Spatial patterns of leaf δ 13 C and δ 15 N of aquatic macrophytes in the arid zone of northwestern China.

Analysis of stable isotope composition is an important tool in research on plant physiological ecology. However, large-scale patterns of leaf-stable isotopes for aquatic macrophytes have received considerably less attention. In this study, we examined the spatial pattern of stable isotopes of carbon (δ ¹³ C) and nitrogen (δ ¹⁵ N) of macrophytes leaves collected across the arid zone of northwestern China (approximately 2.4 × 10 ⁶  km ² ) and attempted to illustrate its relationship with environmental factors (i.e., temperature, precipitation, potential evapotranspiration, sediment total carbon and nitrogen). Our results showed that the mean values of the leaf δ ¹³ C and δ ¹⁵ N in the macrophytes sampled from the arid zone were -24.49‰ and 6.82‰, respectively, which were far less depleted than those measured of terrestrial plants. The order of averaged leaf δ ¹³ C from different life forms was as follows: submerged > floating-leaved > emergent. Additionally, our studies indicated that the values of foliar δ ¹³ C values of all the aquatic macrophytes were only negatively associated with precipitation, but the foliar δ ¹⁵ N values were mainly associated with temperature, precipitation, and potential evapotranspiration. Therefore, we speculated that water-relation factors are the leaf δ ¹³ C determinant of macrophytes in the arid zone of northwestern China, and the main factors affecting leaf δ ¹⁵ N values are the complex combination of water and energy factors.
Competing Interests: None declared.
(© 2021 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.)