Search

The Caucasus Region belongs among the most remarkable biodiversity hotspots globally. Local mountain floodplain forests represent highly endangered ecosystems and possess the status of protective forests. However, they have not been extensively phytosociologically assessed using Braun-Blanquet methods to date. Here, we present a novel dataset of vegetation plots recorded in two remarkable areas of forest plant diversity in this region. They were Enguri (Black Sea watershed) and Aragvi (Caspian Sea watershed) River basins in the Western and Eastern Greater Caucasus, respectively. Based on 49 relevés, sampled on a broad elevation gradient (980-1830 m), we distinguished three vegetation types using unsupervised classification. Main gradients in their species composition reflect biogeographical and climatic differences. Alnus incana dominated two types. The Enguri type (Brunnero macrophyllae-Alnetum incanae) was characterized by numerous species typical of the western part of the Greater Caucasus, including tall forbs and mountain species. The Aragvi type (Veronico filiformis-Alnetum incanae) showed a diagnostic combination of common Caucasian species and relatively thermophilous forest species. The subdivision of this unit included three subtypes according to grazing intensity. The last type (Sedo stoloniferi-Alnetum barbatae) was significant by a putative Tertiary relict Alnus glutinosa subsp. barbata as a canopy dominant. It occupied lower elevations of the Enguri Region, significantly influenced by the nearby Colchic Region. To provide a regional context of the sampled vegetation, we compiled an expanded dataset of alluvial alder forests from the Caucasus and its surroundings. Their joint classification highlighted the uniqueness of the recorded communities with A. incana and clearly distinguished them from the Euxinian alliance Alnion barbatae delimited by relict species typical of the Colchic refugium (e.g. Diospyros lotus, Pterocarya fraxinifolia). A comparison of the Caucasian A. incana forests with the alluvial forests of the boreonemoral alliance Alnion incanae supported the individuality of the Caucasian stands in terms of floristic composition and allowed us to describe them as a new alliance (Veronico filiformis-Alnion incanae all. nova). It is characterized by the dominance of A. incana accompanied by numerous geographically restricted species (e.g. Senecio propinquus, Symphytum asperum) coupled with boreo-montane forest species (e.g. Oxalis acetosella, Polygonatum verticillatum). Caucasian alluvial forests face many ongoing threats, including constructing of new water reservoirs and hydropower plants, overgrazing and illegal cutting. [ABSTRACT FROM AUTHOR]

The Caucasus harbours unique forest vegetation so far only little studied using the Braun-Blanquet approach. This study is mostly based on a dataset (N = 110) of original phytosociological relevés of oak-hornbeam and ravine forests in the Eastern Greater Caucasus, Georgia. Their unsupervised classification produced seven communities. Five belong to oak-hornbeam forests (order Lathyro-Carpinetalia caucasicae). Of the zonal Caucasian alliance Crataego-Carpinion, the association Corno australis-Carpinetum inhabits valleys of the Greater Caucasus, and Clinopodio umbrosi-Carpinetum is confined to the warm Eastern Greater Caucasus promontories. The association Astrantio maximae-Carpinetum of the alliance Astrantio-Carpinion represents distinctive Caucasian montaneoak-hornbeam forests. The other two communities, documented by a few relevés, were described at the community level only. Within ravine forests (order Aceretalia pseudoplatani), we introduce a new Caucasian alliance Pachyphragmo macrophyllae-Tilion begoniifoliae with two associations. Valeriano tiliifoliae-Ulmetum glabrae comprises Caucasian montane ravine forests whereas Hedero pastuchovii-Aceretum velutini inhabits the foothills of the Eastern Greater Caucasian. To provide a broader context of the recognized communities, an expanded dataset (N = 231) of original relevés and previously published relevés of Georgian deciduous forests was analysed. It indicated a major turnover in species composition following biogeographical patterns presumably driven by macroclimate and vegetation history. [ABSTRACT FROM AUTHOR]

