Field validation of isotopic procedures for determining sources of water used by plants in a semi-arid environment

Brunel, Jean-Pierre; Walker, Glen; Kennett-Smith, A.

doi:10.1016/0022-1694(94)02575-v

Cited by 196 publications

(171 citation statements)

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“…Zimmermann et al (1967) demonstrated that no fractionation of the isotopes occurred during water transfer from the soil to the plant. Therefore, comparison of the isotopic composition in the plants and possible sources of water can be used to infer the depth of water uptake (Brunel et al, 1995). The proportion of varying potential water sources accessed by plants was preliminarily determined using stable isotope analysis in conjunction with two-or three-compartment linear mixing models (Snyder and Williams, 2000;Darrouzet-Nardi et al, 2006;McCole and Stern, 2007).…”

mentioning

confidence: 99%

Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

Song

2016

Science of The Total Environment

107

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mentioning

confidence: 99%

Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

Song

2016

Science of The Total Environment

107

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“…The total error involved in sampling, extraction, analysis and the other assumptions for the procedure used in this study appears to be less than 5‰ for 2 H and 1‰ for 18 O (Brunel et al, 1995). If the natural variation of the isotopic composition in source waters is greater than this, then this technique is likely to be useful in determining sources of water used by trees.…”

Section: Theorymentioning

confidence: 92%

“…The lack of fractionation in the uptake of water by roots has been shown in laboratory and glasshouse experiments (Walker & Richardson, 1991;Thorburn et al, 1992) and under field conditions (Brunel et al, 1995). The only exception demonstrated thus far is for halophytes such as mangrove (Lin & Sternberg, 1993).…”

Section: Theorymentioning

confidence: 93%

“…In these habitats mesquite probably develops an extensive surface root system, which can compete actively with those of grassland, and possibly just a single tap root giving access to groundwater when needed. Functional variation related to the sources of water used by trees of semi-arid regions has likewise been observed: in Australia for eucalypts (Eucalyptus camadulensis) (Mensforth et al, 1994) and for phreatophytic plants (Dawson & Pate, 1996); in Niger for Guiera senegalensis (Brunel, 1995(Brunel, , 1997; and in the American southwest for cottonwood (Populus) (Snyder et al, 1998), boxelder (Kolb et al, 1997), woody riparian phreatophytes (Busch et al, 1992), pinyon and juniper (Flanagan et al, 1992), and cold desert shrub community (Lin et al, 1996).…”

Section: The δmentioning

confidence: 99%

“…Thus the isotopic composition of water in the plant should be a mixture of that of the different soil compartments from which the plant is deriving water. The methodology for using stable isotopes of water to determine water sources of vegetation relies upon a number of specific assumptions (after Brunel et al, 1995): 1. there is no isotopic fractionation of water during extraction by the roots; 2. there is no significant change in the isotopic composition of sap water within the plant, except in the vicinity of the leaf; 3. no significant errors are associated with the sampling of isotopes, or in the extraction and analysis of water from plants and soil; 4. the isotopic composition of the soil water is laterally homogeneous within the rooting area; and 5. the time of sampling was such that time delays associated with transport of water through the plant are unimportant. All of the values for isotope composition are reported in delta notation (δ, ‰) relative to standard mean ocean water (SMOW) provided by the laboratory of the International Atomic Energy Agency (IAEA) in Vienna, Austria, where: 1000 sample…”

Section: Theorymentioning

confidence: 99%

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Sources of water used by natural mesquite vegetation in a semi-arid region of northern Mexico

