Vegetation plots yield first syntaxonomic classification of Armenia’s dry grasslands and thorn-cushion communities

A plot-based classification study has produced the first syntaxonomic scheme for dry grasslands and thorn-cushion communities in Armenia. Researchers analyzed 111 vegetation plots and distinguished 12 clusters: one was a single-plot scree community that could not be assigned confidently, while the remaining clusters were interpreted at association level as formally described associations or, where supported by fewer than 10 relevés, informal communities. The fieldwork was conducted during the Eurasian Dry Grassland Group’s 13th Field Workshop from 26 June to 6 July 2019.

Investigators sampled 10-square-metre plots in five of Armenia’s 11 administrative provinces and seven of its 12 floristic regions, concentrating on northwestern and central areas and an elevation range of 1,338–2,350 metres above sea level. Each plot included records of vascular plants, terricolous bryophytes and lichens, along with plant cover, vegetation structure, land use and soil properties. The resulting species-composition and plot data were deposited in GrassPlot as the dataset “AM_B” and made available in the study’s supplementary materials.

This was an observational vegetation-classification study, not an experimental trial or review. The researchers used modified TWINSPAN, an unsupervised classification method, to identify floristically differentiated clusters and used phi values to determine diagnostic species at the association, alliance, order and class levels. Detrended correspondence analysis assessed relationships between plant composition, elevation, climate and measured site variables.

For regional comparison, the Armenian observations were combined with 487 plots from Turkey, northern Iran and the northern Caucasus, yielding 598 relevés and 1,556 taxa after taxonomic standardization. Most were assigned to the established Festuco-Brometea, which represented meso-xeric and xeric grasslands and mountain steppes at higher elevations. The other major group contained lower-elevation semi-deserts, dry grasslands and xeric thorn-cushion communities.

The researchers provisionally named this group the “Ziziphora tenuior–Stipa arabica grasslands,” but did not formally describe it as a class because a broader regional analysis would be needed to establish its rank beyond Armenia. Within Festuco-Brometea, the study recognized the order Plantagini atratae–Bromopsietalia variegatae for high-mountain meadow-steppe communities. It included the formally described Ranunculo caucasici–Bromopsietum variegatae association and the informal Tragopogon reticulatus–Astracantha aurea community.

A second order, Onobrychido transcaucasicae–Stipetalia pulcherrimae, represented Transcaucasian mountain steppes through one alliance, two informal communities and two formally described associations. The lower-elevation potential new class was organized into one order and three alliances covering rocky dry grasslands, wormwood semi-deserts, and highland xerophytic vegetation with thorn cushions. Five alliances were recognized across the Armenian scheme.

Only Artemisio chamaemelifoliae–Bromopsion variegatae had previously been described, from the northern Caucasus. Most of the other units were described as new to science, including the orders and alliances and several associations. In addition to the single unassigned scree plot near Hermon, the classification included the formally described Marrubio parviflorae–Stipetum capillatae, Noaeo mucronatae–Artemisietum fragrantis and Acantholimono caryophyllacei–Stipetum holosericeae associations, as well as several communities that were left informal because they had fewer than 10 relevés.

Ordination associated the principal separation among the Armenian plots with a moisture-and-temperature gradient linked to elevation. Drier communities occurred at lower elevations, while more mesic communities were concentrated higher up. Festuco-Brometea communities generally had greater herb-layer and litter cover and a higher proportion of hemicryptophytes, whereas the lower-elevation group had more therophytes and chamaephytes.

The Plantagini atratae–Bromopsietalia variegatae order occurred on slightly acidic soils with a mean pH of about 6.5, while many communities in the other group occupied neutral to slightly alkaline soils. Across all 111 plots, researchers recorded 739 vascular-plant taxa, 40 bryophyte taxa and 13 lichen taxa. Total species richness ranged from 21 to 85 species per plot, with a mean of 47.3, including averages of 46.8 vascular-plant species, 0.4 bryophyte species and 0.1 lichen species.

Galium verum was the most frequent vascular plant, appearing in 72% of plots, followed by Thymus kotschyanus in 59% and Teucrium capitatum in 58%. Total richness did not differ significantly between the two major class-level groups, although some individual association-level communities differed. The study’s geographic and taxonomic coverage limits the completeness of the scheme.

Sampling covered only five provinces and seven floristic regions, and the single scree plot near Hermon could not be assigned to an existing class. The authors said additional Armenian plots would be needed to complete the system and confirm diagnostic species, while the potential Ziziphora tenuior–Stipa arabica class would require validation through a broader plot-based analysis of the Caucasus, Anatolia and northern Iran.

Subject of Research: Syntaxonomic classification of Armenian dry grasslands and thorn-cushion vegetation based on 111 vegetation plots

Article Title: Dry grasslands and thorn-cushion communities of Armenia: a first syntaxonomic classification

Article References: Vynokurov, D., Aleksanyan, A., Becker, T., Biurrun, I., Borovyk, D., Fayvush, G., García-Mijangos, I., Magnes, M., Palpurina, S., Becker, U., Berastegi, A., Cykowska-Marzencka, B., Dembicz, I., Frank, D., Hilpold, A., Kirschner, P., Mayrhofer, H., Oganesian, M., Vasheniak, I., & Dengler, J. (2024). Dry grasslands and thorn-cushion communities of Armenia: a first syntaxonomic classification. Vegetation Classification and Survey, 5, 39-73. https://doi.org/10.3897/vcs.119253

Image Credits: AI Generated

DOI: 10.3897/VCS.119253

Keywords: Armenia, dry grasslands, thorn-cushion communities, syntaxonomy, vegetation plots, TWINSPAN, plant communities, Caucasus, Irano-Turanian region, grasslands, thorn-cushion, communities