Abstract: In the desert-oasis transitional zone in southern fringe of Taklimakan Desert, Xinjiang of Northwest China, the mean annual precipitation is only about 35 mm, but occasional strong precipitation sometimes happens, like the event in 2010. How the perennial species adapt to the short-term heavy precipitation is less known. In this paper, a site-specific field investigation was conducted to understand the morphological and growth characteristics of Calligonum caputmedusae Schrenk under different soil water conditions. At seedling period, the morphological characteristics (including plant height, crown width, basal diameter, and root depth) and population density of C. caputmedusae were positively correlated with soil water content, and increasing root/shoot ratio was an effective strategy of C. caputmedusae to adapt to soil water shortage. Especially in July and August, the root/shoot ratio increased with decreasing soil water content. The plants allocated more biomass into aboveground part in their early growth period to compete for light resource, and allocated more biomass into root in the late growth period to explore underground space resources. The seedlings could selfregulate their growth proportion to adapt the environment when soil water content changed. An allometric relationship between plant height and basal diameter was always observed under different soil water condition. To some extent, these results reflected the growth pattern of the C. caputmedusae seedlings under different soil water conditions, and provided theoretical support for the vegetation restoration in the south fringe of the Taklamakan Desert.

Key words: land use change, habitat quality, InVEST, basin, BeijingTianjinHebei Area.