Importance of temperate deserts
The Eurasian temperate deserts are outstanding species-rich areas even if they gradually differ from each other due to different desert forms. The extreme climatic conditions represent particular challenges for the adaptive capacity of the flora and fauna. Due to that fact endemism in the temperate deserts is extremely high. For instance, among 350 species of vascular plants, 56% of endemics in the sand deserts of Karakum and Kyzylkum can be identified (Schröder 1998). Overall in Turan deserts (see What are temperate deserts?) approx. 1.600 plant species can be found, thereof 246 Chenopodiaceae (15%), 148 leguminous plants (9%), and Cruciferae (6%). There are more than 100 species of Artemisia, 67 of Calligonum, 54 species of Salsola, 31 species of Zygophyllum, 26 species of Ammodendron as well as 22 species of Limonium (ibid.). It is noteworthy that flora of a barren landscape represents often a stony and rocky area of gypsum deserts, for instance, the plateau of Ustyurt with more than 400 species. It is one of the most species-rich areas in comparison to the other deserts forms of Eurasian temperate deserts. The major part of the vegetation cover makes small- and dwarf shrubs up. However, the density of a vegetation cover is significantly lower than in other deserts form of temperate deserts, as for instance sand deserts.
Saline deserts are species-poor habitats and include primarily halophytes with salt-tolerant plants with overall no more than 100 different species (ibid.). One of the special features of the temperate deserts is ephemeral deserts. They are situated in the Turan deserts and represent an endemic form of deserts. Ephemeral plants depend on winter precipitation and ideally on the loess substrates. During the shortest period between March and May the deserts starting to flourish (ibid.).
To the globally threatened bird species in the Eurasian temperate deserts belong breeding or migratory birds, which can be encountered during the whole year. These are Eastern imperial eagle (Aquila heliacal, IUCN VU), Houbara bustard (Chlamydotis undulate, IUCN VU), Saker falcon (Falco cherrug, IUCN EN), Egyptian vulture (Neophron percnopterus, IUCN EN), Pale-backed pigeon (Columba eversmanni, IUCN VU). Further typical representatives of the avifauna in the Eurasian temperate deserts, which are partially defined by the Red List of relevant countries, are as follows: Greater sand plover (Charadrius leschenaultia, IUCN LC), Pallas’s sandgrouse (Syrrhaptes paradoxus, IUCN LC), Pallid scops owl (Otus brucei, IUCN LC), Egyptian nightjar (Caprimulgus aegyptius, IUCN LC), White-winged woodpecker (Dendrocopos leucopterus, IUCN LC), Desert lark (Ammomanes deserti, IUCN LC), Asian short-toed lark (Calandrella cheleensis, IUCN DD), Turkestan ground-jay (Podoces panderi, IUCN LC), Brown-necked raven (Corvus ruficollis, IUCN LC), Asian desert warbler (Sylvia nana, IUCN LC), Turkestan tit (Parus bokharensis, IUCN LC) (subspecies of great tit), Saxaul sparrow (Passer ammodendri, IUCN LC), Desert sparrow (Passer simplex, IUCN DD), Desert finch (Rhodospiza obsolete, IUCN LC), Little bustard (Tetrax tetrax, IUCN NT), Lesser Krestel (Falco naumanni, IUCN LC), Red-footed falcon (Falco vespertinus, IUCN NT), Black-winged pratincole (Glareola nordmanni, IUCN NT), Pallid harrier (Circus macrourus, IUCN NT), Cinereous vulture (Aegypius monachus, IUCN NT), Bearded vulture (Gypaetus barbatus, IUCN NC) or Golden Eagle (Aquila chrysaetos, IUCN LC) (Kashkarov et al. 2008, Rustamov et al. 2009, Sklyarenko et al. 2008).
The herpetofauna is particularly species-rich in the temperate deserts. Within this wide range of species, the flagship species is the Desert monitor (Varanus griseus). Typical representatives of sandy deserts are toad-headed agamas (Phrynocephalus), Eversmann’s gecko, Turkestan plate-tailed gecko, Racerunners (Eremias ssp.) and Sand boas (Eryx ssp.) (Rustamov 2007).
The Eurasian temperate deserts are (among others) habitat of several cat species. Most prominent indeed is the Asiatic subspecies of Cheetah (Acinonyx jubatus, IUCN CR). It has disappeared from all the former distribution range in Central Asia. The last observations with Asiatic Cheetah were recorded in the 1980s there. However, today the only remaining wild population of this cat inhabits a wildlife reserve in North-Eastern Iran in a very vulnerable state. Its gene pool became very limited already. Other rare cat species in the Eurasian temperate deserts are Pallas’s Cat (Otocolobus manul, IUCN NT), Subspecies Sand Cat (Felis margarita), and Turkmen Caracal (Caracal caracal). They are also included in the Red Data Books of Kazakhstan, Turkmenistan, and Uzbekistan. Much more common and widely distributed are Asian Wildcat (Felis lybica) and Jungle Cat (Felis chaus). A feline species that became globally extinct in the course of the 20th century is the Turanian Тiger (Panthera tigris, IUCN EX), which still occurred in Central Asia until the 1960s.
