Abstract:Plant water-use strategy is considered to be a function of the complex interactions between species of different functional types and the prevailing environmental conditions. Within the current background of global climate change, significant increase in precipitation has been recorded in the arid region of central Asia over the past 50 years. In addition, in some transition regions between sandy deserts and oases, the groundwater table has fallen significantly as a result of the over exploitation of groundwater. Variation in precipitation in arid ecosystem is leading to plant adaptation in water use strategies; significant inter-species difference in responses will change the composition of desert plant commumities. To understand the effects of these widely acknowledged changes in water conditions, the current study is carried out at south fringe of Guerbantonggute Desert, where H. ammodendron is a typical dominated species. The aim of the study is to test what are the key factors that affect the success of H. ammodendron at germination and very early stage of seedling. The basic hypothesis is that the water is the key factor affecting germination or survival/death of H. ammodendron at its very beginning of life cycle. On March 2008, 9 treatments whit 3 replicates each (3m by 3m) were set up, which were normal snow, 3 times of normal snow and no snow, and on each snow treatment there was normal rainfall, rainfall plus, and no rainfall. At each treatment, soil moistures, the amount of H. ammodendron seedling and epidermal plants were monitored every 5 days from Aril 11 to June 2008. The result revealed that H. ammodendron germination was not significantly correlated with water conditions (snow amount)：the number of H. ammodendron germination has no significantly difference among snow treatments. However, the amount of epidermal plants germinated was significantly correlated with snow amount: under 3 times of snow treatment the amount of epidermal plants germinated was highest; in contrast, the amount was lowest under no snow treatment. Apparently because of competition for water, at treatments with good water conditions, the survival ratio of H. ammodendron seedling was low. On the other hand, at treatments with poor water conditions, because of low competition from epidermal plants, the survival ratio of H. ammodendron seedling was high. Namely, at the very early stage, H. ammodendron seedling was at disadvantage in competition for water with early spring epidermal plants. As a result, because of competition for water from epidermal plants, good water condition does not necessarily result in high survival ratio of H. ammodendron seedling. In conclusion, this integrated study has advanced our understanding of the H. ammodendron regeneration at very early stage.