Biological diversity of deserts

1 China’s desert biodiversity

2 Threats to China’s desert biodiversity

3 The urgent rescue of China’s desert biodiversity

China’s deserts are roughly distributed to the northwest of the line Lang Shan-Helan Shan-Burhan Budai Shan and have a total area of 1,920,000km², accounting for 20% of the national territory. It includes three large basins (Junggar, Tarim, Qaidam) and a high plain (Alxa). Surrounding the whole desert area and between its basins exist high mountain ranges. The natural conditions and biological diversity on these mountains are different from those on flat ground. This section deals with the latter only.

Strong continentality, little precipitation, extreme climatic variations, intense sunshine, strong winds and sandstorms in winter and spring are typical climatic features of deserts. According to their substrata, deserts may be divided into sandy, gravel (Gobi), loam (loess deposits), clay (saline desert) and rocky (inselbergs). The first two have the largest areas and biodiversities encountered in different substrata differ from each other.

1 China’s desert biodiversity

(1) Plant species diversity

a. Poorness

Compared with other terrestrial ecosystems, the species composition of deserts is relatively poor. The total number of seed plants encountered in the vast desert areas of Northwest China is just a little more than 600. The Junggar Basin plain with an area of 200,000 km² is considered to have the richest flora, yet, only about 500 species have been recorded. The flora of the Tarim Basin (500,000 km²) comprises less than 200 species. The Ga Shun Gobi of East Xinjiang has a still poorer floral composition and only 34 species of plants have been collected from within its area of 20,000 km².

b. Ancientness

Although plant species richness is low, deserts contain large numbers of ancient and relic elements. Many plants occurring here are relics of the Tertiary, even the Cretaceous, representing the dry and hot environment of the Tethys Sea. The species composition of most such desert communities is dominated by them.

c. Uniqueness

The ancientness of its flora and fauna, combined with extremely harsh ecological conditions, has determined the uniqueness of the biotic elements of China’s deserts. Large numbers of native endemic genera and species have been found here. The following five genera are well-known: Tetraena, Potaninia, Tugarinovia, Stilpnolepis and Synstemon. They are either monotypic or oligotypic genera and characterized by their specialized morphology, narrow distribution range and, for some, their phylogenetic position is hard to determine.

The genus Ammopiptanthus has only two species. A. mongolicus is distributed in the eastern part of the Alxa desert, while another species, A. nanus, is distributed in the southwestern corner of the Tarim Basin, occupying a small area on the northern slope of the Kunlun Mountain. These two ammopiptanthuses are the only evergreen shrubs to be found in Northwestern China’s deserts. They are xerophytic relic species of subtropical evergreen broadleaved forests of the Old Tertiary.

There are more native endemic species. Large numbers (>100) of edificator and dominant species of the desert vegetation of this region are native endemics. The 29 species identified in Table 1 may be cited as representative.

Considering the number of species and the roles they play in such ecosystems, the Chenopodiaceae, Zygophyllaceae, Tamaricaceae, Compositae and Polygonaceae may be thought of as leading families in the deserts of Northwestern China. Four other characteristic families of flora occur in the same area: Cynomoriaceae, Frankeniaceae, Cistaceae and Gymnocarpaceae.

Table 1 Major endemic plant species of Northwest China’s deserts

Species	Distribution
	Junggar	Tarim	East Xinjiang	Qaidam	He Xi Corridor	Alxa	Eastern Alxa	Whole area
Ephedra przewalskii	+	+	+	+
E. pr. var. Kaschgarica		+
Calligonum roborovskii		+
Anabasis brevifolia	+	+	+		+	+
Iljinia regelii	+	+	+
Kalidium gracile	+			+	+	+
Salsola passerina					+	+
S. laricifolia	+				+	+
S. abrotanoides	+			+	+
Sympegma regelii			+	+	+	+
Gymnocarpus przewalskii					+	+
Potaninia mongolica						+
Amygdalus mongolicus							+
Ammopiptanthus nanus		+
Nitraria sphaerocarpa	+	+	+		+	+
N. roborovskii						+
N. tangutorum						+
Zygophyllum xanthoxylon	+	+	+		+	+
Z. kaschgaricum		+
Tetraena mongolica							+
Myricaria pulcherima		+
Reaumuria songorica								+
R. kaschgarica		+
R. trigyna							+
Tamarix toklamakanensis		+
Asterothamnus centriasiaticus					+	+
Brachanthemum gobicum							+
B. pulvinatum					+	+
Canovinia maximowiczii							+

(2) Ecosystem diversity

At the level of the ecosystem, desert types in Northwestern China are diversified, and not as monotonous as generally imagined. Based on preliminary statistics, the sandy desert has eight ecosystems, the gravel-sand and gravel desert (Gobi) has 13, the rocky-crushed stone desert has 10, while the clay desert has 7. Along the banks of desert rivers and in other azonal habitats, there are at least 9 ecosystems.

