysia sinica var. nipponica communityZoysia sinica var. nipponica Nagaminonishiba ･ ･ ･ ･ 2 3-5 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Cladium jamaicense subsp. chinense communityCladium jamaicense subsp. chinense Hitomotosusuki ･ ･ ･ ･ ･ 1 4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Zoysia japonica communityZoysia japonica Shiba ･ ･ ･ ･ ･ ･ 1 5 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Cynodon dactylon var. nipponicus communityCynodon dactylon var. nipponicus Ogyogishiba ･ ･ ･ ･ ･ ･ ･ 2 2-4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Cynodon dactylon communityCynodon dactylon Gyogishiba ･ ･ ･ 1 2 ･ ･ ･ ･ 3 4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Zoysia pacifica communityZoysia pacifica Koraishiba ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 2 ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Setaria viridis var. pachystachys communitySetaria viridis var. pachystachys Hamaenokoro Ⅰ + ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅴ 1-4 ･ ･ ･ ･ ･ 1 + ･ ･Sagina maxima Hamatsumekusa ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ 2 ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Phyla nodiflora communityPhyla nodiflora Iwadareso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 4 ･ ･ ･ ･ ･ ･ ･

Differential species of Fimbristylis pacifica communityFimbristylis pacifica Isotentsuki ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 4 ･ ･ ･ ･ ･ ･

Differential species of Oenothera laciniata communityOenothera laciniata Komatsuyoigusa Ⅱ + ･ ･ ･ ･ ･ ･ 2 +-1 2 + ･ ･ 1 1 ･ 1 3 1 + ･ ･ ･ ･Xanthium orientale subsp. orientale Oonamomi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 1 ･ ･ ･ ･ ･Elymus tsukushiensis var. transiens Kamojigusa ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･

Differential species of Silene gallica var. quinquevulnera communitySilene gallica var. quinquevulnera Mantema ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 +-2 ･ ･ ･ ･Aira elegantissima Hananukasusuki ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 + ･ ･ ･ ･Viola mandshurica Sumire ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 + ･ ･ ･ ･

Differential species of Sphagneticola calendulacea communitySphagneticola calendulacea Kumanogiku ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 4 ･ ･ ･

Differential species of Cirsium maritimum communityCirsium maritimum Hamaazami ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 1-2 ･ ･Dianthus japonicus Hamanadeshiko ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅲ +-1 ･ ･ ･ ･ ･ 1 2 ･ ･Raphanus sativus var. hortensis f. raphanistroides Hamadaikon ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･

Differential species of Euphorbia jolkinii communityEuphorbia jolkinii Iwataigeki ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ + ･ ･ ･ ･ 1 1 ･ 2 3-4 ･Boehmeria arenicola Hamayabumao ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 2 ･

Differential species of Ipomoea indica communityIpomoea indica Noasagao ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 5

Pueraria lobata Kuzu ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 1

Boehmeria nivea var. concolor f. nipononivea Karamushi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 +-2

Arundo donax Danchiku ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 3

Species of Glehnietea littoralisCalystegia soldanella Hamahirugao Ⅱ +-4 ･ 1 + ･ ･ 1 1 ･ 2 +-3 2 1-2 ･ Ⅴ +-4 ･ ･ ･ 1 + 1 + ･ ･ ･Ixeris repens Hamanigana Ⅱ +-1 ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Glehnia littoralis Hamabofu ･ ･ ･ ･ ･ 1 + ･ 1 + 1 + ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･Carex pumila Koboshiba Ⅱ 1-2 ･ ･ ･ ･ 1 2 ･ 1 + 1 1 ･ ･ ･ 1 2 ･ ･ ･ ･ ･ ･Carex kobomugi Kobomugi Ⅰ + ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ 1 ･ ･ ･ ･ ･ ･ ･ ･Ischaemum anthephoroides Kekamonohashi ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

73Traditional vs ISOPAM vegetation classification

communities classified using phytosociological tabular comparison. Eleven communities were extracted. The Pittosporum tobira community (Sa) was characterized by Pittosporum tobira, Litsea japonica, Rhaphiolepis indica var. umbellata, Cyrtomium falcatum subsp. falcatum, Eurya emarginata, and Elaeagnus pungens and corresponded to the Cyrtomio-Litseetum japonicae Sumata, Mashiba et Suz.-Tok. 1969 association. The Melanthera biflora com-munity (Sb) was characterized by Melanthera biflora and corresponded to the Wedelietum biflorae Miyawaki et K. Suzuki 1976 association. The Juniperus chinensis var. procumbens community (Sc) was characterized by Juniper-us chinensis var. procumbens and Aster spathulifolius and corresponded to the Vitici rotundifoliae-Juniperetum pro-cumbentis Itow et Kawasato 1980 association (Itow & Ka-wasato 1980). In the same region, these authors also de-scribed an Astero-Juniperetum procumbentis Itow et Kawasato 1980 association, which is difficult to distinguish from Vitici rotundifoliae-Juniperetum procumbentis. The Vitex rotundifolia community (Sd-Sf) was divided into three units characterized by Vitex rotundifolia, which is a character species of the Viticetalia rotundifoliae Ohba, Mi­yawaki et Tx. order. The Ipomoea pes-caprae community in unit Sd was characterized by Ipomoea pes-caprae, Vigna marina, Paspalum scrobiculatum var. orbiculare, and Mis-canthus boninensis. Unit Se lacked the differential species of the other units. The Imperata cylindrica var. koenigii community in unit Sf was characterized by Imperata cylin-drica var. koenigii. The Linaria japonica-Vitex rotundifo-lia community (Sg) was characterized by Linaria japonica, Artemisia capillaris, and Viola mandshurica f. crassa and corresponded to the Linario-Viticetum rotundifoliae Ohba, Miyawaki et Tx. 1973 association.

