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Acta Botanica Croatica, Vol. 79 No. 2, 2020.

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https://doi.org/10.37427/botcro-2020-017

Phytosociological study of submontane genistoid scrub communities from the Southeastern Balkans

Georgi Kunev ; Department of Ecology and Environmental Protection, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., BG–1164 Sofia, Bulgaria
Rossen Tzonev ; Department of Ecology and Environmental Protection, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., BG–1164 Sofia, Bulgaria
Ioannis Tsiripidis ; Department of Botany, Aristotle University of Thessaloniki, GR–54124, Thessaloniki, Greece
Kalina Pachedjieva ; Department of Ecology and Environmental Protection, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., BG–1164 Sofia, Bulgaria

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Sažetak

Genista lydia Boiss. is an endemic Balkan-Anatolian species which forms rare communities in the territory of south Bulgaria and northeast Greece. They are spread exclusively on acidic, siliceous substrates. This study presents new data on their distribution, floristic and ecological structure and phytosociological affinities. The research is based on 156 phytosociological relevés. Unweighted pair–group method with arithmetic averages (UPGMA) was employed and a detrended correspondence analysis (DCA) was performed prior to the syntaxonomical decision. Three new associations and the new alliance Genistion lydiae have been described and classified within the order Lavandulo stoechadis-Hypericetalia olympici Mucina in Mucina et al. 2016 of the class Cisto-Lavanduletea stoechadis Br.-Bl. in Br.-Bl. et al. 1940. The study has also emphazised the potential threats concerning a decline of the habitat area and proposed some conservation measures.

Ključne riječi

Cisto-Lavanduletea stoechadis; Genistion lydiae; grazing impact; shrub vegetation; vulnerable habitat types

Hrčak ID:

239827

URI

https://hrcak.srce.hr/239827

Datum izdavanja:

1.10.2020.

Posjeta: 1.816 *

Publication date (print and electronic): October 2020

Volume: 79

Issue: 2

Pages: 170-184

Publisher ID: ABC-79-170

DOI: 10.37427/botcro-2020-017

Article Information (continued)

Categories:

Subject: Full articles

Key words: :

Key words:

Keyword: Cisto-Lavanduletea stoechadis

Keyword: Genistion lydiae

Keyword: grazing impact

Keyword: shrub vegetation

Keyword: vulnerable habitat types

Phytosociological study of submontane genistoid scrub communities from the Southeastern Balkans

Georgi Kunev[1][*]

Rossen Tzonev[1]

Ioannis Tsiripidis[2]

Kalina Pachedjieva[1]

 

[1] Department of Ecology and Environmental Protection, Faculty of Biology, Sofia University “St. Kliment Ohridski”, 8 Dragan Tzankov Blvd., BG–1164 Sofia, Bulgaria

[2] Department of Botany, Aristotle University of Thessaloniki, GR–54124, Thessaloniki, Greece

Author notes:

Correspondence to: [*] Corresponding author e-mail: gorokunev@abv.bg

Abstract

Genista lydia Boiss. is an endemic Balkan-Anatolian species which forms rare communities in the territory of south Bulgaria and northeast Greece. They are spread exclusively on acidic, siliceous substrates. This study presents new data on their distribution, floristic and ecological structure and phytosociological affinities. The research is based on 156 phytosociological relevés. Unweighted pair–group method with arithmetic averages (UPGMA) was employed and a detrended correspondence analysis (DCA) was performed prior to the syntaxonomical decision. Three new associations and the new alliance Genistion lydiae have been described and classified within the order Lavandulo stoechadis-Hypericetalia olympici Mucina in Mucina et al. 2016 of the class Cisto-Lavanduletea stoechadis Br.-Bl. in Br.-Bl. et al. 1940. The study has also emphazised the potential threats concerning a decline of the habitat area and proposed some conservation measures.

Introduction

The communities of Genista lydia Boiss. and G. rumelica Velen. represent indigenous and rare vegetation described from the Southern Balkans and mostly south Bulgaria (Bondev 1991). The dominant species are low shrubs, with erect or ascending branches, which lose their leaves during the summer drought (Kuzmanov 1976,Strid 1986). According to the Bulgarian floristic literature G. lydia is clearly distinguished from G. rumelica at species level (Kuzmanov 1976,Evstatieva et al. 2004, Delipavlov and Chesmedzhiev 2011). However, for the purpose of the study, a broader description of G. lydia (incl. G. rumelica) has been adopted, one that seems more widely accepted at present (Strid 1986,Zieliński et al. 2004,Roskov et al. 2006,Dimopoulos et al. 2013,The Plant List 2013).

Those communities are floristically rich and occur in the transitional (sub-Mediterranean) zone, influenced by Mediterranean and Continental (Temperate) climate. Because of the rarity and vulnerability of this vegetation type, it was assessed for the national (Tzonev and Gussev 2015) and European (Janssen et al. 2016) Red Data Books of Habitat Types.

The communities dominated by G. lydia have been presented (Velčev and Bondev 1984a) as an original and typical part of the Balkan vegetation. These communities are strongly influenced by anthropogenic activities and have a very limited range and for these reasons, they have been determined as "Endangered" (Velčev and Bondev 1984b). More data on their distribution in Bulgaria have been published in the vegetation map of Bulgaria (1:600 000) (Bondev 1991).Bondev (1991) has also concluded that those communities are of secondary origin, because they often replace destroyed xerothermic oak or black pine forests.

The most detailed studies on the G. lydia communities, have been focused on their habitat types and their floristic and ecological structure and their range (Tzonev and Gussev 2015,Janssen et al. 2016,Kunev and Tzonev 2019). In those studies, this habitat type is described as mosaic vegetation composed of shrub, herbaceous and chasmophytic plants, typical of the Balkan regions, influenced by the transitional continental-Mediterranean climate.

Despite comparatively detailed information at the habitat level, the syntaxonomic position of this vegetation type is still indefinite. In general, different plant communities dominated by or with a high abundance of Genista species are widespread in the Mediterranean regions of Europe. Most of these communities occupying siliceous substrates were classified within the Calluno-Ulicetea, Cytisetea scopario-striati and Cisto-Lavanduletea classes (Rivas-Martínez et al. 2002;Gianguzzi et al. 2015). For example, some associations have been recorded from the Balkans, such as the association Genisto-Ericetum manipuliflorae Horvatić 1958 from the Croatian coastal region (Horvatić 1958) or the shrub communities of the association Genisto acanthocladae-Ouercetum cocciferae Dimopoulos et al. 1996 from Peloponnisos, Southern Greece (Dimopoulos et al. 1996). The species Genista januensis Viv. demonstrates great morphological similarity and is also closely related to G. lydia. Genista januensis typically inhabits forest fringes and open woodlands dominated by Quercus pubescens and Carpinus orientalis in some regions of west Bulgaria (Tzonev et al. 2019). It is also diagnostic species to the basophilic Pinus sylvestris and P. nigra forests of the Southeastern and Dinaric Alps (Genisto januensis-Pinetum Tomažič 1940) (Chiapella and Longo 1987,Dakskobler 1999).

However, after the first assessment for the Red List of European habitat types (Janssen et al. 2016), Bulgaria and Greece were the only countries that provided information on the scrub vegetation dominated by G. lydia. Therefore, its occurrence in other Balkan countries or Western Anatolia continues to be unclear.

The aim of this study is to propose a new syntaxonomic framework for G. lydia communities, based on abundant phytosociological material collected from south Bulgaria and northeastern Greece.

