Vegetation Science 38 : 67-80, 2021 Traditional vs ISOPAM vegetation classification 67 Original article

Comparison of traditional and automated approaches in classifica- tion of Japanese coastal beach and dune vegetation

Seiya 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- ■ INTRODUCTION sociations. However, it requires considerable time and ex- Countries around the world have constructed large-scale pert knowledge, especially for large datasets. In contrast, vegetation databases for use in environmental conservation automatic classification methods require minimum labor (Dengler et al. 2012). The Japanese government also col- and time without the need for specialist judgment. lects vegetation data, accompanied by nationwide vegeta- Schmidtlein et al. (2010) recently introduced a novel brute- tion mapping, and publishes it in a database (Japanese Min- force approach to vegetation classification named ISOPAM istry of the Environment 2018). Plot data are collected as by combining Isomap dimensional reduction (Tenenbaum reference standards for vegetation map legends, but they et al. 2000) and partitioning around medoids (PAM) cluster can also be used for vegetation research. For example, partitioning (Kaufman & Rousseeuw 1990). The ISO- Abe (2018) studied the habitats of near-threatened plants PAM algorithm automatically extracts indicator species by analyzing data from this database at the order and alli- from fidelity to groups of sites and obtains a hierarchical ance levels for environmental impact assessments. How- classification result by repeating nonhierarchical partition- ever, the database is better to be classified into vegetation ing. Černý et al. (2015) classified an extensive vegetation units at the community level to clarify the habitats of more database of Korean forests and successfully identified the conservation target species and for ecosystem protection. primary environmental gradient in the Korean peninsu- Vegetation scientists traditionally analyze plant commu- la. Peterka et al. (2017) classified large datasets of Euro- nities using phytosociological tabular comparison (Braun- pean fen vegetation and identified alliance-level vegetation Blanquet 1964; Müller-Dombois & Ellenberg 1974). units. These studies suggest that ISOPAM automatically This method compares data obtained from the field or a da- produces classification results from large datasets similar to

