European Coastal Dune Vegetation Gets a sweeping Nomenclatural Makeover

Europe’s shifting and stable coastal dunes host some of the most iconic plant communities on the continent, from the marram grass that anchors the first dune ridge to the grey hair-grass swards of the inland dune plains. Yet the scientific names attached to these communities have long been a patchwork of corrections, synonyms and invalid designations. A new study published in the journal Vegetation Classification and Survey now delivers a comprehensive nomenclatural revision of the phytosociological syntaxa of European coastal dune vegetation, bringing the classification of three major vegetation classes into line with the fourth edition of the International Code of Phytosociological Nomenclature (ICPN).

The classes concerned are Ammophiletea arundinaceae, the vegetation of shifting dunes dominated by Ammophila arenaria subsp. arundinacea; Honckenyo peploidis-Elymetea arenarii, the communities of stable dune grasslands of northern Europe; and Koelerio glaucae-Corynephoretea canescentis, the grey dune vegetation of the Mediterranean and Atlantic coasts. The revision, carried out by a team led by Corrado Marcenò and colleagues, reviews the original diagnoses and descriptions of every syntaxon name in these classes, checks the name-giving taxa against the most authoritative recent floras and checklists, and proposes corrections, mutations and, in two cases, formal conservation of names.

Phytosociology, the science of classifying plant communities, uses a hierarchical system of syntaxa: classes, orders, alliances and associations. Each syntaxon name is formed from the scientific names of its characteristic species, the name-giving taxa, and is governed by the ICPN, which operates on the principle of priority: the earliest validly published name is the correct one, unless it is conserved or corrected. The revision follows the fourth edition of the ICPN published by Theurillat and colleagues in 2021, which refined the rules for validating, correcting and typifying syntaxon names.

One of the most consequential outcomes of the revision concerns the class Ammophiletea arundinaceae. The authors demonstrate that the order Ammophiletalia was already validly described by Braun-Blanquet in 1933, dealing with Mediterranean vegetation, and that the name Ammophiletalia Braun-Blanquet et Tüxen ex Westhoff et al. 1946, adopted by Mucina and colleagues in the EuroVegChecklist of 2016, is therefore a later synonym. Because only Ammophila arenaria subsp. arundinacea is listed in the original tables of Braun-Blanquet’s 1933 study, this subspecies is the unambiguous name-giving taxon of both the order and its holotype alliance, Ammophilion arundinaceae.

However, the alliance name Ammophilion arundinaceae Braun-Blanquet 1933 and the association Medicagini marinae-Ammophiletum arundinaceae Braun-Blanquet 1933 face a nomenclatural problem: under the ICPN, the correct names would be Ammophilion arenariae and Medicagini marinae-Ammophiletum arenariae, based on the 1921 publication by Braun-Blanquet. Because these widely used names would otherwise be displaced by older, less familiar forms, the authors submit two formal proposals (numbers 37 and 38) to conserve the names under Article 52 of the ICPN. Conservation proposals are reviewed by the European Vegetation Classification Committee (EVCC), the body established by the Working Group European Vegetation Survey of the International Association for Vegetation Science, which evaluates such requests according to established procedures before names are adopted on the European vegetation classification website floraveg.eu.

The revision also resolves a long-standing dispute over the alliance Ononidion ramosissimae Pignatti 1953. Various authors, including Rivas-Martínez and colleagues and Mucina and colleagues in the EuroVegChecklist, had considered this name invalid, either as a nomen dubium or because the bibliographical reference to Braun-Blanquet’s 1933 study was not in the same part of Pignatti’s work as the description of the alliance. The authors show, however, that Pignatti validly published the alliance by including the association Crucianelletum maritimae Braun-Blanquet 1933 with a sufficient bibliographical reference in the last part of his study. Consequently, Ononidion ramosissimae has priority over the later homotypic synonym Crucianellion maritimae Rivas Goday et Rivas-Martínez 1958, which had been considered the valid name.

Another significant correction involves the alliance Diantho attenuati-Scrophularion caninae, originally published as Diantho-Scrofularion humifusae by Baudière and Simonneau in 1974. The name-giving taxon Dianthus pyrenaicus subsp. catalaunicus must be corrected to Dianthus pyrenaicus subsp. attenuatus, because Nyman formally established the autonym Dianthus attenuatus Sm. subsp. attenuatus in 1878–1882, giving the epithet attenuatus nomenclatural priority over catalaunicus at the subspecies rank. Similarly, Scrophularia humifusa is treated as a synonym of Scrophularia canina in current taxonomic literature, prompting a mutation of the alliance name. The associated association Diantho attenuati-Corynephoretum canescentis is likewise corrected, and the authors demonstrate that the name is validly published because the original tables contain relevés with both Corynephorus canescens and Dianthus catalaunicus.