The Juniperus conferta community (Sh) was character-ized by Juniperus conferta. Ohba et al. (1973) proposed two associations characterized by Juniperus conferta: Viti-ci rotundifoliae-Juniperetum confertae Ohba, Miyawaki et Tx. 1973, belonging to the class Viticetea rotundifoliae

Ohba, Miyawaki et Tx. 1973, and Roso-Juniperetum con-fertae Ohba, Miyawaki et Tx. 1973, belonging to the class Rosetea multiflorae Ohba, Miyawaki et Tx. 1973. The Rosa rugosa communities (Si-Sj) were characterized by Rosa rugosa, Festuca rubra var. rubra, Rubus parvifolius, Arenaria lateriflora, and Rubia jesoensis and were divided into two units. The Thermopsis lupinoides under unit (Sj) was characterized by Thermopsis lupinoides, Iris ensata var. spontanea, Adenophora triphylla var. japonica, San-guisorba tenuifolia, Artemisia montana, Achillea alpina var. longiligulata, Geranium yesoense var. yesoense, Gera-nium yesoense var. pseudopalustre, Calamagrostis pur-purea subsp. langsdorfii, Angelica sachalinensis, Bupleu-rum longiradiatum var. elatius, Hieracium umbellatum, Vicia cracca, Stachys aspera var. hispidula, and Pleuro-spermum uralense, but the typical under unit (Si) lacked these species. These units roughly coincided with the Rosion rugosae Ohba, Miyawaki et Tx. 1973 alliance but were difficult to apply to the four previously proposed asso-ciations of Ohba et al. (1973). The Chrysanthemum yezoense-Empetrum nigrum var. japonicum community (Sk) was characterized by Empetrum nigrum var. japonicum, Chrysanthemum yezoense, Potentilla fragarioides var. ma-jor, Scabiosa japonica, Trifolium lupinaster, and Swertia tetrapetala subsp. tetrapetala var. tetrapetala. This com-munity is corresponded to Empetrum nigrum var. japoni-cum-Trifolium lupinaster community reported in the Bansei Beach in Hokkaido (Sato 2007).

Automatic classification by ISOPAMFigure 1 shows the ISOPAM partitioning results. Six-

teen vegetation types were divided at partitioning level 5. Figure 2 shows the relationship between the ISOPAM parti-tioning level and number of vegetation types. The number of vegetation types gradually increased with increasing par-titioning level but reached an inflection point at level 3. Table 4 is the constancy table of the coastal vegetation ana-lyzed by ISOPAM. Type A was characterized by Ipomoea

Table 2. Continued.Community type Ra Rb Rc Rd Re Rf Rg Rh Ri Rj Rk Rl Rm Rn Ro Rp Rq Rr RsNumber of releve 8 1 1 2 2 1 1 2 3 1 6 1 1 1 2 1 2 2 2

Zoysia macrostachya Onishiba ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･ ･ ･

Species of Viticetea rotundifoliaeVitex rotundifolia Hamago ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ + ･ ･ ･ ･ 1 1 1 3 1 1 ･

CompanionsLathyrus japonicus Hamaendo Ⅰ 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ + ･ ･ ･ ･ ･ ･ ･ ･Digitaria ciliaris Mehishiba Ⅱ + ･ ･ ･ ･ ･ ･ ･ 2 +-1 ･ Ⅱ + ･ ･ 1 1 ･ ･ ･ ･ ･Imperata cylindrica var. koenigii Chigaya Ⅰ 3 ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Artemisia capillaris Kawarayomogi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ 1 ･ ･ ･ ･ ･ ･ ･ ･Rosa luciae Terihanoibara ･ ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･ 1 3 1 3 ･ ･Oenothera biennis Mematsuyoigusa ･ ･ ･ ･ ･ ･ ･ ･ 1 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Artemisia indica var. maximowiczii Yomogi ･ ･ ･ ･ ･ 1 + ･ ･ ･ ･ Ⅱ + ･ ･ ･ ･ ･ ･ ･ 2 +

Crinum asiaticum var. japonicum Hamaomoto ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 + ･ ･

Vegetation Science Vol. 38, No. 1, 202174

Table 3. Synoptic table of beach and dune scrub communities in Japanese coastal regions. Roman numerals indicate constancy classes (Ⅰ: 0-20%, Ⅱ: 20-40%, Ⅲ: 40-60%, Ⅳ: 60-80%, Ⅴ: 80-100%) and superscript numerals show ranges of dominance classes. Species with less than 34 spots (less than 5% of all stands) are omitted.