Material and methods

The principles and methods of the study follow the Braun-Blanquet phytosociological approach (Braun-Blanquet 1964). The plant communities of Genista lydia were sampled between March and October of the years 2016 to 2018. All localities of the dominant species in Bulgaria known from the literature data and herbaria collections have been visited. The localities of the studied communities in Greece were provided by one of the authors. In these areas, relevés were set in places where the coverage of the species exceeded 30%. In total, 156 unpublished phytosociological relevés were used in the present study. Their plot sizes vary between 16 and 25 m2. At each sampling plot, a complete list of vascular plants, mosses and lichens taxa was made together with their cover–abundance values according to the 9–degree modified Br-Bl scale. The Braun-Blanquet categories were transformed to ordinal numbers from 1 to 9 for further statistical analysis (van der Maarel 1979). The data set was subjected to hierarchical classification by the SYN–TAX program (Podani 2001). The unweighted pair–group method with arithmetic averages (UPGMA) as an average–linkage type of clustering algorithm was used as clustering method. The floristic similarity between relevés in the dissimilarity matrix was calculated by using Horn’s index (seePodani 2001). Five relevés from the dendrogram of the cluster analysis were not considered in further analysis since they represented strongly ruderalized stands. Some of these plots were set within the built-up area of the town of Plovdiv, while others were placed in abandoned vineyards. Diagnostic species of each cluster were determined on the basis of their fidelity (phi) measures using the phi coefficient of association between groups (Chytrý et al. 2002) in the JUICE 7.0 program (Tichý 2002). The size of target groups was fixed at 25% of the total data set. The threshold phi value for the diagnostic species was set at 0.30 and Fisher’s exact test was calculated to exclude those species from diagnostic ones when their fidelity was not statistically significant (P < 0.001). The results of the classification are summarized inTab. 1, in which the diagnostic species are ranked according to decreasing fidelity. Species are considered as constant if their frequency exceeded 50% for a given group, and species with cover higher than 50% in a minimum of 5% of relevés were considered to be dominant. New syntaxa are named according to the rules of the 3rd edition of the International Code of Phytosociological Nomenclature (Weber et al. 2000). Syntaxonomic nomenclature followsMucina et al. (2016).

Tab. 1 Frequency–fidelity synoptic table of the communities of Genista lydia. Frequencies of species are presented as percentages with phi values multiplied by 100 in superscript (group sizes were equalized before the calculation of phi values). Diagnostic species of each cluster are shaded and ranked by decreasing fidelity. Only species with phi values higher than 0.30 are considered to be diagnostic. Species with less than 20% frequency in the whole data set have been omitted.
Group No.1234
No. of releves7954144
No. of species with less than 20% occurrence32927210861
Diantho pinifolii-Genistetum lydiae
Centaurea rhenana ssp. rhenana8282.2.---14---.---
Sedum grisebachii2443.8.---.---.---
Asperula aristata ssp. scabra7040.231---.---25---
Anthemis tenuiloba2337.---7---.---
Thymus longicaulis4932.811---43---.---
Dianthus pinifolius ssp. pinifolius3931.611---14---.---
Romuleo graecae-Genistetum lydiae
Romulea linaresii ssp. graeca.---7080.---.---
Tuberaria guttata.---5065.5.---.---
Cerastium gracile.---5065.5.---.---
Trifolium tenuifolium.---4158.3.---.---
Erodium botrys.---3755.3.---.---
Dianthus corymbosus.---2645.6.---.---
Galio flavescentis-Genistetum lydiae
Anthemis cretica.---.---7180.8.---
Sempervivum erythraeum4---.---5765.---
Hypericum montbretii.---4---5061.3.---
Galium flavescens.---.---4360.---
Verbascum humile9---.---5052.6.---
Plantago subulata4126.62---7142.7.---
Lembotropis nigricans.---.---2141.2.---
Genista lydia and Satureja pilosa community
Satureja pilosa.---.---7---7581.6
Crucianella angustifolia3---.---7---7578.6
Linaria simplex.---.---.---5065.5
Cionura erecta.---.---.---5065.5
Geranium purpureum.---.---.---5065.5
Genistion lydiae
Genista lydia100---100---100---100---
Minuartia hirsuta ssp. falcata3530.36---29---.---
Centaurea cuneifolia8---4844.87---25---
Viola tricolor ssp. macedonica20---26---.---25---
Rorippa thracica25---11---21---.---
Lavandulo stoechadis-Hypericetalia olympici Mucina et 2016 and Cisto-Lavanduletea stoechadis Br.-Bl. in Br.-Bl. et al. 1940
Hypericum olympicum32---24---21---.---
Genista carinalis22---11---.---.---
Vicia lathyroides16---13---.---.---
Stachys angustifolia19---4---7---.---
Campanula lingulata18---4---.---.---
Cistus creticus.---1938.2.---.---
Thymus sibthorpii10---2---.---.---
Festuco-Brometea Br.-Bl. et Tx. ex Soó 1947
Eryngium campestre58---8731.4.---100---
Festuca valesiaca8142.841---7---.---
Sanguisorba minor48---7025.2.---50---
Teucrium chamaedrys5824.841---.---.---
Cruciata pedemontana56---41---.---.---
Hieracium hoppeanum49---28---43---.---
Chrysopogon gryllus23---7651.67---.---
Euphorbia cyparissias43---24---21---100---
Scabiosa triniifolia39---24---29---.---
Achillea coarctata4844.62---36---.---
Hypericum perforatum39---7---64---.---
Dichanthium ischaemum32---33---.---.---
Thymus glabrescens29---35---.---.---
Koeleria macrantha5367.8.---.---.---
Luzula campestris20---31---.---.---
Phleum montanum3844.1.---21---.---
Helianthemetea guttati Rivas Goday et Rivas-Mart. 1963
Aira elegantissima33---6936.37---.---
Trifolium arvense41---31---14---75---
Cerastium brachypetalum27---46---.---.---
Cynosurus echinatus29---39---14---.---
Galium divaricatum35---31---.---25---
Linaria pelisseriana14---4132.7.---.---
Teesdalia coronopifolia16---35---7---.---
Hypochaeris glabra8---3736.57---.---
Vulpia myuros13---31---.---.---
Crupina vulgaris18---20---14---.---
Trifolium strictum8---3031.2.---.---
Ornithopus compressus.---3956.8.---.---
Myosotis stricta8---2627.2.---.---
Vulpia ciliata.---3553.8.---.---
Trifolium cherleri1---2641.6.---.---
Trifolium striatum ssp. striatum16---4---.---.---
Alyssum minutum13---4---.---50---
Sedum rubens5---13---.---75---
Koelerio–Corynephoretea Klika in Klika et Novák 1941 and Sedo–Scleranthetea Br.–Bl. 1955
Cladonia foliacea65---52---10039.4.---
Rumex acetosella34---59---64---.---
Trifolium campestre5735.924---7---.---
Potentilla argentea44---30---.---.---
Bromus squarrosus4627.520---.---50---
Potentilla neglecta4639.811---7---.---
Myosotis ramosissima32---26---14---.---
Moenchia mantica11---5041.114---.---
Scleranthus perennis29---15---43---.---
Petrorhagia prolifera14---35---7---50---
Filago vulgaris22---26---.---.---
Chondrilla juncea24---15---.---100---
Cerastium pumilum3448.22---.---.---
Racomitrium canescens24---9---14---.---
Veronica praecox16---19---.---.---
Scabiosa argentea16---15---.---.---
Other species with high frequency
Poa bulbosa51---8330.536---50---
Plantago lanceolata51---52---7---.---
Anthoxanthum odoratum30---6935.229---.---
Galium verum33---41---.---.---
Agrostis capillaris5458.3.---21---.---
Euphorbia niciciana16---4427.2.---100---
Geranium columbinum22---39---7---.---
Leontodon crispus322911---.---.---
Poa compressa28---15---.---.---
Sherardia arvensis4---5057.2.---.---
Hieracium bauhinii23---19---14---.---
Dianthus giganteus ssp. giganteus3335.94---14---.---

