Flora of Mount Soffeh in Isfahan, Iran

Introduction

Iran, characterized by its predominantly mountainous topography, hosts two major mountain chains, namely the Alborz and Zagros ranges and isolated peaks such as Karkas, Shirkuh, and Kerman, are recognized for their exceptional species richness and high proportion of endemic species (Zohary, 1973). Vegetation cover in these areas plays a vital role in preserving the integrity of natural ecosystems, warranting studies aimed at protecting endangered species. Furthermore, understanding the patterns of plant diversity at the species level is fundamental for biodiversity conservation efforts in these regions (Naqinezhad et al., 2009). Mountains serve as global biodiversity hotspots, harboring nearly a quarter of terrestrial biodiversity, with half of the world's biodiversity hotspots concentrated in these regions. (Mittermeier et al., 2011). Iran, covering 1.6 million km², is characterized by elevated plateaus in southwest Asia, with approximately half of its landmass comprising highlands, plains, and extensive mountain ranges, including the Alborz, Zagros, Azerbaijan, Kopet Dag, and Makran ranges (Noroozi et al., 2008).

The Zagros mountain range, spanning about 1400 km and covering an area of 323,000 km², is particularly significant, representing 20% of Iran's total land area. Stretching from northwest to southeast, the Zagros range encompasses diverse landscapes and habitats, with Mount Dena standing as its highest peak at 4409 m (Noroozi et al., 2020). Recognized as one of the 35 global biodiversity hotspots, the Zagros range hosts a remarkable array of flora and fauna (Sloan et al. 2014). Isfahan province, situated on the eastern flank of the Zagros mountains, boasts rich plant diversity (Noroozi et al., 2019).

Floristic studies play an important role in documenting vegetation diversity, assisting in environmental understanding, and facilitating conservation and management initiatives for natural areas (Memariani et al., 2016). Several floristic studies have been undertaken in central Iran, particularly in Isfahan province, encompassing diverse ecosystems such as the Mouteh Wildlife Refuge, Vanak Semirom area, Chadegan, Afus area, and Golestankooh (Asri, 2008; Parishani, 2005; Yousofi et al., 2011; Shirvani Shahenayati et al., 2020; Akhavan Roofigar & Bagheri, 2021, Mohammadi et al., 2021).

Mount Soffeh, located south of Isfahan city and reaching an elevation of 2250 m, has historically attracted tourists due to its nearness to Isfahan. Notably, well-known European botanists such as Stapf, Kaempfer, Haussknecht, and Wendelbo have conducted botanical expeditions on Mount Soffeh since the 18^th century, resulting in the collection of numerous plant specimens, including type specimens of Iran's flora (Akhavan Roofigar & Borhani, 2022).

Regarding Mount Soffeh, a comprehensive study has not yet been conducted. Recently, Akhavan Roofigar & Borhani (2022) compiled a list of plants collected from Mount Soffeh based on relevant literatures or specimens present in the SFAHAN herbarium in a review study. However, there remains a gap in our understanding of the botanical diversity and floristic composition of Mount Soffeh. This research aims to address this gap by preparing a comprehensive list of species and determining the floristic composition through a comparison of the species collected in this study with previous reports.

Materials and Methods

Study Area

Mount Soffeh, situated at an elevation range of 1700 to 2250 m at the southernmost tip of Isfahan city (Figure 1), is regarded as one of the most significant mountains in the province. Climatically, according to the Köppen classification, Mount Soffeh falls within the cold steppe zone. The average precipitation in this area is approximately 115 mm, and the mountain is situated in the steppe region. The average annual temperature ranges between 13 to 15 °C, aligning the plant elements of the region with the dry mountains of steppe areas. The highest precipitation occurs towards the end of winter (February) and the beginning of spring (March), reflecting the area's steppe climate (IRIMO).

Data Collection

Plant specimen collection was conducted throughout the growing season, from March 2021 to December 2023 across various regions of Mount Soffeh. Over 350 plant specimens were collected during this research, representing more than 250 species, all of which are now preserved in the Herbarium of the University of Isfahan (HUI). Specimens were identified using the main botanical references of Iran include: Flora Iranica (Rechinger, 1963–2015) and Flora of Iran (Assadi et al., 1988-2023). Additionally, The International Plant Names Index (IPNI) and Plants of the World Online (POWO) were utilized to compile the list of identified species. The floristic list was then organized alphabetically. Endemic species of Iran found on Mount Soffeh were identified using Flora Iranica (Rechinger, 1963–2015) and the website www.powo.science.kew.org.

FIG. 1. Geographical location of Mount Soffeh in the south of Isfahan. (A) taken from Google Earth, (B) photo by the last author.

Determining Life Forms and Chorotypes

For the classification of life forms, the Raunkiaer system (Raunkiaer, 1934) was utilized. Chorotypes were identified using authoritative sources (Zohary, 1973; Takhtajan, 1986). Chorotypes were categorized based on their distribution across one, two, or three regions. Those found in more than three regions were classified as pluriregional elements, while those with widespread distribution were categorized as cosmopolitan elements.