Community type Sa Sb Sc Sd Se Sf Sg Sh Si Sj SkNumber of releve 1 2 4 5 114 21 14 7 38 13 12

Differential species of Cyrtomium falcatum subsp. falcatum-Litsea japonica communityPittosporum tobira Tobera 1 4 ･ 1 1 ･ r +-3 ･ ･ Ⅰ 1 ･ ･ ･Litsea japonica Hamabiwa 1 2 ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･Rhaphiolepis indica var. umbellata Sharimbai 1 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Cyrtomium falcatum subsp. falcatum Oniyabusotetsu 1 1 ･ 1 + ･ ･ ･ ･ ･ ･ ･ ･Eurya emarginata Hamahisakaki 1 1 ･ 1 2 ･ ･ ･ ･ ･ ･ ･ ･Elaeagnus pungens Nawashirogumi 1 + ･ ･ ･ r + ･ ･ ･ ･ ･ ･

Differential species of Melanthera biflora communityMelanthera biflora Kidachihamaguruma ･ 2 4 ･ ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Juniperus chinensis var. procumbens communityJuniperus chinensis var. procumbens Haibyakushin ･ ･ 4 3-5 ･ ･ ･ ･ ･ ･ ･ ･Aster spathulifolius Darumagiku ･ ･ 2 1 ･ ･ ･ ･ ･ ･ ･ ･

Differential species of Vitex rotundifolia communityVitex rotundifolia Hamago ･ ･ 1 2 Ⅴ 3-5 Ⅴ 1-5 Ⅴ 1-5 Ⅴ 1-5 Ⅰ 1 + 1-3 ･ ･

Differential species of Ipomoea pes-caprae under unitIpomoea pes-caprae Gumbaihirugao ･ ･ ･ Ⅲ 1-2 ･ r 1 ･ ･ ･ ･ ･Vigna marina Hamaazuki ･ ･ ･ Ⅱ 1 ･ ･ ･ ･ ･ ･ ･Paspalum scrobiculatum var. orbiculare Suzumenokobie ･ ･ ･ Ⅱ +-1 r +-3 ･ ･ ･ ･ ･ ･Miscanthus boninensis Muninsusuki ･ ･ ･ Ⅱ +-1 ･ ･ ･ ･ ･ ･ ･

Differential species of Imperata cylindrica var. koenigii under unitImperata cylindrica var. koenigii Chigaya ･ ･ 1 1 ･ r + Ⅴ +-5 Ⅱ 2-4 Ⅱ 1-2 Ⅰ +-2 ･ ･

Differential species of Linaria japonica-Vitex rotundifolia communityLinaria japonica Unran ･ ･ ･ ･ ･ ･ Ⅴ +-3 ･ Ⅱ +-3 ･ ･Artemisia capillaris Kawarayomogi ･ ･ ･ ･ + +-3 Ⅰ + Ⅲ +-2 Ⅱ +-1 Ⅰ +-1 ･ ･Viola mandshurica f. crassa Anamasumire ･ ･ ･ ･ ･ r 1 Ⅱ +-1 ･ ･ ･ ･

Differential species of Juniperus conferta communityJuniperus conferta Hainezu ･ ･ ･ ･ ･ ･ ･ Ⅴ 4-5 r 1 ･ ･

Differential species of Rosa rugosa communityRosa rugosa Hamanasu ･ ･ ･ ･ ･ ･ ･ Ⅱ + Ⅴ 1-5 Ⅴ 1-4 Ⅲ +-1

Festuca rubra var. rubra Oushinokegusa ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +-3 Ⅳ +-3 Ⅲ +

Rubus parvifolius Nawashiroichigo ･ ･ ･ ･ ･ r + ･ ･ Ⅱ +-3 Ⅲ +-1 + +

Arenaria lateriflora Oyamafusuma ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +-1 Ⅱ +-1 Ⅱ +

Rubia jesoensis Akanemugura ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ +-2 Ⅲ +-2 + +

Differential species of Thermopsis lupinoides under unitThermopsis lupinoides Sendaihagi ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅳ +-1 + 3

Iris ensata var. spontanea Nohanashobu ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅳ +-2 + +

Adenophora triphylla var. japonica Tsuriganeninjin ･ ･ ･ ･ ･ ･ ･ Ⅰ 1 ･ Ⅳ +-2 Ⅱ +-1

