Water uptake patterns differ markedly among different sand-fixing plants in Mu Us Sandy Land in Northwest China

Aim: This study aimed to investigate the seasonal variations and controls of water uptake patterns of different sand-fixing plants in water-limited desert ecosystem. Methods: δ 2 H and δ 18 O in precipitation water, soil water, groundwater and xylem water were obtained to determine the seasonal changes in water uptake by three representative plant species ( P. sylvestris, A. pcdunculata and S. psammophila ) in the Mu Us Sandy Land in Northwest China. Results: Annually, P. sylvestris, A. pcdunculata and S. psammophila respectively derived of their water from the deep (59.2% moist layer and groundwater), intermediate (57.4% stable and moist layers) and shallow (54.4% active and stable layers) water sources. Seasonally, the three plant species absorbed more than 60% of their water from moist layer and groundwater in the early dry season (June) and then switched over to water sources in active and stable layers (50.1–62.5%) in the rainy season (July–September). From October to November (late dry season), P. sylvestris (54.5–66.2%) and A. pcdunculata (52.9–63.6%) mainly used water from stable and moist layers, while S. psammophila (52.6–70.7%) still predominantly extracted its water from active and stable layers. Conclusions: Variations in soil water profile induced by seasonal fluctuations in precipitation and groundwater level and then differences in plant root distribution and water requirement were the main factors affecting seasonal patterns of water use by the three plant species. By analyzing the sources and controls of plant water uptake, this study opened a new door of research on vegetation restoration and water management in water-limited desert regions.