The biodiversity of the high-cold Qingzang plateau

 

1 Species diversity

2 Ecosystem diversity

3 Severe threats to the biodiversity of the Qingzang Plateau

4 Urgent measures to protect the biodiversity of the high-cold areas of the Qingzang Plateau

 

       The Qingzang Plateau, with an average elevation of 4,500 m, towers over the west of China. The length of the plateau from east to west is 2,500 km, the widest place from the south to the north is 1,200 km, and the total area is 2 million km2. It is the highest plateau on Earth, and known as “The roof of the world”. The characteristics of the plateau are freezing weather, dry, windy, low oxygen, strong solar radiation, great temperature differences between day and night, and a unique biodiversity.

1 Species diversity

       (1) Species abundance

       According to the results of several dozen biological surveys, over 12,000 species in 1,500 genera of vascular plants, i. e., 40% of the total of the country, have been found in the plateau, including the Himalayas and the Hengduan Mountains. Of the lower animals, it is known that there are 458 species of aquatic protozoans, 208 species of rotifer, and 59 species of Crustacea, in addition to 2,340 species in 1,160 genera, 173 families and 20 orders of insects in the Tibetan part of the plateau, Of the vertebrates, there are 152 species in 45 genera, 5 families and 3 orders of fish in the plateau, and there are 1,047 species in 343 genera of terrestrial vertebrates which is 43.7% of the total in China. (Table 1).

Table 1 Species abundance of terrestrial vertebrates in the Qingzang Platean.

Class

Family

Genus

Species

Percentage of the country

Mammalia

28

102

206

41.3

Aves

63

263

678

54.5

Reptilia

8

43

83

22.1

Amphibia

9

21

80

28.7

Total

108

434

1047

43.7

       In the high-cold areas above 4,000 metres, there are 955 species of vascular plants, making up 8% of this kind of plant in the plateau and 3.2% in the country. Corresponding figures for terrestrial vertebrates are 215, 20.5% and 9.2%, respectively (table 2).

Table 2 Species abundance of vertebrates in the high-cold Qingzang Plateau

Class

Species in the high cold area

Percentage of the total species in the Qingzang Plateau

Percentage of the total species in China

Mammalia

53

25.7

10.6

Aves

150

22.1

12.6

Reptilia

5

6.0

1.3

Amphibia

7

8.9

2.5

Total

215

20.5

9.2

       (2) Endemic species

       Based on a preliminary survey, there are about 60 endemic genera of vascular plants on the plateau. The exact number of species is not, however, clear. Some endemic species are: Ajaniopsis penicillifomis, Bolocephalus saussureoides, Parapteropyrum tibeticum, Lomatogoiopsis alpia, Cortilla hookeri, Sinoleontopodium lingianum and Xizangia serrata.

       By comparing the original endemic species in the high-cold areas (mainly distributed in high-cold meadows, steppes and deserts) with the endemic species of the surrounding mountains, it is known that: (a), the numbers of high-cold endemic mammals and birds are more than in the surrounding mountains. In a sense, the higher the elevation and the more specific the ecological conditions, the more endemic species; (b), in contrast, there are more mountain-specific endemic species of reptiles and amphibians in the surrounding areas below 4,000 m where the mild and humid weather is more favorable for their survival (Table 3).

Table 3 The endemic terrestrial vertebrates of the Qingzang Plateau,

as compared with the surrounding mountains*

Class

Mammalia

Aves

Reptilia

Amphibia

Endemic species

Species

%

Species

%

Species

%

Species

%

Plateau

25

12.10

33

6.13

8

9.60

5

6.40

Hengduan Mountains

19

9.20

10

1.87

7

8.40

23

29.50

Himalayas

7

3.40

15

2.80

17

20.50

17

22.00

Hengduan-Himalayas

8

3.90

83

15.50

4

5.00

Total

59

28.60

141

26.30

32

38.5

49

62.90

         *percentage=endemic species/total species in Qingzang Plateau (×%).

