Floristic, Chorology, and Life form investigation of the Kopal region, Khuzestan province

Introduction

Natural resources are considered one of the basic capitals of any country. The first step toward properly utilizing these resources is to study and examine their various components. In this field, vegetation studies are of special importance and serve as the foundation for both applied and theoretical research. One of the essential activities for the proper use of natural resources in an area is floristic study, which involves identifying and introducing the plants (Farsi et al., 2021). The relatively high diversity and richness of the flora of Iran have caused its different places to be studied by foreign and Iranian researchers in terms of the floristic, along with the collection of many plant samples. However, the importance of such research has not diminished (Kiani et al., 2017; Hassanpouraghdam et al., 2022). The phenomenon of desertification is one of the most important problems in arid and semi-arid areas. Some of the main reasons for the expansion and growth of these areas in Iran include: climate change, lack of rainfall, and human activities (Khaledi 2006). Khuzestan province is located in the southwest of Iran and is of special importance from various historical, industrial, and natural dimensions. Following the increase in population and the growth of industry, the destruction of its nature and its negative effects are more evident than in other provinces of the country. According to available reports, the ultra-arid to arid climate covers nearly 65% of the surface of Khuzestan province (Azhdari et al., 2015) The habitats of Khuzestan are situated in two topographic positions: plains and mountains. The plain part comprises wetlands, salt marshes, sand dunes, and moorlands, while the mountainous part, located to the north and northeast, consists of oak forests or dry shrublands and the vegetation of snow-covered alpine zone. According to the report of Dinarvand and Sharifi (2008), plants belonging to 102 plant families grow in this province, of which 80 families are found in dry habitats, 13 families only in aquatic habitats, and 10 families in both habitats. According to the research results of Akhani and Gorbanli (1993), a large part of the vegetation of this province is formed by the communities of annual, moisture-loving, woody halophytes, hydrophile with the ability to tolerate salinity in the saturated areas with salt and grass perennial halophyte species, especially in most of the southern regions. In the past decade, floristic studies have been carried out in the different regions of Khuzestan province, including the floristic study of the Behbahan river forest (Basiri et al., 2011), the introduction of the flora of Shimbar (Dinarvand et al., 2015), the introduction of the plants of the Ala region and Yellow River (Taghipour et al., 2011), and the ethnobotanical survey of Susan district (Baroonian and khodayari, 2023). Currently, the Kopal region is considered one of the critical areas of dust formation in Khuzestan province. Given the location, geographical, and phytogeographic characteristics of this region, and considering that there is no documented botanical study for it, this is necessary to investigate the vegetation of the Kopal region from a floristic point of view.

Materials and methods

Introduction of the Kopal region

The location of the Kopal basin is shown in Figure 1. t is limited to the north by the southern part of Masjed Soleyman County, to the south by Ramshir, to the west by Ahvaz and Mollasani, and to the east by Ramhormoz and Baghmalek. This area is located between 29°29' to 31°42' north latitude and 48°58' and 49°32' east longitude (Figure 1). The lowest height of this area is 20 meters and the highest is about 400 meters above sea level (Dehghanianpour, 2018). According to Azhdari et al. (2015), the maximum temperature in this region sometimes exceeds 50 °C and the minimum temperature rarely to zero or below zero. The temperature rises rapidly in the spring, and this causes the formation of a nature with a dry and harsh appearance and low pasture value.

Figure 1: The approximate location of the Kopal basin in Khuzestan province and Iran, along with determination of its boundaries (Prepared based on a drawn map by Department of Natural Resources and Watershed Management of Khuzestan province (Dehghanianpour, 2018).

Based on the classification of climate conditions and according to the Ombrothermic diagram obtained from the data of Kopal station No. 3, this region has a dry climate with hot and long summers and mild and short winters (Figure 2). In total, the average annual precipitation in the area is about 228 mm, based on the average yearly rainfall at this station. Accordingly, investigating the long-term distribution of precipitation during 59 years, the months of December and January have been the rainiest months with an average precipitation of more than 50 mm, and four to six months of the year without precipitation or less than 10 mm. This region is considered a part of the Ramshir sub-basin in terms of the divisions of the basic study of the country's water resources, and the Kopal River is the main water artery, which is one of the branches of the Ramhormoz River. Runoff amount of this river has a positive and increasing slope from the beginning of autumn, changes its direction in the middle of winter and has a decreasing trend in spring and summer (Assistant of basic studies and water resources comprehensive plans of Khuzestan Water and Electricity Organization, 2018). The highlands in the region are part of the Zagros highlands, which were formed during the Tertiary period as a result of Movements of the Arabian plate towards the Eurasian plate, and they include a small part of its area. The main part of the region is a plain area which is the result of erosion and sedimentation of floods and flowing rivers of the Quaternary period (Bahrami et al., 2013).

