Seasonal changes in the water use strategies of three co-occurring desert shrubs

Abstract

Water is a major limiting factor in desert ecosystems. In order to learn how plants cope with changes in water resources over time and space, it is important to understand plant–water relations in desert region. Using the oxygen isotopic tracing method, our study clarified the seasonal changes in the water use strategies of three co‐occurring desert shrubs. During the 2012 growing season, δ18O values were measured for xylem sap, the soil water in different soil layers between 0 and 300 cm depth and groundwater. Based on the similarities in δ18O values for the soil water in each layer, three potential water sources were identified: shallow soil water, middle soil water and deep soil water. Then we calculated the percentage utilization of potential water sources by each species in each season using the linear mixing model. The results showed that the δ18O values of the three species showed a clear seasonal pattern. Reaumuria songarica used shallow soil water when shallow layer was relatively wet in spring, but mostly took up middle soil water in summer and autumn. Nitraria tangutorum mainly utilized shallow and middle soil water in spring, but mostly absorbed deep soil water in summer and autumn. Tamarix ramosissima utilized the three water sources evenly in spring and primarily relied on deep soil water in summer and autumn. R. songarica and N. tangutorum responded quickly to large rainfall pulses during droughts. Differential root systems of the three species resulted in different seasonal water use strategies when the three competed for water. Copyright © 2013 John Wiley & Sons, Ltd.

Root distribution of Nitraria sibirica with seasonally varying water sources in a desert habitat

“…Plant root distribution and morphology determine the area where plants can potentially absorb soil water (Zencich et al 2002), as well as the plants' water-use patterns and responses to occasional rainfall pulses in desert ecosystems (Wu et al 2013;Xu and Li 2006). The root distribution and morphology we found for N. sibirica in northwestern China clearly shows that more than 51 % of the species' lateral roots (in terms of surface area) were restricted to the shallow soil profile (Fig.…”

“…Although extracted stem water of some species can contain compounds that interfere with accurate isotope ratio measurements, we solved this issue with the Spectral Contamination Identifier (LWIA-SCI) post-processing software to identify and quantify spectral contamination, and to correct the isotope values of contaminated water samples. For details of the procedure, see Wu et al (2013). Because hydrogen isotope fractionation has been observed during water uptake in some xerophytes (Ellsworth and Williams 2007 …”

A deuterium-based labeling technique for the investigation of rooting depths, water uptake dynamics and unsaturated zone water transport in semiarid environments

“…Other applications of environmental isotopes include the identification of water use strategies of certain species (i.e. Brunel et al, 1995;Chimner and Cooper, 2004;Edwin et al, 2014;Li et al, 2007), changes in water-use strategies (Wu et al, 2013), quantifications of preferential flow (Stumpp and Maloszewski, 2010) and investigations on hydraulic lift (Ceperley et al, 2014). Dawson et al (2007) used measurements of stable isotopes in woody plants to identify nighttime transpiration.…”

Phylogenetic structure and formation mechanism of shrub communities in arid and semiarid areas of the Mongolian Plateau

“…As an example, Reaumuria songarica + N. sphaerocarpa is a widely distributed typical desert community. Reaumuria songarica is a shallow-rooted plant with more lateral roots and most roots distributed in the range of 20-60 cm underground (Wu, Zhou, Zheng, Li, & Tang, 2014). In contrast, N. sphaerocarpa has deeper root distribution, enabling it to use groundwater below 80cm underground (Cui, Ma, Sun, Sun, & Duan, 2015).…”