Sanguisorba tenuifolia Nagabonowaremoko ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅳ +-1 Ⅲ +-1

Artemisia montana Oyomogi ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ +-2 Ⅳ +-1 + +

Achillea alpina var. longiligulata Nokogiriso ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ + Ⅲ +-1 Ⅱ +

Geranium yesoense var. yesoense Ezofuro ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅲ +-2 + 1

Geranium yesoense var. pseudopalustre Hamafuro ･ ･ ･ ･ ･ ･ ･ ･ r + Ⅱ +-2 Ⅱ +

Calamagrostis purpurea subsp. langsdorfii Iwanogariyasu ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅲ +-3 + +

Angelica sachalinensis var. sachalinensis Ezonoyoroigusa ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅲ +-2 ･Bupleurum longiradiatum var. elatius Hotarusaiko ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ 1-2 + +

Hieracium umbellatum Yanagitampopo ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +-1 Ⅱ +

Vicia cracca Kusafuji ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ + ･Stachys aspera var. hispidula Inugoma ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +-1 ･Pleurospermum uralense Okasamochi ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +-1 ･

Differential species of Chrysanthemum yezoense-Empetrum nigrum var. japonicum communityEmpetrum nigrum var. japonicum Gankoran ･ ･ ･ ･ ･ ･ ･ ･ ･ + 2 Ⅴ 3-5

Chrysanthemum yezoense Kohamagiku ･ ･ ･ ･ ･ ･ ･ Ⅰ 1 ･ + + Ⅲ +-3

Potentilla fragarioides var. major Kijimushiro ･ ･ ･ ･ ･ ･ ･ ･ ･ + + Ⅲ +-1

Scabiosa japonica Matsumushiso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅲ +-2

Trifolium lupinaster Shajikuso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +

Swertia tetrapetala subsp. tetrapetala var. tetrapetala Chishimasemburi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅱ +

75Traditional vs ISOPAM vegetation classification

pes-caprae, Thuarea involuta, and Spinifex littoreus. Types B-E were characterized by Vitex rotundifolia and di-vided into four community units: typical, Melanthera prostrata, Imperata cylindrica var. koenigii, and Rosa luc-ieae units. Types F-I were characterized by Carex kobo-mugi and Ixeris repens and were divided into four units, of which only type F had differential species. The remaining three types were difficult to distinguish by indicative spe-cies constancy. Type J was characterized by Tetragonia tetragonioides, and type K was characterized by Carex pumila. Types L and M were characterized by Leymus mollis and divided into two units: Lathyrus japonicus and typical units. Types N-P were characterized by Rosa ru-gosa and Miscanthus sinensis and were divided into three units: typical, Empetrum nigrum var. japonicum, and Fes-tuca rubra var. rubra units.

Table 5 shows the relationships between vegetation types

Table 3. Continued.Community type Sa Sb Sc Sd Se Sf Sg Sh Si Sj SkNumber of releve 1 2 4 5 114 21 14 7 38 13 12

Species of Glehnietea littoralisCalystegia soldanella Hamahirugao ･ ･ ･ Ⅰ 1 Ⅲ +-5 Ⅲ +-2 Ⅲ +-2 Ⅲ + Ⅱ +-2 ･ ･Ixeris repens Hamanigana ･ ･ ･ ･ Ⅰ +-2 + +-1 Ⅲ +-1 Ⅰ + r + ･ ･Glehnia littoralis Hamabofu ･ ･ ･ ･ Ⅰ +-1 + + Ⅲ +-1 Ⅰ + + +-1 ･ ･Ischaemum anthephoroides Kekamonohashi ･ ･ ･ Ⅰ + Ⅰ +-3 Ⅱ +-3 Ⅳ +-3 Ⅲ 1 + + ･ ･Zoysia macrostachya Onishiba ･ ･ ･ ･ r 1-4 Ⅰ +-1 Ⅰ 1-2 Ⅰ + + + ･ ･Carex kobomugi Kobomugi ･ ･ ･ ･ Ⅱ +-4 + +-3 Ⅱ 1-4 ･ + +-2 ･ ･

CompanionsOenothera laciniata Komatsuyoigusa ･ ･ ･ Ⅱ + Ⅱ +-3 Ⅱ +-2 Ⅰ + ･ ･ ･ ･Lathyrus japonicus Hamaendo ･ ･ ･ ･ Ⅱ +-3 r + Ⅰ + ･ Ⅱ +-1 Ⅰ + Ⅰ +-2