Methods

To access the studied area with the help of the map and preliminary visits investigated access routes, geographical features, natural complications, and the general condition of its vegetation. Based on the data obtained from the 1:100,000 topographic map and the information of local people, the region boundary was determined, and plant sample collection was planned during the 2019-2023 growing seasons. In order to investigate the flora of the region, the ground survey method was used, which is a common method in taxonomic investigations, and herbarium samples were prepared from the collected samples according to conventional scientific methods. In the next step, the taxa were examined and identified using available scientific resources in this field, such as Flora Iranica (Rechinger, 1963-2015), Flora of Turkey (Davis 1965-1984), Flora of Iraq (Townsend and Guest, 1985-1966), Flora of Palestine (Zohary, 1966-1986), Flora of Iran (Assadi et al., 1989-2023), Flore del'Iran (Ghahreman, 1979-2014), Flora of Khuzestan (Mozaffarian, 1999), Flora of Khuzestan province (Dinarvand, 2021), Plants and vegetation of North-West Persian Gulf (Akhani and Samadi, 2015), etc. All identified specimens will be kept in the herbarium of the Faculty of Science, Shahid Chamran University of Ahvaz. Correct spelling of scientific names was verified by referring to the databases of the International Plant Names Index (IPNI), Plants of the World Online (POWO), and Global Biodiversity Information Facility (GBIF). To determine the geographical distribution of the taxa was used of Flora Iranica (Rechinger, 1963-2015), Floristic regions of the world (Takhtajan, 1986), Geobotanical Foundations of the Middle East (Zohary, 1973), A contribution to the flora and vegetation of the deserts of Iran (Léonard, 1988) and Flora of Iran (Assadi et al., 1989-2023). Based on the Raunkiaer method, the life form of the identified taxa was determined (Raunkiaer, 1934) and the conservation status of the species was registered using the Red Data Book of Iran (Jalili and Jamzad, 1999).

Figure 2: The Ombrothermic diagram (temperature-rain) of Kopal station No. 3

Results and observations

The outcomes of the floristic study of the Kopal region are given in table format 1 (Table 1) (Figure 3), including the list of taxa in alphabetical order, life form, Persian or vernacular name, conservation status, and geographical distribution of the identified species. Based on the produced results, 320 plant species belonging to 55 families were identified including 10 monocotyledonous and 45 dicotyledonous families, among which Asteraceae (54 species), Poaceae (45 species), Fabaceae (31 species), Amaranthaceae (18 species), Apiaceae (15 species), Brassicaceae (12 species) and Caryophyllaceae and Lamiaceae (each with 10 species) were determined as the most diverse the plant families in terms of number of species in the region (Figure 4). Astragalus is the largest genus in the Kopal region with 8 species, followed by Plantago and Centaurea with 5 species each. Also, there are many genera with 4 or 3 species in that. Most life forms in the region belong to therophytes or annual plants at the rate of 62.5% (199 species) (Figure 5- A and B) and in the next ranks are placed hemicryptophytes (14.5%, 46 species), chaemophytes (8.8%, 28) species), geophytes (8.2%, 26 species), phanerophytes (4.1%, 14 species), helophytes (1.6%, 5 species) and hydrophytes (0.3%, one species) (Figure 6). The results showed that the chorotype spectrum of the region is formed of plant elements one regional including Sahara-Sandi (18.1%, 58 species), Iran-Turanian (11.3%, 36 species) and Mediterranean (2.2%, 7 species), elements two regional including: Iran-Turanian/Mediterranean (11.3%, 36 species), Iran-Turanian/Sahara-Sandian (9.7%, 31 species), Sahara-Sandian/Mediterranean (7.2%, 23 species) and Iran-Turanian/Europe-Siberian (2.2%, 7 species), elements three regional including: Iran-Turanian/Sahara-Sindian/Mediterranean (12.2%, 39) species), Iran-Turanian/Mediterranean/European-Siberian (3.4%, 11 species), Iran-Turanian/Sahara-Sindian/European-Siberian (1.5%, 5 species), Iran-Turanian/Sahara-Sindian/Eastern Asiatic (0.6%, 2 species) and Iran-Turanian/European-Siberian/Eastern Asiatic (0.3%, 1 species), elements multi-regional including elements of four regional and more (12.5%, 40 species) and finally Cosmopolitan plants (7.5%, 24 species) (Figure 7). 13 species endemism were identified in Iran from the total number of available plants. Based on the contents of the Red Data Book of Iran (1999), the protection rank of endemic species of the studied area is placed in two levels: low risk and lack of data. Of course, 3 endemic species in this area have been introduced after the publication of this book, and therefore their protection rank has not been determined. All plant specimens associated with this research are preserved in the herbarium of the Faculty of Science at Shahid Chamran University of Ahvaz.