Aim: The aim of the paper is to describe species composition, ecology and syntaxonomy of unique mesophilous forests in Georgian Colchis in the context of the Euxinian forests. Location: SW Georgia, western part of the Caucasus Region, slopes of the Lesser Caucasus (80-990 m). Methods: Forest vegetation was sampled following the Braun-Blanquet approach and basic environmental characteristics were recorded for each relevé (n = 53). The dataset was clustered using modified TWINSPAN and diagnostic species for each cluster were defined by phi fidelity index. Links between the species composition of vegetation and environmental factors were analysed by detrended correspondence analysis. Numerical comparison of the distinguished clusters with previously published associations from northern Turkey was carried out (expanded dataset, n = 173). Results: Among the new relevés, we distinguished three vegetation types subsequently described as new associations: (i) Digitali schischkinii-Carpinetum betuli, chestnut-hornbeam forests of slightly dry sites, with low cover of evergreen shrubs, (ii) Rusco colchici-Castaneetum sativae, chestnut-hornbeam forests with a dense evergreen shrub layer, and (iii) Polysticho woronowii-Ulmetum glabrae, ravine forests with noble hardwood trees and ravine forest specialists. These associations were classified to the alliances of Euxinian forests, the first two to Castaneo-Carpinion and the third to Alnion barbatae. Major turnover in species composition within the dataset followed gradients of rockiness, slope inclination, altitude and mean annual temperature. The analysis of the expanded dataset revealed a decreasing occurrence of Mediterranean species and an increasing number of fern species along an easterly gradient. This change in species composition is likely to be driven by macroclimatic gradients. Conclusions: This paper presents the first numerical comparison of chestnut-hornbeam and ravine forests across central and eastern parts of the Euxinian Province. Our results have highlighted the uniqueness of Georgian Colchic forests, described as new associations, in the context of Euxinian forest vegetation. [ABSTRACT FROM AUTHOR]

An Correction to this paper has been published: https://doi.org/10.1007/s12224-021-09391-x [ABSTRACT FROM AUTHOR]

Questions: What are the main vegetation types of forest and shrubland vegetation in central and eastern Euxine Turkey and SW Georgia? What are the main environmental factors affecting their diversity? What is their syntaxonomic position? Can we integrate them into the European vegetation classification system? Location: Central and eastern Euxine Turkey and SW Georgia. Methods: We collected 3104 vegetation plots of forest and shrubland vegetation in the study region and performed Two‐Way Indicator Species Analysis (TWINSPAN) classification. We described vegetation types based on the classification results, expert knowledge and information from literature sources. We defined diagnostic species and prepared distribution maps for each vegetation type. To determine the most significant environmental variables on floristic differentiation, we used canonical correspondence analysis. Detrended correspondence analysis with passive projection of most significant environmental variables was run to interpret the environmental variation of vegetation types. Results: The studied vegetation was divided into 29 vegetation types related to seven main vegetation groups: relict Mediterranean forests and shrubland (mainly along the coastline, beside some inland localities), lowland to submontane forests, central Euxine mountain forests, eastern Euxine (Colchic) mountain forests, subeuxine forests, azonal riparian forests and subalpine and alpine shrubland. Elevation is the most important factor causing the differentiation in vegetation. It is followed by longitude and latitude. Among climatic variables, temperature seasonality, annual precipitation and precipitation of the wettest quarter are the most significant factors for vegetation differentiation. These factors correlate with the reduction of maritime climate and geomorphological features. Conclusions: Vegetation types mostly correspond to the syntaxa accepted in the EuroVegChecklist. However, some of them do not appear in the EuroVegChecklist since they appear only beyond Europe. We described three syntaxa as new: Abietion equi‐trojani, Querco cerridis‐Carpinion orientalis and Piceo orientalis‐Fagenion orientalis. The study revealed high vegetation diversity of the region that should be taken into consideration in ecosystem management and used as a reference in restoration and mitigation of the effects of global changes. [ABSTRACT FROM AUTHOR]

Please be informed that the wrong table was inadvertently published in the following paper [ABSTRACT FROM AUTHOR]