Chin J Plan Ecolo ›› 2017, Vol. 41 ›› Issue (2): 175-185.DOI: 10.17521/cjpe.2016.0253

Special Issue: 稳定同位素生态学

• Research Articles • Previous Articles     Next Articles

Soil water use strategy of dominant species in typical natural and planted shrubs in loess hilly region

Ting LÜ1, Xi-Ning ZHAO2,3,*(), Xiao-Dong GAO2,3, Yan-Hui PAN4   

  1. 1College of Water Resources and Architectural Engineering, Northwest A & F University, Yangling, Shaanxi 712100, China

    2Institute of Soil and Water Conservation, Northwest A & F University, Yangling, Shaanxi 712100, China

    3Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling, Shaanxi 712100, China

    4Key Laboratory of Western China’s Environmental Systems of Ministry of Education, Lanzhou University, Lanzhou 730000, China
  • Received:2016-08-01 Accepted:2016-12-25 Online:2017-02-10 Published:2017-03-16
  • Contact: Xi-Ning ZHAO
  • About author:

    KANG Jing-yao(1991-), E-mail: kangjingyao_nj@163.com

Abstract:

Aims Artemisia gmelinii is a dominant specie naturally established after abandonment of cultivated lands in the Loess Plateau, and Caragana korshinskii is one of the main planted shrub species to control soil erosion. Improved understanding of water use strategies of these two species is of great significance to evaluate the sustainable development of the Loess Plateau under the trend of climate warming and increasing drought events.
Methods Stable oxygen-18 isotope was used to determine seasonal variations in the water sources of native A. gmelinii communities established after abandonment of cultivated lands for 7 and 30 years and planted C. korshinskii after 30 years. The contributions of soil water from different depths to water uptake were estimated by the MixSIR Bayesian mixing model. The geometric mean regression method was used to fit the line of precipitation to get the local meteoric water line (LWML).
Important findings The stable hydrogen isotope rate (δD) and stable oxygen isotope rate (δ18O) of soil water and xylem water plotted to the right side of the LWML, indicating that the isotopic compositions of soil water were enriched due to evaporation. The native A. gmelinii communities established after abandonment of cultivated lands for 7 years and planted C. korshinskii after 30 years showed plasticity in switching water sources from different soil layers, extracting water from shallow soil (0-40 cm) when soil water was available, but deeper soil (40-80 cm) when shallow soil water was dry. In contrast, A. gmelinii growing in site after cultivation abandonment for 30 years mainly relied on water from the surface soil (0-10 cm) throughout the growing season. Our results suggest that the ability of A. gmelinii to compete for soil water reduces with aging of the community while the planted C. korshinskii will have competitive advantage under the condition of increasing frequency of drought events in the future.

Key words: oxygen stable isotopes, water-use source, MixSIR model, Artemisia gmelinii, Caragana korshinskii