Ramsar international wetlands of Alagol, Almagol and Ajigol in eastern parts of the Caspian Sea: a floristic and habitat survey

Ramsar international wetlands of Alagol, Almagol and Ajigol in eastern parts of the Caspian Sea: A floristic and habitat survey

Hamedani H.¹, Naqinezhad A.¹*, FadaieF.²

1. Department of Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran

2. Research Division of Natural Resources, Golestan Agricultural and Natural Resources Research and Education Center, AREEO, Gorgan, Iran

Ramsar international wetlands of Alagol, Almagol and Ajigol with a surface of 3027 ha are located in the vast Turkmen-Sahra plains (Golestan prov.) in east of Caspian Sea and in the vicinity of the Iran-Turkmenistan political border. Flora, vegetation and habitat diversity of the wetlands were surveyed during growing seasons of 2014 and 2015. A total of 159 plant taxa belonging to 123 genera and 42 families were determined in the studied wetlands. Asteraceae, Amaranthaceae (including Chenopodiaceae) and Poaceae were the most species rich families and Suaeda, Salsola, Atriplex, Plantago and Tamarix were the most species rich genera. A floristic analysis indicated that therophytes and pluriregional elements predominated life form and chorological spectra, respectively. Studied sites were physiognomically classified into aquatic, emergent, and dry upland habitats which represent 6, 68 and 26 percent of all plant taxa, respectively. Halophytic species constitute a large part of flora, among them Puccinellia poecilantha recently recorded in the area is considered as a rare plant. The results may be applied in designing conservation areas and developing conservation strategies for this unique wetland ecosystem.

INTRODUCTION

Wetlands are one of the most sensitive ecosystems in the world with remarkable biodiversity (Hammer 1996). They are considered important ecosystems playing as “the kidneys of the landscape” and “biological supermarkets” (Cronk & Fennessy 2001; Mitch & Gosselink 2015). However, they are disappearing at an alarming rate due to climate change and the human economic utility. The most significant wetland alteration is particularly dredging, filling, drainage, hydrologic modification, peat mining and water pollution (Behruzi Rad 2010; Mitch & Gosselink 2015). This threatening alarm would be particularly dangerous for arid/semi-arid regions with continuous declining of underground water resources. Iran with possessing 24 Ramsar International Wetlands (Behruzi Rad 1999; Ramsar 2016) shows a tragedy example in the Middle East. Many of the wetland sites even with considerable surface have become dried or nearly so in the recent decades. Hoor-Alazim, Dasht-Arjan, Parishan, Gavkhooni and Jazmorian are some affected wetlands.  Knowledge on flora and vegetation of each region is pre-requisite bases for the biological protection, natural resources management, ecological potential, conservation of rare and endemic plants and finally for restoration studies (Singh & Rawat 1999; Jafari & Akhani 2008; Noori et al. 2017). The results of such studies are essential for ecology, biogeography and evolutionary investigations (Khodadadi et al. 2009; Ravanbakhsh et al. 2013). Alagol, Almagol and Ajigol wetland complex is one of 24 Ramsar wetland sites in NE of Iran which is categorized as seasonal saline wetlands (Ramsar 2016). Jalili et al. (2014) provided a full list of publication related to wetland flora and vegetation of Iran. Most of the previous investigations were devoted to flora and vegetation in different international wetland ecosystems of Iran such as Amirkelayeh, Anzali, Fereydoonkenar and Miankaleh. Among the most relevant investigation on afro-mentioned wetland complex and similar ecosystems are conducted by Karimi (2010) and Ghorbanli et al. (2013) on flora and vegetation of Gomishan international wetland and its habitat conditions using satellite imagery. Moreover, Tavan et al. (2010) studied on floristic composition and plant species richness of plains and hills at Agh-Ghala rangelands in the Golestan province. An analysis and evaluation of land use changes in Alagol, Almagol and Ajigol was carried out by Ghorbani et al. (2012). Flora and vegetation of Soofikam and Inchehboroon areas were studied by Ghorbanli et al. (2011) and Bakhshi et al. (2011). Moreover, some studies have been conducted on saline/semi-saline wetlands of Iran (Asri & Ghorbanli 1997; Asri 1998; Ejtehadi et al. 2003; Asri et al. 2002, 2007; Dolatkhahi & Yousofi 2009; Dolatkhahi et al. 2011; Rabie & Asri 2014; Akhani 2015). The current paper aims (1) to present characteristics of flora and habitats of international wetland complex in eastern coastal region of the Caspian Sea and its surrounding environments, (2) to provide detailed information on life forms and chorology of plants for whole wetlands and for each habitat separately and (3) to compare floristic results of the studied wetlands with those already published elsewhere. Results of the current study are particularly important for making appropriate conservational decision for these fragile wetland ecosystems.

