Afforestation has been an effective measure for ecological restoration of desertification in Qinghai Lake basin since the 1980s. Revealing water and nutrient use efficiency of typical sand-fixing plantations and analyzing influencing factors at spatial-temporal scales would be beneficial, offering a better understanding of sand-fixing plantations' resource utilization strategies in alpine arid environments and providing valuable insights for vegetation restoration in fragile desert areas. We selected Hippophae rhamnoide along revegetation chronosequence (1987, 2008, and 2015) in desert located on the eastern shore of Qinghai Lake as our study objects. Stable carbon and nitrogen isotope techniques were used to determine the δ¹³C, δ¹⁵N, carbon (C) and nitrogen (N) contents (%) per unit mass of leaves. Then we calculated the ratio of C and N. Based on soil water content, leaf water content and local meteorological data, we explored the spatio-temporal variation of δ¹³C and δ¹⁵N and their responses to pedon and local climate. The results showed that: (1) At the temporal scale, δ¹³C and δ¹⁵N values initially decreased, then increased, and subsequently decreased from May to October. While the content of C showed a fluctuation trend of increasing- decreasing-increasing, meanwhile, the content of N gradually decreased. However, C/N showed a trend of increasing along with seasons increasing. (2) At the spatial scale, δ¹³C values were the highest in young stands and the lowest in old plantations, while δ¹⁵N values showed the opposite trend, whereas the contents of per unit mass of leaves carbon and nitrogen and their ratios did not show any significant differences. (3) The values of δ¹³C of were affected by different factors as restoration years increasing, while there was a significant negative correlation between the values of δ¹⁵N and mean relative humidity (MRH) (P < 0.05). The seasonal variation of δ¹³C resulted from local climate influencing, whereas the seasonal variation of δ¹⁵N was affected by both local meteorological factors and leaf nutrient contents such as the content of carbon and nitrogen. In our study, the values of δ¹³C decreased as well as δ¹⁵N values increased followed by H. rhamnoide fixation years increasing. There is likely a trade-off between water use efficiency (WUE) and nitrogen use efficiency (NUE) in the succession process of plantations from a stage of young to mature in the alpine desert ecosystem, which could give us an insight into the simultaneous consideration of the effects of nutrients and water on plantations in ecological restoration projects in alpine ecologically fragile area.