Water (WUE) and nutrient (NutUE) use efficiencies are key adaptive traits that balance carbon (C) gain with resource acquisition under limited conditions. To elucidate the interspecific differences and environmental drivers of resource use efficiency, this study measured leaf stable isotope and stoichiometry in Hippophae rhamnoides and Pinus tabuliformis plantations along a precipitation gradient on the semiarid Loess Plateau. The results indicated that H. rhamnoides exhibited significantly higher intrinsic WUE (WUEi, 77.45 +/- 3.25 mu mol mol(-1)) and phosphorus use efficiency (PUE, carbon to phosphorus ratio, 449.43 +/- 19.75 g C g(-1) P) than P. tabuliformis. However, P. tabuliformis showed a significantly higher nitrogen use efficiency (NUE, carbon to nitrogen ratio, 44.09 +/- 1.63 g C g(-1) N) than H. rhamnoides (15.84 +/- 0.42 g C g(-1) N). Both species improve WUEi at the expense of NutUE as mean annual precipitation (MAP) decreases (P < 0.01). H. rhamnoides and P. tabuliformis exhibited lower WUEi-PUE and WUEi-NUE tradeoffs, respectively, to cope with the corresponding leaf P and N limitations (P < 0.05). WUEi was primarily and negatively influenced by MAP, the relative importance was 28.9% and 42.6% for P. tabuliformis and H. rhamnoides (P < 0.01); NUE and PUE were significantly constrained by soil N and P availability, respectively (P < 0.05). These findings indicate that plant WUEi-NutUE tradeoffs represent an adaptive strategy for optimizing use of the most limiting resource, providing a scientific basis for ecological restoration on the semiarid Loess Plateau.