Figure 3: Pictures of some natural plants of Kopal: A- Albraunia foveopilosa, B- Visnaga daucoides, C- Gymnocarpus decander, D- Matricaria chamomilla, E- Arnebia decumbens, F- Adonis dentata, G- Calendula persica, H- Hyoscyamus insanus, J- Pycnocycla cespitosa, K- Diplotaxis harra, L- Verbascum kochiiforme, M- Astragalus baba-alliar.

Figure 4: Diagram of the number of species of plant families in the Kopal region

In addition to the natural flora in the Kopal region, the implanted plants in agricultural lands and tree-planted areas, in order to prevent soil erosion or create green spaces, are observed (Figure 5- C). Among the cultivated plants, we can refer to different cultivars of Triticum aestivum (Gandom), Hordeum vulgare (Jo) and Phoenix dactylifera (Khorma) and from the cultivated trees there are various species of Acacia, Albizia lebbeck (Burhan), Cassia fistula (Floss, Senna), Leucaena leucocephala (Sobabel), Prosopis juliflora (Kahur-e-Pakistaniani), Vachellia farnesiana (Moshk), Dalbergia sissoo (Derakht-e-Sheshum), Senna pendula (Burhan goli, Senna maki), Bougainvillea spectabilis (Gol-e-kaghazi), Cordia dichotoma, Cordia myxa (Sepistan), Cascabela thevetia (Kharzahr-e-zard), Nerium oleander (Kharzahreh), Hibiscus rosa-sinensis (Khatmi Chini), Morus alba (Tot), Ficus religiosa (Anjir-e-Maeabed), Ficus benghalensis (Lol), Dodonaea viscosa (Natarakeh), Conocarpus erectus, various species of  Eucalyptus including E. camaldulensis and E. microtheca, Melaleuca viminalis (Shisheh shor), Syzygium cumini (Ogen), Olea europaea (Zeyton), Citrus × aurantium (Narenj), Lantana camara (Shahpasand-e-derakhti), Vitex trifolia, Volkameria inermis (Shemshad Abadani), Tecoma stans, Tamarix aphylla (Ghaz-e-Shahi), etc.

Figure 5: A- Seasonal Pond created in the Kopal region, B- Kopal's ephemeral vegetation, C- The Forests created in the Kopal region, D- Kopal's halophytic vegetation