*Central Research Institute of Electric Power Industry, Abiko 1646, Abiko-shi, Chiba 270-1194, Japan E-mail: [email protected] The Society of Vegetation Science ♦ Received September 18, 2020 ╱ Accepted March 1, 2021 68 Vegetation Science Vol. 38, No. 1, 2021 the communities obtained from traditional tabular compari- info/, accessed May 2019). son. However, it has not been investigated whether com- munity units such as associations defined by the traditional Data analysis phytosociology approach correspond to those obtained by I divided the collected records into the following three the automatic classification approach. It is necessary to datasets based on physiognomy, species characteristics, and verify the consistency with the conventional established habitat: (1) herbaceous beach and dune communities, (2) community system for practical application. other herbaceous coastal communities, and (3) beach and Many researchers have proposed phytosociological asso- dune scrub communities. I applied traditional phytosocio- ciations and their upper units for coastal beach and dune logical tabular comparison (Braun-Blanquet 1964; Müller- plant communities and revealed the character and differen- Dombois & Ellenberg 1974) to these datasets and referred tial species of the vegetation units (Ohba et al. 1973; Mi­ to published phytosociological reports and classification yawaki & Suzuki 1976; Itow & Kawasato 1980). These systems to define basic classification units, such as associa- vegetation units can be easily identified by traditional phy- tions. Classified plant communities were organized into tosociological tabular comparison referring to previous re- three separate constancy tables. To compare traditional ports. Thus, they are suitable to confirm whether the auto- and automatic classification methods, I applied the ISO- mated approach can extract community units similar to the PAM algorithm to the same datasets without prior physiog- traditional approach. Besides, the automatic classification nomical division. The ISOPAM algorithm first calculated approach requires considering weight between the upper dissimilarities between input objects (e.g., relevés) for Iso- and lower layers in multi-layered communities such as for- map nonlinear dimension reduction. I therefore selected ests, while there is no need for single-layered plant com- the default Bray-Curtis distance measures. Braun-blan- munities such as beach and dune vegetation. Natural dune quet’s dominant value was used as an ordinal scale to cal- areas are rapidly decreasing because of tsunami disasters culate the distance between survey points, but the non-nu- and embankment construction and urgently need conserva- merical + value was converted to the median percentage tion. The recent distribution of coastal beach and dune coverage of 0.1. Hierarchical partitioning levels were set communities needs to be classified on a national scale to set automatically and not limited to a specific value. I ar- conservation targets. I therefore tested automatic classifi- ranged the ISOPAM calculations into a constancy table cation to identify coastal beach and dune plant communities similar to the table from the traditional tabular compari- and evaluated its applicability to constructing vegetation son. Differential species groups were rearranged by ap- systems by comparing it to traditional phytosociological plying the phytosociological abundance criteria based on tabular comparisons. the species groups extracted by fidelity during the ISOPAM calculation. Subsequently, I compared vegetation types obtained with ISOPAM and manual phytosociological tabu- ■ METHODS lar methods. I used Fisher’s exact to test statistically sig- Data collection nificant associations between vegetation units classified by I collected phytosociological relevés from Japanese na- ISOPAM and traditional tabular comparison. It is a statis- tional vegetation survey data (http://gis.biodic.go.jp/webgis/ tical test for analyzing categorized data when the sample sc-016.html, accessed March 2019), which could provide size is small, and the chi-square test is inappropriate. All information on predefined categories corresponding to the statistical analyzes were performed using R 3.6.0 and pack- legends of actual vegetation maps. I selected 695 records age isopam 0.9-13. defined as dune vegetation in the broad category, including not only dune scrub and grassland but also vegetation on ■ RESULTS cobbles, pebbles, and shingle beaches. All these relevés were collected from September 2000 to October 2017 in the Traditional phytosociological classification field on almost all coasts of Japan in the range of latitude Table 1 shows the synoptic table of beach and dune her- 45°31′3.6″ in the north and latitude 24°2′58″ in the south, baceous plant communities classified using phytosociologi- and geographical coordinates were included in the Japanese cal tabular comparison. Twenty-three communities were Geodetic Datum 2000. However, these records contain extracted by referring to previously published phytosocio- incorrect and outdated local species names because of in- logical classification systems (Miyawaki et al. 1994) and sufficient plant name confirmation. Thus, I revised all some other reports (Ohba et al. 1973; Miyawaki & Suzuki species names to standard names by referring to the Japa- 1976; Itow & Kawasato 1980). The Spinifex littoreus nese scientific botanical name index, Y-list (http://ylist. community (Ba) was characterized by Spinifex littoreus, Traditional vs ISOPAM vegetation classification 69

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 Bw Number 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 involutae Thuarea 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 community Spinifex 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 community +-2 +-5 +-1 + +-1 1 Ipomoea pes-caprae Gumbaihirugao II V ･ III 1 ･ ･ ･ ･ ･ ･ ･ ･ r + ･ ･ ･ ･ ･ ･ ･ ･ Vigna marina Hamaazuki II +-2 II 1-5 ･ I 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

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

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

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

Differential species of Canavalia lineata-Crinum asiaticum var. japonicum community Crinum 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 community Imperata 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 kobomugi Carex 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 community Ischaemum 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 community Zoysia macrostachya Onishiba ･ ･ ･ ･ ･ ･ ･ II +-1 V +-5 + 1 ･ ･ + +-1 + +-1 + + ･ ･ ･ ･ I +-1 + +-4 ･ ･

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

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

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

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

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

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

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

Differential species of Mertensia maritima subsp. asiatica community Mertensia 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 mollis Leymus 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 + 70 Vegetation Science Vol. 38, No. 1, 2021

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 Bw Number 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 community Sonchus brachyotus Hachijona ･ ･ ･ ･ ･ ･ ･ r + ･ ･ ･ ･ ･ r + ･ ･ ･ ･ ･ ･ r 1 V +-2 I +

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

Species of Glehnietea littoralis Calystegia 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 rotundifoliae Vitex rotundifolia Hamago ･ II +-1 ･ II +-1 ･ III +-3 + + I +-2 r + III +-2 ･ I + + +-2 + + + + ･ ･ ･ ･ r 3 r + ･ ･