Serengeti of the North
Eurasian desert ecosystems are of crucial importance because they comprise a multiplicity of migratory ungulates species. Besides the Eurasian steppes, Eurasian temperate deserts represent the last large-scale ecosystems for migratory ungulates worldwide. Despite the lacking public awareness, it is not exaggerated to speak about the Serengeti of the North. Saiga Antilope (Saiga tatarica, IUCN CR) migrate among the steppes and desert habitats and represent one of the most distinctive and threatened species. In addition, a large number of Goitered Gazelles (Gazella subgutturosa, IUCN VU) can be encountered. Due to enormous efforts during the Soviet time, the number of the Asiatic Wild Ass (Equus hemionus kulan, IUCN EN) is increasing. In the meantime, this species can be encountered also in Uzbekistan again, even though until recently it was listed in the Red Book of Uzbekistan as one of the extinct in the wild species. A Urial (Ovis vignei arkal, IUCN VU) can be encountered as well.
The vast and still largely interconnected ecosystems of Central Asia region harbor a number of large mammal species that are listed in the Convention on Migratory Species (CMS), most of which are in decline due to poaching, illegal trade, habitat loss, and degradation and fragmentation of their habitat from mining and (linear) infrastructure development as well as from overgrazing by and competition with livestock and conversion to agriculture. Therefore, many stakeholders from conservation and policy elaborated under the CMS the so-called Central Asian Mammals Initiative (CAMI) in order to provide a common strategic framework for action at the international level to conserve migratory mammals and their habitats in the region. It aims at bringing together and harmonizing the implementation of existing CMS instruments and mandates as well as initiatives undertaken by other stakeholders. All in all, there are 15 species addressed within CAMI of which most of all Asiatic Wild Ass, Goitered gazelle, Mongolian gazelle, Saiga antelope, Bactrian camel (Camelus bactrianus) and Asiatic cheetah are of relevance for the temperate desert ecosystems.
A strong focus of CAMI is on promoting synergies between stakeholders and existing conservation frameworks, as well as on sharing communication and strengthening cooperation across borders, facilitating building on successes, and raising awareness.
Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA)
Another agreement at CMS level is the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA). It is an intergovernmental treaty dedicated to the conservation of migratory waterbirds and their habitats across Africa, Europe, the Middle East, Central Asia, Greenland, and the Canadian Archipelago.
AEWA brings together countries and the wider international conservation community in an effort to establish coordinated conservation and management of migratory waterbirds throughout their entire migratory range including the flyway through the temperate desert ecosystems from breeding sites to wintering sites and back. The many wetlands and azonal riparian forests of Amudarya, Syrdarya, and others within the temperate deserts are important stepovers on the migratory route.
AEWA covers 255 species of birds ecologically dependent on wetlands for at least part of their annual cycle, including many species of divers, grebes, pelicans, cormorants, herons, storks, rails, ibises, spoonbills, flamingos, ducks, swans, geese, cranes, waders, gulls, terns, tropicbirds, auks and frigate birds. All AEWA species cross international boundaries during their migrations and require good quality habitat for breeding as well as a network of suitable sites to support their annual journeys. International cooperation across their entire migratory range, as provided by AEWA, is therefore essential for the conservation and management of migratory waterbird populations and the habitats on which they depend.
Another example of a CMS species is the Siberian crane (Leucogeranus leucogeranus) IUCN CR. An MoU under the CMS concentrates efforts on the monitoring of that rare species and the ecosystem conservation on which it is dependent in all the migration countries. The temperate deserts are located at their western and Central flyways.
This critically endangered species is now only found in two populations, the eastern and western. A central population (central Asian flock) of Siberian Cranes once nested in western Siberia and wintered in India. The last documented sighting of Siberian Cranes of the central Asian flock was during the winter months in 2002 in India. The loss of the central population and the decline of the western population to single digits is also undoubtedly a consequence of hunting, especially during migration.
A success in monitoring and conservation is also worth to be referred to. Only in recent years the CADI and Birdlife International partner organization in Kazakhstan, the Association for the Conservation of Biodiversity in Kazakhstan (ACBK), managed to track migratory routes of IUCN critically endangered (IUCN CR) bird species Sociable Lapwing (Vanellus gregarius), starting from steppes in Kazakhstan with stopover sites in Uzbekistan until their wintering places in Turkey. This was so far undiscovered.