Leymus mollis Tenkigusa ･ ･ ･ ･ ･ r 1 + 1 Ⅱ +-1 Ⅲ +-3 Ⅰ +-2 ･Carex pumila Koboshiba ･ ･ ･ ･ Ⅰ +-2 Ⅰ +-2 ･ ･ Ⅰ +-5 ･ ･Digitaria ciliaris Mehishiba ･ ･ ･ ･ Ⅰ +-3 Ⅰ +-1 Ⅰ + ･ ･ ･ ･Salsola komarovii Okahijiki ･ ･ ･ ･ + +-1 ･ Ⅰ +-1 ･ + + ･ ･Melanthera prostrata Nekonoshita ･ ･ ･ Ⅰ 1 + +-2 Ⅰ +-2 Ⅰ + Ⅰ 2 ･ ･ ･Rosa luciae Terihanoibara ･ ･ 3 + ･ Ⅰ +-3 Ⅰ +-1 + + ･ ･ ･ ･Cynodon dactylon Gyogishiba ･ ･ ･ ･ + +-1 r + + 2 ･ ･ ･ ･Oenothera biennis Mematsuyoigusa ･ ･ ･ ･ + +-1 Ⅰ +-1 Ⅰ +-2 ･ Ⅰ + ･ ･Artemisia indica var. maximowiczii Yomogi ･ ･ ･ ･ + + r + + + ･ Ⅰ +-3 ･ ･Crinum asiaticum var. japonicum Hamaomoto ･ ･ 1 1 ･ + +-2 Ⅰ + ･ ･ ･ ･ ･

Fig. 1. ISOPAM partitioning results.

Fig. 2. Relationship between number of vegetation types and partitioning level. Arrow indicates inflection point.

Vegetation Science Vol. 38, No. 1, 202176

classified using ISOPAM and plant communities recognized by traditional tabular comparisons. Plant communities with eight or more sites tended to correspond to one type classified by ISOPAM, and Fisher’s exact tests showed sig-nificant correspondence. No significant association was found for plant communities with seven or fewer sites, ex-

cept for the Juniperus chinensis var. procumbens, Senecio pseudoarnica and Setaria viridis var. pachystachys commu-nities. One vegetation type of ISOPAM sometimes corre-sponded to one plant community (e.g., types B or K) but of-ten included two or three plant communities. Carex kobomugi communities, which had relatively many points,

Table 4. Constancy table of ISOPAM results. Roman numerals indicate constancy classes. Species with less than 34 spots (less than 5% of all stands) are omitted.

Types A B C D E F G H I J K L M N O PNumber of releve 59 95 40 38 28 69 27 32 51 53 41 32 65 39 12 14

Ipomoea pes-caprae Gumbaihirugao III r ･ + ･ ･ + ･ ･ r ･ ･ ･ ･ ･ ･Thuarea involuta Kuroiwazasa II r r ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･Spinifex littoreus Tsukiige II ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

Vitex rotundifolia Hamago I V V III III II II ･ I I r ･ r + ･ ･

Melanthera prostrata Nekonoshita + r III + II I I + + ･ + ･ r ･ ･ ･Artemisia capillaris Kawarayomogi ･ r II I r II ･ ･ + r ･ + r I ･ ･

Imperata cylindrica var. koenigii Chigaya + + r V II r + + r + r r r I ･ ･

Rosa luciae Terihanoibara r I r I II ･ ･ + r r r r r ･ ･ ･Crinum asiaticum var. japonicum Hamaomoto I + + + II r I r ･ r r ･ ･ ･ ･ ･Miscanthus condensatus Hachijosusuki r r r ･ II r ･ ･ ･ ･ r ･ ･ r ･ ･Canavalia lineata Hamanatamame + + ･ ･ II ･ r ･ ･ + ･ ･ ･ ･ ･ ･

Carex kobomugi Kobomugi + I II + r IV V V V + II + II + ･ ･Ixeris repens Hamanigana r + II + r III II II V + I I III r ･ ･

Ischaemum anthephoroides Kekamonohashi + I III II I V II I I r II + I + ･ ･Zoysia macrostachya Onishiba ･ ･ r I + II I + II + I ･ I + ･ ･

Tetragonia tetragonoides Tsuruna r r r ･ I ･ ･ ･ ･ II r ･ ･ ･ ･ ･

Carex pumila Koboshiba + I + II r I + I + I V I II II ･ ･

Leymus mollis Tenkigusa ･ r r r ･ I I r I ･ + IV V III II II

Lathyrus japonicus Hamaendo r II r I I I I ･ II I + V II II III IISonchus brachyotus Hachijona ･ ･ ･ ･ ･ r r ･ r ･ ･ II + + ･ ･Artemisia stelleriana Shiroyomogi ･ ･ ･ r ･ r ･ ･ + ･ ･ II I + ･ ･

Rosa rugosa Hamanasu ･ ･ ･ + ･ r ･ r r r ･ ･ r V IV VMiscanthus sinensis Susuki + + ･ r r r ･ ･ r r ･ ･ ･ II II II

Empetrum nigrum var. japonicum Gankoran r ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r V ･Maianthemum dilatatum Maizuruso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ III IIPotentilla fragarioides var. major Kijimushiro ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + III ･Chrysanthemum yezoense Kohamagiku ･ ･ ･ ･ ･ r ･ ･ ･ ･ ･ ･ ･ + III +Trientalis europaea Tsumatoriso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ III +