(3) Animal species diversity

Because of similar ecological conditions, an obviously universal convergence of species can be detected in deserts on different continents. This is also seen in animal species between China’s deserts and elsewhere: rodents, reptiles and ungulates are numerous while there are few amphibians.

An abundant and unique ungulate fauna has developed in the deserts of China. Among these, ancestors of our present livestock can be found. These include, for example, Equus przewalskii, E. hemionus, Camelus bactrianus, Cervus elaphus yarkandensis, Saiga tatarica, Procapra przewalskii and Gazella subguttarosa. Other species come down from the surrounding arid mountains to the borders of such deserts, and include Capra ibex, Ovis ammon and Pseudois nayaur.

Rodents, especially representatives of the Dipodidae (12 species) and Gerbillinae (Cricetidae) (7 species), are particularly conspicuous in desert ecosystens. Compared with adjacent humid regions, the species of birds and larger mammals differ less, but birds of prey are more numerous (12 species).

Reptiles are widely distributed in the desert ecosystems of Northwest China. Both species and individuals are numerous. The most commonly seen are species of Phrynocephalus. And Eremias. In the western part of the deserts of Xinjiang lives a unique terrestrial tortoise, Testudo horsfieldi. The genus Phrynocephalus is an endemic Palaeo-Arctic genus containing about 30 species in the world, and China has 12.

The poorest are desert amphibians. There are only two toads found in Xinjiang, i. e., Bufo viridis and B. raddei. The former is distributed in Western Xinjang, the latter is more widely distributed.

China’s deserts are also relatively poor in insects. Middle-Asian elements dominate, but certain endemic groups can be found. For example, the family Pamphagidaes has 5 endemic genera in Xinjiang, while Sphingonotus (Oedipadidae) has 14 endemic species, also in Xinjiang.

Table 2 lists several representative endemic desert animal species.

2 Threats to China’s desert biodiversity

Though deserts are generally considered to be territorially vast and sparsely populated, the impact of human activities ought to be relatively low. Many parts of the deserts of Northwest China have, however, been severely damaged. The biological resources are being seriously deveasteated and biodiversity reduced rapidly. Threats come from:

Table 2 Representative endemic animals of the northwestern deserts of China

Ungulata	Procapra przewalskii	China, endemic
	Equus hemionus	China, and Mongolia, endemic
	Equus przewalskii	China, and Mongolia, endemic
	Camelus bactrianus	China, and Mongolia, endemic
	Cervus elaphus yarkandensis	Tarim, endemic
Carnivora	Ursus arctos pruinosus	China, and Mongolia, endemic
Lagomorpha	Lepus yarkandensis	Tarim, endemic
Rodentia	Allactaga elater	China, and Mongolia, endemic
	A.bullata
	Stylodipus andrewsi	China, and Mongolia, endemic
	Sapingotus kozlovi Euchoreutes naso Meriones chengi	China, and Mongolia, endemi; in Tarim China, and Mongolia, endemic Only in Turpan
	Brachiones przewalskii	China, and Mongolia, endemic; in Tarim
	Citellus erythrogenys
	Phodopus roborowskii	Xinjiang, Qinghai, Inner Mongolia
Reptilia	Testudo horsfieldi	Ili valley, Middle Asia
	Phrynocephatus przewalskii
	P. versicolor
	Eremias przewalskii
	E. vermiculata
	Teratosincus przeualskii ect.

(1) Gathering fuel and digging medicinal herbs

It is estimated that in desert areas of the Junggar Basin, on the average, each inhabitant family utilises at least 2 tonnes of Saxoul (Haloxylon ammodendron and H. persicum) each year. This means that 6~7 ha of natural Saxoul forests must be cut, and is leading to their severe destruction on the southern fringe of the Gurbantuggut Sandy Desert. Within this area, large quantities of sand dunes have been created. The Populus euphratica forests of South Xinjiang, with an area of 530,000 ha ten years ago, now has only less than half left. Most of the original 4 million ha of Tamarix shrublands in Xinjiang have also been destroyed. In the Alxa desert of Inner Mongolia, the Saxoul forests have been reduced by 60% within 20 years since 1958. In addition, valuable medicinal plants, such as licorice (Glycyrrhiza spp.), Ephedra (Ephedra przewalskii), Cynomorium (Cynomorium songaricum) and others have all decreased owing to severe collection and uprooting.