The Eurasian temperate deserts provide a variety of ecosystem services. Besides their importance for the regional and global cycle of materials and water, these are, among others, the production of below and above-ground biomass and thus fixing and binding of sedimentation cargoes as well as carbon sequestration. In addition, the deserts provide fuelwood, pastures, and medicinal plants.
An outstanding ecosystem function in the Eurasian temperate deserts fulfills the Saxaul, which occurs as White Saxaul (Haloxylon persicum) and Black Saxaul (Haloxylon aphyllum). The potential distribution of Saxaul in Central Asia covers an area of about 500,000 km² (Rachkovskaya et al. 2003) spreading from Turkmenistan through Uzbekistan and Kazakhstan towards North-West China (Xinjiang) and Mongolia.
The White Saxaul is a summer-green shrub with up to 3 m in height. It covers its water demand from rainwater. The White Saxaul is found in sandhills, deserts and sand ridges, where it often forms pure stands, with an average density up to 400-500 trees per ha.
The Black Saxaul, which is also summer-green, reaches heights of up to 10 m. It has a deep pivotal root system allowing it to thrive in dry, saline, and sandy environments. The Black Saxaul dominates the shrub vegetation in lowlands as well as current and former riparian or lacustrine flood plains. It covers its water demand from the groundwater (Kurochkina 1966).
According to the Soviet classification, Saxaul stocks belong to woods.
Due to their dominance, the two Saxaul species can be considered as ecological key species which provide the following significant ecosystem services (Buras et al. 2012):
(1) Enrichment of phytomass and humus as well as the production of wood biomass and thus carbon sequestration.
(2) Sand fixation and stabilization of moderate eroded areas, which reduces the risk of sand and soil dust storms. Particularly, a large-scale degradation of the vegetation cover has led to intensive sediment and salt fraction processes. The wind-blown movement of Barchan dunes buries entire settlements and infrastructure. In addition, the movement of dunes can cause significant health diseases of the population through blow-out of soil pesticides, herbicides, and fungicides. Wind-blown salty minerals from the Aral Sea ground were detected up to the Inner Asian high-altitude mountain regions. This phenomenon accelerates the melting process of the glaciers and increases the disruption of the large-scale hydrological regime.
(3) Fodder production for animals.
(4) Regulation of the hydrological regime of the ecosystem through shading and small-scale evapotranspiration.
(5) Habitat for many species, such as the Saxaul Sparrow (Passer ammodendri) or the Pander’s Ground Jay (Podoces panderi).
In arid and semi-arid ecosystems large quantities of biomass are stored underground and due to the dry climate conditions carbon in a middle term is derived from the global carbon cycle. Therefore, the Eurasian temperate deserts with their enormous landmasses – they cover an area of 2.5 million km2 (roughly equivalent to the size of the Mediterranean Sea) – have a globally important carbon sink potential.
Despite their continental and arid climate, large parts of the temperate deserts are potentially naturally covered by a shrub or tree vegetation formed by the White and Black Saxaul (Haloxylon persicum and Haloxylon aphyllum). The potential natural overall distribution of Saxaul in the temperate deserts in Central Asia is about 500,000 km² (Rachkovskaya et al. 2003). The Saxaul, therefore, has a great potential for the fixation of carbon.
Thevs et al. (2013) estimated the potential carbon stock of above-ground and below-ground biomass of Saxaul in the temperate deserts with approx. 51.4 million t-133,5 million t.
Listed by the main CADI target countries, the total potential carbon stock of the living biomass amounts to 11,2-28,8 million t for Kazakhstan, 25,7-64.9 million t for Turkmenistan, and 14,6-40,2 million t for Uzbekistan.
Over the last 50 years, degradation of the deserts and over-utilization as fuelwood resources have led to a significant reduction of the potential carbon stock of Saxaul. According to recent estimates, the Saxaul distribution has now declined to about 116,865 km2, representing about 25% of the potential natural Saxaul vegetation (Thevs et al. 2013).
Conservation, sustainable use, and reforestation of the natural Saxaul vegetation in Central Asia, therefore, offer great potential for carbon fixation in the target countries and thus make an important contribution to climate protection.
Registration of a Nationally Appropriate Mitigation Action Project Idea Note (NAMA PIN)
In addition to the support of various conservation measures, within the scope of CADI, the climate relevance of Saxaul as a national measure of Uzbekistan to mitigate climate change is to be developed by registering a NAMA PIN (“Nationally Appropriate Mitigation Action Project Idea Note”). Hereby, Uzbekistan shall be supported to meet its national commitments under the UN Framework Convention on Climate Change (UNFCCC).
„Aromatic smoke of Saxaul” (Fjodor Karpov, Journal “Ветер странствий”, No 67, in the Russian language)