On the General Characteristics of Plant Diversity of Gurbantunggut Sandy Desert

The Gurbantunggut Sandy Desert is located at the transitional belt between Central Asia and Middle Asia. Though its climate is characterized by aridness with scarce precipitation, intense evapotranspiration, windy, strong sunshine and severe variation of temperature, and is a kind of continental desert climate, yet, because of the rather evenness of seasonal distribution of precipitation, with certain amount of rain and snow falling in winter and spring, its vegetation is relatively luxuriant. Most parts of the deserts are fixed or semi\|fixed. The characteristic features of plant diversity of Gurbantunggut Sandy Desert may be summarized as follows: (1) The species richness is relatively high. Compared with other sandy deserts of Central Asia (Takilmakan, Qaidam, Alxa), the flora of Gurbantunggut is more rich than others. There has been collected and identified 208 species of higher plants in Gurbantunggut. Among them, Chenopodiaceae (53 species), Cruciferae (22 species) and Compositae (20 species) are the three most dominant families. (2) The floral\|geographical elements are diverse. According to studies by predecessors, the geographical elements of the flora of Gurbantunggut Sandy Desert consist of Central\|Asian element, Middle\|Asian element, Mediterranean element, North\|Eastern African\|Central Asian element and Euro\|Asian element, so it has transitional character, though, that of Middle\|Asian is more abundant. (3) The endemism of this sandy desert is weak. Nevertheless, there are many plant species which distribute only in Gurbantunggut Sandy Desert within the territory of China. (4) The species of Chenopodiaeceae possesses obvious dominant position in the composition of plant diversity. There are 24 genera and 53 species of Chenopodiaeceae, which account for 19 5% and 25 5% respectively of the floral total of this sandy desert and much higher than that of the rest dominant families such as Cruciferae, Compositae, Leguminosae and Gramineae. Not only the species composition, their role in plant communities are also outstanding. Large areas are occupied by plant communities with edificators from Chenopodiaceae, such as Haloxylon persicum, H.ammodendron, Ceratoides latens, Salsola arbuscula, Anabasis brevifolia, A.aphylla and others. (5) The ecotypes mainly consist of xerophytes. (6) The life forms are diverse. 11 categories of plant life forms have been found in Gurbantunggut Sandy Desert. Among them, the dominant ones are ephemerals (55 species), annuals with long period of nourishment (42 species). This two categories come to 97 species, accounting for 47% of the total. Next are plants with axial roots (38), shrubs (29) and nanoshrubs (16). (7) Annuals with long period of nourishment make up relatively large proportion, as mentioned above. (8) Ephemerals and ephemeroides obtain certain development. There are 66 species of ephemerals and 11 species of ephemeroides. Both of them are short\|living plants and mainly grow on sandy soils. (9) Types of plant communities are rich. Compared with other deserts of Central Asia, the plant communities of Gurbantunggut are richer. 18 communities have been recorded. Owing to the overgrazing (many sites of the desert, especially along its border, are livestocks wintering places) and over\|collecting and digging of fuels, as well as economic plants, the plant diversity of Gurbantunggut has been severely damaged. It is urgent at present time to adopt measures to protect its plant diversity, and for some endangered species, even to rescue them.