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Research Paper
Plant biogeography, endemism and vegetation types of Dena Mts, Zagros, West Iran
expand article infoJalil Noroozi, Amir Talebi§, Michael Suen, Gerald M. Schneeweiss
‡ University of Vienna, Vienna, Austria
§ University of Tehran, Tehran, Iran
Open Access

Abstract

Questions: The highest mountain peak of Zagros is located in the Dena mountain system (4409 m a.s.l.), which is identified as the second richest center of plant endemism of Zagros. In this study we (1) investigate floristic affinities of Dena Mts to adjacent mountain ranges based on the endemic species of the Iranian Plateau, (2) identify the species reaching the subnival zone, and (3) characterize the plant communities of the subnival zone of Dena Mts. Study area: Dena Mts is a calcareous mountain system in southern Zagros, Iran. Methods: The list of taxa endemic to the Iranian Plateau present also in Dena Mts was taken from our previously published data. Novel vegetation data were collected using the methodology of Braun-Blanquet. Classification was carried out in JUICE using the Modified TWINSPAN method. Results: Of the 242 taxa endemic to the Iranian Plateau present in Dena Mts, 22 taxa are endemic to the latter. Dena Mts have the strongest floristic affinity with the Yazd-Kerman massif, with which they share 84 taxa compared to 51 taxa shared with Alborz, 37 taxa shared with the Azerbaijan Plateau, and 15 taxa shared with Kopet Dagh-Khorassan. In Dena Mts, 38 taxa reach the subnival zone, most of them being endemic to the Iranian Plateau (68%). From scree habitats in the subnival zone, two new plant associations are described, Aethionemetum umbellati and Zerdanetum anchonioidei. These constitute a newly described alliance Galion pseudokurdici, classified within the class Didymophyso aucheri-Dracocephaletea aucheri. Conclusions: Although Dena Mts lie within a protected area, this will not prevent shrinking of alpine and subnival habitats due to global warming. Consequently, strong attention to the conservation of all range-restricted species of this mountain system, especially of alpine and subnival species, is highly recommended.

Taxonomic reference: Flora of Iran (Assadi et al. 1989–2021) and, for families not yet covered in the previous source, Flora Iranica (Rechinger 1963–2015).

Keywords

biogeography, conservation, Dena Mts, endemism, subnival zone, vegetation, Zagros

Introduction

Global biodiversity hotspots, many of which are located in mountainous areas, are known as regions with high conservation priorities due to their rich endemic diversity and, at the same time, high pressure from human activities (Myers et al. 2000; Mittermeier et al. 2005, 2011). One such hotspot is the Irano-Anatolian biodiversity hotspot, which is a mountainous region in South-West Asia with very heterogenous climate and topography (Zohary 1973; Djamali et al. 2012) and, consequently, harboring a rich endemic diversity, especially at high elevations (Mittermeier et al. 2011; Noroozi et al. 2021). The Irano-Anatolian biodiversity hotspot includes several areas of endemism that are strongly associated with the major mountain ranges (Noroozi et al. 2019a, 2019b).

Zagros mountain range, the most extensive mountain range of Iran (Figure 1), is one of the richest areas of endemism of the region with numerous centers of endemism, mostly located in areas with very high elevations (Noroozi et al. 2019a). Among those areas, Dena Mts are the highest mountain system, reaching 4409 m a.s.l. at its highest peak (Figure 1). Dena Mts are the second-richest center of plant endemism in Zagros and the fourth-richest in Iran (Noroozi et al. 2019a). The Austrian botanist Theodor Kotschy (1813–1866), the most important collector of natural history objects active in the nineteenth century in South-West Asia (Edmondson and Lack 2006), was the first botanist to collect plants from the alpine and subnival zones of Dena Mts (in 1842), and many of the numerous collected plants were described as new species by Edmond Boissier in his Flora Orientalis (Boissier 1867–1884). Although Dena Mts have been frequently visited by national botanists, only few botanists have ascended to the high alpine and subnival zones after Kotschy, so that data pertaining to these elevation zones remained scarce and became potentially outdated. This is also the case for the “Flora of Dena Mts.” (Jafari Kokhedan 2003). Despite the prominent role as a center of biodiversity in Zagros, endemic diversity, biogeography, vegetation as well as conservation aspects of Dena Mts have only been poorly studied.

The subnival flora is an important component in SW Asia contributing a high proportion of endemics that are highly threatened (Noroozi et al. 2011). Although exploration of the alpine and subnival flora of Dena Mts dates back to Kotschy, a thorough survey of it has been lacking. Connected to the poor exploration of the alpine zone, little is known about the vegetation types in this area, especially in a phytosociological context.

As a basis for putative conservation strategies, we here provide a biogeographic characterization of Dena Mts with a focus on the particularly poorly studied high elevation zones. To this end, we use the following approaches: (1) The floristic affinities and thus biogeographic connections of Dena Mts to other mountain ranges of the region are analyzed; (2) a full account of the subnival plant diversity of Dena Mts is given; (3) plant communities from the subnival zone are described and classified.

Study area

Dena Mts is a calcareous mountain system in southern Zagros, ca. 60 km long and ca. 10 km wide. Nearly 100 peaks exceed 4000 m a.s.l., with the highest one reaching 4409 m a.s.l., being the highest summit of the entire Zagros mountain range (Figure 1). Dena Mts have a Mediterranean precipitation regime with cold-wet winters and warm-dry summers (Figure 2). Western slopes receive more precipitation than eastern slopes, and in the alpine zone the annual precipitation exceeds 1000 mm (Jafari Kokhedan 2003).

The main vegetation types of the study area can be summarized as follows (see Noroozi et al. 2020 and references therein):

Quercus woodlands (Figure 3A) occupy the montane zone of Dena Mts, especially on the western slopes up to 2700 m a.s.l. These woodlands are dominated by Quercus species, especially Q. brantii (Jafari Kokhedan 2003). Other frequent shrubs and trees are Cotoneaster luristanica, Daphne mucronata, Lonicera nummularifolia, Pistacia khinjuk and Rhamnus kurdica.

Subalpine tall-umbelliferous vegetation types (Figure 3B) mostly cover steep slopes with scree in elevations ranging from ca. 2500 to 3500 m a.s.l. In term of physiognomy, environmental features and species composition, they can be classified in the provisional class Prangetea ulopterae, described from Alborz mountain range (Klein 1988, 2001). The most dominant species of this vegetation type in Dena Mts is Ferulago angulata (Figure 3B).

Chasmophyte vegetation types (Figure 3C, D) have a high elevational amplitude from the montane to the subnival zone. Characteristic species in these habitats include Arenaria minutissima, Dielsiocharis kotschyi, Dionysia bryoides (Figure 3C), D. termeana (Figure 3D), Graellsia saxifragifolia, Pentanema multicaule, Rhamnus cornifolia, and Tanacetum kotschyi.

Subalpine and alpine thorn-cushion grasslands (Figure 4A, B) are the main formation of the subalpine and alpine zone, having more developed soils compared to other communities of these zones. In the subalpine zone, up to 3500 m a.s.l., the main dominant thorn-cushion species is Astragalus brachycalyx, mostly accompanied by Bromus tomentellus, Daphne mucronata, Euphorbia polycaulis, Fritillaria imperialis, and Tulipa systola. In the alpine zone, from ca. 3500 m a.s.l. up to ca. 4100 m a.s.l., this formation is dominated by Astragalus murinus (Figure 4A, B) and A. myriacanthus. Other accompanying species are Acantholimon melananthum, Arenaria persica, Arnebia euchroma, Cousinia bakhtiarica, Euphorbia microsciadia, Marrubium astracanicum, Micrantha multicaulis, Phlomis anisodonta subsp. occidentalis, Scorzonera subaphylla, and Tanacetum dumosum.