Results

The research conducted on the flora of Mount Soffeh exposes the presence of 258 plant species, distributed across 189 genera and 46 families. Of these families, 40 (86.95%) are dicotyledons, 4 (8.69%) are monocotyledons, one (2.17%) is a gymnosperm, and another (2.17%) is a pteridophyte. The most prominent families on Mount Soffeh include the Asteraceae with 57 species, Poaceae with 24 species, Brassicaceae with 18 species, Amaranthaceae, Fabaceae, and Lamiaceae each with 15 species, Boraginaceae with 13 species, Apiaceae with 11 species, and Caryophyllaceae with 8 species. Detailed in Table 1 are the species, categorized by family, alongside details on endemism, phytogeographical elements (chorotypes), life forms, and herbarium vouchers. Figure 2 displays a bar chart illustrating the number of genera within each family, while Figure 3 details the species count per family, including only those families that comprise more than one genus and species.

FIG. 2. Bar chart showing the number of genera belonging to each family on Mount Soffeh (only families with more than one genus are indicated).

FIG. 3. Bar chart showing the number of species belonging to each family on Mount Soffeh (only families with more than one species are indicated).

The largest plant genera on Mount Soffeh include Astragalus L. (with 7 species) and Atriplex L., Bromus L., Centaurea L., Echinops L., Euphorbia L., Tragopogon L. (each with 4 species). In terms of life forms, the plants of the area comprise 96 therophyte species (37.2%), 91 hemicryptophyte species (35.27%), 42 chamaephyte species (16.27%), 13 phanerophyte species (5.03%), 13 geophyte species (5.03%), two parasite species (0.77%), and one helophyte species (0.38%). The geophyte and helophyte species are subcategories of the cryptophyte life form. Figure 4 displays the percentages of life forms in a pie chart.

FIG. 4. Pie chart of the life form percentages of the species studied on Mount Soffeh.

Of the studied plants, 117 species (45.34%) belong to the Irano-Turanian phytogeographical region, 19 species (7.36%) to the Irano-Turanian, Saharo-Sindian regions, 18 species (6.97%) to the Irano-Turanian, Euro-Siberian regions, 17 species (6.58%) to the Irano-Turanian, Mediterranean regions, 20 species (7.75%) to the Irano-Turanian, Euro-Siberian, Mediterranean regions, 7 species (2.71%) to the Irano-Turanian, Saharo-Sindian, Mediterranean regions, 6 species (2.32%) to the Irano-Turanian, Euro-Siberian, Saharo-Sindian regions, 36 species (13.95%) belong to more than three phytogeographical regions (pluriregional), and 18 species (6.97%) are cosmopolitan. Figure 5 demonstrates the percentage of species belonging to each phytogeographical region in a pie chart.

FIG. 5. Percentage of species belonging to each phytogeographic region: Irano-Turanian (IT), Irano-Turanian, Saharo-Sindian (IT-SS), Irano-Turanian, Euro-Siberian (IT-ES), Irano-Turanian, Mediterranean (IT-M), Irano-Turanian, Euro-Siberian, Mediterranean (IT-ES-M), Irano-Turanian, Saharo-Sindian, Mediterranean (IT-SS-M), Irano-Turanian, Euro-Siberian, Saharo-Sindian (IT-ES-SS), pluriregional (Plur), and cosmopolitan (Cosm).

Additionally, 45 species (17.44%) of the plants on Mount Soffeh are endemic or sub-endemic to Iran, accounting for 1.73% of all endemic and sub-endemic plants (2597 species) in Iran (Noroozi et al., 2019). These species are distributed among families as follows: Asteraceae (14 species), Fabaceae and Apiaceae (each with 6 species), Lamiaceae and Brassicaceae (each with 3 species), Caryophyllaceae, Rosaceae, and Plumbaginaceae (each with 2 species), and Amaranthaceae, Amaryllidaceae, Boraginaceae, Malvaceae, Papaveraceae, Ranunculaceae, and Phyllanthaceae (each with one species). Among the endemic species, Tanacetum stapfianum (Rech.f.) Podlech, previously reported only in central regions of Fars province, was collected for the first time in Isfahan province and Mount Soffeh. Figure 6 shows some species in this mountain.

FIG. 6. Pictures of a number of species in Mount Soffeh. All photos are taken by the last author. A: Allium bungei Boiss., B: Prangos uloptera DC., C: Pycnocycla spinosa Decne., D: Zosima absinthiifolia (Vent.) Link, E: Anthemis gayana Boiss., F: Centaurea ispahanica Boiss., G: Echinops cephalotes DC., H: Jurinea carduiformis (Jaub. & Spach) Boiss.

FIG. 6. continued. I: Caccinia macranthera Brand, J: Heliocarya monandra Bunge, K: Campanula incanescens Boiss., L: Acanthophyllum bracteatum Boiss., M: Paronychia kurdica Boiss., N: Rosularia elymaitica A.Berger, O: Astragalus supervisus E.Sheld., P: Ebenus stellata Boiss.