MATERIALS AND METHODS

Studied areas

International wetlands of Alagol, Almagol and Ajigol (37º 20' N to 37º 25' N and 54º 35' to 54º 40' E) are located in the Turkmen-Sahra plain near to the border of Iran and Turkmenistan and on western parts of Inchehboroon area (Golestan prov.) (Fig. 1) (Kiabi et al. 1999; Mohandesin Sabzandish Payesh 2008). These wetlands in their highest water content, with 3027 ha (Alagol with 2500 ha, Almagol with 207 ha and Ajigol with 320 ha) has been considered as a refugee for migratory birds and their breeding. They were registered under a wetland complex site in the framework of the international Convention of Ramsar in 1975 (Bagherzadeh Karimi & Ruhani Rankuhi 2007). The study wetlands and all surrounding environment are physiognomically grouped under “herbaceous and semi-woody salt swamps” in the vegetation map proposed by Frey & Kürschner (1989).  Limestone, schist and sands are the main components of soil deposits which were remained after sea retreats in the coastal places (Ghorbani et al. 2012). Based on the recent bioclimatic classification of Iran, the area is classified within “Mediterranean xeric continental” bioclimate (Djamali et al. 2011). The latter bioclimate is characterized with high continentality (Ic > 21), low precipitation during growing season or months with mean temperature > 0°C and long dry season lasting six months. Based on the climatic diagram of the nearest station (Agh-Ghala), much precipitation occurs within November to April with dry period of May to October. The annual precipitation and mean annual temperature is 412.5 mm and 19.1ºC, respectively (Fig. 2).

Data collection and analysis

A floristic and vegetation survey was carried out during growing seasons of 2014 and 2015 using the topographic maps and the local guides. Whereas most annual and some perennial species cover predominantly in the spring time, halophytic annual and perennial taxa were collected in autumn time. We used 115 plots of 25m² (drylands and marginal parts) and 1m² (open lakes) to record vegetation and floristic composition. Plants were determined using Flora Iranica (Rechinger 1963-2010), Flora of Iran (Assadi et al. 1988-2011), Flora of Turkey (Davis 1965-1988), Flora of USSR (Komarov 1934-1954) and Color Flora of Iran (Ghahreman 1975-2005). Plant taxa were classified based on APG III (2009) and the scientific names of the taxa were checked using the plant list website (http://www.theplantlist.org/). Raunkiaer life form system was used for determination of the life form of the plants (Raunkiaer 1934). General distribution of each taxon in the afro-mentioned literatures was used to indicate its chorotype sensu   Zohary (1973), Takhtajan (1986) and Léonard (1989). We classified all habitats of the area physiognomically based on dominant and co-dominant species. All materials studied here were deposited in the herbarium of Mazandaran University (HUMZ) and herbarium of Golestan Agricultural and Natural Resources Research and Education Center.

Fig. 1. The position of three International wetlands of Alagol, Almagol and Ajigol in East of the Caspian Sea.

Fig. 2. The climatic diagram of Agh-Ghala station (1984-2015).

RESULTS

A total of 159 taxa belonging to 123 genera and 42 families of vascular plants were determined in the studied area. 27 genera (22%) and 32 species (20%) were monocotyledons and 96 genera (78%) and 127 species (80%) were dicotyledons (Table 1). Asteraceae (28 taxa, 18%), Amaranthaceae (including Chenopodiaceae) (24 taxa, 15%) and Poaceae (21 taxa, 13%) were the most species rich families in the area. Considering the number of genera in the families, Asteraceae (23), Poaceae (16), Amaranthaceae (12), Brassicaceae (9), Fabaceae (5), Apiaceae, Boraginaceae and Papaveraceae (each with 4) were the richest families. Suaeda (6), Atriplex, Salsola and Plantago (each with 4), Tamarix, Malva and Juncus (each with 3) were the richest genera in the area.

Some plant species were rarely found in the studied wetlands. They were Arnebia decumbens, Asparagus officinalis, Bromus brachystachys, Puccinellia poecilantha, Suaeda maritima, Tetradiclis tenella and Tripolium pannonicum.

Life form and chorology of plants

Life form spectrum of the areas indicates that therophytes and hemicryptophytes were dominant life forms with 65% and 18% of total flora, respectively (Fig. 3). Pluriregional elements (23%) had the highest proportion of total flora followed by Irano-Turanian (22%) and Irano-Turanian/Mediterranean/Euro-Siberian (14%) (Fig. 4). Detailed information of life form and chorotype spectrums for each specific habitat are given in Figures 5 and 6.

Table 1. A checklist of plant taxa and their life forms, chorotypes and habitats in Alagol, Almagol and Ajigol international wetland complex and their surroundings. The plant nomenclature is based on APG III.

Abbreviations: Life forms: Ch = Chamaephyte, Geo = Geophyte, Hl= Helophyte, Hem = Hemicryptophyte, Hy = Hydrophyte, Ph = Phanerophyte, Th = Therophyte. Chorotypes: IT = Irano-Turanian, ES = Euro-Siberian, M = Mediterranean, SS = Sahara-Sindian, PL= Plurireginoal. Cult = cultivated. Habitats: Aq = Aquatic open lake, Em = Emergent plant, Sa = Salt marsh habitat surrounding the wetlands, Su = Submerged plant, St = Semi-dry steppes growing in upper lands.