Companions Oenothera 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 + + ･

Pandanus odoratissimus, Volkameria inermis, and Lepturus group (Ohba et al. 1973). The Melanthera prostrata com- repens and corresponded to the Glehnio-Spinificetum lit- munity (Bj) was characterized by Melanthera prostrata, torei Ohba, Miyawaki et Tx. 1973 association (Ohba et al. which is a differential species of the following three 1973). The Vigna marina-Ipomoea pes-caprae communi- associations: Wedelio-Ischaemetum anthephoroidis Ohba, ty (Bb) was characterized by Ipomoea pes-caprae and Vig- Miyawaki et Tx. 1973, Wedelio prostrate-Zoysietum mac- na marina, and corresponds to the Vigno-Ipomoeetum pe- rostachyae Ohba, Miyawaki et Tx. 1973, and Wedelio-Car- dis-caprae Miyawaki et K. Suzuki 1976 association icetum kobomugi Ohba, Miyawaki et Tx. 1973 (Miyawaki (Miyawaki & Suzuki 1976). The Melanthera robusta et al. 1994). The Fimbristylis sericea community (Bk) community (Bc) was characterized by Melanthera robusta was characterized by Fimbristylis sericea and corresponded and has been reported in Hinomisaki, Wakayama prefecture to the Ixerido-Fimbristylidetum sericeae Ohba, Miyawaki (Suzuki 1984a). The Cassytha filiformis community (Bd) et Tx. 1973 association (Ohba et al. 1973). The Lathyrus was characterized by Cassytha filiformis and Chamaesyce japonicus community (Bl) was characterized by Lathyrus atoto. These four communities were grouped into the Ix- japonicus and has been reported in southwestern Japan as a erido-Thuareion involutae Ohba 1973 alliance, which is Calystegia soldanelia-Lathyrus japonicus community, characterized by Thuarea involuta, Bidens pilosa var. radi- which grows near the shoreline on shingle beaches (Naka­ ata, and Scaevola taccada. The Panicum repens commu- nishi 1981, 1984). The Carex pumila community (Bm) nity (Be) was characterized by Panicum repens. The Can- was characterized by Carex pumila and corresponded to the avalia lineata-Crinum asiaticum var. japonicum Caricetum pumilae Shimizu et Nagata 1980 association community (Bf) was characterized by Crinum asiaticum (Miyawaki et al. 1986). Communities Bh-Bm were var. japonicum and Canavalia lineata and corresponded to grouped into the Caricion kobomugi Ohba, Miyawaki et the Vitici-Crinetum japonici Nakanishi 1980 association Tx. 1973 alliance, which is characterized by Carex kobo- (Nakanishi 1980). The Imperata cylindrica var. koenigii mugi. The Carex kobomugi community (Bn) was also community (Bg) was characterized by the dominance of grouped into this alliance but lacked character or differen- Imperata cylindrica var. koenigii. tial species. This community corresponded to the Carice- The Ischaemum anthephoroides community (Bh) was tum kobomugi association group (Ohba et al. 1973). characterized by Ischaemum anthephoroides and corre- The Calystegia soldanelia community (Bo) was charac- sponded to the Ischaemetum anthephoroidis association terized by the dominance of Calystegia soldanelia but group (Ohba et al. 1973). The Zoysia macrostachya com- lacked the character and differential species of other com- munity (Bi) was characterized by Zoysia macrostachya and munities and alliances. The Ammophila breviligulata corresponded to the Zoysietum macrostachyae association community (Bp) was characterized by Ammophila brevilig- Traditional vs ISOPAM vegetation classification 71 ulata, which is native to the North American East Coast and monietum tetragoni Miyawaki et Ohba 1969 association Great Lakes Region (Seabloom & Wiedemann 1994) and is (Miyawaki & Ohba 1969). The Zoysia sinica var. nippon- an invasive alien species in Japan (Sasaki 2007). The Se- ica community (Re) was characterized by Zoysia sinica var. necio pseudoarnica community (Bq) was characterized by nipponica and corresponded to the Zoysietum sinicae nip- Senecio pseudoarnica, a character species of the Senecioni ponicae Miyawaki et Ohba 1969 association (Miyawaki & pseudo-arnicae-Elymion mollis Ohba, Miyawaki et Tx. Ohba 1969). The Cladium jamaicense subsp. chinense 1973 alliance (Ohba et al. 1973; Miyawaki et al. 1994). community (Rf) was characterized by Cladium jamaicense This community has also been reported in Hokkaido (Suzu- subsp. chinense and corresponded to the Cladietum chinen- ki 1988). The Heliotropium japonicum community (Br) sis Ohba et Sugawara 1980 association (Ohba & Sugawara was characterized by Heliotropium japonicum and corre- 1980). sponded to the Messerschmidio-Elymetum mollis Ohba, The Zoysia japonica community (Rg) was characterized Miyawaki et Tx. 1973 association (Ohba et al. 1973). The by Zoysia japonica, a character species of the Zoysion ja- Mertensia maritima subsp. asiatica community (Bs) was ponicae Suz.