2 Ecosystem diversity

       The main ecosystems of the plateau comprise forest, high-cold bush and meadow, high-cold steppe and high-cold desert. The first of these has been discussed in Chapter 3.3 and will be omitted here. The other ecosystems occupy a vast area which makes up more than three fourths of the whole plateau and are spread in a zonal pattern from the southeast to the northwest. The environmental conditions of the ecosystems are high altitude, drought, low temperature, low oxygen, very windy and strong solar radiation. The composition, structure and feature of these ecosystems are unique, due to the high-cold conditions.

       (1) The high-cold bush and meadow ecosystem

      This is distributed in the northeast of the plateau with an average elevation of 4,000 m and an annual rainfall of between 300~700 mm. The annual mean temperature is 3 to –4, the mean temperature of the hottest month is 5~13, and the maximum highest temperature is 20~28. The mean temperature in the coldest month is -7 to -17 and the minimum lowest temperature is -30 to -40. Solar radiation is very strong. It is very windy in winter and storms and hail are frequent in summer.

       The principal part of the ecosystem is elevated-cold meadow with Kobresia pygmaea, K. pusilla, K. prainii, K. royleana and K. littledalei as dominant species; the elevated-cold plateau bushes are distributed as patches in areas with mild environmental conditions, or as scattered individuals in grassy marshlands where the dominant species are Rhododendron trichostomum, R. nivale, R. setosum, R. laudandum, Potentilla glabra, P. fruticosa, Salix oritrepha and Caragana jubata.

       There are 7 species of Amphibia in the high-cold bush and meadow ecosystems, such as Batrachuperus tibetanus, Scutiger boulengeri, S. mammatus and Andrias davidianus. The first two species are endemic to Tibet and the latter two are Chinese endemics. In addition, there are Rana temporaria and Nanorana. There are only 3 species of reptiles: Phrynocephalus vlangalii, Leiolopisma tsinlingensis and Agkistrodon strauchi. These are endemic to the plateau, except the second. The common species of birds is bush niches are Perdix hodgsoniae, Phasianus colchicus, Anthus hodgsoni, A. roseatus, Turdus ruficollis, Phylloscopus affinis and Carpodacus pulcherrimusm, while the dominant species of birds in the meadows are Calandrella rufescens and Melanocorypha maxima. Of the mammals, fur animals such as Martes foina, Vulpes ferrilate, V. vulpes and Felis manul and endemic species such as Cervus albirostris, Moschus sifanicus, Myospalax baileyi and Ochotona thibetana used to inhabit the bush environment.

       The species number and representatives of the dominant species in the ecosystem are listed in Table 4.

Table 4 Species numbers and representative species in the high-cold bush

and meadow ecosystems of the Qingzang Plateau

 

Class

Family

Genera

Species

Typical species

Higher plants

Seed plants

43

140

500

Dominated by Kobresia with shrubs, Rhododendron spp., Caragana spp., Salix spp.

Vertebrates

Amphibia

4

5

7

Batrachupperalus tibetanus, Andrias davidianus, Satiger spp., Rana temporaria

 

Reptilia

3

3

3

Phrynocephalus valangalii, Leiolopisma tsingensis, Agkistrodon strauchi

 

Aves

29

70

103

Perdix hodgsoniae, Calandrella rufescens, Anthus roseatus, A. hodgsonii, Turdus ruficollis, Carpodacus pulcherrimus, Phasianus colchicus

 

Mammalia

14

31

45

Martes foina, Vulpes ferrilata, V. Vulpes, Cervus albirostris, Moschus sifanicus, Myospalox baileyi, Ochotoma thibetana

 

Total

930

249

648

 

       Compared with the mountain bush meadows at the upper limit of the forest in the Henduan Mountains and the Himalayas, many typical mountain forest and bush species such as Lerwa lerwa, Tetraophasis obscursu, Crossoptilon crossoption, Certhia himalayana, Alcippe striaticollis, Moschus fuscus, Hemitragus jemlahicus, Ochotona royle and O. Himalayana, are not foumd in the former. The large Artiodactyla which inhabit the open gentle high-cold meadows, such as Procapra picticaudata, are also not found on the mountain bush meadows.