Fig. 3. Life form spectrum of plants in the Alagol, Almagol and Ajigol wetland complex (Ch = chamaephyte, Geo = geophyte, Hl = helophyte, Hm= hemicryptophyte, Hy = hydrophyte, Ph = phanerophyte, Th = therophyte).

Fig. 4. Percentage of chorotypes of plants in the Alagol, Almagol and Ajigol wetland complex (IT = Irano-Turanian, ES = Euro-Siberian, M = Mediterranean, SS = Saharo-Sindian, PL= pluriregional).

Fig. 5. The proportion of life form categories in different habitat types of Alagol, Almagol and Ajigol wetland complex. (Ch = chamaephyte, Geo = geophyte, Hl= helophyte, Hm = hemicryptophyte, Hy = hydrophyte, Ph = phanerophyte, Th = therophyte, Aq = Aquatic open lake, Sa = Salt marsh habitat surrounding the wetlands, St = Semi-dry steppes growing in upper lands).

Fig. 6. The proportion of chorotypes in different habitat types in the Alagol, Almagol and Ajigol wetland complex. (IT = Irano-Turanian, ES = Euro-Siberian, M = Mediterranean, SS = Saharo-Sindian, PL = pluriregional, Aq = Aquatic open lake, Sa = Salt marsh habitat surrounding the wetlands, St = Semi-dry steppes growing in upper lands).

Habitat characteristics

All plants studied in the area were classified into three separate habitats which were physiognomically separated based on the dominant species:

1- Aquatic open lakes

This habitat is characterized with open surface water at least for an annual period and includes six percent of total plant taxa both as submerged (e.g. Myriophyllum spicatum, Najas minor, Stuckenia pectinata and Zannichellia palustris) and emergent (e.g. Schoenoplectus litoralis, Phragmites australis and Typha laxamanni).

2- Salt marshes

The habitat is located in vast plain areas surrounding the wetlands and affected by various amount of wetland humidity. Both groups of perennial and annual plants particularly halophytic species constitute considerable proportion of the flora of the habitat. 68% of total identified plant taxa belonged to this habitat. Some annual plants are Atriplex tatarica, Salicornia europaea, Climacoptera turcomanica, Suaeda altissima, Spergularia diandra, Climacoptera crassa and perennial plants are Halostachys belangeriana, Halocnemum strobilaceum, Salsola sclerantha, Aeluropus lagopoides, Aeluropus littoralis, Lycium depressum, Tamarix spp.

3- Upland semi-dry steppes

Upland sites surrounding the wetlands are characterized with semi-dry steppe vegetation covered by a total of 26% of the studied plants. Whereas few perennials such as Artemisia kopetdaghensis and A. scoparia permanently cover the habitat,    ephemeral plants such as Avena barbata, Stipa capensis, Adonis aestivalis, Plantago coronopus, Plantago loeflingi play a considerable role in the vegetation. In the spring time, salinity of the upland hills is declined due to higher precipitation and the habitat become more favorable for annual species.

DISCUSSION

Alagol, Almagol and Ajigol are three Ramsar international wetlands located on salty plains of eastern coastal regions of the Caspian Sea. However, surface water of the wetlands is fed by both precipitation and freshwater river discharge (i.e. Atrak River).

The latter situation influences flora and vegetation of the wetlands, so that no real halophytic aquatic plants found in the ecosystems. Ruppia, Potamogeton (= Stuckenia), Althenia, Zannichellia, Lepilaena are some aquatic submerged vascular plants with high capacity for growing in saline water (Melack 1988).

Except Zannichellia and Potamogeton (= Stuckenia) which are often found in temporary ponds, wetlands with wide range of salinity and fluctuations (personal observations), other genera are lacking in the studied wetlands. Seasonality of these ecosystems and freshwater charges into the wetlands are considered to be the main reasons.

Water table content and soil physical and chemical variables are critical factors controlling floristic composition of different habitats of salt marshes and halophytic vegetation (e.g. Rabie & Asri 2014).

In our survey, there is a continuum of vegetation from open water lakes to the surrounding Artemisia steppes and reflected by a gradual change of water table and soil salinity.

Concerning the richest plant families existing in the area, there are some similarities between the results of current investigation and that of other wetland ecosystems such as Miankaleh (Ejtehadi et al. 2003), Amirkelayeh (Ghahreman et al. 2004), Gomishan (Karimi 2010) and Soofikam (Ghorbanli et al. 2013) (Table 2).

Table 2. Comparative floristic richness and taxonomic diversity. Miankaleh (Ejtehadi et al. 2003); Amirkelayeh (Ghahreman et al. 2004); Gomishan (Karimi 2010) and Soofikam (Ghorbanli et al. 2013).