Sources of water used by riparian Eucalyptus camaldulensis overlying highly saline groundwater

Abstract

Water sources of Eucalyptus camaldulensis Dehn. trees were investigated on a semiarid floodplain in south-eastern Australia. The trees investigated ranged in distance from 0.5 to 40 m from a stream, with electrical conductivity 0.8 dSm, and grew over groundwater with electrical conductivity ranging from 30 to 50 dSm. The sources of water being used by the trees were investigated using the naturally occurring stable isotopes of water and measurements of soil water potential. Xylem water potential and leaf conductance were also examined to identify the trees' response to using these sources of water. Trees at distances greater than about 15 m from the stream used no stream water. The trees used groundwater in summer and a combination of groundwater and rain-derived surface-soil water (0.05-0.15 m depth) in winter. In doing so they suffered water stress at electrical conductivities higher than approximately 40 dSm (equivalent to approximately -1.4 MPa). Trees adjacent to the stream used stream water directly in summer, but may have used stream water from the soil profile in winter, after the stream had risen and recharged the soil water. E. camaldulensis appeared to be partially opportunistic in the sources of water they used.

Stable Isotopic Analysis on Water Utilization of Two Xerophytic Shrubs in a Revegetated Desert Area: Tengger Desert, China

“…The D and 18 O contents of the stem, soil, precipitation and river water was measured using a Flash 2000 HTelemental analyzer (Thermo Scientific, Bremen, Germany) coupled to a Finnigan MAT253 isotope ratio mass spectrometer. 18 O content was determined with the H2O-CO2 equilibration method [25], and D content was determined with the gaseous H2-H2O equilibration technique [26]. Overall analytical precision of the spectrometer was ± <0.2‰ for δ …”

“…Eucalyptus spp. used various combinations of groundwater, rainfall-derived shallow soil water, and stream water in Australia [18,19]. Trees along a perennial, montane stream in California absorbed water from upper soil layers early in the growing season, and then used groundwater primarily when the soil dries [20].…”

“…The local meteoric water line (LMWL) at Shapotou is described as: δD = 7.39δ 18 O + 3.91 (R 2 = 0.93; n = 26), thereby exhibiting low slope and intercept values that are located away to the right of the Global Meteoric Water Line (GMWL) [29]. LMWL depended on seasonal and geographical variability in local climatic conditions; this observation indicated that rain likely undergoes substantial secondary evaporation and elicits related isotopic effects on arid desert regions.…”

Ground Water Chlorinated Ethenes in Tree Trunks: Case Studies, Influence of Recharge, and Potential Degradation Mechanism

“…For example, in areas where rainfall is unreliable, riparian trees may develop roots primarily in the capillary fringe and phreatic zone rather than throughout the soil profile (Ehleringer and Dawson 1992) western Arizona used ground water throughout the growing season regardless of the depth to ground water (Busch et al 1992). Plants with roots distributed in multiple soil zones may use various combinations of ground water, rainfall infiltrate, and stream water, sometimes responding opportunistically to rainfall events (Mensforth et al 1994;Thorburn and Walker 1994;Dawson and Pate 1996;Jolly and Walker 1996). Trees near a perennial stream in California used shallow soil water early in the growing season and then primarily used ground water in the latter part of the season when the soil dried (Smith et al 1991).…”

Management Strategies for Large River Floodplain Lakes Undergoing Rapid Environmental Changes

“…Composition and diversity of naturally occurring riparian forests such as river red gum trees (Eucalyptus camaldulensis) in MDB have declined as a result of river regulation . For example, stable isotope ratios of oxygen reveal that river red gum (E. camaldulensis) forests are efficient for utilizing water at varying salinity gradients (Mensforth et al, 1994) through reduced transpiration rates (Costelloe et al, 2008). However, continued low flows occur as a result of a rise in ground water salinity.…”