Stable carbon isotope characteristics of desert plants in the Junggar Basin, China.

Desert plants have unique strategies for survival and growth to cope with the limited water availability in arid regions. The stable carbon isotope ( δC) provides an integrated measurement of internal plant physiological and external environmental properties affecting photosynthetic gas exchange and water use efficiency. The δC values of 84 species in the Junggar Basin were categorized into two groups (ranged from −30.1 to −23.3‰ for C and −14.9 to −9.9‰ for C species, respectively). No life form differences in δC values were detected in C ( p = 0.78) and C plants ( p = 0.63). Small differences among life forms were observed in δC values in C species with shrubs slightly depleted (−13.3‰) relative to perennials (−13.1‰) and annuals (−12.5‰). These differences suggested that δC value could not represent a plant functional group classification based on life forms in C plants in extremely arid regions. Ephemerals are all using C photosynthetic pathway and no significant differences ( p = 0.92) in δC values were observed between annuals (−26.5‰) and perennials (−26.4‰). The δC values of Tulipa iliensis (an important ephemeral species distributed widely in the Junggar Basin) among nine natural populations were positively correlated with leaf ( r = 0.46, p = 0.046) and soil ( r = 0.67, p = 0.007) total nitrogen content, and negatively correlated with leaf ( r = 0.48, p = 0.039) and soil ( r = 0.79, p = 0.001) water content. This indicated that the variation in δC values of T. iliensis was probably caused by both water availability associated stomatal openness and nitrogen availability associated photosynthetic capacity. T. iliensis is very sensitive to water and nitrogen availability in soil. [ABSTRACT FROM AUTHOR]