Alpine snowbeds (Figure 4C, D) are mostly found at elevations between ca. 3500 m a.s.l. and 4100 m a.s.l., where snow cover can persist till July and August. The growing season of these vegetation types is short, and most of the species are small hemicryptophytes. Structure and composition (mostly at the generic level) of these communities are the same as those from Alborz, which belong to the order Taraxaco brevirostris-Polygonetalia serpyllacei. The most important character species of the order present in Dena Mts is Polygonum serpyllaceum. Other characterstic species in the region are Arenaria balansae, Plantago atrata, Primula capitellata, and Ranunculus elymaiticus (Figure 4C, D).

Alpine and subnival scree vegetation types (Figure 5) occur, where the ground is mostly covered by scree and big stones. They harbor only scattered vegetation and have a low species richness. Phytosociologically, these vegetation types belong to the class Didymophyso aucheri-Dracocephaletea aucheri described from Alborz and mountains of NW Iran (Noroozi et al. 2014). Character species of this class occurring in Dena Mts are Didymophysa aucheri (rare), Elymus longearistatus, Astragalus melanodon (Figure 5A), Bromus frigidus (Figure 5B), Euphorbia aucheri (Figure 5C), Galium pseudokurdicum (Figure 5D), Physoptychis gnaphalodes (Figure 5E), and Stachys obtusicrena (Figure 5F). The highest elevations of this mountain system, above ca. 4100 m a.s.l., are mostly covered with subnival scree vegetation types.

Figure 1. 

Location of Dena Mts in the Zagros mountain range in Iran.

Figure 2. 

Climate diagram of the study region.

Figure 3. 

A) Quercus brantii woodlands (2000–2600 m a.s.l.). B) Umbelliferous vegetation types and Ferulago angulata as dominant species (2500–3500 m a.s.l.). C) Chasmophyte habitats, Dionysia bryoides (2800 m a.s.l.). D) Chasmophyte habitats, Dionysia termeana (2500 m a.s.l.).

Figure 4. 

A, B) Thorn-cushion grasslands and Astragalus murinus as dominant species (3800 m a.s.l.). C, D) Snowbed vegetation types and Ranunculus elymaiticus as dominant species (3800 m a.s.l.).

Figure 5. 

Subnival scree vegetation types (4100–4409 m a.s.l.). A) Astragalus melanodon (4150 m a.s.l.). B) Bromus frigidus (4200 m a.s.l.). C) Euphorbia aucheri (4200 m a.s.l.). D) Galium pseudokurdicum (4150 m a.s.l.). E) Physoptychis gnaphalodes (4250 m a.s.l.). F) Stachys obtusicrena (4200 m a.s.l.).

Methods

The list of taxa (species, subspecies and varieties) endemic to the Iranian Plateau and also present in Dena Mts was prepared using the list of all endemic vascular plant species of Iran published by Noroozi et al. (2019b) and our updated data (Table 1). Presence of these taxa in the adjacent mountain ranges, i.e., the Azerbaijan Plateau, Alborz, Kopet Dagh, and Yazd-Kerman, was used to quantify the floristic connections between Dena Mts and these mountain ranges. To explore the flora and vegetation of the subnival zone, an expedition dedicated to the high elevations of this mountain was undertaken in summer 2019. The plots were taken at subnival scree sites at elevations above 4100 m a.s.l. The alpine grasslands and subnival scree vegetation types are easily distinguishable in this area. Vegetation data from 19 plots, each 10 m × 10 m, were collected following the methodology of Braun-Blanquet (Braun-Blanquet 1964; Dengler et al. 2008). The proportional covers of the vegetation, scree, soil, and rock were estimated in each plot. The plot data were stored in Turboveg (Hennekens and Schaminée 2001). Classification was carried out in JUICE version 7.1 (Tichý 2002) using the Modified TWINSPAN and four cutlevel values (0%, 5%, 25%, 50%). A synoptic table was constructed based on the percentage frequency and fidelity of the species in each described association. We followed the phytosociological nomenclature code (Theurillat et al. 2020) to describe and propose new syntaxa. Associations were delimited according to Willner (2006). We used the phi value as fidelity measure and a threshold of 0.3. A synoptic table showing the character species of both the three alliances previously described for high alpine and subnival scree vegetation types of the Iranian Plateau and the alliance newly described in this paper is presented.

Table 1.

Endemic taxa of the Iranian Plateau recorded in Dena Mts. For each species, the following information is provided: family, distribution in different areas of endemism (Al: Alborz; Az: Azerbaijan Plateau; Ke: Yazd-Kerman; Ko: Kopet Dagh-Khorassan; Za: Zagros, endemics of Dena Mts given in bold) based on Noroozi et al. (2019b), elevational range in the entire geographical range of the species, and main habitat types (Alp. Scree: Alpine Scree; Chasm.: Chasmophytic vegetation; M Grass.: Montane Grasslands; Oak W.: Oak Woodland; Subn. Scree: Subnival Scree; Th.-Cu.: Thorn-Cushion vegetation; Umb.: Umbelliferous vegetation).