-Tok et Abe 1959 ex. Suganuma 1970 alli- characterized by Mertensia maritima subsp. asiatica, ance. The Cynodon dactylon var. nipponica community Honckenya peploides var. major and corresponded to the (Rh) was characterized by Cynodon dactylon var. nipponi- Mertensio asiaticae-Elymetum mollis Ohba, Miyawaki et ca. The Cynodon dactylon community (Ri) was character- Tx. 1973 association. ized by Cynodon dactylon and has been reported on the The Carex kobomugi-Leymus mollis community (Bt) coastline of central and southwestern Honshu (Suzuki was characterized by the co-occurrence of Carex kobomugi, 1981, 1982, 1983, 1984b, 1985). The Zoysia pacifica an alliance-level character species, and Leymus mollis, an community (Rj) was characterized by Zoysia pacifica and order-level character species. The Leymus mollis commu- has been reported in Yakusima (Suzuki 1980). The Setar- nity (Bu) was also characterized by Leymus mollis but ia viridis var. pachystachys community (Rk) was character- lacked the character and differential species of the other ized by Setaria viridis var. pachystachys and Sagina maxi- communities that belong to the same upper unit. The Son- ma and corresponded to the Setario pachystachyos- chus brachyotus-Leymus mollis community (Bv) was char- Saginetum maximae Miyawaki et al. 1980 association. acterized by Sonchus brachyotus and corresponded to the The Phyla nodiflora community (Rl) was characterized by Soncho brachyotus-Elymetum mollis Tx. 1966 association Phyla nodiflora and has been reported in Omaezaki, Shi- (Tüxen 1966). Finally, the Carex macrocephala-Leymus zuoka prefecture (Miyawaki et al. 1986). The Fimbristylis mollis community (Bw) was characterized by Carex macro- pacifica community (Rm) was characterized by Fimbristylis cephala and corresponded to the Glehnio littoralis-Carice- pacifica. The Oenothera laciniata community (Rn) was tum macrocephalae Ohba, Miyawaki et Tx. 1973 associa- characterized by Oenothera laciniata, Xanthium orientale tion (Ohba et al. 1973). The last four communities were subsp. orientale, and Elymus tsukushiensis var. transiens. grouped in the Honckenyo majoris-Elymetalia mollis The Silene gallica var. quinquevulnera community (Ro) Ohba, Miyawaki et Tx. 1973 order. was characterized by Silene gallica var. quinquevulnera, Table 2 is the synoptic table of herbaceous coastal plant Aira elegans, and Viola mandshurica. The Sphagneticola communities, excluding beach and dune perennial herb calendulacea community (Rp) was characterized by Sphag- communities, classified via phytosociological tabular com- neticola calendulacea. The Cirsium maritimum commu- parison. Nineteen communities were identified. The nity (Rq) was characterized by Cirsium maritimum, Dian- Salsola komarovii community (Ra) was characterized by thus japonica, and Raphanus sativus var. hortensis f. Salsola komarovii and corresponded to the Calystegio sol- raphanistroides and corresponded to the Cirsietum maritimi danellae-Salsoletum komarovii Ohba, Miyawaki et Tx. Ohba et Sugawara 1979 association (Ohba & Sugawara 1973 association (Ohba et al. 1973). The Atriplex patens 1979b). The Euphorbia jolkinii community (Rr) was community (Rb) was characterized by Atriplex patens and characterized by Euphorbia jolkinii and Boehmeria arenic- corresponded to the Polygono polyneuron-Atriplicetum ola and corresponded to the Euphorbietum jolkinii Ohba et gmelinii Ohba, Miyawaki et Tx. 1973 (Ohba et al. 1973) Sugawara 1979 association (Ohba & Sugawara 1979b). association. The Tetragonia tetragonioides community The Ipomoea indica community (Rs) was characterized by (Rc) was characterized by Tetragonia tetragonioides and Ipomoea indica, Pueraria lobata, Boehmeria nivea var. corresponded to the Tetragonietum tetragonoides Ohba et concolor f. nipononivea, and Arundo donax. Similar com- Sugawara 1979 association (Ohba & Sugawara 1979a). munities have been reported in the Nansei Islands (Muraka- The Limonium tetragonum community (Rd) was character- mi 1991). ized by Limonium tetragonum and corresponded to the Li- Table 3 shows the synoptic table of beach and dune scrub 72 Vegetation Science Vol. 38, No. 1, 2021