Vegetation groups are described on the basis of their diagnostic, constant and dominant species in the “Results” section. The values of fidelity, relative frequency and number of relevés for dominants with at least 50% cover are given in brackets for diagnostic, constant and dominant species respectively. In addition to the syntaxa names of the groups, their geographical names are also included according to the proposal on the subdivision of the habitat S3-4 Balkan-Anatolian submontane genistoid scrub from the EUNIS habitat classification into three subhabitat types: S3-41 Balkan-Range submontane genistoid scrub, S3-42 Thracian submontane genistoid scrub and S3-43 Rilo-Rhodopean submontane genistoid scrub (Schaminée et al. 2019;Kunev and Tzonev 2019).

For the visualization and interpretation of the relevé groups, a detrended correspondence analysis (DCA) was performed using the vegan 2.5–3 package for R (https://cran.r–project.org/web/packages/vegan/index.html). All 151 relevés, together with the diagnostic species given in the synoptic table and selected ecological variables, were projected onto two–dimensional ordination space of DCA, with centroids calculated for each of the four clusters. Species ecological indicator values (EIVs) for temperature, light, moisture, continentality, soil reaction and nutrients (Pignatti et al. 2005) and selected bioclimatic variables from the WorldClim database (Fick and Hijmans 2017) were used as explanatory ecological variables. EIVs were calculated as unweighted average indicator values of taxa for each relevé. All bioclimatic variables available in the WorldClim database were extracted for each relevé on the basis of their geographical coordinates and with the use of the finest spatial resolution provided (30 seconds; ~1 km2). The possible effect of climatic variables on the vegetation composition was tested by using canonical correspondence analysis (CCA) in CANOCO 5.0 software (Ter Braak and Šmilauer 2012) using the global Monte-Carlo permutation test with 999 permutations. Forward selection together with Monte-Carlo permutation test was used to indicate the bioclimatic variables most effective on species composition. Rare species were down-weighted in CCA. In both ordination techniques the digital cover–abundance values (numbers from 1 to 9) were used without any further transformation. The three bioclimatic variables with the highest explanatory value calculated in CCA were selected and together with the EIVs according toPignatti et al. (2005) were passively projected onto the DCA-ordination diagram.

The taxonomic nomenclature of the vascular plants followsDelipavlov and Chesmedzhiev (2011), except for the genera Juniperus L., Genista L., Cistus L., Anthemis L., Tolpis Adans. and Tripleurospermum Sch. Bip., for which some additional sources were used, mostly from other Bulgarian floras (Jordanov et al. 1963-2012;Assyov and Petrova 2012) or occasionally, on-line databases (Roskov et al. 2006,The Plant List 2013, Euro+Med 2006-2018). Nomenclature of mosses followsHill et al. (2006); lichens are given afterMayrhofer et al. (2005). Chorological and life-form spectra were calculated for each vegetation unit and are presented as percentages on the basis of presence of a species (On–line Suppl. Tab. 1). The chorotypes were initially indicated in accordance withAssyov and Petrova (2012) and then grouped in 10 larger categories for better representation of the general trends in the phytogeographical relationships. The chorotypes of lichens and mosses have not been included in these calculations due to insignificant species richness of these taxa in the communities of Genista lydia. The biological spectrum is presented following the classification ofRaunkiær (1934). The endemic taxa are given afterPetrova and Vladimirov (2010),Assyov and Petrova (2012) and Euro+Med PlantBase (2006-2018). The soil types and composition of the bedrock outcrops are presented in accordance with the soil (Ninov 2002) and the geological map of Bulgaria (Cheshitev and Kânčev 1989). Analysis of representative soil samples taken from selected relevés were performed in an authorized laboratory – NIK Agro Service Ltd. The samples were analyzed (seeTeoharov et al. 2009) in accordance with ISO standards as follows: pH (ISO 10390), specific electrical conductivity (ISO 11265), total organic carbon (ISO 10694) and carbonate content (ISO 10693).

Results

The floristic composition of the communities of Genista lydia is very rich and includes 580 taxa. The average number of species per plot is 46. The mean vegetation cover is 80.14%. The elevation is significantly variable, ranging between 150 and 1500 m a.s.l. The slope inclination varies between 1°- 60° (mean 10°), while the exposure is most frequently southern. The soil sample analysis (Tab. 2) demonstrates that in most localities the soils have a sandy texture. They are slightly to moderately acidic (pH 5.02 – 7.13), with conductivity ranges between 0.02 and 0.13 dS m-1, while the carbonate content is represented only as traces. The amount of soil organic carbon varies significantly (0.24 to 10.03%), although it rarely exceeds (3%), which is an indicator for their low nutrition content.

Tab. 2 Soil properties of representative plots occupied by the communities of Genista lydia. EC – specific electrical conductivity (dS m-1), and C org – total organic carbon content (%). Group 1 – Diantho pinifolii-Genistetum lydiae, Group 2 – Romuleo graecae-Genistetum lydiae, Group 3 – Galio flavescentis-Genistetum lydiae.
Relevé no.Soil depth (cm)pHEC (dS m-1)C org
(%)		CaCO3 (%)
Group 15915-306.660.020.450.41
6515-306.480.020.4Traces
700-55.080.099.22Traces
710-56.090.031.850.03
1005-156.650.020.440.08
1025-156.220.020.7Traces
1110-56.80.020.46Traces
11215-305.380.021.79Traces
1195-157.130.020.24Traces
Group 21315-305.390.021.65Traces
1140-56.520.040.51Traces
1335-155.620.022.61Traces
Group 31280-55.340.138.99.57
1350-55.020.0710.03Traces

The cluster analysis resulted in the distinction of four groups (Fig. 1). Two of them are found only in the territory of Bulgaria, while the rest are also found in Northern Greece. These four units are geographically, ecologically and floristically well defined. The differences between them are also supported by the DCA-ordination diagram (Fig. 2). The interpretation of the DCA-diagram is assisted by the passively projected EIVs and the three bioclimatic variables with the highest explanatory value. Analysis with forward selection in CCA provided a ranking of the relative importance of the tested bioclimatic variables (On–line Suppl. Tab. 2). All 19 bioclimatic variables were statistically significant (P < 0.001) and explained 31.19% of the total variance of the data set. The three with strongest effect on vegetation composition are precipitaton of warmest quarter (Bio 18), precipitation seasonality (Bio 15) and mean temperature of coldest quarter (Bio 11).

