Foliar stable carbon isotope discrimination and nutrients contents in two desert plant species

Variation of foliar stable Carbon Isotope Discrimination (CID Delta parts per thousand) and nutrient contents of Artemisia ordosica (Krasch) (semi-shrub species) and Caragana korshinskii (Kom.) (shrub species) were studied at the southeastern margin of the Tengger Desert, China. Foliar CID Delta, total phosphorus content (TP) and potassium content (K) in A. ordosica were markedly higher than in C. korshinskii while foliar total nitrogen content (TN) and water-use efficiency (WUE) (calculated from foliar CID Delta) in C. korshinskii were significantly higher than those in A. ordosica. There were significant and positive relationships between foliar CID Delta, TN and TP contents (P < 0.001) in C. korshinskii, while in A. ordosica a strong and significant positive correlation existed between CID A and K content (P < 0.001). Based on WUE, TN, TP, and K contents, as well as their relationships, we may conclude that in arid environments, the survival of C. korshinskii profits from its higher WUE, while the survival of A. ordosica from its higher TP and K contents in leaves. In addition, the correlations of foliar CID A values with TN and TP contents in C. korshinski and with K content in A. ordosica revealed that the water was one of the main factors limiting the absorption capacity for N and P in C. korshinskii, and for K in A. ordosica. While nutrient conditions were not the factors affecting the growth of C. korshinskii and A. ordosica in the study areas.