Response of grass growth and productivity to enhanced water input in ephemeral desert grassland in Gurbantunggut desert
增加降水对荒漠短命植物当年牧草生长及群落结构的影响

Spring ephemerals form significant plant synusiae in the Gurbantunggut desert during April and May and are a crucial forage resource for livestock in early spring. In recent years global climate change has caused warming, increasing rainfall and flooding from snowmelt in Gurbantunggut desert. However, little is known about how the enhanced water input may influence the growth of individual plant species and the productivity of plant communities in desert grassland. A randomized block designed field trial, which contained three watering treatments (0, 40 and 80 mm), was conducted in the Gurbantunggut desert, Xinjiang, northwestern China.The sum of the biomass of six dominant ephemeral species contributed more than 60 percent of the total above-ground biomass of the synusia. Five of the six dominant species (Erodium oxyrrhynchum, Trigonella arcuata, Alyssum linifolium, Ceratocarpus arenarius and Hyalea pulchella) showed a significant positive growth response with increasing water input. Compared to the control, the above-ground biomass productivity of the five plant species watered with 40 or 80 mm was increased by 86%-230%. The composition (%) of total above-ground biomass of individual species was significantly changed by enhanced water input; values for C. arenarius and E. oxyrrhynchum increased more than for the other species. This result indicated that these two species would potentially become even more dominant in the spring ephemeral synusia following the trend of enhanced precipitation. At the same time, plant density and coverage of the ephemerals were also significantly increased by enhanced water input. Such results implied that the role of ephemerals in stabilizing sand dunes may be strengthened by enhanced water input. It is concluded that enhanced precipitation could both increase the potential livestock carrying capacity of the desert grassland and promote restoration of the desert ecosystem.