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 Rs Number 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 community Salsola komarovii Okahijiki Ⅴ 1-3 ･ ･ 1 1 ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Differential species of Ipomoea indica community Ipomoea 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 littoralis Calystegia 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 + ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Traditional vs ISOPAM vegetation classification 73

Table 2. Continued.

Community type Ra Rb Rc Rd Re Rf Rg Rh Ri Rj Rk Rl Rm Rn Ro Rp Rq Rr Rs Number 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 rotundifoliae Vitex rotundifolia Hamago ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ Ⅰ + ･ ･ ･ ･ 1 1 1 3 1 1 ･

Companions Lathyrus 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 + ･ ･ communities classified using phytosociological tabular Ohba, Miyawaki et Tx. 1973, and Roso-Juniperetum con- comparison. Eleven communities were extracted. The fertae Ohba, Miyawaki et Tx. 1973, belonging to the class Pittosporum tobira community (Sa) was characterized by Rosetea multiflorae Ohba, Miyawaki et Tx. 1973. The Pittosporum tobira, Litsea japonica, Rhaphiolepis indica Rosa rugosa communities (Si-Sj) were characterized by var. umbellata, Cyrtomium falcatum subsp. falcatum, Eurya Rosa rugosa, Festuca rubra var. rubra, Rubus parvifolius, emarginata, and Elaeagnus pungens and corresponded to Arenaria lateriflora, and Rubia jesoensis and were divided the Cyrtomio-Litseetum japonicae Sumata, Mashiba et into two units. The Thermopsis lupinoides under unit (Sj) Suz.-Tok. 1969 association. The Melanthera biflora com- was characterized by Thermopsis lupinoides, Iris ensata munity (Sb) was characterized by Melanthera biflora and var. spontanea, Adenophora triphylla var. japonica, San- corresponded to the Wedelietum biflorae Miyawaki et K. guisorba tenuifolia, Artemisia montana, Achillea alpina Suzuki 1976 association. The Juniperus chinensis var. var. longiligulata, Geranium yesoense var. yesoense, Gera- procumbens community (Sc) was characterized by Juniper- nium yesoense var. pseudopalustre, Calamagrostis pur- us chinensis var. procumbens and Aster spathulifolius and purea subsp. langsdorfii, Angelica sachalinensis, Bupleu- corresponded to the Vitici rotundifoliae-Juniperetum pro- rum longiradiatum var. elatius, Hieracium umbellatum, cumbentis Itow et Kawasato 1980 association (Itow & Ka- Vicia cracca, Stachys aspera var. hispidula, and Pleuro- wasato 1980). In the same region, these authors also de- spermum uralense, but the typical under unit (Si) lacked scribed an Astero-Juniperetum procumbentis Itow et these species. These units roughly coincided with the Kawasato 1980 association, which is difficult to distinguish Rosion rugosae Ohba, Miyawaki et Tx. 1973 alliance but from Vitici rotundifoliae-Juniperetum procumbentis. The were difficult to apply to the four previously proposed asso- Vitex rotundifolia community (Sd-Sf) was divided into ciations of Ohba et al. (1973). The Chrysanthemum three units characterized by Vitex rotundifolia, which is a yezoense-Empetrum nigrum var. japonicum community (Sk) character species of the Viticetalia rotundifoliae Ohba, Mi­ was characterized by Empetrum nigrum var. japonicum, yawaki et Tx. order. The Ipomoea pes-caprae community Chrysanthemum yezoense, Potentilla fragarioides var. ma- in unit Sd was characterized by Ipomoea pes-caprae, Vigna jor, Scabiosa japonica, Trifolium lupinaster, and Swertia marina, Paspalum scrobiculatum var. orbiculare, and Mis- tetrapetala subsp. tetrapetala var. tetrapetala. This com- canthus boninensis. Unit Se lacked the differential species munity is corresponded to Empetrum nigrum var. japoni- of the other units. The Imperata cylindrica var. koenigii cum-Trifolium lupinaster community reported in the Bansei community in unit Sf was characterized by Imperata cylin- Beach in Hokkaido (Sato 2007). drica var. koenigii. The Linaria japonica-Vitex rotundifo- lia community (Sg) was characterized by Linaria japonica, Automatic classification by ISOPAM Artemisia capillaris, and Viola mandshurica f. crassa and Figure 1 shows the ISOPAM partitioning results. Six- corresponded to the Linario-Viticetum rotundifoliae Ohba, teen vegetation types were divided at partitioning level 5. Miyawaki et Tx. 1973 association. Figure 2 shows the relationship between the ISOPAM parti- The Juniperus conferta community (Sh) was character- tioning level and number of vegetation types. The number ized by Juniperus conferta. Ohba et al. (1973) proposed of vegetation types gradually increased with increasing par- two associations characterized by Juniperus conferta: Viti- titioning level but reached an inflection point at level 3. ci rotundifoliae-Juniperetum confertae Ohba, Miyawaki et Table 4 is the constancy table of the coastal vegetation ana- Tx. 1973, belonging to the class Viticetea rotundifoliae lyzed by ISOPAM. Type A was characterized by Ipomoea 74 Vegetation Science Vol. 38, No. 1, 2021