Figure 6: Life Form percentage of plants identified in the Kopal region

Figure 7: Chorology of plant elements present in the Kopal region

Discussion

Increased pressure on biodiversity resulting from the development of local or regional access roads and the extraction of underground resources will change the species composition of the region, which will have important effects on its ecosystem (Peres et al., 2010; Feeley et al., 2011; Swaine and Liebsch, 2011; Murguía et al., 2016). On the other hand, probably the increasing demographic changes the biodiversity of the region gradually, and will cause more negative ecological and economic changes, by putting higher pressure on natural resources through the development of agriculture, the intensity of grazing, and the occurrence of fires (Mehring et al., 2020; IPCC, 2022). With attention to the location of the Kopal region, its natural resources have been severely affected by destruction. The Kopal's flora natural face has been changed, due to human dominance along with road construction operations for agriculture and the setting up of oil wells, indiscriminate and unplanned grazing, afforestation, and the construction of green spaces to prevent soil erosion and dust formation by planting some non-native species. Like other floristic studies in hot and dry regions (Basiri et al., 2011; Taghipour et al., 2011; Alsherif et al. 2013; Hassani et al., 2014; Malekshahi et al., 2022), the results of this research indicate the presence of a larger number (almost four times) of dicotyledonous plants (with 256 species) than monocotyledonous plants (with 64 species) in the region, which is the result of greater ecological adaptability of dicotyledonous in dry environments than monocotyledonous. According to the results, more than half of the plants identified in the region belong to 8 large plant families with a wide distribution range and high species diversity, among which the Asteraceae (with 54 species) is considered the most diverse plant family in this region. Hamzeh’ee (2016) and Ghahremani-Nejad and Aeqli (2009) consider the causes of this diversity to include the destruction of vegetation due to excessive grazing and human activities and the high power of dispersal due to the evolutionary nature of the plants of this family. Like most of the previous floristic studies, Astragalus with 8 species was identified as the largest plant genus in the Kopal region, which is in concordance with Maassoumi's opinion based on the domination of Astragalus in Iran (Maassoumi, 2003). The presence of similar life forms in a habitat indicates the same response of plants to environmental factors and as a result it will have the same effect on its processes (Prochazka et al., 2024). Nearly two-thirds of the plants in the region belonging to therophytes have been identified. The presence of a large number of therophytes in the zone not only indicates the dominance of a hot and dry climate but also indicates the effect of human intervention and the transfer of seeds to it from the surrounding regions (Tavakkoli and Mozaffarian, 2005). The presence of 14 species of trees and shrubs, scattered or in the form of patchy masses along the waterways, shows the lack of diversity of phanerophytes in the region, efforts have been made to fix this defect by planting trees in different parts of the region. One of the obvious main factors in determining the type of vegetation in dissimilar areas is its edaphic factors (Amitha Bachan, 2003). Due to the high salinity of the soil and its chalkiness in a large part of the Kopal region, both in lowland and higher places, a large number of halophyte species can be identified among the flora of the region (Figure 5- D). The Kopal region is located in a dry and tropical climate, in other words, in the Sahara-Sindian area of Iran, and the presence of a relatively larger number of elements related to this area (18.1%) can be understood. Of course, it is noteworthy that the elements tri- or pluriregional in Kopal have the highest percentage. This situation has likely occurred due to the introduction and establishment of pluriregional taxa in the region, facilitated by extensive human activities. These taxa are better adapted to the prevailing climatic conditions and more resilient to the regional environment. The results of the present study showed that 13 endemic species are found in the region, which includes about 4% of its flora. According to Ghahramane-Nejad and Aqeli (2009), the low percentage of endemic species has occurred as a result of the expansion of resistant species with a wide range of distribution and the cessation of continuous speciation due to overgrazing. Our results indicate that some taxa previously listed in the Red Data Book (1999) and considered endemic to Iran have now been confirmed to exist in neighboring countries. Consequently, their conservation status has become questionable. Accurate identification of plant species and having information about plant biodiversity, habitat diversity, plant communities, and the potential of resources available in each region is essential for planning sustainable development and managing its natural resources (Jamzad, 2008). The extremely low and rare abundance of numerous existing species poses a risk of their eradication and elimination for the Kopal region, even though according to sources, they are not considered endangered plants for Iran. The elimination of plant species and the weakening of the species richness of the region will cause the plant formations to become monospecific, and the continuation of this process will increase the intensity of desertification in the region. There is a need for careful management of the harvesting of its natural resources to prevent the expansion of critical dust-producing areas, considering the abundance of ephemeral and ruderal plants in the Kopal region as a result of warm and dry weather conditions, excessive livestock grazing, destructive human activities, etc. Ultimately, it is hoped that this study will help complete the description of the plant biodiversity of the region.

Acknowledgment

This article is based on approximately four years of continuous sampling in the Kopal region. Therefore, the author considers it his duty to thank and acknowledge all the individuals who played a role in identifying each of the taxa, as well as the organizations, particularly the Vice Chancellor for Research of Shahid Chamran University of Ahvaz, for providing financial support through an annual grant, which made this research possible.