Fig. 1 Cluster dendrogram of Genista lydia communities. Group 1 – Diantho pinifolii-Genistetum lydiae, Group 2 – Romuleo graecae-Genistetum lydiae, Group 3 – Galio flavescentis-Genistetum lydiae, Group 4 (G4) – Genista lydia-Satureja pilosa communities, X – excluded plots.
ABC-79-170-f1
Fig. 2 Detrended correspondence analysis (DCA) spider-plot of the151 relevés classified in the four groups distinguished. The length of the first DCA axis is 3.31 SD units, while of the second axis 3.80 SD units. Numbers refer to the centroids of vegetation groups corresponding to: 1 – Diantho pinifolii-Genistetum lydiae, 2 – Romuleo graecae-Genistetum lydiae, 3 – Galio flavescentis-Genistetum lydiae, 4 – Genista lydia-Satureja pilosa communities. Ecological indicator values and bioclimatic variables are represented by arrows (temp - temperature, light - light, pH - soil reaction, cont – continentality, moist – moisture, nutr – nutrients, Bio 15 – precipitation seasonality, Bio 11 – mean temperature of coldest quarter, Bio 18 – precipitation of warmest quarter). Diagnostic species for the relevant groups are represented by dots and abbreviated names as follows: Anthcre – Anthemis cretica, Anthten – Anthemis tenuiloba, Aspesca – Asperula aristata ssp. scabra, Centrhe – Centaurea rhenana ssp. rhenana, Ceragra – Cerastium gracile, Cionere – Cionura erecta, Crucang − Crucianella angustifolia, Diancor – Dianthus corymbosus, Dianpin – Dianthus pinifolius ssp. pinifolius, Erodbot – Erodium botrys, Galifla – Galium flavescens, Genicar – Genista carinalis, Genilyd – Genista lydia agg., Gerapur – Geranium purpureum, Hypemon – Hypericum montbretii, Hypeoly – Hypericum olympicum, Lembnig – Lembotropis nigricans, Linasim − Linaria simplex, Plansub – Plantago subulata, Romugrae – Romulea linaresii ssp. graeca, Satupil – Satureja pilosa, Sedugri – Sedum grisebachii, Sempery – Sempervivum erythraeum, Thymlon – Thymus longicaulis, Triften – Trifolium tenuifolium, Tubegut – Tuberaria guttata, Verbhum – Verbascum humile.
ABC-79-170-f2

The first axis onFig. 2 can be interpreted as an altitudinal gradient, positively correlated also with continentality and precipitation, the latter being represented by the precipitation of the warmest quarter. The other two bioclimatic variables plotted in the ordination space are more or less negatively correlated with the first DCA axis. These are the temperature of the coldest quarter and precipitation seasonality. The second DCA axis is probably related to soil moisture as revealed by the corresponding environmental parameter used in the DCA-diagram, as well as from the discrimination at the top of this axis of the Genista lydia-Satureja pilosa community (group 4) which grows on well drained substrates of sandy gravel bars.

Description of the communities

Group 1: Association Diantho pinifolii-Genistetum lydiae ass. nova hoc loco (On–line Suppl. Tab 1), holotypus rel. 55 (Appendix,Fig. 3a) (Rilo–Rhodopean submontane genistoid scrub)

Fig. 3 Physiognomy of Genista lydia communities: a – Diantho pinifolii-Genistetum lydiae, b – Romuleo graecae-Genistetum lydiae, c – Galio flavescentis-Genistetum lydiae, d – Genista lydia-Satureja pilosa community.
ABC-79-170-f3

Diagnostic species: Centaurea rhenana ssp. rhenana (82.2), Sedum grisebachii (43.8), Asperula aristata ssp. scabra (40.2), Anthemis tenuiloba (37), Thymus longicaulis (32.8), Dianthus pinifolium ssp. pinifolius (31.6)

Constant species: Genista lydia (100), Centaurea rhenana ssp. rhenana (82), Festuca valesiaca (81), Asperula aristata ssp. scabra (70), Cladonia foliacea (65), Teucrium chamaedrys (58), Eryngium campestre (58), Trifolium campestre (57), Cruciata pedemontana (56), Agrostis capillaris (54), Koeleria macrantha (53), Poa bulbosa (51), Plantago lanceolata (51)

Dominant species: Genista lydia (20)

Distribution: Mesta (Nestos) River valley in Bulgaria and Greece, Central Rhodope Mts., 600 – 1500 m a.s.l.

This association is distributed on volcanic rocks and soils with a sandy structure. Its altitudinal range corresponds to submontane and montane belt on slopes with more pronounced inclinations (mean 14.5°). The soils are Umbric Leptosols and less often Dystric Cambisols (especially in the Central Rhodope Mts.). This group is characterized by its more frequent occurence at higher altitudes and in sites with higher annual precipitation, lower annual temperatures and less pronounced summer drought, as compared to all other groups (On–line Suppl. Tab. 3). The influence of colder and more humid mountain climate is a reason for more significant participation of some European and Boreal species as well as more xeromesophytes or mesophytes, such as Agrostis capillaris, Brachypodium sylvaticum, Arrhenatherum elatius, Vicia incana and Trifolium medium. The herbaceous layer is dominated by hemicryptophytes (46.8%), although therophytes are still well represented (34.5%) (Figs. 4,5). There is also high number of Balkan endemics and subendemics (13.04%), such as Viola aetolica, Sedum grisebachii, S. stefčo, Silene velenovskyana and Anthemis macedonica.

Fig. 4 Proportion of chorotypes within the different units of the Genista lydia communities: 1 – Diantho pinifolii-Genistetum lydiae, 2 – Romuleo graecae-Genistetum lydiae, 3 – Galio flavescentis-Genistetum lydiae, 4 – Genista lydia-Satureja pilosa community, 5 – The last column represents the proportion of chorotypes within all community types from the dataset. Chorotypes abbreviation: Msm – Mediterrenean and sub-Mediterrenean, Eur – European, Pal – Palearctic, Bor – Boreal, Psp – Pontic and sub-Pontic, Be – Balkan endemic, Bse – Balkan subendemic, Kos – Cosmopolitan. The Adventive and Holarctic elements are insignificant part of compared chorotypes, thus they are not marked in the figure.
ABC-79-170-f4
Fig. 5 Biological spectrum of the Genista lydia communities: 1 – Diantho pinifolii-Genistetum lydiae, 2 – Romuleo graecae-Genistetum lydiae, 3 – Galio flavescentis-Genistetum lydiae, 4 – Genista lydia-Satureja pilosa community, 5 – The last column represents the proportion of life-forms of community types 1, 2, 3 and 4. Life-form abbreviations: Ph – Phanerophytes, Ch – Chamaephytes, H – Hemicryptophytes, G – Geophytes, Th – Therophytes.
ABC-79-170-f5

Group 2: Association Romuleo graecae-Genistetum lydiae ass. nova hoc loco (On–line Suppl. Tab 1), holotypus rel. 131 (Appendix,Fig. 3b) (Thracian submontane genistoid scrub)

Diagnostic species: Romulea linaresii spp. graeca (80), Tuberaria guttata (65.5), Cerastium gracile (65.5), Trifolium tenuifolium (58.3), Erodium botrys (55.3) and Dianthus corymbosus (45.6)

Constant species: Genista lydia (100), Eryngium campestre (87), Poa bulbosa (83), Chrysopogon gryllus (76), Romulea linaresii spp. graeca (72), Sanguisorba minor (70), Anthoxanthum odoratum (69), Aira elegantissima (69), Rumex acetosella (59), Plantago lanceolata (52) and Cladonia foliacea (52)

Dominant species: Genista lydia (15)

Distribution: Eastern Rhodope Mts., both in Bulgaria and Greece, on schist, sandstones, tuffs, 150 – 600 m a.s.l.