Festuca rubra var. rubra Oushinokegusa ･ ･ ･ ･ ･ r ･ ･ ･ ･ ･ ･ r I III IVArtemisia montana Oyomogi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + r I II IVAdenophora triphylla var. japonica Tsuriganeninjin ･ ･ ･ ･ ･ r ･ ･ ･ ･ ･ ･ ･ ･ II IVRubus parvifolius Nawashiroichigo ･ ･ ･ r r ･ ･ ･ ･ ･ ･ ･ r II ･ IIIPolygonatum humile Himeizui ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + II IIIThermopsis lupinoides Sendaihagi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r I IIIIris ensata var. spontanea Nohanashobu ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + IIIArenaria lateriflora Oyamafusuma ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r I III IIIAchillea alpina var. longiligulata Nokogiriso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + r I II IIISanguisorba tenuifolia Nagabonowaremoko r ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r III IIIGeranium yesoense var. pseudopalustre Hamafuro ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ II IIICalamagrostis purpurea subsp. langsdorfii Iwanogariyasu ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + III

Calystegia soldanella Hamahirugao + II III III II IV V IV IV V IV II IV III ･ ･Oenothera laciniata Komatsuyoigusa II II III II ･ II II II + I II r I ･ ･ ･Glehnia littoralis Hamabofu r + II + I II III II III + II I I + ･ ･Digitaria ciliaris Mehishiba r I II I I r I II II II I ･ + ･ ･ ･Linaria japonica Unran ･ r I + ･ II r ･ II r r + I II + ･Salsola komarovii Okahijiki ･ r + + r + II r + II r ･ I r ･ ･Cynodon dactylon Gyogishiba r + r + I + + I ･ I I r + ･ ･ ･Oenothera biennis Mematsuyoigusa ･ + + + r + ･ + + r I + + I ･ ･Artemisia indica var. maximowiczii Yomogi r + + + I r ･ + ･ + r r + I ･ ･

77Traditional vs ISOPAM vegetation classification

Table 5. Correspondence table comparing results of traditional and ISOPAM vegetation classification. Numerals indicate the number of relevés identified as each community. Fisher’s exact test column’s symbols indicate the statistical significance level (**: p<0.01, －: n.s).

Vegetation types A B C D E F G H I J K L M N O P Fisher’sexact test

Plant communities which is a significant difference between the expected frequencyBb Vigna marina-Ipomoea pes-caprae community 30 ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **Ba Spinifex littoreus community 11 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **

Se Vitex rotundifolia community typical under unit ･ 81 22 2 ･ 3 2 ･ 3 1 ･ ･ ･ ･ ･ ･ **

Sg Linaria japonica-Vitex rotundifolia community ･ 1 7 3 ･ 3 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **Bj Melanthera prostrata community ･ ･ 4 ･ 2 1 1 1 2 ･ ･ ･ ･ ･ ･ ･ **

Sf Vitex rotundifolia community Imperata cylindrica var. koenigii under unit ･ 5 ･ 13 2 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **Bg Imperata cylindrica var. koenigii community ･ ･ ･ 10 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **

Bf Canavalia lineata-Crinum asiaticum var. japonicum community 2 ･ ･ ･ 7 ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ **Sc Juniperus chinensis var. procumbens community ･ ･ ･ ･ 4 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ **

Bh Ischaemum anthephoroides community ･ ･ 4 ･ 1 46 5 5 4 1 8 ･ ･ ･ ･ ･ **Bi Zoysia macrostachya community ･ ･ ･ ･ ･ 8 2 2 6 2 1 ･ 1 ･ ･ ･ **

Bo Carex kobomugi community ･ ･ ･ ･ ･ ･ 15 16 23 1 1 ･ ･ ･ ･ ･ **

Bo Calystegia soldanella community ･ ･ ･ ･ ･ ･ ･ ･ ･ 18 1 ･ ･ ･ ･ ･ **Ra Salsola komarovii community ･ ･ ･ 1 ･ ･ ･ ･ ･ 7 ･ ･ ･ ･ ･ ･ **Rk Setaria viridis var. pachystachys community ･ ･ ･ ･ 1 ･ ･ ･ ･ 5 ･ ･ ･ ･ ･ ･ **

Bm Carex pumila community ･ 1 ･ 2 1 ･ 1 5 4 4 24 ･ 1 ･ ･ ･ **

Bv Sonchus brachyotus-Leymus mollis community ･ ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ 8 5 ･ ･ ･ **Bq Senecio pseudoarnica community ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 3 ･ ･ ･ ･ **

Bu Leymus mollis community ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ 11 30 2 2 ･ **Bt Carex kobomugi-Leymus mollis community ･ ･ ･ ･ ･ ･ 1 ･ 3 ･ 1 1 22 ･ ･ ･ **Bw Carex macrocephala-Leymus mollis community ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 5 1 ･ ･ **