       (2) The high-cold steppe ecosystem

       The high-cold steppe ecosystem spreads to the west of the high-cold bush meadow ecosystem and the middle Qingzang Plateau. The elevation here is about 4,500~5,000m with a typically continental plateau climate characterized by freezes, drought, and average annual temperature from 0 to -5, a lowest temperature of -40, and an annual rainfall of between 100~400 mm. In winter, it is very windy, clear and dry, with extremely strong evaporation and very strong solar radiation.

       Stipa purpurea is the most important, widespread, and typical species in the high-cold steppe, followed by S. basiplumosa, S. glareosa, S. roborowskyi and S. subsessiflora. Other species are Carex moorcroftii, Artemisia younghushandii, A. wellbyi and A. stracheyi.

       A few common species of reptiles in the high-cold steppe ecosystem are Phrynocephalus vlangalii, P. theobaldi and Agkistrodon stauchi. Dominant species of birds are Calandrella acutirostris, Alauda gulgula, Eremophila alpestris, Pseudopodoces humilis, Mongtifringilla adamis, M. tazanowskii, M. blanfordi, Syrrhaptes tibetanus and Tetraogallus tibetanus. All the above species, except Calandrella and Alauda, are endemic to the Qingzang Plateau. Species of mammals, such as Marmota himalayana and Pitymys leucurus, Ochotona curzoniae, Lepus oiostolus, Procapra piticaudatea, Pantholops hodgsoni and Bos mutus, are not only representative of the high-cold steppes, but are also endemic to the Qingzang Plateau.

       The ecosystem was formed during the uplifting of the plateau in the Caenozoic Era. Species diversity is thus much lower than on long-standing temperate steppes. In addition, the harsh ecological condition also decreases its species abundance which is even lower than that of the high-cold bush meadow ecosystem, e. g., there are no amphibians (Table 5).

Table 5 Species numbers and representative species in the high-cold steppe ecosystem

Class

Family

Genus

Species

Typical species

Higher plants

Seed plants

40

133

300

Stipa purpurea, S. basiplumosa, S. glareosa, S. roborowskyi, S. subsessiliflora, Carex moorcroftii Artemisia younghusbandii, A. wellbyi, A. stracheyi

Vertebrates

Reptilia

2

2

3

Phrynocephalid vlangalii, P. theobaldi, Agkistrodon stauchi

 

Aves

33

79

118

Calandrella acutirostris, Alauda gulgula, Eremophila. Alpestris, Pseudopodoces humilis, Mongtifringilla adamis, M. traogallus tibetanus

 

Mammalia

15

28

35

Marmota himalayana, Pitymys leucurus, Ochotona curzoniae, Lepus oiostolus, Procapra piticaudata, Pantholops hodgsoni

 

Total

90

242

456

 

       In the high-cold steppes, in comparison with the temperate steppes of northern China, there is a striking lack of those species which inhabited forest steppes, bushes at the forest fringe, and bushes such as Crossoptilon auritum, Petaurista xanthotis, Tamiops spp., Cervus elaphus and Felis bengalensis.

       (3) The high-cold desert ecosystem

       This kind of ecosystems spreads to the west and northwest of the Qingzang Plateau, where the elevation is between 4,200~4,500 m with freezing conditions and extraordinary droughts. The main features of the climate are: an average annual temperature from –3 to –10; 9~10 months with a monthly mean temperature of below 0; minimum lowest temperature of below -40; an annual precipitation of less than 20~100 mm and mostly in the form of snow; strong solar radiation; windy winters; and extremely strong evaporation. The plants of the area are more sparse (the cover is less than 10%) than that in the high-cold steppes, and the species are extremely monotonous, dominated by xerophytes and cushion plants. There are no amphibians and reptiles. Species diversity is simple.

       The principal plants of the ecosystem are cushiony Ceratiodes compacta, Ajania tibetica and Artemisia rhodantha. The representative bird species are Syrrhaptes paradoxus, Prune