The association occupies sandy soils, sandstones or mining deposits composed of white zeolites. The soil types are mostly Lithic and Umbric Leptosols. The precipitation regime has a winter maximum in November and a well pronounced summer drought between July and September (On–line Suppl. Tab. 3). The Mediterranean climate influence is significant in this association, and possibly is one of the reasons for it having the highest species richness amongst all groups. This is justified by the high frequency of therophytes (47.18%), and Mediterranean and sub-Mediterranean species (38%) (Figs. 4,5). In early spring, the herbaceous layer is dominated by geophytes like Romulea linaresii ssp. graeca, Ornithogalum spp. and Crocus chrysanthus. Therophytes with a typical Mediterranean origin dominate from the late April till the end of May, such as many annual clovers, Vulpia ciliata, Tuberaria guttata, Molineriella minuta, Aira elegantissima and Aegilops neglecta. In the summer period, the flowering aspect is influenced by yellow flowering Compositae species like Hypochaeris glabra, H. cretensis, H. radicata and Crepis setosa. The endemics are not so frequent/abundant, as compared to the other groups. Balkan endemics recorded in the association are Armeria rumelica, Chamaecytisus jankae, Daucus guttatus ssp. zahariadii, Dianthus corymbosus, Anthemis virescens and Romulea linaresii ssp. graeca.

Group 3: Galio flavescentis-Genistetum lydiae ass. nova hoc loco (On–line Suppl. Tab 1), holotypus rel. 41 (Appendix,Fig. 3c) (Balkan–Range submontane genistoid scrub)

Diagnostic species: Anthemis cretica (80.8), Sempervivum erythraeum (65), Hypericum montbretii (61.3), Galium flavescens (60.0), Verbascum humile (52.6), Plantago subulata (42.7) and Lembotropis nigricans (41.2)

Constant species: Genista lydia (100), Cladonia foliacea (100), Polytrichum pilifermum (71), Plantago subulata (71), Anthemis cretica (71), Rumex acetosella (64), Hypericum perforatum (64), Festuca dalmatica (64) and Viola arvensis (57)

Dominant species: Genista lydia (7)

Distribution: Southern slopes of East Balkan Range (Sliven district) and East Rhodope Mts., 300 – 1000 m a.s.l.

The communities of this association mostly occur on acidic rocks such as andesites, diorites, conglomerates. They are found on rock cliffs and terraces with a predominantly southern exposure. The soils are shallow Umbric Leptosols. Although this association demonstrates a more pronounced continental character, the number of Mediterranean species in their floristic composition continues to be significant (34.93%) (Fig. 4). On the other hand, the annual species (28.77%) are fewer in number than other groups. Another specific feature of the group is the higher frequency and abundance of shrub and juvenile tree species (Fig. 5) such as Syringa vulgaris, Lembotropis nigricans and Fraxinus ornus. This is due to the abandonment of grazing practices, since this association is mostly located in some protected areas such as Sinite Kamuni Nature Park. These communities are also rich in Balkan endemics and subendemics (17.81%), like Sesleria latifolia, Sempervivum erythraeum, Verbascum humile, Chamaecytisus calcareus, Scabiosa triniifolia and Silene lerchenfeldiana.

Group 4. Genista lydia-Satureja pilosa community (Fig. 3d)

Diagnostic species: Satureja pilosa (81.6), Crucianella angustifolia (78.6), Linaria simplex (65.5), Geranium purpureum (65.5) and Cionura erecta (65.5)

Constant species: Genista lydia (100), Euphorbia niciciana (100), Euphorbia cyparissias (100), Eryngium campestre (100), Chondrilla juncea (100), Vicia cracca (75), Trifolium arvense (75), Senecio vulgaris (75), Sedum rubens (75), Satureja pilosa (75), Orlaya grandiflora (75), Melica ciliata (75), Medicago minima (75), Linaria genistifolia ssp. genistifolia (75), Koeleria nitidula (75), Geranium rotundifolium (75), Galium lucidum (75), Euphorbia myrsinites (75), Crucianella angustifolia (75), Buglossoides arvensis (75) and Asperula purpurea (75)

Dominant species: Genista lydia (25)

Distribution: East Rhodopes Mts., 150 – 300 m a.s.l.

This community is distributed on the alluvial sandy terraces of Arda River and its tributaries. Typical species are many psamophytes as well as some species that inhabit the gravel bars like Satureja pilosa, Cionura erecta, Euphorbia niciciana, etc. The highest proportion of therophytes and the absence of geophytes in this community could be explained through its development on unstable (pioneer) substrates, influenced by river floods (Fig. 5). The floristic composition is also highly influenced by trampling by cattle and sheep that take water from the streams of the Arda River.

Discussion

The largest areas occupied by Genista lydia communities are on the slopes of Pirin, Rila and the Rhodope Mountains. (in both Bulgarian and Greek parts). The northernmost localities areon the southern slopes of the Eastern Balkan Mountains. (Fig. 6).

Fig. 6 Distribution map of Genista lydia communities: ● – Diantho pinifolii-Genistetum lydiae, ○ – Romuleo graecae-Genistetum lydiae, ▲ – Galio flavescentis-Genistetum lydiae, ▲ – Genista lydia-Satureja pilosa community.
ABC-79-170-f6

The communities of G. lydia are known to have very limited distribution in Bulgaria covering a total area of 5.2 km2, area of occupancy (AOO) - 26 (2600 km2) and extent of occurrence (EOO) - 9670 km2 (Kunev and Tzonev 2019). Their distribution in Greece has not been completely investigated. However, the data presented in the habitat's description from the European Red List of Habitats (Janssen et al. 2016) shows a wider distribution area, which is 20 km2 for the territory of Greece and 60 km2 in Bulgaria. These data suggests that the occupied area in the Red List is probably overestimated.

The studied shrub communities could develop as primary vegetation on extreme sites, such as sheer rocks, rock crevices and terraces, where the soil is often absent or very shallow. However, secondary expansion of these communities has been also observed in some areas. It is initiated largely due to habitat degradation as a result of overgrazing, deforestation and following soil erosion. Those secondary communities are distributed mostly close to the settlements and in extensively grazed areas. The soil layer is more developed there, although it rarely reaches 30 cm in depth.

The present distribution of the studied vegetation has probably resulted also from some historical events. These communities occur mostly on the slopes of the Mesta (Nestos) and Arda River Valleys in Southern Bulgaria and Northern Greece and also penetrate into the valleys of their tributaries. Before the 1950s, these river valleys were used as transition route during the annual migration of the livestock from the winter grazing sites (in the lowlands) to the summer pasturelands (in the mountains). This type of grazing, known as "transhumance", was widespread until 19th century in Bulgaria (Stoynov 2008). Therefore, probably the recent distribution and abundance of G. lydia communities in these areas is also related with the trampling and seed dispersal by the grazing animals. This fact is also supported by the abundance of G. lydia communities mostly close to the settlements where these grazing practices are still maintained. In the mountainous areas, these communities are often found near shieling sites. At the same time, in the sites with low or zero grazing intensity, the phytocoenoses have lower density and patchy distribution (Kunev and Tzonev 2019).

The information for the distribution of the studied communities on the territory of other Balkan countries and Turkey is very limited. G. lydia is reported mostly as an accompanying species in various vegetation types, but mostly forests and grasslands.

For example, this species in Serbia is distributed in the scrublands or forest fringes of the mountain regions (Diklić 1972). The species also has been reported to participate in the floristic composition of the association Trifolio-Trisetetum flavescentis N. Ranđelović 1975 (Chrysopogono-Danthonion calycinae Kojić 1957 of Festuco-Brometea) from Central Serbia (Aćić et al. 2014).