Si Rosa rugosa community typical under unit ･ ･ ･ ･ ･ 1 ･ 1 ･ 1 ･ ･ ･ 32 ･ 3 **

Sk Chrysanthemum yezoense-Empetrum nigrum var. japonicum community 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 9 ･ **

Sj Rosa rugosa community Thermopsis lupinoides under unit ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 1 11 **Bl Lathyrus japonicus community ･ ･ ･ 1 ･ 1 ･ ･ 4 5 ･ 5 1 ･ ･ ･

Plant communities which is no significant difference between the expected frequencySh Juniperus conferta community 1 ･ 1 ･ 1 3 ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ －Sd Vitex rotundifolia community Ipomoea pes-caprae under unit ･ 5 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Bd Cassytha filiformis community 4 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Bp Ammophila breviligulata community 3 ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Be Panicum repens community ･ ･ ･ 2 ･ ･ ･ 1 ･ ･ ･ 1 ･ ･ ･ ･ －Br Heliotropium japonicum community ･ ･ ･ ･ ･ 1 ･ ･ 1 1 ･ ･ ･ ･ ･ ･ －Bs Mertensia maritima subsp. asiatica community ･ ･ ･ ･ ･ ･ ･ ･ ･ 2 ･ 1 ･ ･ ･ ･ －Ri Cynodon dactylon community ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 2 ･ ･ ･ ･ ･ －Re Zoysia sinica var. nipponica community 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Sb Melanthera biflora community 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rd Limonium tetragonum community 1 ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rq Cirsium maritimum community ･ 1 ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Ro Silene gallica var. quinquevulnera community ･ ･ 1 ･ ･ ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ －Rr Euphorbia jolkinii community ･ ･ ･ ･ 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rs Ipomoea indica community ･ ･ ･ ･ 2 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rh Cynodon dactylon var. nipponicus community ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 1 ･ ･ ･ ･ ･ －Rb Atriplex patens community 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rj Zoysia pacifica community 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rg Zoysia japonica community ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rl Phyla nodiflora community ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rn Oenothera laciniata community ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Bc Melanthera robusta community ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Rp Sphagneticola calendulacea community ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Sa Cyrtomium falcatum subsp. falcatum-Litsea japonica community ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ －Bk Fimbristylis sericea community ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ ･ ･ －Rc Tetragonia tetragonoides community ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ ･ －Rm Fimbristylis pacifica community ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ －Rf Cladium jamaicense subsp. chinense community ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ 1 ･ ･ ･ ･ ･ －

Vegetation Science Vol. 38, No. 1, 202178

were divided into three types, namely G, H, and I, accord-ing to the division of ISOPAM classification above level 4 (Table 5; Figure 1).

■ DISCUSSIONComparison of automatic and traditional methods

In this study, vegetation data collected from Japanese beaches and dunes were classified into 53 communities us-ing traditional phytosociological tabular comparisons and 16 vegetation types via automatic ISOPAM classifica-tion. The large dataset containing data on dune vegetation mainly consisted of plant communities belonging to the Glehnietea littoralis, Honkenyo-Elymetea, and Viticetea ro-tundifoliae classes and Rosetalia rugosae order. The phy-tosociological tabular comparison revealed that this dataset contained a small number of plant communities other than dune vegetation belonging to Pittosporion tobira alliance (Camellietea japonicae class) and Farfugion japonici alli-ance (Artemisietea principis class). On the other hand, ISOPAM analysis classified most of the data as communi-ties of dune vegetation and ignored community units with few data recognized by traditional tabular compari-sons. Although the two classification approaches yielded roughly similar results, ISOPAM tended to combine multi-ple community units into one vegetation type and split the same community with few data into several vegetation types. These results suggested that automatic classifica-tion, which is superior in terms of speed and objectivity, did not properly handle outliers that deviate from the overall pattern, unlike traditional manual tabular comparisons.

Generally, coastal vegetation, such as dune vegetation, has a small number of species per point and is susceptible to invasion of species from adjacent communities (Carboni et al. 2010; Malavasi et al. 2014). Traditional tabular comparison uses existing knowledge of community systems and their differential species to exclude data that deviate from the overall trend and treat data that include species from neighboring communities as subcommunities. On the other hand, the automated classification method deter-mined the vegetation homogeneity based on the statistical distance between the position on the ordination. There-fore, communities with few data, including species from adjacent communities, might be merged into different vege-tation types. Most previously proposed numerical meth-ods for vegetation classification are types of unsupervised classification because they only use the provided dataset.

Traditional tabular comparisons are similar to supervised classification, because the classification is performed by re-ferring to existing community systems. A machine-learn-ing method that incorporates expert classification has re-

cently been proposed (Tichý et al. 2019) and is likely to make progress in the future. Generally, the accuracy and generalization performance of supervised machine-learning classification are determined by training data quality and quantity. It is therefore necessary not only to establish a classification system as a training label but also to deter-mine the character species and standard reference data and obtain a sufficient number of high-quality vegetation data for the future development of vegetation classification methods.