(2) Overhunting and habitat destruction

Equus przewalskii, Saiga tatarica, Xinjiang tiger (Panthera tigris lecoqi), Desert bear (Ursus arctos pruinosus), Camelus bactrianus, Equus hemionus and Procapra przewalskii are all desert dwellers, and were rather numerous in the deserts of Northwest China a few centuries ago. Equus przewalskii disappeared from the wild in the nineteen-sixties mainly because of overhunting. Saiga tarica, originally widely distributed in Middle Asia, Mongolia and the Junggar basin of China, has not been seen in China since the early nineteen-fifties. The Xinjiang tiger is a unique subspecies of Asian tiger, with an original distribution along the lower course of the Tarim River and in the vicinity of Nobnor. Because of hunting and habitat changes, it became extinct at the beginning of this century.

(3) Irrational agricultural reclamation

Irrational agricultural reclamation in some areas has directly destroyed many wild plant resources and wildlife habitats have been greatly decreased, resulting in a reduction in numbers and even extinctions.

(4) Recent large scale prospecting and exploitation of petroleum and mineral ores, as well as the construction of roads and cities, threatens wild animals and plants in various ways (habitat destruction, blocking the migration routes of wild animals and disturbance).

(5) Irrational use of water resources

Excessive use of water from the upper and middle courses of rivers, has caused the decline and withering of large tracts of both natural and artificial forests in the lower course, depending on supply. For example, the Tarim River, because a large amount of water in its upper course is used for agricultural irrigation, the flow into the lower course has decreased rapidly and eventually ran out, leading to a reduction in the area of the Populus euphratica forests from 45,000 to 16,000 ha along the 100 km section from Yensu to Korgan. Because of the large amounts of water intercepted in the He Xi Corridor for agricultural irrigation in its middle course, the flow in the lower course of the Ruo Shui River decreased from 1,200,000,000 m³ in the 1960s to less than 500,000,000 m³ in the 1980s, resulting in a reduction of the Populus euphratica forests which have similarly declined from 50,000 ha in the 1940s to 22,700 ha today. Tamarix ramosissima forests have declined from 150,000 to 100,000 ha. There are few Elaeagnus angustifolia forests left. The reduction in flow of the lower course of the Shi Yang River has caused a 2/3 deterioration in the vegetation of artificial forests, natural Populus euphratica forests and Tamarix forests at the Mingin Oasis.

Desertificaion is a complex result of climatic variation and human factors, but vegetation destruction, the irrational utilization of water resources, blindly reclaiming and overgrazing are also important factors. The desertified lands of China are still expanding at a rate of over 2,000km² each year, The southern border of the Tarim Basin, the southern fringe of the Gurbantunggut Desert, the He Xi Corridor, the eastern part of Qaidam and the southeastern part of Alxa are regions of intense desertification.

In most cases, along with the growth in desertification, species richness has been lowered, valuable and rare species have decreased and inferior grass and weeds have increased simultaneously. The recent, rapid, expansion of desertified lands in arid regions constitutes a complex threat to China’s desert biodiversity.

Due to all the various destructive agents mentioned above, some plants and animals have been verified to be extinct in recent decades. Examples include the plants Betula halophila and Glycyrrhiza triphylla, and animals such as the Xinjiang tiger, Equus przewalskii, Saiga tatarica (extinct in China’s territory) and Aspiorhynchus laticeps (extinct within the last 20~30 years). There are many more endangered ones. Table 3 provides a representative list of 25 endangered plant species:

Table 3 Representative rare and endangered desert plants

Ephedra leptidosperma	small shrub	endemic on rocky hills of Alxa
Calligonum alaschanicum	shrub	east Alxa, steppe-desert endemic
Cornulaca alaschanica	annual	sandy massive of south Alxa, endemic
Adonis bobroviana	perennial herb	Qilian-longshou Shan, endemic
Corydalis kaschgarica	perennial herb	Southslope of Tian Shan, endemic
Pugionum calcaratum	annual	Alxa endemic
Symstemon petrovii	annual or biannual herb	Hexi corridor and Helanshan, endemic
Medicago alaschanica	perennial herb	East Alxa-Helan Shan foot Hills, endemic
Astragalus dengkouensis	perennial herb	East Alxa steppe-desert, endemic
Ammopiptanthus nanus	small shrub	Wuqia, Xinjiang, endimic
Tetraena mongolica	small shrub	foot of Zhuozi Shan, East Alxa, endemic
Tamarix taklamakanensis	shrub	Tarim desert, endemic
Myricaria pulcherrima	shrub	South Tarim Basin, endemic
Helianthemum songaricum	small shrub	East Alxa, endemic
Ferula sinkiangensis	perennial herb	terraces of Ili R, endemic
F. fukonensis	perennial herb	Fukan, endemic
Scutellaria alaschanica	perennial herb	mountain of East Alxa, endemic
Stilpnolepis centiflora	annual	Tengger desert, Endemic
Hippolytia kaschgarica	small semi-shrub	Southslope of TianShan, endemic
Canovinia maximowiczii	small semi-shrub	Hexi-Qaidm, endemic
Brachanthemum pulvinatum	small semi-shrub	South Alxa-Qaidum, endemic
Jurinea pilostemonoides	perennial herb	South border of Junsgar
Saussurea yabulaiensis	perennial herb	Yablai Shan-Long Shou Shan, endemic
Saussurea popovii	perennial herb	Nearby Urmqi, gravely mountain slopes
Tulipa sinkiangensis	perennial herb	Rock hillls, North Xinjang, endemic

3 The urgent rescue of China’s desert biodiversity

As mentioned above, the severity of the biodiversity threats suffered by China’s deserts is no less than that suffered by other ecosystems. During this century, the number of verified extinct animal and plant species are even more here than in other areas, and the actual number of extinct species may be far more than we know. More attention should be paid to the rescue and protection of biodiversity in desert regions.

The significance of protecting desert organisms:

(1) The animals and plants of desert regions

Living under extreme natural conditions (drought, bitter cold in winter and extreme heat in summer, a large range of temperature variations, intense sunshine, strong wind erosion and sand burial, coarse and crude soil, salinization, and gypsum accumulated in the soil profile) many desert plants have successfully developed many adaptive mechanisms including ecological, physiological, morphological, behavioral, and genetic. Many wild plants are important for combating desertification with biotic measures, and some desert animals are ancestors of our present-day livestock. The conservation of desert organisms not only, therefore, has important scientific significance, but is absolutely necessary for medicinal treatment and health care.

(2) Desert animals and plants contain a large number of species with an economic value

For example, many grasses and small semi-shrubs are nutritious forage, and many have a medicinal value. According to a survey, there are 356 species of medicinal plants in sandy desert (including sandy areas outside the desert), 103 of which are commonly used.

(3) Desert ecosystems play a vital role in fixing shifting sand dunes, reducing wind erosion and improving the environment

The destruction of desert ecosystems will lead to environmental deterioration.

To protect and rescue desert biodiversity, we suggest:

(1) Pay more attention to survey and research work, the timely monitoring of population changes, projects for protecting priority species and habitats, i. e., endemics, keystone species, important habitats, centres of origin, and the reproduction of native species.

(2) Enhancing the construction of protected areas, improving their facilities and providing research equipment. More than 30 nature reserves have been established within desert regions, but this is still not enough. Some important endangered species, such as Ammopiptanthus nanus, Tetraena mongolica and Helianthemum songoricum, are not yet included in reserves, and supplementary “protected sites” or “protected small areas” need to be established.

Several ex situ facilities have also been established in the desert regions of China with the purpose of protecting wild animals, e. g., at Fukan and Wuwei, and they are playing a role in re-introducing extinct species (such as Equus przewalskii, Saiga tatarica) and increasing the population number of endangered species (Equus hemionus, Canelus bactranus). These ventures should be further supported and improved.

(3) Strengthening the construction of legal institutions, first, for controlling the use of biological resources. Considering the special situation of desert regions, it is necessary to create Regulations for Biodiversity Conservation in Arid Lands. Regulations, such as strictly prohibiting digging, collecting, seizing or killing rare and endangered plants and animals also need to be developed. Ecological assessment should be conducted before agricultural reclamation and mining take place. At the same time, it is useful to levy ecological (or resource) compensation taxes.

(4) To raise the level of public awareness, ecological education needs to be strengthened. Improving the knowledge of decision makers, managers and native people with regard to the value of desert biodiversity, the significance of protecting them and the vulnerability of desert ecosystems, is also important.

(5) Developing international exchange and co-operation. Deserts are distributed all over the world. Various countries are located in desert regions. Many of them have accumulated rich experiences and knowledge of how to protect desert ecosystems and rationally use their biological resources. It is worthwhile drawing lessons from them. Second, China’s northwest is contiguous with Middle Asia’s and Mongolian deserts. Many desert animal species gather in border regions, and some migrate between the two sides. They are shared resources of the two countries. In order to protect them effectively, co-operation is necessary. In addition, international co-operation is beneficial to technological improvement and international aid.