Adaptive water use strategies of artificially revegetated plants in a groundwater dependent ecosystem: Implications for sustainable ecological restoration

Understanding the water use patterns of artificially revegetated plants in arid and semi-arid desert regions with shallow groundwater is crucial for sustainable water resource management and effective vegetation restoration strategies. Despite extensive vegetation rehabilitation in China’s Mu Us Sandy Land, the interspecific and seasonal variations in plant water sources under similar groundwater conditions remain unclear. We conducted isotopic analysis of hydrogen and oxygen in main sand-fixing plants—Pinus sylvestris var. mongolica, Amygdalus pcdunculata Pall, and Artemisia desertorum Spreng—alongside potential water sources during the three growing seasons. Our aim was to elucidate seasonal changes in plant water uptake patterns by correcting isotopic offsets in xylem water using the MixSIAR model. Results indicated that A. desertorum predominantly utilized water from the 0–150 cm soil layer (67.52±14.44 %) throughout all seasons. Conversely, P. sylvestris and A. pedunculata shifted their primary water sources from the 60–240 cm soil layer during the dry season (55.20±2.12 and 57.96±1.45 %, respectively) to the 0–150 cm soil layer during the rainy season (68.44±4.46 and 66.19±1.68 %, respectively), suggesting greater water uptake adaptability in trees and shrubs compared to grasses. Groundwater contribution to plant water uptake showed no significant interspecies difference during the rainy season (P > 0.05). However, P. sylvestris and A. pedunculata significantly increased groundwater absorption during the dry season compared to the rainy season (P < 0.05). Correcting δ²H offsets in xylem water revealed an underestimation of groundwater contributions by 16.06±9.09 % in the dry season and 4.25±0.55 % in the rainy season. Given these interspecific and seasonal variations in water uptake patterns among sand-fixing plants, and the imperative for sustainable groundwater use, tailored water management strategies are essential to prevent the degradation of restored ecosystems in this water-limited desert region.