Species Family Distribution Elevation range (m) Main Habitat
Allium austroiranicum R.M. Fritsch Alliaceae Za, Ke 1700–3300 Umb., Th.-Cu.
Allium brachyodon Boiss. Alliaceae Za, Ko 3000–3200 Th.-Cu.
Allium kazerouni Parsa Alliaceae Za 1660–2900 Th.-Cu.
Allium kotschyi Boiss. Alliaceae Za, Ke 2500–3600 Th.-Cu.
Kochia prostrata (L.) Schrad. var. alpina Bornm. Amaranthaceae Za 2500–3000 Th.-Cu.
Astrodaucus persicus (Boiss.) Drude in Engler & Prantl Apiaceae Za, Al, Az, Ko 1000–2750 Oak W., Th.-Cu.
Dorema aucheri Boiss. Apiaceae Za, Ke 1700–3250 Umb., Th.-Cu.
Echinophora cinerea (Boiss.) Hedge & Lamond Apiaceae Za 2000–3300 Umb., Th.-Cu.
Ferula microcolea (Boiss.) Boiss. Apiaceae Za, Al, Az 1600–3050 Umb.
Ferulago angulata (schlecht.) Boiss. Apiaceae Za, Al, Az, Ke, Ko 2000–3700 Umb.
Ferulago carduchorum Boiss. & Haisskn. Apiaceae Za, Az, Ke 1700–3990 Umb.
Ferulago contracta Boiss. & Hausskn. Apiaceae Za, Ke 1700–2500 Umb.
Johreniopsis scoparia (Boiss.) Pimenov Apiaceae Za 2370–3000 Umb.
Leutea cupularis (Boiss.) M. Pimen. Apiaceae Za, Al 1800–3700 Umb.
Pimpinella deverroides (Boiss.) Boiss. Apiaceae Za 1500–3500 Umb., Th.-Cu.
Pimpinella dichotoma (Boiss. et Hausskn.) Wolff Apiaceae Za, Ke 1500–2750 Umb., Th.-Cu.
Pseudotrachydium kotschyi (Boiss.) Pimenov & Kljuykov Apiaceae Za 1950–3900 Th.-Cu., Alp. Scree
Rhabdosciadium aucheri Boiss. Apiaceae Za 1830–3960 Th.-Cu., Alp. Scree
Semenovia dichotoma (Boiss.) Manden. Apiaceae Za 2800–4200 Th.-Cu.
Semenovia frigida (Boiss.) Hausskn. Apiaceae Za, Ke 2400–3500 Th.-Cu.
Semenovia tragioides (Boiss.) Manden. Apiaceae Za, Al, Az, Ko 1500–3550 Th.-Cu.
Tetrataenium lasiopetalum (Boiss.) Manden. Apiaceae Za 2000–4000 Umb., Alp. Scree
Thecocarpus meifolius Boiss. Apiaceae Za, Ke 1500–3200 Th.-Cu.
Trachydium depressum Boiss. Apiaceae Za, Al, Ke 2100–3800 Th.-Cu.
Trachydium kotschyi (Boiss.) Boiss. Apiaceae Za 2000–3900 Th.-Cu.
Zeravschania aucheri (Boiss.) Pimenov Apiaceae Za, Al, Az 1300–3300 Th.-Cu.
Bellevalia heweri Wendelbo Asparagaceae Za 2200–2300 Wetland
Ornithogalum pycnanthum Wendelbo Asparagaceae Za 2400–3200 Th.-Cu.
Centaurea persica Boiss. Asteraceae Za 1550–3000 Oak W.
Cephalorrhynchus microcephalus (D.C.) Schchian Asteraceae Za, Al, Az 700–2800 Oak W.
Cicerbita polyclada (Boiss.) Beauverd Asteraceae Za 3300–3500 Oak W.
Cirsium bracteosum DC. Asteraceae Za, Ke, Al, Az 1800–3200 Oak W., Th.-Cu.
Cirsium spectabile DC. Asteraceae Za, Ke 1750–3000 Th.-Cu.
Cousinia albida DC. Asteraceae Za 2300–2600 Th.-Cu.
Cousinia amplissima (Boiss.) Boiss. Asteraceae Za, Al, Az 1000–2300 Oak W., Th.-Cu.
Cousinia araneosa DC. Asteraceae Za, Ke 1653–3600 Th.-Cu.
Cousinia assadii Attar Asteraceae Za 3000–3400 Th.-Cu.
Cousinia bachtiarica Boiss. & Hausskn. Asteraceae Za 2400–3000 Umb., Th.-Cu.
Cousinia barbeyi C.Winkl. Asteraceae Za 1570–2400 Th.-Cu.
Cousinia calcitrapa Boiss. Asteraceae Za, Ke 2100–3000 Th.-Cu.
Cousinia canescens DC. Asteraceae Za, Az 1850–2500 Th.-Cu.
Cousinia denaensis Attar & Djavadi Asteraceae Za 1800–2900 Oak W., Th.-Cu.
Cousinia gracilis Boiss. Asteraceae Za 2700–2800 Th.-Cu.
Cousinia iranshahriana Attar & Maroofi Asteraceae Za 2000–2800 Th.-Cu.
Cousinia kotschyi Boiss. Asteraceae Za, Ke 1200–3000 M Grass., Umb., Th.-Cu.
Cousinia longifolia C. Winkl. & Bornm. Asteraceae Za, Ke 3000–3400 Th.-Cu.
Cousinia oligocephala Boiss. Asteraceae Za 3200–3700 Th.-Cu.
Crepis heterotricha DC. Asteraceae Az, Al, Za, Ke 3000–4300 Th.-Cu., Alp.-Subn. Scree
Echinops ceratophorus Boiss. Asteraceae Za, Ke 1500–2800 Th.-Cu.
Echinops iranshahrii Rech.f. Asteraceae Za 1600–1800 Oak W.
Echinops kotschyi Boiss. Asteraceae Za 3000–3200 Th.-Cu.
Echinops macrophyllus Boiss. & Hausskn. var. laciniatus Mozaff. Asteraceae Za 1000–2500 Oak W.
Echinops macrophyllus Boiss. & Hausskn. var. papillosus Mozaff. Asteraceae Za, Al 1600–2500 Oak W.
Echinops mosulensis Rech.f. var. papillosus Mozaff. Asteraceae Za 500–2500 Oak W.
Echinops viscidulus Mozaff. Asteraceae Za 1500–3200 Umb., Th.-Cu.
Erigeron daenensis Vierh. Asteraceae Za 3700–4300 Chasm., Subn. Scree
Helichrysum artemisioides Boiss & Hausskn Asteraceae Za 1400–2100 Th.-Cu.
Helichrysum oligocephalum DC. Asteraceae Za, Al, Az 1600–3600 Umb., Th.-Cu.
Iranecio paucilobus (DC.) B. Nord. Asteraceae Za, Al, Ke 1800–3600 Th.-Cu., Alp. Scree
Lactuca denaensis N. Kilian & Djavadi Asteraceae Za 3600–4000 Chasm.
Lactuca polyclada Boiss. Asteraceae Za 3200–3400 Th.-Cu.
Myopordon persicum Boiss. Asteraceae Za 3800–4400 Subn. Scree
Pentanema multicaule Boiss. Asteraceae Za 2100–3750 Chasm.
Phagnalon persicum Boiss. Asteraceae Za, Ke 1700–3400 Chasm.
Picris strigosa M.Bieb. subsp. gonicaula (Boiss.) Lack Asteraceae Za, Al, Ke 1250–2800 Th.-Cu.
Psychrogeton chionophilus (Boiss.) Krasch. Asteraceae Za 3500–3700 Th.-Cu., Snowbed
Scorzonera calyculata Boiss. Asteraceae Za, Al, Az, Ke 1000–3000 Oak W., Th.-Cu.
Scorzonera stenocephala Boiss. Asteraceae Za, Al, Az, Ko 2400–3600 Th.-Cu.
Scorzonera subaphylla Boiss. Asteraceae Za 2700–3400 Th.-Cu.
Senecio kotschyanus Boiss. Asteraceae Za, Ke 3800–4200 Subn. Scree
Tanacetum dumosum Boiss. Asteraceae Za 2100–3300 Th.-Cu.
Tanacetum persicum (Boiss.) Mozaff. Asteraceae Za, Al, Az, Ke, Ko 1700–3800 Chasm.
Tanacetum polycephalum Sch.Bip. subsp. farsicum Podl. Asteraceae Za, Ke 1500–3990 Th.-Cu.
Taraxacum kotschyi Soest Asteraceae Za 1640–2800 Chasm.
Tragopogon caricifolius Boiss. Asteraceae Za, Al, Az, Ke 1000–4000 Th.-Cu.
Alkanna frigida Boiss. Boraginaceae Za, Al 1500–3400 Oak W., Th.-Cu.
Caccinia kotschyi Boiss. Boraginaceae Za 1500–2500 Oak W., Chasm.
Onosma kilouyense Boiss. & Hausskn Boraginaceae Za, Al 1500–3500 Th.-Cu.
Onosma kotschyi Boiss. Boraginaceae Za, Al, Ke 1220–3150 Th.-Cu.
Onosma platyphylla H.Riedl Boraginaceae Za 1400–3000 Th.-Cu.
Onosma stenosiphon Boiss. Boraginaceae Za, Al, Ke, Ko 3000–4000 Th.-Cu.
