title: Correlations of carbon isotope discrimination with element and ash contents in two Sabina evergreen trees in northwest China: patterns and implications.
abstract: Foliar carbon isotope discrimination (Δ) is widely used as an integrator of physiological plant responses to environmental change. However, the relationship between foliar Δ and mineral nutrient accumulation is still not well-known. The foliar Δ, K, Ca, Mg, Si and ash contents of S. przewalskii Kom. (SP) and S. chinensis (Lin.) Ant. (SC), two over-winter trees distributed on high altitude plateaux and lower altitude plains, respectively, were measured at monthly intervals over two years under the same growing conditions to examine the genetic and seasonal variation in foliar nutrient concentrations in relation to foliar Δ. The foliar Δ, Mg, K and ash contents were markedly lower in SP than in SC, and the foliar Si content was significantly higher in SP than SC, while the differences in Ca contents between the two Sabina trees were not significant. There was higher foliar Δ in winter than in summer for both Sabina trees. Close negative correlations of foliar Δ with K and Mg content, and significant positive correlations between foliar Δ and Si contents, were observed in SP but not in SC. Thus, higher water-use efficiency of SP than of SC is related to higher Si and lower Mg and K contents that have positive effects on the reduction of transpiration rates or stomatal conductances. The results obtained by the present study will advance the understanding of the adaptive strategies of mineral nutrition and water use in harsh environments.
authors: State Key Laboratory of Cryospheric Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China.
authors: Youfu
authors: Y
authors: Zhang
authors: Tuo
authors: T
authors: Chen
authors: Guangxiu
authors: G
authors: Liu
authors: Manxiao
authors: M
authors: Zhang
authors: Lizhe
authors: L
authors: An
authors: Yingwu
authors: Y
authors: Chen