干旱区生态环境知识资源中心

Nitraria tangutorum and Artemisia arenaria are two dominant C-3 shrub species widely distributed on interdune at Southeast edge of Badain Jaran Desert, Northwest China. Water is prime factor limiting their survival, growth and regeneration. In this study, the main sources at which two shrub species obtain water were tested by comparing hydrogen stable isotope ratio (delta D) of their xylem water and potential water source, including different depths of soil water (0-30, 30-60, 60-90 and 90-120 cm), rain water and ground water (replaced by well water on farmland near shnibland), and their long-term water use efficiency was evaluated by leaf carbon stable isotope ratio (delta C-13). Soil water contents of four depths were examined to indicate soil water availability, and leaf water content was used to evaluate plant water status. The results showed that N. tangutorum and A. arenaria competed for the same water source on interdune: shallower soil water in May (30-90 cm) and July (0-30 cm) which was recharged by small rain in spring and early summer, and deeper soil water (> 120 cm) in September which was recharged by rainstorm in late summer. The water use efficiencies indicated by leaf delta C-13 value of N. tangutorum and A. arenaria were similar and constant during the growing season. Leaf water content of N tangutorum was not affected by low soil moisture in July. However, leaf water content of A. arenaria was significantly lower in July than that in May. It is suggested N. tangutorum and A. arenaria showed a resource-dependent water use strategy, using different depth of soil water according to their availability in different months of growing season and thus they could coexist on interdune at desert edge for a long time.