Trichodesma aucheri DC. Boraginaceae Za, Ke 1500–3050 Th.-Cu.
Aethionema alpinum Moazzeni & Noroozi Brassicaceae Za, Ke 3000–4000 Alp. Scree
Aethionema umbellatum (Boiss.) Bornm. Brassicaceae Za 3900–4300 Subn. Scree
Didymophysa aucheri Boiss. Brassicaceae Za, Al, Az, Ko 3000–4800 Subn. Scree
Dielsiocharis kotschyi (Boiss) O.E. Schulz Brassicaceae Za, Ke, Al, Az, Ko 1300–4000 Chasm.
Fibigia umbellata (Boiss.) Boiss. Brassicaceae Za, Al, Ke 1900–3900 Th.-Cu.
Micrantha multicaulis (Boiss.) Dvorak Brassicaceae Za 1200–3600 Th.-Cu.
Physoptychis gnaphalodes Boiss. Brassicaceae Za, Al, Az, Ke 3000–4700 Alp.-Subn. Scree
Pseudocamelina aphragmodes (Boiss.) N. Busch Brassicaceae Za 3000–4200 Alp.-Subn. Scree
Pseudocamelina glaucophylla (DC.) N. Busch Brassicaceae Za, Al, Az, Ke 2500–3800 Alp.-Subn. Scree
Zerdana anchonioides Boiss. Brassicaceae Za,Ke 3500–4400 Subn. Scree
Campanula luristanica Freyn Campanulaceae Za 2000–2800 Chasm.
Acanthophyllum crassifolium Boiss. Caryophyllaceae Za, Al, Az 1100–3000 Th.-Cu.
Arenaria minutissima Rech.f. & Esfand. Caryophyllaceae Za, Ke 3700–4200 Alp.-Subn. Scree
Arenaria persica Boiss. Caryophyllaceae Za, Ke 3000–4200 Th.-Cu.
Bufonia kotschyana Boiss. Caryophyllaceae Za, Al, Az 1600–3100 Th.-Cu.
Bufonia macrocarpa Ser. Caryophyllaceae Za, Al 1300–3000 Th.-Cu.
Dianthus austroiranicus Lemperg Caryophyllaceae Za, Ke 1600–2300 Th.-Cu.
Dianthus denaicus Assadi Caryophyllaceae Za 2600–3700 Th.-Cu.
Dianthus orientalis Adams subsp. aphanoneurus Rech.f. Caryophyllaceae Za 2000–4140 Th.-Cu., Chasm.
Dianthus orientalis Adams subsp. scoparius (Fenzl ex Boiss.) Bornm. Caryophyllaceae Za 2300–2500 Th.-Cu., Chasm.
Dianthus stenocephalus Boiss. Caryophyllaceae Za 2100–2500 Th.-Cu.
Minuartia sublineata Rech.f. Caryophyllaceae Za, Az 1650–4200 Chasm.
Silene albescens Boiss. Caryophyllaceae Za 1315–3000 Th.-Cu.
Silene daenensis Melzh. Caryophyllaceae Za 3000–4400 Alp.-Subn. Scree
Silene elymaitica Bornm. Caryophyllaceae Za 1700–3350 Chasm.
Silene farsistanica Melzh. Caryophyllaceae Za 1800–3000 Th.-Cu.
Silene gynodioica Ghaz. subsp. glandulosa Melzh. Caryophyllaceae Za, Ko 1900–3500 Th.-Cu.
Silene gynodioica Ghaz. subsp. peduncularis (Fenzl ex Boiss.) Melzh. Caryophyllaceae Za, Az, Ke 1150–3500 Th.-Cu.
Silene nurensis Boiss. & Hausskn. Caryophyllaceae Za, Ke 3600–4400 Subn. Scree
Silene persica Boiss. Caryophyllaceae Za 2400–3500 Chasm.
Silene rhynchocarpa Boiss. Caryophyllaceae Za 2000–3000 Chasm.
Silene tragacantha Fenzl ex Boiss. Caryophyllaceae Za 3800–4000 Th.-Cu.
Colchicum wendelboi K. Persson Colchicaceae Za 850–3000 Wetland
Convolvulus urosepalus Pau Convolvulaceae Za 2500–3450 Umb.
Sedum callichroum Boiss. Crassulaceae Za 1300–3000 Oak W.
Sedum kotschyanum Boiss. Crassulaceae Za, Ke 2100–4000 Alp.-Sub. Scree
Cephalaria juncea Boiss. Dipsacaceae Za, Az 1500–3100 Oak W.
Pterocephalus persicus Boiss. Dipsacaceae Za, Ke 1600–3100 Oak W.
Euphorbia hebecarpa Boiss. Euphorbiaceae Za, Ke, Az 3000–3800 Th.-Cu.
Euphorbia plebeia Boiss. Euphorbiaceae Za 2000–2500 Oak W., Th.-Cu.
Astragalus argyrostachys Boiss. Fabaceae Za 1650–2400 Oak W.
Astragalus brachycalyx Fisch. subsp. eriostylus (Boiss. & Hausskn.) Zarre Fabaceae Za 2000–3200 Th.-Cu.
Astragalus campylanthus Boiss. Fabaceae Za, Ke 1550–3100 Th.-Cu.
Astragalus cephalanthus DC. Fabaceae Za, Ke 1150–3000 Th.-Cu.
Astragalus chalaranthus Boiss. & Hausskn. Fabaceae Za 2200–3050 Th.-Cu.
Astragalus chartostegius Boiss. & Hausskn. Fabaceae Za 2500–4000 Th.-Cu.
Astragalus cyclophyllon Beck Fabaceae Za, Az 1000–2800 Oak W.
Astragalus daenensis Boiss. Fabaceae Za, Ke 3300–4200 Alp.-Subn. Scree
Astragalus fragiferus Bunge Fabaceae Za 1700–3600 Th.-Cu.
Astragalus horridus Boiss. Fabaceae Za 2400–3700 Th.-Cu.
Astragalus ibicinus Boiss. & Haussk. Fabaceae Za 1600–3250 Th.-Cu.
Astragalus inexspectatus Maassoumi & Podlech Fabaceae Za 2400–3000 Umb., Th.-Cu.
Astragalus ischredensis Bunge Fabaceae Za, Ke 1000–3100 M Grass.
Astragalus johannis Boiss. Fabaceae Za, Ke 1300–3780 Oak W., Th.-Cu.
Astragalus lateritiiformis Zarre Fabaceae Za 2102–3100 Th.-Cu.
Astragalus maassoumii Podl. Fabaceae Za 2000–2400 Th.-Cu.
Astragalus managettae Sirj. & Rech.f. Fabaceae Za 1800–2200 Oak W.
Astragalus melanodon Boiss. Fabaceae Za 3500–4400 Alp.-Subn. Scree
Astragalus microphysa Boiss. Fabaceae Za, Ke 1900–3800 Th.-Cu.
Astragalus murinus Boiss. Fabaceae Za 2500–3900 Th.-Cu.
Astragalus myriacanthus Boiss. Fabaceae Za, Ke 2000–3800 Th.-Cu.
Astragalus plagiophacos Maassoumi & Podlech Fabaceae Al 2200–3900 Th.-Cu.
Astragalus plebejus Boiss. Fabaceae Za 1800–3650 Th.-Cu.
Astragalus ptychophyllus Boiss. Fabaceae Za 1600–3000 Oak W., Th.-Cu.
Astragalus quinquefoliolatus Bunge Fabaceae Za 1600–2400 Th.-Cu.
Astragalus rhodosemius Boiss. & Hausskn. Fabaceae Za, Az, Ke 1300–3500 Th.-Cu.
Astragalus sisakhtianus Podlech & Maassoumi Fabaceae Za 2400–2500 Oak W.
Astragalus spachianus Boiss. & Buhse Fabaceae Za, Ke 1200–3300 Th.-Cu., Oak W.
Astragalus sphaeranthus Boiss. Fabaceae Za 2200–3800 Th.-Cu.
Astragalus susianus Boiss. subsp. sericeus Tietz Fabaceae Za 1210–3355 Th.-Cu.
Astragalus susianus Boiss. subsp. susianus Fabaceae Za 1400–3040 Th.-Cu.
Astragalus tenuiscapus Freyn & Bornm. Fabaceae Za, Ke 2450–3950 Umb.
Astragalus turgidus Podlech Fabaceae Za 2700–3900 Alp. Scree
Astragalus zerdanus Boiss. Fabaceae Za 3500–4400 Subn. Scree
Cicer spiroceras subsp. spiroceras Jaub. & Spach Fabaceae Za, Ke 1500–3700 Umb.
Cicer tragacanthoides Jaub. & Spach Fabaceae Za, Al, Ke, Ko 2600–4000 Alp.-Subn. Scree
Hedysarum criniferum Boiss. Fabaceae Za 1600–3000 Th.-Cu.
Onobrychis melanotricha Boiss. Fabaceae Za, Al 900–3200 Th.-Cu., Oak W.
Oxytropis chrysocarpa Boiss. Fabaceae Za, Al, Ko 1900–3000 Oak W.
Vicia ciceroidea Boiss. Fabaceae Za, Al, Az 2600–4200 Alp.-Subn. Scree
Vicia kotschyana Boiss. Fabaceae Za 2400–4100 Alp.-Subn. Scree
