Water and nutrient use efficiencies of Stipa purpurea Griseb. along a precipitation gradient of the Tibetan Plateau

Abstract

Water and nutrient use efficiencies are important adaptive features of plants in arid and semi-arid environments. In this study, water, nitrogen (N), and phosphorus (P) use efficiencies of Stipa purpurea Griesb., an endemic and dominant grass species, were investigated in the alpine steppe along precipitation gradients on the Tibetan Plateau. The leaf N content of S. purpurea increased along the precipitation gradient, but leaf P decreased, whereas carbon (C) remained unchanged. Leaf δ13C (water use efficiency, WUE) and C:N ratio (N use efficiency, NUE) decreased with increasing precipitation. But leaf C:P (P use efficiency, PUE) and N:P ratios increased with increasing precipitation. A trade-off was found between WUE and PUE but not between WUE and NUE. The changes in leaf traits were associated with changes in soil water, organic C, total N and P. These findings offer insights into understanding alpine plant water and nutrient use strategies along a precipitation gradient, as well as facilitate the prediction of alpine ecosystem responses to precipitation changes.

Keywords

• grassland
• water availability
• nutrient limitation
• correlation
• soil characteristic