Application of automatic classification to vegetation analysis

The results of the ISOPAM and traditional classification approaches agreed except for vegetation types with few samples. This suggested that ISOPAM is suitable for pre-liminarily classifying vegetation and extracting broad pat-terns from large datasets. Compared to TWINSPAN (Hill 1979), which is widely used in vegetation science, ISOPAM requires fewer parameters to be defined. Furthermore, the default setting yields good classification results, which is a significant advantage when dealing with large datasets. Researchers also need to select a distance for ISOMAP co-ordination between individual survey points. In this study, I obtained good results with the default setting of the Bray-

Curtis distance. However, future studies should verify ap-propriate distance measures.

ISOPAM classification divided a given vegetation dataset into 14 units at the third level and added two units at the fourth and fifth levels. Groups G and H separated at the fourth and fifth levels were characterized by the presence of Carex kobomugi and Ixeris repens and the absence of Isch-aemum anthephoroides and Zoysia macrostachya, and it was difficult to recognize the differences between these groups. Group I showed the same species composi-tion. All three units corresponded primarily to the Carex kobomugi community in traditional classification. These results suggested that the vegetation type classified after de-creasing the number of added units may be less significant in vegetation classification.

Effectiveness of and issues in vegetation databasesIn this study, I used a traditional tabular comparison ap-

proach to extract plant communities from a national vegeta-tion database and compared it with an automatic classifica-tion approach. Most of the obtained plant communities were consistent with the existing phytosociological classifi-cation system. However, some vegetation types, such as the communities belonging to the Glehnietea littoralis class and the Rosa rugosa community, did not coincide with the existing associations but with association groups or allianc-

79Traditional vs ISOPAM vegetation classification

es set as higher units. Ohba et al. (1973) divided Rosa ru-gosa-dominated vegetation into three associations: Viti coignetiae-Rosetum rugosae, Elaeagno umbellatae-Rose-tum rugosae, and Potentillo fragarioidis-Rosetum rugo-sae. However, it was difficult to identify these associa-tions from the national vegetation database. Jung (2000) also reported only one community of Rosa rugosa-dominat-ed vegetation in the Korean Peninsula. This study further revealed that the Ixerido-Thuareion involutae alliance lacked many species of the Glehnietea littoralis class. Pig-natti (1996) investigated Ipomoea pes-caprae and Spinifex littoreus dominant vegetation on the coast of Thailand and proposed the Spinifici-Scaevoletea sericeae class and Can-avalietalia maritimae order as upper units. Data collected in both Japan and the Asia-Pacific region should be com-pared to establish a coastal beach and dune vegetation clas-sification system from a global perspective.

Many recent studies have reported the Zoysietum sinicae Ohba, Miyawali et Tx. 1973 association on the islands around Okinawa and Amami (Terada & Ooya 2012a, b; Terada et al. 2014, 2016, 2019), but no relevant data were found in the national vegetation database. The data-base likely did not contain survey data on plant communi-ties distributed in small and restricted areas, because it re-corded only representative communities in the vegetation maps. To establish an automatic classification method that reflects the existing vegetation community system, a high-

quality national database covering all previously reported communities is essential.

■ ACKNOWLEDGEMENTSI would like to thank the Biodiversity Center for Natural

Environment, Ministry of the Environment of Japan for providing valuable data and permission for the purpose of this research.

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■  要約　日本の海浜植生の分類における伝統的手法と自動化手法の比較．阿部聖哉 （電力中央研究所） 近年，大規模な植物社会学的調査データが世界中で収集され，データベースとして様々な目的に活用されている．日本でも，植生図の作成に伴って収集された植生調査データがデータベースとして公開されている．こうした大規模な植生データベースを分類する際に，従来の植物社会学的な表操作では多くの時間と労力を要していた．本研究では．日本の海浜植生を分類するために，最近開発された自動化アプローチであるISOPAMを適用し，伝統的な手法による分類と比較した．従来の手法では，42の草本群落と 11の低木群落が分類され，そのほとんどが既報告の植物社会学的植生単位に対応していた． 一方，ISOPAMは同じデータセットを自動的に 16の植生単位に分類した．両者は，データ数の多い主要な群落ではよく一致したが，データが少ない植物群落は他の植生単位に統合され，ISOPAMでは分類されなかった．ISOPAMなどの自動分類手法は，大規模なデータセットに対して大局的なパターンを分類するのには適しているが，データ数の少ない群落や外れ値の検出は難しいと考えられた．大規模なデータを精度良く効率的に分類するには，植物社会学的に識別された調査データをトレーニングデータとした教師付分類手法の開発と，ラベル付き植生調査データの蓄積が必要である．