Ajuga austro-iranica Rech. f.,F Fabaceae Za 400–3600 Chasm.
Ajuga chamaecistus Ging. ex Benth. Lamiaceae Za, Al, Az, Ko 1200–2800 M Grass.
Dracocephalum kotschyi Boiss. Lamiaceae Za, Al, Az 1500–3500 M Grass., Umb.
Dracocephalum surmandinum Rech.f. Lamiaceae Za 3000–3900 Th.-Cu.
Mentha longifolia (L.) Hudson var. kermanensis Rech.f. Lamiaceae Za, Al, Ke 1300–3800 Wetland
Nepeta glomerulosa Boiss. Lamiaceae Za, Al, Ke, Ko 200–3800 Umb.
Nepeta kotschyi Boiss. Lamiaceae Za 1100–2930 Umb.
Nepeta lasiocephala Benth. Lamiaceae Za, Ke 3500–4400 Subn. Scree
Nepeta macrosiphon Boiss. Lamiaceae Za, Az 1800–3800 Umb.
Nepeta oxyodonta Boiss. Lamiaceae Za, Ke 1000–3300 Chasm.
Nepeta schiraziana Boiss. Lamiaceae Za, Al, Ko 1500–3000 Oak W.
Phlomis anisodonta Boiss. subsp. occidentalis Jamzad Lamiaceae Za 950–3300 Th.-Cu.
Phlomis persica Boiss. Lamiaceae Za, Al 0–2800 Oak W., Th.-Cu.
Phlomoides adenantha Jaub. & Spach Lamiaceae Za, Ke 150–2900 Oak W.
Satureja bachtiarica Bunge Lamiaceae Za, Ke 1550–3000 Chasm.
Scutellaria multicaulis Boiss. Lamiaceae Za, Al, Ke 3000–4200 Alp.-Subn. Scree
Stachys acerosa Boiss. Lamiaceae Za, Ke 1700–3500 Th.-Cu.
Stachys ixodes Boiss. & Hausskn. ex Boiss. Lamiaceae Za 1700–2860 Chasm.
Stachys obtusicrena Boiss. Lamiaceae Za, Ke 3500–4200 Subn. Scree
Stachys persepolitana Boiss. Lamiaceae Za, Ke 800–2600 Chasm.
Stachys pilifera Benth. Lamiaceae Za 1700–3350 Th.-Cu.
Thymus daenensis Celak. Lamiaceae Za, Al, Az, Ke 1100–3100 Th.-Cu.
Linum persicum Ky. ex Boiss. Linaceae Za 1900–3200 Th.-Cu.
Alcea iranshahrii Pakravan Malvaceae Za 2400–2600 Umb.
Fraxinus angustifolia Vahl. subsp. persica (Boiss.) Azadi Oleaceae Za 850–2500 Oak W.
Acantholimon flexuosum Boiss. & Hausskn. ex Bunge Plumbaginaceae Za, Al, Ke 1600–3000 Th.-Cu.
Acantholimon melananthum Boiss. Plumbaginaceae Za 2500–3500 Th.-Cu.
Acantholimon oliganthum Boiss. Plumbaginaceae Za, Ke 1600–3500 Th.-Cu.
Acantholimon tomentellum Boiss. Plumbaginaceae Za 3100–4200 Alp.-Subn. Scree
Bromus frigidus Boiss. & Hausskn. Poaceae Za 3500–4200 Alp.-Subn. Scree
Colpodium violaceum (Boiss.) Griseb. Poaceae Za 3000–3400 Snowbed
Elymus gentryi (Melderis) Melderis var. ciliatiglumis Assadi Poaceae Za 2500–3000 Th.-Cu.
Elymus zagricus Assadi Poaceae Za 2800–2900 Th.-Cu.
Piptatherum denaense Hamzehee & Assadi Poaceae Za 3200–3300 Th.-Cu.
Polygonum aridum Boiss. & Hausskn. Polygonaceae Za 1700–2800 Th.-Cu.
Rheum persicum Los. Polygonaceae Za 1650–2200 Umb.
Primula gaubaeana Bornm. Primulaceae Za, Ke 700–2800 Chasm.
Dionysia bryoides Boiss. Primulaceae Za 1850–3200 Chasm.
Dionysia diapensiifolia Boiss. Primulaceae Za 1000–2500 Chasm.
Dionysia revoluta Boiss. subsp. canescens (Boiss.) Wendelbo Primulaceae Za, Ke 1600–3300 Chasm.
Dionysia revoluta Boiss. subsp. revoluta Primulaceae Za, Ke 1700–3700 Chasm.
Dionysia termeana Wendelbo Primulaceae Za 2680–3500 Chasm.
Dionysia zagrica Grey-Wilson Primulaceae Za 2050–2850 Chasm.
Delphinium saniculifolium Boiss. Ranunculaceae Za, Ke 1700–2700 Umb.
Ranunculus elymaiticus Boiss. & Hausskn. Ranunculaceae Za 2200–4200 Snowbed
Rhamnus cornifolia Boiss. & Hohen. var. cornifolia Rhamnaceae Za, Az 1700–3700 Chasm.
Rhamnus cornifolia Boiss. & Hohen. var. denudata Bornm. Rhamnaceae Za 2400–3000 Chasm.
Amygdalus elaeagnifolia Spach subsp. elaeagnifolia Rosaceae Za, Ke 1300–3467 Th.-Cu.
Amygdalus elaeagnifolia Spach subsp. leiocarpa (Boiss.) Browicz Rosaceae Za, Ke 1600–3400 Th.-Cu.
Amygdalus haussknechtii (C.K.Schneider.) Bornm. Rosaceae Za 1400–2900 Oak W.
Cerasus brachypetala Boiss. var. bornmuelleri (C. K. Schneid.) Browicz Rosaceae Za 2100–3000 Chasm.
Cerasus brachypetala Boiss. var. brachypetala Boiss. Rosaceae Za 2100–3600 Chasm.
Cerasus microcarpa (C.A.Mey.) Boiss. subsp. diffusa (Boiss. & Hausskn.) Browicz Rosaceae Za, Al 800–2400 Oak W.
Cotoneaster persicus Pojark. Rosaceae Za, Ke 1000–3300 Oak W.
Potentilla elvendensis Boiss. et Hohen. Rosaceae Za 2200–2800 Th.-Cu.
Potentilla flaccida Th. Wolf Rosaceae Za, Al 2600–3750 Snowbed
Potentilla lignosa Willd. ex D. F. K. Schltdl Rosaceae Za, Al 2000–3200 Chasm.
Potentilla nuda Boiss. Rosaceae Za, Al, Az, Ke 2000–3900 Snowbed
Potentilla nurensis Boiss. & Hausskn. Rosaceae Za, Az 1650–3350 Wetland
Pyrus glabra Boiss. Rosaceae Za 1578–2600 Oak W.
Asperula fragillima Boiss. & Hausskn. ex Boiss. Rubiaceae Za 1800–3300 Chasm.
Asperula glomerata (M.Bieb.) Griseb. subsp. condensata (Ehrend.) Ehrend. Rubiaceae Za 3200–3500 Umb.
Asperula glomerata (M.Bieb.) Griseb. subsp. dasycarpa Ehrend. & Schönb.-Tem. Rubiaceae Za 1500–3500 Umb.
Asperula glomerata (M.Bieb.) Griseb. subsp. filiformis (Bornm.) Ehrend. & Schönb.-Tem Rubiaceae Za, Ke 3000–4200 Alp.-Subn. Scree
Asperula rechingeri Ehrend. & Schönb.- Tem Rubiaceae Za 2000–3900 Umb., Th.-Cu.
Crucianella gilanica Trin. subsp. glauca (A. Rich ex D.C.) Ehrend. Rubiaceae Za 1530–3204 Chasm.
Galium anguineum Ehrend & Schönb.-Tem. Rubiaceae Za 2150–4000 Wetland
Galium pseudokurdicum (Ehrend.) Schönb.-Tem. Rubiaceae Za 3500–4200 Alp.-Subn. Scree
Galium schoenbeck-temesyae Ehrend. Rubiaceae Za 2400–2900 Chasm.
Rubia albicaulis Boiss. Rubiaceae Za, Ke 1300–2800 Umb.
Rubia pauciflora Boiss. Rubiaceae Za 3000–4200 Alp.-Subn. Scree
Salix issatissensis Maassoumi, Moeeni & Rahimin. Salicaceae Za, Ke 1800–2500 Wetland
Scrophularia crassiuscula Grau Schrophulariaceae Za 1300–3300 Chasm.
Scrophularia subaphylla Boiss. Schrophulariaceae Za, Al, Az, Ke 3000–4150 Alp.-Subn. Scree
Verbascum austroiranicum Hub.-Mor. Schrophulariaceae Za 1900–2400 Oak W.
Verbascum hasarense Freyn & Bornm. Schrophulariaceae Za, Ke 2400–3600 Th.-Cu.
Veronica kurdica Benth. subsp. filicaulis (Freyn) M. A. Fischer Schrophulariaceae Za, Ke 3000–4300 Th.-Cu., Subn. Scree
Veronica rubrifolia Boiss. subsp. rubrifolia Schrophulariaceae Za, Al, Ke 1800–3000 Snowbed, Th.-Cu.
Ulmus boissieri Graudz Ulmaceae Za, Ke 1300–2600 Oak W.

