## 2 Origin of the Grasslands  
In the recent review by [PERSON] et al. [5] it is argued that much of the contemporary natural grassland region was covered by subtropical forests and savanna woodlands during the Tertiary period. The grasslands formed as a consequence of the uplift of the QTP that blocked the monsoon rains from the south. The region became drier, favoring the gradual development of xerophilous steppes replacing the former mesophilous vegetation. The evolutionary history of biodiversity and endemism on the QTP is still debated, depending on differing hypotheses on highland uplift and climate history. Similarly, the history and intensity of human impact on Tibetan grasslands are still under discussion based on evidence from diverse disciplines [2; 6; 7].  
The present day QTP supports various alpine vegetation types that include meadow, steppe, cold desert and subnival cushion plant communities [2; 5] at elevations ranging from 3500 to nearly 6000 m above sea level (m ASL). The southern and eastern edges of the steppe have grasslands which can sustainably support populations of nomadic herdsmen. Frosts occur for six months of the year and there is permafrost under extensive parts of the region. Annual precipitation ranges from 100-300 mm and occurs mainly as hailstorms. Within the QTP, moisture determines whether a specific subregion supports meadow, steppe or alpine desert vegetation. Alpine (Here the word \"alpine\" does not strictly refer to a mountain climate which is not warm enough to allow for tree growth, here it indicates high-elevation distribution (see Box 1) Grassland is the dominant ecosystem covering over 50 per cent of the QTP [2; 4; 5; 7]. Alpine steppes are commonly found on the QTP [8]. The grasslands on the QTP, including alpine steppes and meadows, are delimited as one alpine vegetation region [9; 10]. The alpine steppes are distributed across the larger part of the QT Plateau, while the alpine meadows occur mainly on the southeastern parts, typically between 2500 and 4000 m ASL [10].  
According to [PERSON] et al. [5] the QTP vegetation region has a very rich, diverse and often endemic flora. It comprises species of Central Asian (semi-) deserts, as well as temperate East Asian and Himalayan elements [8]. The dominant herbaceous species are not typically grasses but are frequently sedges from the genus _Kobresia_ (Studies by Global Carex Group [11] suggest that the genus _Kobresia_ should  
Figure 4: Alpine grasslands on the Qinghai–Tibet Plateau, especially alpine meadows, are prime grazing lands. Government policy is to regulate grazing pressure through imposition of grazing bans and restrictions on herder mobility (transhumance) (photo: [PERSON]).  
be included into _Carex_) and _Carex_, especially in alpine and subalpine meadows. A total of 5766 plant species have been documented for the Tibetan Autonomous Region [10]. More than 2000 of these species are recorded for the grassland region, of which 86% are forage plants and occur mainly in the more humid and sub-humid grasslands of eastern Tibet, while 540 species occur in the arid and semi-arid rangelands that lie further west [12; 13]. The flora of alpine steppes consists of Eurasian steppe species (_Festuca kryloviana_, _F. pseudovina_, _Stipa glareosa_, _S. krylovii_, _S. bungaena_), as well as Central Asian alpine (_S. subessiliflora_), Pamir-QTP (_S. purpurea_, _S. uroborowskyi_, _F. olgae_, _Carex moorcrofiti_) and QTP endemics (_S. subessiliflora_ var. _basiplumosa_ and _S. capillacea_) [11; 12; 13]. A'snapshot' of the variety and distribution of key functional groups of alpine plants is shown in Table 1.