After revision of herbaria colectionsTeofilovski (2011) concluded, based onZieliński et al. (2004), that part of the specimens previously cited byMicevski (2001) as G. lydia, actually belong to G. januensis. Therefore, the occurrence of G. lydia in North Macedonia should be accepted as uncertain.

Genista lydia in Greece is distributed mainly in the northeastern parts of the country (Strid 1986,Zieliński et al. 2004). It has been reported as a common species in the forest clearings from the Rhodope Mountains., as well in the shrub layer of forests dominated by Betula pendula and Pinus sylvestris (Theodoropoulos et al. 2003,Eleftheriadou et al. 2009). It is also reported as diagnostic species to the associations Centaureo affinis-Festucetum koritnicensis Karagiannakidou et al. 2001, especially in its high–altitudinal variant described from Pangeon Mt., where it occupuies schistose substrates at altitudes of 1500–1800 m a.s.l. However, this association is classified in the alliance of oromediterranean dry grasslands and thorhy–cushion dwarf shrub – Astragalo angustifolii-Seslerion coerulantis Quézel 1964 from the class Daphno-Festucetea Quézel 1964 (Karagiannakidou et al. 2001).

The association Minuartio hirsutae-Dianthetum pinifolii (variant with G. lydia) has been described from Nomos of Chalkidiki, Greece (Bergmeier et al. 2009). As diagnostic species are referred Centaurea diffusa, C. grisebachii, Dianthus pinifolius, Hypericum olympicum, Minuartia hirsuta ssp. falcata, Phleum phleoides, Psilurus incurvus, Rumex acetosella and Thymus sibthorpii.Bergmeier et al. (2009) also noted that these communities inhabit slightly acidic, skeletal soils and classified them into the alliance Diantho pinifolii-Jasionion heldreichii Bergmeier et al. 2009 of Sedo-Scleranthetea. These communities differ from the studied vegetation by poorer species composition and lower abundance of therophytes.

The distribution range of G. lydia in Turkey includes its European parts as well as the western Asia Minor, and especially mountainous areas near the coastline (Gibbs 1970,Zieliński et al. 2004). The species occurs mostly on schistose substrates and participates in the floristic structure of macchia and phryganic vegetation, as understory of degraded mixed deciduous or coniferous forests and even in subalpine shrub communities (Quézel and Pamukçuoǧlu 1970,Quézel 1986, Uğurlu and Senol 2005, Kaya and Aladağ 2009).

However, the community Genista lydia-Hypericum linarioides described from the Mount Uludağ (Quézel and Pamukçuoǧlu 1970) is the only unit reported from Turkey with definitive dominance or codominance of G. lydia. These dwarf shrubs occur on schistose substrates, on 1800–2200 m a.s.l., at the fringes of Abies bornmuelleriana forests. From the pointed diagnostic species only Juniperus nana and Thymus sibtorpii are presented also in the Bulgarian and Greek communities of G. lydia, but with a low constancy.Quézel and Pamukçuoǧlu (1970) have also noted the secondary origin of the community, which probably is related to the grazing in the subalpine zone. The proposed classification of the unit in the alliance Bruckenthalion (Vaccinio-Piceetalia) may be considered as provisional because it was based on four relevés only.

The diagnostic value of G. lydia communities for other, hierarchically higher, syntaxa is very poorly known. For example, according toStefanov (1921), G. lydia (referred as G. rumelica) is an evergreen species from the pseudomaquis formations in the Western Thrace region and Northeastern Greece. The dominants in this type of vegetation are also Pistacia terebinthus, Juniperus oxycedrus, J. excelsa, Cistus creticus, Calicotome villosa, etc. Specific characteristic of these vegetation formations are also the abundance of annuals and geophytes, especially in more disturbed locations. Typical species mentioned byStefanov (1921), such as Teesdalia coronopifolia, Trifolium subterraneum, Ornithopus compressus, Crepis zacintha, Plantago bellardii, Orchis papilionacea, Ranunculus paludosus, Campanula phrygia, are also found in the stands of G. lydia studied here.

The shrub communities, dominated by Cistus incanus from the southern parts of Bulgaria demonstrate also very similar ecological and floristic structure to those of G. lydia.Gussev (2015) suggested that they have some intermediate characteristics between the two plant associations described from neighbouring countries: Diantho-Cistetum incani Micevski et Matevski 1984 and Calicotomo villosae-Cistetum cretici Oberd. 1954. For example, the first association from the southern regions of North Macedonia was classified within the alliance Trifolion cherleri Micevski 1972 of Festuco-Brometea (Micevski and Matevski 1984,Čarni et al. 2010). Some of its diagnostic species such as Cistus incanus, Dianthus pinifolius, Micropyrum tenellum, Anthemis macedonica, Briza maxima, Scabiosa triniifolia, Lupinus angustifolius have been also found in the communities of G. lydia. A common feature to both vegetation types is the high constancy of leguminosae and especially Trifolium species.

On the other hand, the association Calicotomo villosae-Cistetum cretici Oberd. 1954 from Thessaloniki, Thrace and Thessaly, North Greece, dominated by the more thermophilous C. incanus ssp. creticus, could be a good example for communities synvicariant to G. lydia. The communities occur on silicate substrates and some of them are maintained by grazing. The association is characterized by the presence of widespread mesophilous species such as Hypericum perforatum, Brachypodium sylvaticum, Plantago lanceolata and Teucrium chamaedrys. Some early spring annuals like Aira elegantissima, Cerastium brachypetalum, Cynosurus echinatus and Vulpia ciliata also participate in its floristic structure (Oberdorfer 1954,Čarni et al. 2010). Additionally, in the mosaics of these shrub communities,Oberdorfer (1954) sampled grassland fragments with high abundance of Poa bulbosa and other therophytes and geophytes - Romulea linaresii ssp. graeca, R. bulbocodium, Ornithogalum spp., Gagea spp. According toOberdorfer (1954), these grasslands represent a regresion stage of the shrub communities, such as Calicotome villosa-Cistetum cretici Oberd. 1954 caused by overgrazing and trampling. Although this association is dominated by some typical Mediterranean species not present in the G. lydia communities, both units have a similar appearance, floristic and ecological structure.

Different vegetation types, occuring in the transitional zone between the Temperate and Mediterranean climatic regions of the Southern Balkans were also reported to have such a complex floristic structure (Stoyanov and Achtarov 1951,Sopotlieva and Apostolova 2014,Čarni et al. 2018). From these data, it could be concluded that complexity and intermediate state (mixture of low shrubs, perennial and annual herbs with Continental-Temperate and Mediterranean origin) of the communities of G. lydia are common phenomenon in these regions. Their specific structure is determined by the transitional position between the two climatic types as well as the variability of their altitudinal range. Other important factors influencing the studied communities are grazing pressure, deforestation, construction and mining activities.