Results and discussion

Endemicity and biogeography

Of the 242 Iranian endemic taxa recorded from the study area, a total of 22 taxa (21 species, 1 variety; Table 1) are restricted to Dena Mts, 122 taxa (105 species, 10 subspecies, 7 varieties; Table 1) are endemic to Zagros as a whole, and 120 taxa (104 species, 13 subspecies, 3 varieties) are shared with outher mountain ranges of the Iranian Plateau (Figure 6, Table 1). From these 120 taxa, 84 taxa are also present in Yazd-Kerman, 51 taxa in Alborz, 37 taxa in the Azerbaijan Plateau, and 15 taxa in Kopet Dagh-Khorassan (Figure 6). Thus, Dena Mts have the strongest floristic affinity to the closest mountain range, the Yazd-Kerman massif. The elevational belt of 2200–2600 m a.s.l. has the richest endemic diversity. Number of endemic species decrease gradually at both lower and higher elevations (Figure 7). From the 22 taxa endemic to the Dena Mts, five have a mean elevational distribution between 1600 and 2500 m a.s.l., 12 taxa between 2500 and 3500 m a.s.l., and five taxa above 3500 m a.s.l.

The subnival vegetation types are dominated by scree and rocks and are very open, the vegetation having a maximum cover of 20%. Most of the 38 taxa reaching the subnival zone of Dena Mts (elevations above 4100 m a.s.l.) are endemics of the Iranian Plateau (68%), and from those, 42% are endemic of Zagros and Yazd-Kerman, and 21% are endemic of Zagros (Table 2). As only ca. 10% of the plant taxa recorded from Dena Mts (1200 taxa; Jafari Kokhedan 2003) are endemic to Zagros, the high rate of endemism for the subnival flora confirms previous findings that the rate of endemism is considerably higher in alpine and subnival habitats compared to lower elevations (Irl et al. 2015; Steinbauer et al. 2016; Noroozi et al. 2019b).

Figure 6. 

Floristic relationships between Dena Mts and other mountain ranges of Iran (areas of endemism), based on the endemic flora of Iran (the numbers written in each area are taxa shared with Dena Mts).

Figure 7. 

Number of endemic species in different elevational belts in Dena Mts. High number of endemics are concentrated in mid-elevational belts.

Table 2.

List of species reaching the subnival zone of Dena Mts (elevation above 4100 m a.s.l.). Al: Alborz; Az: Azerbaijan Plateau; Ke: Yazd-Kerman; Ko: Kopet Dagh-Khorassan; Za: Zagros.