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 Sk Number of releve 1 2 4 5 114 21 14 7 38 13 12

Differential species of Cyrtomium falcatum subsp. falcatum-Litsea japonica community Pittosporum 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 community Melanthera biflora Kidachihamaguruma ･ 2 4 ･ ･ ･ ･ ･ ･ ･ ･ ･

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

Differential species of Vitex rotundifolia community Vitex 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 unit 1-2 1 Ipomoea pes-caprae Gumbaihirugao ･ ･ ･ Ⅲ ･ r ･ ･ ･ ･ ･ 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 unit Imperata cylindrica var. koenigii Chigaya ･ ･ 1 1 ･ r + Ⅴ +-5 Ⅱ 2-4 Ⅱ 1-2 Ⅰ +-2 ･ ･

Differential species of Linaria japonica-Vitex rotundifolia community Linaria 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 community Juniperus conferta Hainezu ･ ･ ･ ･ ･ ･ ･ Ⅴ 4-5 r 1 ･ ･

Differential species of Rosa rugosa community Rosa 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 unit Thermopsis 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 community Empetrum 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 + Traditional vs ISOPAM vegetation classification 75

Table 3. Continued.

Community type Sa Sb Sc Sd Se Sf Sg Sh Si Sj Sk Number of releve 1 2 4 5 114 21 14 7 38 13 12 Species of Glehnietea littoralis Calystegia 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 ･ ･

Companions Oenothera 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.

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- Fig. 2. Relationship between number of vegetation types and tuca rubra var. rubra units. partitioning level. Arrow indicates inflection point. Table 5 shows the relationships between vegetation types 76 Vegetation Science Vol. 38, No. 1, 2021

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 P Number 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 II Sonchus brachyotus Hachijona ･ ･ ･ ･ ･ r r ･ r ･ ･ II + + ･ ･ Artemisia stelleriana Shiroyomogi ･ ･ ･ r ･ r ･ ･ + ･ ･ II I + ･ ･

