Abstract: Based on the mass balance data of east and west branches of Glacier No. 1 at Urumqi riverhead during 1990/1991-2009/2010, this paper analyzed the mass balance change in these branches. In the east branch, the amount of mass loss was greater than that in the west branch. The equilibrium line altitude (ELA) of the east branch was generally lower than that of the west branch, and the downward trend of accumulation area ratio (AAR) was greater in the east branch than in the west branch. During 1990/1991-2009/2010, the average mass balance and cumulative mass balance in the east branch were -582 mm·a^-1 and -11638 mm, and those in the west branch were -485 mm·a^-1 and -9692 mm, respectively. The ELA of east and west branches showed a rising trend, with an increase of 143 m and 131 m,  the AAR decreased by 29.8% and 19.6%,  respectively. The mass balance was significantly negatively correlated with ELA, and significantly positively correlated with AAR. When the mass balance in east and west branches decreased by 100 mm, the ELA was decreased by 19 m and 23 m   respectively,   and the AAR decreased by 4.5%. The sensitivity analysis of glacier mass balance response to climate change showed that when the precipitation unchanged, and if the summer temperature raised 1 ℃,  mass balance in the east branch would be decreased by 487 mm, and that in the west branch would be decreased by 398 mm; when the summer temperature unchanged, and if precipitation increased 100 mm,  mass balance in the east branch would be increased by 164 mm, and that in the west branch would be increased by 185 mm. In the context of future global warming,  mass balance in the east and west branches of Glacier No. 1 would be continued to decrease.

Key words: P. opulifolius, soil drought, photosynthesis capacity, Physocarpus amurensis, chlorophyll fluorescence.