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