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

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

Festuca rubra var. rubra Oushinokegusa ･ ･ ･ ･ ･ r ･ ･ ･ ･ ･ ･ r I III IV Artemisia montana Oyomogi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + r I II IV Adenophora triphylla var. japonica Tsuriganeninjin ･ ･ ･ ･ ･ r ･ ･ ･ ･ ･ ･ ･ ･ II IV Rubus parvifolius Nawashiroichigo ･ ･ ･ r r ･ ･ ･ ･ ･ ･ ･ r II ･ III Polygonatum humile Himeizui ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + II III Thermopsis lupinoides Sendaihagi ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r I III Iris ensata var. spontanea Nohanashobu ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + III Arenaria lateriflora Oyamafusuma ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r I III III Achillea alpina var. longiligulata Nokogiriso ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ + r I II III Sanguisorba tenuifolia Nagabonowaremoko r ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ r III III Geranium yesoense var. pseudopalustre Hamafuro ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ ･ II III Calamagrostis 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 ･ ･ classified using ISOPAM and plant communities recognized cept for the Juniperus chinensis var. procumbens, Senecio by traditional tabular comparisons. Plant communities pseudoarnica and Setaria viridis var. pachystachys commu- with eight or more sites tended to correspond to one type nities. One vegetation type of ISOPAM sometimes corre- classified by ISOPAM, and Fisher’s exact tests showed sig- sponded to one plant community (e.g., types B or K) but of- nificant correspondence. No significant association was ten included two or three plant communities. Carex found for plant communities with seven or fewer sites, ex- kobomugi communities, which had relatively many points, Traditional vs ISOPAM vegetation classification 77

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).