The complexity and the mixed structure of the open shrubland communities in these transitional areas make them difficult to be classified on the higher than the association level. For example,Oberdorfer (1954), who described the association Calicotomo villosae-Cistetum cretici, classified it in the alliance Cistion orientale Oberd. 1954 of the class of "eastern Mediterranean hedgehog heaths and low–grown broom phryganas” – Cisto-Micromerietea julianae Oberd. 1954 (see alsoČarni et al. 2010). However, the name Cistion orientale was illegitimate and thus was replaced by Hyperico olympici-Cistion cretici (Oberd. 1954) R. Jahn et Bergmeier (Mucina et al. 2009). According toMucina et al. (2016), this alliance belongs to the class Cisto-Lavanduletea stoechadis Br.-Bl. in Br.-Bl. et al. 1940. The similarities of the association Calicotome villosa-Cistetum cretici with the western mediterranean phryganic communities of Cisto-Lavanduletea have been also noted byOberdorfer (1954). Genista lydia is also a low, evergreen to semi–evergreen shrub, which dominates communities developed mostly on siliceous substrates. This indicates the affiliation of such communities to the class Cisto-Lavanduletea stoechadis and its Eastern Mediterranean order Lavandulo stoechadis-Hypericetalia olympici. The diagnostic species of the order, found in the studied communities, are Cistus creticus, Anthemis cretica, Dianthus pinifolius, Hypericum olympicum, Genista carinalis and Stachys angustifolia. Moreover, it was recently reported from the southern regions of the Crimean peninsula (Ryff 2018), a fact that presents the order as notstrictly Mediterranean. The order consists of three alliances, from which Hyperico olympici-Cistion creticiMucina et al. (2009) was described as thermo-meso-Mediterranean silicicolous phrygana of Northern Hellas. This alliance is the most floristically, biogeographically and ecologically similar to the studied communities. From the characteristic species of the alliance, Campanula lingulata, Vicia lathyroides and Thymus sibthorpii (Čarni et al. 2010) have been also recorded in the G. lydia communities. However, the studied vegetation could be determined as submediterranean silicicolous garigue distributed in southern parts of Central and Eastern Balkans, as well as locally in West Anatolia. Their floristic composition, structure and richness in Balkan endemics are sufficient to differentiate them from the already described syntaxa on the alliance level and to justify the establishment of a new independent alliance, which is described below.

Alliance: Genistion lydiae all. nov hoc loco

Holotypus hoc loco: Romuleo graecae-Genistetum lydiae Kunev et all. nov. hoc loco

Diagnosis: Low-growing shrub communities dominated by the evergreen to semi-evergreen species G. lydia distributed in the south-eastern part of the Balkan Peninsula and probably Western Anatolia. These communities are acidophilus and occupy eroded places with shallow, poor soils or also rocky sites. The bedrock is of volcanic origin (andesites, rhyolites, volcanic schist, zeolites, gneisses), but also of sandstones. These communities occur as primary vegetation on rocky areas, but may also have a secondary origin replacing other communities on overgrazed grasslands. They are often open and with rich floristic composition which includes different plant life-forms. Many typical herbaceous species of the class of perennial grasslands Festuco-Brometea (in the foothill and mountain areas) and of the class of the therophytic pseudosteppes - Helianthemetea guttati (in the areas with a stronger Mediterranean climatic influence) participate in the stands of G. lydia. Such species are Festuca valesiaca, F. dalmatica, Agrostis capillaris, A. castellana, Poa bulbosa, Chrysopogon gryllus, Koeleria macrantha, Aira elegantissima, Eryngium campestre, Sanguisorba minor, Trifolium cherleri and T. subterraneum. In the canopy gaps of more open stands or on steep slopes of river valleys many ecologically flexible species, which generally belong to Koelerio-Corynephoretea and Sedo-Scleranthetea classes can be also found, such as Rumex acetosella, Bromus squarosus, Scabiosa argentea, Scleranthus perennis, Erysimum diffusum, Myosotis ramosissima, Sedum spp., etc.

Characteristic species: Genista lydia, Satureja pilosa, Thymus atticus, Hypericum montbretii, Anthemis tenuiloba, Galium flavescens, Minuartia hirsuta ssp. falcata, Centaurea cuneifolia, Viola tricolor ssp. macedonica and Rorippa thracica.

Transgressive and differential species: Asperula aristata ssp. scabra, Carlina corymbosa, Centaurea rhenana ssp. rhenana, Chamaecytisus absinthioides, Daucus guttatus, Dianthus pinifolium ssp. pinifolius, Erodium botrys, Romulea linaresii spp. graeca, Sedum grisebachii, Tuberaria guttata, Trifolium tenuifolium and T. strictum.

This new alliance is similar and close to the alliance Hyperico olympici-Cistion cretici, but it is differentiated by its biogeographical range (Southeast Balkans and adjacent regions of Asia Minor), its transitional position between Mediterranean and Continental (Temperate) climatic types and its floristic composition rich in Balkan endemics and subendemics.

Proposed syntaxonomic scheme

  • Class Cisto-Lavanduletea stoechadis Br.-Bl. in Br.-Bl. et al. 1940

  • Order Lavandulo stoechadis-Hypericetalia olympici Mucina in Mucina et al. 2016

  • Alliance Genistion lydiae Kunev, Tzonev, Tsiripidis et Pachedjieva all. nov. hoc loco

  • Association Diantho pinifolii-Genistetum lydiae Kunev, Tzonev, Tsiripidis et Pachedjieva ass. nova hoc loco

  • Association Romuleo graecae-Genistetum lydiae Kunev, Tzonev, Tsiripidis et Pachedjieva ass. nova hoc loco

  • Association Galio flavescentis-Genistetum lydiae Kunev, Tzonev, Tsiripidis et Pachedjieva ass. nova hoc loco

Genista lydia-Satureja pilosa community

Conclusion

The current study is the first attempt to describe appropriately the syntaxonomy of Genista lydia communities. The establishment of an endemic Southeast Balkan-West Anatolian alliance of sub-Mediterranean low evergreen to semi-evergreen scrub vegetation is proposed. The G. lydia communities have conservation significance on the European scale (Janssen et al. 2016). The major threat to the habitat is the abandonment of traditional grazing and pasture management as well as the changes in the land use. The latter threat concerns the transformation of pasturelands into crop fields or artificial forest plantations. If grazing is suspended, rapid successional changes will lead to the complete replacement of the shrub communities with hemicryptophytic grasslands or tall scrublands. Therefore, certain conservation measures, such as specific grazing maintenance, should be applied in order to prevent the decline of the communities. The inclusion of the “Balkan–Anatolian submontane genistoid scrub” habitat in the Annex I of the Habitat Directive is considered as a necessary policy measure that can ensure the conservation of this rare and vulnerable habitat type.

Appendices

Appendix

Nomenclatural type relevés of the newly described syntaxa:

1. Diantho pinifolii-Genistetum lydiae ass. nova hoc loco

Holotypus hoc loco: Bulgaria, Dobrinishte; Relevé no. 55 (On–line Suppl. Tab 1); relevé collector: G. Kunev, 23.06.2016; plot size 25 m2; alt. 739 m a.s.l.; slope: 20°, S; vegetation cover: 70%; latitude: 41.82577°, longitude: 23.62033°