Taxon Family Distribution range Type from Dena Mts
Semenovia dichotoma (Boiss.) Manden. Apiaceae Iran (Za) Kotschy 1842
Crepis heterotricha DC. Asteraceae Iran (Az, Al, Za, Ke)
Erigeron daenensis Vierh. Asteraceae SE Anatolia, Iran (Za) Kotschy 1842
Myopordon persicum Boiss Asteraceae Iran (Za) Kotschy 1842
Psychrogeton amorphoglossus (Boiss.) Novopokr. Asteraceae Irano-Anatolia to C Asia Kotschy 1842
Arnebia euchroma (Royle) I. M. Johnst. Boraginaceae Iran (Za, Ke) to Himalaya
Didymophysa aucheri Boiss. Brassicaceae Iran (Za, Az, Al)
Dielsiocharis kotschyi Boiss. Brassicaceae Iran (Za, Az, Al, Ke)
Draba aucheri Boiss. Brassicaceae Iran and C Asia
Graellsia saxifragifolia (DC.) Boiss. Brassicaceae Iran, Hindu Kush
Physoptychis gnaphalodes Boiss. Brassicaceae Iran (Za, Al, Az, Ke, Ko)
Pseudocamelina aphragmodes (Boiss.) N. Busch Brassicaceae Iran (Za)
Zerdana anchonioides Boiss. Brassicaceae Iran (Za, Ke)
Arenaria balansae Boiss. Caryophyllaceae Anatolia and Iran
Arenaria persica Boiss. Caryophyllaceae Iran (Za, Ke)
Arenaria minutissima Rech. f. & Esfand. Caryophyllaceae Iran (Za, Ke)
Minuartia sublineata Rech.f. Caryophyllaceae Iran (Za, Az)
Silene daenensis Melzh. Caryophyllaceae Iran (Za)
Chenopodium foliosum Asch. Chenopodicaceae Casmopolite
Euphorbia aucheri Boiss. Euphorbiaceae Irano-Anatolia region, Hindu Kush
Astragalus melanodon Boiss. Fabaceae Iran (Za) Kotschy 1842
Astragalus zerdanus Boiss. Fabaceae Iran (Za)
Onobrychis cornuta (L.) Desv. Fabaceae SW Asia
Vicia ciceroidea Boiss. Fabaceae Iran (Za, Al, Az) Kotschy 1842
Nepeta lasiocephala Benth. Lamiaceae Iran (Za) Kotschy 1842
Scutellaria multicaulis Boiss. Lamiaceae Iran (Za, Al, Ke)
Stachys obtusicrena Boiss. Lamiaceae Iran (Za, Ke)
Gagea cf. alexeenkoana Micsz. Liliaceae Caucasus, Iran
Acantholimon tomentellum Boiss. Plumbaginaceae Iran (Za)
Bromus frigidus Boiss. & Hausskn. Poaceae Iran (Za) Kotschy 1842
Elymus longearistatus (Boiss.) Tzvelev Poaceae Irano-Anatolian region
Piptatherum laterale (Regel) Roshev. Poaceae From Anatolia to Central Asia and Himalaya
Polygonum serpyllaceum Jaub. & Spach Polygonaceae Iran, Hindu Kush Kotschy 1842
Potentilla flaccida Th.Wolf ex Bornm. Rosaceae Iran (Za, Al)
Asperula glomerata (M.Bieb.) Griseb. subsp. filiformis (Bornm.) Ehrend. & Schönb.-Tem. Rubiaceae Iran (Za, Ke)
Galium pseudokurdicum (Ehrend.) Schönb.-Tem. Rubiaceae Iran (Za) , Iraq Kotschy 1842
Rubia pauciflora Boiss. Rubiaceae Iran (Za)
Scrophularia subaphylla Boiss. Schrophulariaceae Iran (Za, Al, Az, Ke) , Iraq Kotschy 1842
Veronica kurdica Benth. subsp. filicaulis (Freyn) M. A. Fischer Scrophulariaceae Iran (Za, Ke)

Description of new sytaxonomic units

We recorded a total of 33 species in 19 plots. The species richness ranged from 3 to 11 species per plot. The two clusters of the first TWINSPAN division level were considered as associations embedded in a new alliance that is proposed for Central and Southern Zagros. Based on the DCA ordination diagram (Figure 8), the associations are well separated from each other. We describe two new associations under a new alliance.

Galion pseudokurdici all. nov. (Table 3)

Type (holotypus hoc loco): Zerdanetum anchonioidis ass. nov. (see below)

Character species: Astragalus melanodon (Figure 5A), Bromus frigidus (Figure 5B), Galium pseudokurdicum (Figure 5D), Stachys obtusicrena (Figure 5F).

This alliance is only known from the subnival zone of Dena Mts. Most of the character species of this unit are distributed in South and Central Zagros and in the Yazd-Kerman mountains. Astragalus melanodon is restricted to Central and Southern Zagros, Bromus frigidus and Galium pseudokurdicum are endemics of Zagros, and Stachys obtusicrena is an endemic of Zagros and Yazd- Kerman mountains. Therefore, this alliance could likely be found in similar habitats of Zagros as a whole and of the Yazd-Kerman mountains.

This alliance fits well under the class Didymophyso aucheri-Dracocephaletea aucheri Noroozi et al. 2014 (Tables 3, 4). This class was described from the high alpine and subnival scree vegetation types of Alborz and mountains of NW Iran, together with two orders and three alliances (Table 4): Didymophysetalia aucheri (with one alliance, Didymophysion aucheri) and Physoptychio gnaphalodis-Brometalia tomentosi (with two alliances, Erigerontion venusti and Elymo longearistati-Astragalion macrosemii). Additional data and studies from other parts of the Zagros and Yazd-Kerman mountains are needed to clarify if our newly described alliance belongs to one of the mentioned orders, or if a new order should be described. Ecological characters like elevational range, steepness, the composition of soil, screes and stones, and also physiognomy of the communities and species richness in the new alliance are closer to Didymophysion aucheri from Central Alborz (see Noroozi et al. 2014).

Aethionemetum umbellati ass. nov. (Figure 9; Table 3)

Type relevé (holotypus hoc loco): Table 3, relevé 10

Character species: Aethionema umbellatum (Figure 9A), Nepeta lasiocephala (Figure 9B), Silene daenensis (Figure 9C).

Differential species: Euphorbia aucheri (Figure 5C).

This unit can be found on steep slopes (with an average inclination of 33°, and a range of 24–40°) that are mostly south- to west-exposed. The ground is mostly covered by scree and gravel (ca. 85%) and the vegetation cover is accordingly sparse (ca. 13%). The species richness of this association ranges from three to 11 (on average seven) species per relevé. This association is endemic to Dena Mts. Aethionema umbellatum and Nepeta lasiocephala are local endemics, whereas Silene daenensis is an endemic of the Zagros mountain range.

Zerdanetum anchonioidis ass. nov. (Figure 10; Table 3)

Type relevé (holotypus hoc loco): Table 3, relevé 13

Character species: Astragalus zerdanus (Figure 10A), Erigeron daenensis (Figure 10B), Myopordon persicum (Figure 10C), Veronica kurdica subsp. filicaulis, Zerdana anchonioides (=Sterigmostemum anchonioides; Figure 10D).

Differential species: Arenaria persica, Piptatherum laterale.

This unit is mostly found on north- to north-eastern-exposed slopes with an average inclination of ca. 20° (range from 10 to 30°). This association occurs on stony and scree grounds with, compared to the previous community, a lower proportion of scree (ca. 55%) and a higher proportion of rocks (on average 28%) and open soil (ca. 10%). The average vegetation cover of the association is ca. 20% and species richness ranges from four to 11 (average of eight) species per relevé. Zerdana anchonioides is an endemic of Southern Zagros and the Yazd-Kerman mountain range. Astragalus zerdanus, Erigeron daenensis and Myopordon persicum are endemic elements of Zagros. Veronica kurdica subsp. filicaulis is an endemic taxon of Zagros and Yazd-Kerman. Based on the distribution of the characteristic species, the geographic extent of this association is expected to cover the subnival zone of Southern and Central Zagros.

Table 3.

Relevés of scree vegetation of the subnival zone classified in Didymophyso aucheri-Dracocephaletea aucheri (character species highlighted in brown). The two associations Aethionemetum umbellati ass. nov (character species in cells with blue shading) and Zerdanetum anchonioidis ass. nov. (character species in cells with green shading) are classified in the alliance Galion pseudokurdici all. nov. (character species in cells with violet shading). Two last columns are the synoptic table (syn. Tab.) presenting the constancy (in %) and fidelity (phi value × 100) of the species in each association.