Fisher’s Vegetation types A B C D E F G H I J K L M N O P exact test Plant communities which is a significant difference between the expected frequency Bb 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 frequency Sh 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 ･ ･ ･ ･ ･ － 78 Vegetation Science Vol. 38, No. 1, 2021 were divided into three types, namely G, H, and I, accord- cently been proposed (Tichý et al. 2019) and is likely to ing to the division of ISOPAM classification above level 4 make progress in the future. Generally, the accuracy and (Table 5; Figure 1). generalization performance of supervised machine-learning classification are determined by training data quality and quantity. It is therefore necessary not only to establish a ■ DISCUSSION classification system as a training label but also to deter- Comparison of automatic and traditional methods mine the character species and standard reference data and In this study, vegetation data collected from Japanese obtain a sufficient number of high-quality vegetation data beaches and dunes were classified into 53 communities us- for the future development of vegetation classification ing traditional phytosociological tabular comparisons and methods. 16 vegetation types via automatic ISOPAM classifica- tion. The large dataset containing data on dune vegetation Application of automatic classification to vegetation mainly consisted of plant communities belonging to the analysis Glehnietea littoralis, Honkenyo-Elymetea, and Viticetea ro- The results of the ISOPAM and traditional classification tundifoliae classes and Rosetalia rugosae order. The phy- approaches agreed except for vegetation types with few tosociological tabular comparison revealed that this dataset samples. This suggested that ISOPAM is suitable for pre- contained a small number of plant communities other than liminarily classifying vegetation and extracting broad pat- dune vegetation belonging to Pittosporion tobira alliance terns from large datasets. Compared to TWINSPAN (Hill (Camellietea japonicae class) and Farfugion japonici alli- 1979), which is widely used in vegetation science, ISOPAM ance (Artemisietea principis class). On the other hand, requires fewer parameters to be defined. Furthermore, the ISOPAM analysis classified most of the data as communi- default setting yields good classification results, which is a ties of dune vegetation and ignored community units with significant advantage when dealing with large datasets. few data recognized by traditional tabular compari- Researchers also need to select a distance for ISOMAP co- sons. Although the two classification approaches yielded ordination between individual survey points. In this study, roughly similar results, ISOPAM tended to combine multi- I obtained good results with the default setting of the Bray- ple community units into one vegetation type and split the Curtis distance. However, future studies should verify ap- same community with few data into several vegetation propriate distance measures. types. These results suggested that automatic classifica- ISOPAM classification divided a given vegetation dataset tion, which is superior in terms of speed and objectivity, did into 14 units at the third level and added two units at the not properly handle outliers that deviate from the overall fourth and fifth levels. Groups G and H separated at the pattern, unlike traditional manual tabular comparisons. fourth and fifth levels were characterized by the presence of Generally, coastal vegetation, such as dune vegetation, Carex kobomugi and Ixeris repens and the absence of Isch- has a small number of species per point and is susceptible aemum anthephoroides and Zoysia macrostachya, and it to invasion of species from adjacent communities (Carboni was difficult to recognize the differences between these et al. 2010; Malavasi et al. 2014). Traditional tabular groups. Group I showed the same species composi- comparison uses existing knowledge of community systems tion. All three units corresponded primarily to the Carex and their differential species to exclude data that deviate kobomugi community in traditional classification. These from the overall trend and treat data that include species results suggested that the vegetation type classified after de- from neighboring communities as subcommunities. On creasing the number of added units may be less significant the other hand, the automated classification method deter- in vegetation classification. mined the vegetation homogeneity based on the statistical distance between the position on the ordination. There- Effectiveness of and issues in vegetation databases fore, communities with few data, including species from In this study, I used a traditional tabular comparison ap- adjacent communities, might be merged into different vege- proach to extract plant communities from a national vegeta- tation types. Most previously proposed numerical meth- tion database and compared it with an automatic classifica- ods for vegetation classification are types of unsupervised tion approach. Most of the obtained plant communities classification because they only use the provided dataset. were consistent with the existing phytosociological classifi- Traditional tabular comparisons are similar to supervised cation system. However, some vegetation types, such as classification, because the classification is performed by -re the communities belonging to the Glehnietea littoralis class ferring to existing community systems. A machine-learn- and the Rosa rugosa community, did not coincide with the ing method that incorporates expert classification has re- existing associations but with association groups or allianc- Traditional vs ISOPAM vegetation classification 79 es set as higher units. Ohba et al. (1973) divided Rosa ru- M., et al. (Eds) 2012. Biodiversity & Ecology 4: Vegetation gosa-dominated vegetation into three associations: Viti Databases for the 21st Century. Hamburg: Biocentre Klein Flottbek and Botanical Garden. coignetiae-Rosetum rugosae, Elaeagno umbellatae-Rose- Hill, M.O. 1979. TWINSPAN: A FORTRAN Program for Ar- - tum rugosae, and Potentillo fragarioidis Rosetum rugo- ranging Multivariate Data in an Ordered Two-Way Table by sae. However, it was difficult to identify these associa- Classification of Individuals and Attributes. New York, tions from the national vegetation database. Jung (2000) NY: Cornell University. also reported only one community of Rosa rugosa-dominat- Itow, S. & Kawasato, H. 1980. The distribution and ecology of ed vegetation in the Korean Peninsula. This study further Juniperus procumbens Sieb. in Western Kyushu, Japan. The Journal of Phytogeography and Taxonomy, 28: 63-71 (In Japa- - revealed that the Ixerido Thuareion involutae alliance nese with an English summary). lacked many species of the Glehnietea littoralis class. Pig- Japanese Ministry of the Environment 2018. National vegetation natti (1996) investigated Ipomoea pes-caprae and Spinifex survey database (H.12-29 version). Available at http://gis.biodic. littoreus dominant vegetation on the coast of Thailand and go.jp/webgis/files/veg_survey_db_h12-29.pdf. [Accessed 20 March 2019] (In Japanese). proposed the Spinifici-Scaevoletea sericeae class and Can- Jung, Y.K. 2000. Rosetalia rugosae and Viticetea rotundifoliae in avalietalia maritimae order as upper units. Data collected South Korea. Vegetation Science, 17: 39-51. in both Japan and the Asia-Pacific region should be com- Kaufman, L. & Rousseeuw, P.J. 1990. Partitioning around Me- pared to establish a coastal beach and dune vegetation clas- doids (Program PAM). In: Kaufman, L. and Rousseeuw, P.J. sification system from a global perspective. (Eds), Finding Groups in Data: An Introduction to Cluster Anal- - Many recent studies have reported the Zoysietum sinicae ysis, Hoboken, NJ: John Wiley & Sons, pp. 68 125. Malavasi, M., Carboni, M., Cutini, M., Carranza, M.L. & Acosta, Ohba, Miyawali et Tx. 1973 association on the islands A.T.R. 2014. Landscape fragmentation, land-use legacy and around Okinawa and Amami (Terada & Ooya 2012a, propagule pressure promote plant invasion on coastal dunes: a b; Terada et al. 2014, 2016, 2019), but no relevant data patch-based approach. Landscape Ecology, 29: 1541-1550. were found in the national vegetation database. The data- Miyawaki, A., Murakami, Y., Suzuki, S. & Suzuki, K. 1986. 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