Pattern of water use by Tamarix ramosissima seedlings in floodplains under varied groundwater depths in the hinterland of the Taklimakan Desert

The water use of Tamarix ramosissima Ledeb. seedlings after flooding were analyzed both to explore the maintenance mechanism and pattern of natural regeneration of riparian forest, which will provide a scientific basis for restoration of desert riparian forest and ecosystem stability in the lower reaches of inland rivers of arid regions. This study area was located in the hinterland of the Taklimakan Desert in Xinjiang, China. Tamarix ramosissima seedlings growing on different groundwater depths at the river floodplain were used as the study system. The rooting depths of T. ramosissima seedlings with different basal stem diameters were ascertained by the root excavation method. The water source for the T. ramosissima seedlings was clarified using hydrogen and oxygen stable isotope methods, and the water use efficiency of T. ramosissima seedlings was investigated by stable carbon isotope (δ¹³C) analysis. As the basal stem diameter classes of the T. ramosissima seedlings increased, their root depths increased. As the groundwater depth increased, the seedlings changed from primarily utilizing deep soil water to utilizing shallow soil water. In the three sample sites, the average depth of water uptake of the seedlings with basal stem diameters of 0–5 mm was 110.5, 44.1 and 39.1 cm, respectively, and that of seedlings with basal stem diameters of 5–11 mm was 83.8, 73.6 and 37.7 cm, respectively. As groundwater depth increased, the average water uptake depth of the seedlings gradually became shallower. There was no significant difference in the δ¹³C values of leaves under different groundwater depths, indicating that the seedlings were not subjected to water stress. Thus, surface water played a greater role than groundwater in T. ramosissima seedling water utilization. Therefore, when analyzing ecological water conveyance patterns, attention should be paid to T. ramosissima located in areas with deep groundwater. Shallow-rooted seedlings with small basal stem diameters face an increased risk of wilting if they do not receive timely recharges of surface water.

Data Availability

All data generated or analyzed during this study are included in this published article.