Brunel¹

2009

Hydrological Sciences Journal

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Vegetation structure in semi-arid regions of northern Mexico and the southwestern USA has changed dramatically over the last century; shrubs such as mesquite (Prosopis sp.) have expanded into, and have become dominant in, ecosystems that once supported semi-arid grassland. The upper San Pedro River watershed, which extends from northern Sonora (Mexico) to southeastern Arizona (USA), highlights these changes. Between 1973 and 1992, grasslands decreased by 18% and the total area dominated by mesquite increased during the same period by 412%. In the areas where the density of mesquite shrub is medium to high, grass has completely disappeared under the shrub canopy and has been replaced by bare soil. Undoubtedly these cover changes have affected surface-atmosphere interactions by introducing a different partitioning of net available energy into sensible and latent heat flux. At the same time, different root system and root density and plant physiology have introduced a change to the surface water balance, reducing inflitration and increasing runoff. Our study addressed the sources of water used by mesquite (Prosopis velutina) along a natural gradient from an area of high mesquite cover with no herbaceous grass cover, to open savanna with high grass cover and widely spaced mesquite. The presented results from the SALSA 1997 monsoon-season campaign (July-October) show that mesquite shrubs that have access to both groundwater and surface water use surface water when available, potentially competing with grass for surface water and out-competing grass during successive periods of drought when only groundwater is available.Key words oxygen-18; mesquite; Prosopis velutina; water use; Sonora, Mexico; Arizona, USA; semi-desert grassland Sources de l'eau utilisée par une végétation naturelle de mesquite dans une région semi-aride du nord du MexiqueRésumé La structure de la végétation dans les régions semi-arides du nord-est du Mexique et du sud-ouest des Etats Unis a changé d'une façon spectaculaire au cours du dernier siècle. Une végétation de buissons de type mesquite (Prosopis sp.) s'est répandue partout pour devenir dominante dans ce qui était autrefois un écosystème de prairies semi-arides. Le haut bassin de la rivière San Pedro qui s'étend du nord-est du Sonora (Mexique) au sud-est de l'Arizona (USA) met bien en relief ces changements. Entre 1973 et 1992, les prairies ont diminué de 18% alors que pendant le même temps la superficie totale dominée par les mesquites s'accroissait de 412%. Dans les zones où la densité de mesquites est moyenne ou forte, l'herbe a complètement disparu sous les arbres et a été remplacée par du sol nu. Il ne fait aucun doute que ces changements de couverture végétale ont affecté les interactions surface-atmosphère en introduisant une répartition différente de l'énergie nette disponible en flux de chaleur sensible et latente. En même temps, l'accroissement du ruissellement, la diminution de l'infiltration mais aussi le développement de systèmes d'enracinement différents, et des densit...

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Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical savanna

Boutton

Archer

Midwood³

1999

Rapid Commun. Mass Spectrom.

140

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Stable isotopes are often utilized as intrinsic tracers to study the effects of human land uses on the structural and functional characteristics of ecosystems. Here, we illustrate how stable isotopes of H, C, and O have been utilized to document changes in ecosystem structure and function using a case study from a subtropical savanna ecosystem. Specifically, we demonstrate that: (1) delta 13C values of soil organic carbon record a vegetation change in this ecosystem from C4 grassland to C3 woodland during the past 40-120 years, and (2) delta 2H and delta 18O of plant and soil water reveal changes in ecosystem hydrology that accompanied this grassland-to-woodland transition. In the Rio Grande Plains of North America, delta 13C values of plants and soils indicate that areas now dominated by C3 subtropical thorn woodland were once C4 grasslands. delta 13C values of current organic matter inputs from wooded landscape elements in this region are characteristic of C3 plants (-28 to -25/1000), while those of the associated soil organic carbon are higher and range from -20 to -15/1000. Approximately 50-90% of soil carbon beneath the present C3 woodlands is derived from C4 grasses. A strong memory of the C4 grasslands that once dominated this region is retained by delta 13C values of organic carbon associated with fine and coarse clay fractions. When delta 13C values are evaluated in conjunction with 14C measurements of that same soil carbon, it appears that grassland-to-woodland conversion occurred largely within the past 40-120 years, coincident with the intensification of livestock grazing and reductions in fire frequency. These conclusions substantiate those based on demographic characteristics of the dominant tree species, historical aerial photography, and accounts of early settlers and explores. Concurrent changes in soil delta 13C values and organic carbon content over the past 90 years also indicate that wooded landscape elements are behaving as sinks for atmospheric CO2 by sequestering carbon derived from both the previous C4 grassland and the present C3 woody vegetation. Present day woodlands have hydrologic characteristics fundamentally different from those of the original grasslands. Compared to plants in remnant grasslands, tree and shrub species in the woodlands are rooted more deeply and have significantly greater root biomass and density than grasslands. delta 18O and delta 2H values of plant and soil water confirm that grassland species acquire soil water primarily from the upper 0.5 m of the soil profile. In contrast, trees and shrubs utilize soil water from throughout the upper 4 m of the profile. Thus, soil water that formerly may have infiltrated beyond the reach of the grassland roots and contributed to local groundwater recharge or other hydrologic fluxes may now be captured and transpired by the recently formed woodland plant communities. The natural abundances of stable isotopes revealed fundamental information regarding the impacts of human land use activities on the structure and function of th...

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Field validation of isotopic procedures for determining sources of water used by plants in a semi-arid environment

Cited by 196 publications

References 10 publications

Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

Using stable isotopes to determine seasonal variations in water uptake of summer maize under different fertilization treatments

Sources of water used by natural mesquite vegetation in a semi-arid region of northern Mexico

Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical savanna

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