Botanists Seek a New Type for a Misunderstood Iberian Hazelnut Forest

A forest association in northwestern Spain has acquired a botanical identity that does not match its official name. The association Omphalodo nitidae-Coryletum avellanae was formally described in 1994 from nut-rich deciduous woods in the westernmost part of the Cantabrian Range, but its designated type specimen came from a different-looking ecosystem: a mature, mesophytic oak forest dominated by Quercus robur. Most of the plots supporting the association instead resembled low, secondary forests in which Corylus avellana, the common or European hazel, formed the principal canopy. A 2022 proposal in Vegetation Classification and Survey asks vegetation scientists to conserve the association’s established name while replacing its type with a representative plot of the hazel forest that later researchers have generally treated as the association’s true subject.

The case illustrates a specialized problem in plant community nomenclature. Unlike the naming of individual species, phytosociological nomenclature attaches names to recurring vegetation assemblages and relies on a type plot to anchor each name in a particular community. A type is intended to resolve ambiguity by showing which vegetation a name refers to. When subsequent fieldwork reveals that most records assigned to a name differ consistently from its original type, however, strict application of the rules can create a mismatch between the label used in scientific literature and the vegetation it formally represents. The authors of the proposal argue that this is precisely what happened with Omphalodo-Coryletum, whose original type was atypical of the association that the name came to designate.

The association was defined using 17 relevés from eastern Lugo province in Galicia, together with a synthetic column assembled from five records in the Terra de Lemos area of the Cabe River basin. These vegetation records documented forests approximately 8 to 10 metres high and generally dominated by hazel, often with a mixture of larger deciduous trees in an upper stratum. The communities also supported numerous shade-associated herbs, including hemicryptophytes and nemoral geophytes. Logging over roughly a century had left much of the sampled vegetation in an immature state, and the original authors interpreted these woods as seral communities that could develop through succession into a more diverse mixed oak forest or even a forest dominated by Quercus pyrenaica.

Most of the 17 records fit that concept of a hazel-dominated secondary forest. Hazel had combined Braun-Blanquet cover values of 4 or 5, meaning that it occupied either a large part of the ground or a clearly dominant share of the vegetation. Other species, including Acer pseudoplatanus, Fraxinus excelsior, Ilex aquifolium and Q. robur, could rise above the hazel canopy, but their cover did not exceed that of the hazel. The selected type relevé was different. It came from Cancelo in Triacastela, Lugo, at 820 metres above sea level, and was dominated by Q. robur with a cover value of 4. Hazel also had a cover value of 4 below the oak canopy, accompanied by Crataegus monogyna, Ilex aquifolium and a rich layer of nemoral herbs. The plot therefore represented a taller, structurally mesophytic oak forest rather than the characteristic physiognomy of the majority of the original records.

Later botanical work sharpened the distinction between the type and the broader body of observations. Studies of Atlantic Iberian forests increasingly separated pre-forest vegetation from mature climatic forests, recognizing that hazel woods can be autonomous pre-climactic communities rather than merely juvenile stages of larger forest types. In influential syntheses of Iberian vegetation, Omphalodo-Coryletum was assigned to the alliance Betulion fontqueri-celtibericae, a group established for pre-forest or “softwood” communities within the class Querco-Fagetea sylvaticae. The name consequently came to represent a seral hazel forest in the western Orocantabrian territory, while the original oak-dominated type was largely treated as an exceptional record. The same interpretation appeared in subsequent floristic inventories and in vegetation checklists for Spain and Portugal.

The proposed solution is based on Article 53 of the fourth edition of the International Code of Phytosociological Nomenclature. As described by the authors, the article permits a name to be maintained with a conserved type when its long-established interpretation has diverged from the original type. The authors are not proposing to abandon Omphalodo nitidae-Coryletum avellanae or rename the community. Instead, they seek a nomenclatural correction that would keep the widely used name and give it a type more consistent with prevailing scientific practice. Such proposals are significant because they can prevent an association name from becoming effectively tied to an atypical habitat while preserving continuity with the literature that has accumulated under that name.

The replacement type is relevé 4 in table 2 of the 1994 publication, rather than the original relevé 12. It was recorded between Moreda and Devesa da Rogueira in Folgoso do Courel, in the Courelian district of the western Orocantabrian sector, at 720 metres above sea level. The site has a 40-degree west-facing slope, 100 percent tree cover, a sampled area of 250 square metres and a total of 41 recorded taxa. Its tree layer includes Corylus avellana with a cover value of 5, together with Acer pseudoplatanus, Castanea sativa, Crataegus monogyna and Ilex aquifolium. The lower layers contain ferns, grasses, woodland herbs and characteristic nemoral plants, creating a structural profile closely aligned with the seral hazel forest recognized in subsequent research.

Several members of the proposed type show why the plot is ecologically informative rather than merely typical. Polystichum setiferum has a cover value of 4, while Hedera hibernica, treated in the record as a subspecies of H. helix, reaches 3. Omphalodes nitida, the species commemorated in the association’s name, is present, along with plants such as Helleborus foetidus, Sanicula europaea, Primula acaulis, Poa nemoralis, Stellaria holostea, Mercurialis perennis and Allium ursinum. The combination of a dense hazel canopy, scattered taller trees and a diverse shaded herb layer captures both the physiognomy and the ecological interpretation of Omphalodo-Coryletum that emerged after 1994. It therefore provides an anchor consistent with the name’s dominant and long-standing use.

Conservation of the new type would also preserve geographic coherence. The original association was defined in the western Orocantabrian subprovince, and nearly all of its original relevés fall in that biogeographical territory. Changes made to regional delimitations after the association was described did not significantly move the relevant western boundary, and the proposed type lies in the same western Orocantabrian sector as the earlier records. The authors therefore argue that the correction does not radically expand the association’s geographic scope or detach the name from its original area of description. Instead, it clarifies the internal relationship between a name, its type and the community consistently recognized under that name. The proposal is ultimately about making plant community taxonomy reflect observed vegetation accurately while allowing the accumulated botanical record to remain usable and internally coherent.

Subject of Research: Conservation of the phytosociological type for the Omphalodo nitidae-Coryletum avellanae forest association in northwestern Spain.

Article Title: Proposal (29) to conserve the name Omphalodo nitidae-Coryletum avellanae Amigo, G. Azcárate et Romero 1994 with a conserved type

Article References: Rodríguez-Guitián, M. A., & Amigo Vazquez, J. (2022). Proposal (29) to conserve the name Omphalodo nitidae-Coryletum avellanae Amigo, G. Azcárate et Romero 1994 with a conserved type. Vegetation Classification and Survey, 3, 145-148. https://doi.org/10.3897/vcs.76387

Image Credits: AI Generated

DOI: 10.3897/VCS.76387

Keywords: plant community nomenclature, phytosociology, conserved type, Omphalodo-Coryletum, hazel forests, Quercus robur, Cantabrian Range, Galicia, Orocantabrian vegetation, Iberian Peninsula, forest succession, International Code of Phytosociological Nomenclature