FIG. 6. continued. Q: Erodium cicutarium (L.) L'Hér., R: Nepeta bituminosa (Fisch. & C.A.Mey.) Jamzad & Serpoosh., S: Scutellaria xylorrhiza Bornm., T: Gagea gageoides (Zucc.) Vved., U: Glaucium calycinum Boiss., V: Acantholimon aspadanum Bunge, W: Pteropyrum aucheri Jaub. & Spach, X: Zygophyllum fabago L.

Discussion

This research on Mount Soffeh's flora, which reports the presence of 258 species across 189 genera and 46 families, indicates the high species richness of this area. Comparing these results with other floristic studies in Isfahan province shows that the order of families mentioned is more or less consistent across studies, indicating the dominance of these families in the region. The genus Astragalus, with 7 species, is the largest on Mount Soffeh, attributed to its adaptation to mountainous regions and cold, dry climatic conditions (Bagheri et al., 2023). This genus is also the largest genus in Isfahan province with 202 taxa (Akhavan et al., 2019). The dominance of therophytes (37.2%) is influenced by various factors, with human intervention in vegetation cover being a significant contributor. Activities such as deforestation and urbanization often lead to a decline in plant abundance, subsequently affecting soil moisture levels (Ghahremaninejad & Agheli, 2009). Given the dry seasons and insufficient rainfall on Mount Soffeh, hemicryptophytes (35.3%) are abundantly observed and represent the most resilient life form, constituting a substantial proportion of the perennial and persistent vegetation of Mount Soffeh. The prevalent presence of Asteraceae species indicates environmental degradation (Pairanj et al., 2011; Saberi et al., 2010).

Another recent study related to Mount Soffeh's vegetation is a review study that examines and reports all plants collected from Mount Soffeh in relevant sources (Akhavan & Borhani, 2022). According to this, prior to the current research, the number of plant species collected by old botanists (such as Wendelbo, Stapf, Kapherr) from Mount Soffeh, according to Flora Iranica and Flora of Iran, is 51 species. Additionally, the list of plant species from Mount Soffeh available in Isfahan's herbaria is 68 species, totaling about 100 species reported from Mount Soffeh since the 18^th century until 2021.

During the present research, the number of identified species has increased to more than 2.5 times, with approximately 190 species reported for the first time on Mount Soffeh, a significant increase. However, about 30 species previously documented (Akhavan & Borhani, 2022) from Mount Soffeh were not found in this study, indicating their disappearance likely due to factors such as drought, land-use changes from mountainous areas to green spaces, destruction of native species' habitats, construction activities across Mount Soffeh, and pressure from the tourist population. Despite being free from grazing, Mount Soffeh faces excessive pressure from tourism, climbing, hiking, road construction, and building activities for tourists, such as cable car installations, which could potentially lead to a decrease in species diversity in this area (Figure 7).

These factors have altered the ecological balance of the region's vegetation. For example, artificial irrigation in natural habitats has led to an increase in non-native species such as Bidens bipinnata L., Erigeron bonariensis L., and Erigeron canadensis L., which typically grow in the high-rainfall areas of the northern country. Additionally, the destruction of natural habitats has increased invasive species such as Echinops sphaerocephalus L. and Tribulus terrestris L.. These species, which are mostly cosmopolitan, grow in degraded soils and over time replace the native species of the region. The extensive planting of coniferous trees such as Pinus spp., Hesperocyparis arizonica (Greene) Bartel, Platycladus orientalis (L.) Franco and Juniperus sabina L. in various parts of Mount Soffeh has changed the soil acidity, preventing the growth of native species in the understory of these trees (Figure 7).

FIG. 7. Human activities in Mount Soffeh: A) building related to the cable car B) routes available for climbers.

The vegetation types reported on Mount Soffeh are Stipa hohenackeriana Trin. & Rupr., Artemisia sieberi Besser, and Acantholimon Scorpius Boiss. (Feizi et al., 2018). During field surveys in 2021-2022, due to the lack of rainfall, the vegetation types of the mentioned species were not observed, but others were documented in spring 2023 following suitable winter rainfall. The main composition of these vegetation types includes the perennial plants Stipa hohenackeriana and Demavendia pastinacifolia (Boiss. & Hausskn.) Pimenov (Figure 8).

FIG .8. The main vegetation types in Mount Soffeh. (A) Demavendia pastinacifolia and (B) Stipa hohenackeriana.

In conclusion, the comprehensive botanical study of Mount Soffeh has significantly expanded our understanding of its flora, revealing a rich biodiversity with a variety of life forms adapted to its unique climatic conditions. These findings highlight the serious need for conservation efforts to preserve this unique ecological treasure and highlight the importance of Mount Soffeh as a key area for biodiversity in Isfahan. Given its closeness to the urban center of Isfahan, it is imperative to implement measures for the protection and sustainable management of species in Mount Soffeh, balancing the demands of urban development with the preservation of its natural habitats.

Acknowledgements

The authors express their gratitude to the University of Isfahan and the Isfahan municipal organization of parks and green spaces for their cooperation in this project. Additionally, we would like to thank the staff of Soffeh Mountain Park for their assistance.

 Table 1 - Floristic list, chorotypes, life forms, and herbarium numbers of the plants of Mount Soffeh. Species marked with * are endemic and sub-endemic to Iran. All herbarium specimens are kept at HUI.