Abstract: Global climate change has altered the atmospheric circulation and hydrologic cycle,and led to the changes of regional precipitation patterns, giving effects on the material cycling and energy flow of terrestrial ecosystems, and accordingly, on the eco-physiological response of plant communities to precipitation change. In this paper, a Mongolian pine (Pinus sylvestris var. mongolica) plantation in Horqin Sandy Land was selected as test object to study its eco-physiological responses to potential precipitation change. Three treatments (natural precipitation, 30% reduced precipitation, and 30% increased precipitation) and two precipitation patterns in growth season (236 mm and 357 mm) were installed, and the tree growth status as well as the needle photosynthetic rate, transpiration rate, water use efficiency, chlorophyll, proline, soluble protein, and malondialdehyde (MDA) contents, and SOD activity in growth season were measured. The needle photosynthetic rate, transpiration rate, and water use efficiency were positively correlated with precipitation, and precipitation change had significant effects on the eco-physiological characteristics. The water stress in growth season had a lag effect on the growth of Mongolian pine. The changes of the needle N content could reflect the co-action patterns of soil nutrient availability and soil moisture change.

Key words: Plant, Species diversity, Gap, Fir forest, Tibet