The revision also addresses the nomenclature of the northern European dune grasslands of the class Honckenyo peploidis-Elymetea arenarii. The order originally published as Elymetalia gigantei Vicherek 1971 must be corrected to Leymetalia racemosi, because Elymus giganteus Vahl is a later taxonomic synonym of Leymus racemosus, and the prevailing taxonomic approach assigns this species to the genus Leymus. The same reasoning applies to the alliance Leymion racemosi and the association Leymetum racemosi, both originally published by Morariu in 1957 as Elymion gigantei and Elymetum gigantei. In the class Honckenyo peploidis-Elymetea arenarii, the authors mutate the class name itself to reflect the current taxonomic treatment of Leymus arenarius, formerly Elymus arenarius, and correct the order name to Leymetalia arenarii, which takes priority over the later Honckenyo-Elymetalia arenarii Tüxen 1966.

The class Koelerio glaucae-Corynephoretea canescentis, the grey dune vegetation of the Mediterranean and Atlantic coasts, also receives substantial nomenclatural attention. The order Artemisio-Koelerietalia albescentis Sissingh 1974 is corrected to Artemisio crithmifoliae-Koelerietalia albescentis, because the correct name for Artemisia lloydii Rouy at the species level is Artemisia crithmifolia L. The authors note that while Flora Iberica accepts Artemisia crithmifolia as a species, other taxonomic works include it in Artemisia campestris subsp. maritima, but a mutation to Artemisio maritimae would be a source of confusion because there is also the accepted species name Artemisia maritima L. The alliance Euphorbio portlandicae-Helichrysion stoechadis and the association Artemisio crithmifoliae-Ephedretum distachyae are likewise corrected. The alliance Koelerion arenariae Tüxen 1937, originally published as Koelerion albescentis, is mutated because Koeleria albescens occurs exclusively on the Atlantic coastal dunes of France and Spain, whereas Koeleria arenaria has a wide range including the coastal areas of the Netherlands and Germany where the original relevés were sampled.

The revision also touches on the nomenclature of bryophytes and other taxa in the grey dune communities. The association Syntrichio ruraliformis-Phleetum arenarii, originally published by Braun-Blanquet and De Leeuw in 1936 as Tortula ruraliformis-Phleum arenarium-Assoziation, is mutated to reflect the current taxonomic treatment of the moss Syntrichia ruraliformis, formerly Tortula ruraliformis. Similarly, the alliance Syntrichio ruraliformis-Lomelosion argenteae and the association Syntrichio ruraliformis-Lomelosietum argenteae, originally published by Pignatti in 1952 as Tortuleto-Scabiosetum, are mutated to reflect the current treatment of Lomelosia argentea, formerly Scabiosa argentea. The authors note that while various floras include Scabiosa ucranica in the synonymy of Scabiosa argentea, they follow the taxonomic treatment used in Eastern European floras where these taxa are not considered conspecific, based on morphological characters and ecology.

The nomenclatural revision is more than an exercise in botanical bookkeeping. The syntaxa of European coastal dune vegetation are the reference units for conservation assessment, habitat mapping and monitoring across the continent, and unstable or ambiguous names undermine these applications. By aligning the classification with the fourth edition of the ICPN, checking every name-giving taxon against authoritative floras, and submitting two formal conservation proposals for the most widely used dune community names, the authors provide a stable nomenclatural foundation for the European vegetation classification. The revised syntaxonomic framework, including syntaxa with no nomenclatural issues that are officially accepted in the EuroVegChecklist, is presented in the appendices of the study, offering readers a comprehensive context and reaffirming the validity of the accepted names.

Subject of Research: Nomenclatural revision of European coastal dune vegetation syntaxa following the fourth edition of the International Code of Phytosociological Nomenclature

Article Title: Nomenclatural revision of the syntaxa of European coastal dune vegetation

Article References: Marcenò, C., Danihelka, J., Dziuba, T., Willner, W., & Chytrý, M. (2024). Nomenclatural revision of the syntaxa of European coastal dune vegetation. Vegetation Classification and Survey, 5, 27-37. https://doi.org/10.3897/vcs.108560

Image Credits: AI Generated

DOI: 10.3897/VCS.108560

Keywords: phytosociology, coastal dunes, vegetation classification, nomenclature, ICPN, Europe, Ammophiletea, Koelerio-Corynephoretea, Nomenclatural, revision, syntaxa, European