Nutrient resorption patterns of Phragmites australis leaves and its response to soil moisture in Yangguan wetland, Dunhuang, Northwest China

Abstract

Nutrient resorption of leaves is an important nutrient conservation mechanism for plants in nutrient-poor habitats. Understanding the responses of leaf nutrient resorption to soil moisture is helpful to reveal the adaptation strategies of plants to the environment. In this study, the dominant plant in the Yangguang wetland of Dunhuang Phragmites australis was used as research material, to explore nitrogen and phosphorus resorption patterns of P. australis leaves and their responses to soil moisture under different moisture regimes, i.e. high (33.5%±1.9%), medium (26.4%±1.3%) and low (11.3%±1.5%). The results showed that: 1) With the decreases of soil moisture, soil N concentration decreased significantly, and N concentrations in mature and senescent leaves increased significantly, the P concentration in mature and senescent leaves as well as in soil did not change. 2) N resorption efficiency of leaves under high moisture condition was 76.1%, which was significantly higher than the medium (65.5%) and low (62.5%) moisture conditions. P resorption efficiency varied among different moisture conditions. 3) The N concentrations of mature and senescent leaves were negatively correlated with N resorption efficiency. There was no significant correlation between P concentration and P resorption efficiency in mature leaves, but the P concentration of senescent leaves was negatively correlated with P resorption efficiency of leaves. As a result, water scarcity is not conducive to leaf N resorption.