Shrub species: Genista lydia 3; Herbaceous species: Festuca valesiaca 2a, Sanguisorba minor 2a, Thymus longicaulis 2a, Dianthus pinifolius ssp. pinifolius 1, Agrostis capillaris 1, Bromus squarrosus 1, Centaurea rhenana ssp. rhenana 1, Chrysopogon gryllus 1, Crupina vulgaris 1, Cynosurus echinatus 1, Eryngium campestre 1, Euphorbia cyparissias 1, Euphrasia pectinata 1, Geranium columbinum 1, Hieracium bauhinii 1, Hypericum rumeliacum 1, Koeleria macrantha 1, Leontodon crispus 1, Melica ciliata 1, Orlaya daucoides 1, Phleum montanum 1, Plantago lanceolata 1, Plantago subulata 1, Potentilla neglecta 1, Stachys angustifolia 1, Stipa pulcherrima 1, Taeniatherum caput-medusae 1, Teucrium chamaedrys 1, Trifolium campestre 1, Trifolium hirtum 1, Trifolium striatum ssp. striatum 1, Xeranthemum annuum 1, Achillea coarctata +, Acinos rotundifolius +, Aegilops triuncialis +, Anagallis arvensis +, Anthemis tenuiloba +, Asperula aristata ssp. scabra +, Campanula lingulata +, Cerastium brachypetalum +, Cerastium pumilum +, Cuscuta approximata +, Hypericum olympicum +, Logfia arvensis +, Nigella arvensis +, Onobrychis gracilis +, Orlaya grandiflora +, Potentilla argentea +, Psilurus incurvus +, Scleranthus perennis +, Sedum caespitosum +, Sedum rubens +, Thesium arvense +, Trifolium arvense +, Valerianella coronata +, Valerianella dentata +

2. Romuleo graecae-Genistetum lydiae ass. nova hoc loco

Holotypus hoc loco: Bulgaria, Dedets; Relevé no. 131 (On–line Suppl. Tab 1); relevé collector: G. Kunev, 22.04.2018; plot size 25 m2; alt. 382 m a.s.l.; slope: 3°, SW; vegetation cover: 80%; latitude: 41.38857°, longitude: 25.22668°

Shrub species: Genista lydia 3, Cistus creticus 2a, Juniperus communis ssp. communis 1, Juniperus deltoides 1, Chamaecytisus albus +, Rosa turcica +; Herbaceous species: Chrysopogon gryllus 2a, Hieracium hoppeanum 2a, Poa bulbosa 2a, Aira elegantissima 1, Anthoxanthum odoratum 1, Carex caryophyllea 1, Centaurea cuneifolia 1, Cerastium gracile 1, Chondrilla juncea 1, Crepis sancta 1, Daucus guttatus 1, Erodium botrys 1, Eryngium campestre 1, Hieracium bauhinii 1, Hypericum cerastoides 1, Hypericum olympicum 1, Hypochaeris glabra 1, Jasione heldreichii 1, Leontodon crispus 1, Moenchia mantica 1, Ornithopus compressus 1, Parentucellia latifolia 1, Petrorhagia illyrica 1, Potentilla recta 1, Romulea linaresii ssp. graeca 1, Rumex acetosella 1, Sanguisorba minor 1, Sherardia arvensis 1, Spergula pentandra 1, Teesdalia coronopifolia 1, Thymus atticus 1, Thymus longicaulis 1, Trifolium nigrescens ssp. petrisavii 1, Trifolium strictum 1, Trifolium tenuifolium 1, Tuberaria guttata 1, Anthemis arvensis +, Cirsium vulgare +, Cnicus benedictus +, Dianthus corymbosus +, Geranium molle +, Lupinus angustifolius +, Moenchia erecta +, Orchis morio +, Scabiosa argentea +, Scilla autumnalis +, Scleranthus verticillatus +, Thesium dollineri; Cryptogams: Cladonia foliacea 1, Cladonia furcata agg. 1, Polytrichum piliferum 1, Racomitrium canescens 1, Cetraria aculeata agg. +

3. Galio flavescentis-Genistetum lydiae ass. nova hoc loco

Holotypus hoc loco: Bulgaria, Sliven, NP “Sinite kamаni”; Relevé no. 41 (On–line Suppl. Tab 1); relevé collector: G. Kunev, 19.06.2016; plot size 16 m2; alt. 612 m a.s.l.; slope: 7°, SW; vegetation cover: 60%; latitude: 42.70712°, longitude: 26.34363°

Shrub species: Genista lydia 3, Amelanchier ovalis +, Lembotropis nigricans +; Herbaceous species: Plantago subulata 2a, Achillea coarctata 1, Anthemis cretica 1, Anthemis tinctoria 1, Festuca dalmatica 1, Galium flavescens 1, Hieracium hoppeanum 1, Hypericum perforatum 1, Koeleria nitidula 1, Logfia arvensis 1, Phleum montanum 1, Rumex acetosella 1, Scabiosa triniifolia 1, Scleranthus perennis 1, Sempervivum erythraeum 1, Stachys angustifolia 1, Thymus callieri ssp. urumovi 1, Verbascum humile 1, Veronica verna 1, Viola arvensis 1, Achillea millefolium +, Allium sphaerocephalon +, Alyssum alyssoides +, Avenula compressa +, Buglossoides arvensis +, Crucianella angustifolia +, Crupina vulgaris +, Cuscuta approximata +, Hypericum montbretii +, Linaria genistifolia ssp. genistifolia +, Micropyrum tenellum +, Orlaya grandiflora +, Ornithogalum kochii +, Psilurus incurvus +, Scandix pectin-veneris ssp. macrorhyncha +, Viscaria vulgaris ssp. atropurpurea +; Cryptogams: Cladonia foliacea 1, Cladonia rangiformis 1, Polytrichum piliferum 1

On-line Supplementary Materials

On-line Suppl. Tab. 1. Diagnostic table of the communities dominated by Genista lydia. Chorotypes abbreviation: Msm – Mediterrenean and sub-Mediterrenean, Eur – European, Pal – Palearctic, Bor – Boreal, Psp – Pontic and sub-Pontic, Be – Balkan endemic, Bse – Balkan subendemic, Kos – Cosmopolitan, Hol – Holarctic, Adv – Adventive. Life-forms: Ph – Phanerophytes, Ch – Chamaephytes, H – Hemicryptophytes, G – Geophytes, Th – Therophytes. Cryptogams are bryophytes and lichens.

On-line Suppl. Tab. 2. Results from forward selection in Cannonical correspondence analysis (CCA) of all 19 bioclimatic variables extracted from WorldClim database, version 2.0 (Fick and Hijmans 2017). The bioclimatic variables with the highest percentage of the total variance of species data explained (in shaded cells) are plotted onto the Detrended correspondence analysis (DCA) ordination plot (Fig. 2 in text). TV is the percentage of the total variance and p is the significance level.

On-line Suppl. Tab. 3. Parameter values of some climatic variables, site characteristics and total vegetation cover for representative locations within the communities of Genista lydia. Group 1 – Diantho pinifolii-Genistetum lydiae, Group 2 – Romuleo graecae-Genistetum lydiae, Group 3 – Galio flavescentis-Genistetum lydiae, Group 4 – Genista lydia-Satureja pilosa community. The values for annual mean temperature, annual precipitation and the months with precipitation maximum were extracted from WorldClim database, version 2.0 (Fick and Hijmans 2017) as raster graphic images (geotif files) with highest spatial resolution (~1 km2). Altitude range is measured by handheld GPS Garmin eTrex Vista HCx. The data on slope, substrates and total vegetation cover are presented according personal observations.

Acknowledgements

The research was partly financed by the project: “Syntaxonomic characteristics of the Rumelian (Genista rumelica Velen.) and Lydian (Genista lydia Boiss.) greenweed communities in Bulgaria and North Greece” – Contract Nº80.10–65/19.04.2018 funded by the Scientific Research Fund of the Sofia University “St. Kliment Ohridski”. We are grateful to Assoc. Prof. Anna Ganeva, PhD for the determination of the bryophytes and also to Assist. Prof. Veselin Shivarov, PhD, for the determination of the lichenized fungi in all studied communities. We are also grateful to Gabriela Petrova, PhD student, for the preparation of the distribution map on the studied vegetation type.

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