Class Didymophyso aucheri-Dracocephaletea aucheri Noroozi et al. 2014 Syn. Tab.
Alliance Galion pseudokurdici all. nov. Constancy (Fidelity)
Association Ass. 1 Aethionemetum umbellati ass. nov. Ass. 2 Zerdanetum anchonioidis ass. nov. 1 2
Relevé Nr. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
Elevation (m) 4084 4084 4094 4103 4106 4280 4278 4291 4249 4013 4280 4226 4218 4190 4189 4171 4164 4165 4162
Aspect SW SW SW SW SW SW SW S NE S NE N N NE NE NE E NE N
Slope (°) 35 35 35 35 40 30 30 30 25 40 30 15 20 30 10 25 15 15 10
Vegetation cover% 15 20 15 15 10 10 5 2 15 20 15 10 10 25 15 15 20 20 35
Scree% 85 80 85 80 90 90 90 90 85 80 70 40 30 60 70 35 80 70 40
Soil% - - - - - - 5 5 - - 15 - - 10 5 - - - 10
Rock% - - - 5 - - - - - - - 50 60 5 10 50 - 10 15
Species richness 8 11 8 7 6 6 3 3 7 9 6 9 10 4 6 11 10 6 9
Aethionema umbellatum + + + + + + 60 (66)
Nepeta lasiocephala + 1 1 1 1 2 1 1 80 (82)
Silene daenensis + + + + + + 2 + 70 (60) 11
Zerdana anchonioides 1 1 + 1 + 56 (62)
Erigeron daenensis + + + 33 (45)
Myopordon persicum 2 1 22 (35)
Astragalus zerdanus + + + 33 (45)
Veronica kurdica subsp. filicaulis + + 22 (35)
Arenaria persica 1 2 2 33 (45)
Piptatherum laterale 1 1 + 1 + + 1 + 10 78 (68)
Bromus frigidus 1 1 2 + + 1 2 1 + 1 + + + 2 70 78 (9)
Galium pseudokurdicum 2 2 1 1 1 + + 1 1 1 1 1 1 + + 90 (28) 67
Astragalus melanodon 1 2 2 1 + 1 + 30 44 (15)
Stachys obtusicrena + + 1 + + 20 33 (15)
Physoptychis gnaphalodes + + 1 2 + 2 1 1 2 2 1 40 78 (38)
Elymus longearistatus + 1 1 2 1 + 1 2 + + 80 (58) 22
Euphorbia aucheri + 1 + 1 40 (50)
Psychrogeton amorphoglossus + + + 10 22 (17)
Potentilla flaccida + + + 20 (12) 11
Dielsiocharis kotschyi + + 22 (35)
Scrophularia subaphylla + 11 (24)
Arnebia euchroma + 11 (24)
Crepis heterotricha 2 11 (24)
Chenopodium foliosum + 10 (23)
Draba aucheri r + 22 (35)
Gagea cf. alexeenkoana + 1 10 11 (2)
Arenaria minutissima + 11 (24)
Onobrychis cornuta + + 22 (35)
Polygonum serpyllaceum + 1 10 11 (2)
Pseudocamelina aphragmodes 1 10 (23)
Rubia pauciflora + 11 (24)
Scutellaria multicaulis + 10 (23)
Acantholimon tomentellum + 10 (23)
Table 4.

Synoptic table of the scree communities in N Iran and Dena Mts. Values are percentage constancies. The constancy values of character species of syntaxa are shaded, and the constancy values of character species of the class present in the newly described alliance are given in bold.

Mountains Alborz and NW Iran Dena
Alliance number All1 All2 All3 All4
Number of relevés 23 69 63 19
Didymophysion aucheri (All1)
Achillea aucheri 39 . 2 .
Veronica aucheri 26 . 2 .
Galium aucheri 52 . . .
Veronica paederotae 30 . . .
Senecio vulcanicus 22 . . .
Erysimum elbrusense 30 . 5 .
Cerastium purpurascens 39 . 5 .
Erigerontion venusti (All2)
Draba bruniifolia . 29 . .
Alopecurus aucheri . 22 . .
Nepeta menthoides . 25 . .
Tripleurospermum caucasicum . 33 . .
Sesleria phleoides . 22 . .
Galium hyrcanicum . 41 . .
Erigeron caucasicus . 62 . .
Pedicularis caucasica . 25 . .
Minuartia glandulosa . 26 . .
Koeleria eriostachya . 38 . .
Festuca alaica 4 75 3 .
Elymo longearistati-Astragalion macrosemii (All3)
Nepeta racemosa . . 24 .
Astragalus macrosemius . . 57 .
Galion pseudokurdici all. nov. (All4)
Bromus frigidus . . . 74
Galium pseudokurdicum . . . 79
Astragalus melanodon . . . 37
Stachys obtusicrena . . . 26
Didymophyso-Dracocephaletea
Physoptychis gnaphalodes 1 16 17 58
Euphorbia aucheri 4 . 24 21
Elymus longearistatus . . 60 53
Didymophysa aucheri 96 32 . .
Dracocephalum aucheri 48 35 32 .
Bromus tomentosus 13 70 78 .
Alopecurus textilis 22 32 . .
Asperula glomerata 30 . 40 .
Ziziphora clinopodioides . 49 25 .
Poa araratica 4 49 37 .
Helichrysum psychrophilum 4 32 8 .
Figure 8. 

DCA ordination of the plots with environmental variables and vegetation features. Aethionemetum umbellati (triangle), Zerdanetum anchonioidis (square).

Figure 9. 

New association Aethionemetum umbellati and its character species. A) Aethionema umbellatum (4200 m a.s.l.). B) Nepeta lasiocephala (4300 m a.s.l.). C) Silene daenensis (4200 m a.s.l.).

Figure 10. 

New association Zerdanetum anchonioidis and its character species. A) Astragalus zerdanus (4150 m a.s.l.). B) Erigeron daenensis (4250 m a.s.l.). C) Myopordon persicum (4200 m a.s.l.). D) Zerdana anchonioides (4300 m a.s.l.).

Conservation concerns

Dena Mts harbor a high amount of endemic species. Although the number of endemic species is also high in mid-elevational belts, the proportion of endemics increases with increasing elevation. Consequently, our newly described communities of the subnival zone harbor a high number of range-restricted species. Shrinking of alpine and subnival habitats and the loss of cold-adapted species of the high mountains have been recorded, and also have been predicted in biodiversity scenarios for the 21st century as the result of a general upward shift of plant species under a warmer climate (Chen et al. 2011; Engler et al. 2011; Pauli et al. 2012). The subnival zone, with a very high proportion of endemic and range-restricted species in South-West Asia (Noroozi et al. 2011; Noroozi et al. 2019b), may be the most fragile habitat under the impact of ongoing climate change due to the absence of alternative habitats for the cold-adapted species to move into. Therefore, subnival species of Dena Mts, which are already restricted to habitats near the summits of the mountain range (in a narrow elevation belt above 4100 m a.s.l. with small area size), are at high risk of population size reduction or even extinction. Moreover, like other high mountains of Iran, overgrazing is a big problem for the natural vegetation types of the high mountains. Most of the big herds of the lowlands and montane zone move to the high elevations in summertime and concentrate in small areas of alpine habitats. Usually, the size of the herds exceed the capacity of these vegetation types, and the natural species composition and range-restricted species are highly endangered (Noroozi et al. 2008; Bagheri et al. 2022). Dena Mts have the highest summit of the entire Zagros and are attractive for mountaineering and tourism. Although Dena Mts lie within a protected area, this will not prevent shrinking of alpine habitats due to the ongoing global warming, or degradation of these ecosystems due to overgrazing or tourism. Consequently, strong attention to increase the efficiency of the protection and to reduce other anthopogenic activities in high elevations of this mountain system in particular and of the entire South-West Asian mountains in general is highly recommended.

Data availability

All data are presented in the paper.

Author contributions

J.N. planned the research, conducted the field sampling, identified the species, and analyzed the data, A.T. identified the species and contributed to data analyzing, M.S. contributed to fieldwork and data collection, and G.M.S. contributed to writing and editing. All authors have read and agreed to the published version of the manuscript.

Acknowledgements

Dr. Wolfgang Willner is acknowledged for his valuable comments and edits made on the manuscript. This study was financially supported by the Austrian Science Fund (FWF P31898 to J.N.).

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