Soil-water dynamics and tree water uptake in the Sacramento Mountains of New Mexico (USA): a stable isotope study

Gierke, Casey; Newton, B. Talon; Phillips, Fred M.

doi:10.1007/s10040-016-1403-1

Cited by 33 publications

(28 citation statements)

References 24 publications

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“…Evidence for the ecohydrological separation hypothesis has been reported in various climate zones (Bowling et al, 2017;Brooks et al, 2010;Evaristo et al, 2016;Gierke et al, 2016;Goldsmith et al, 2012;Hervé-Fernández et al, 2016;McCutcheon et al, 2017;Zhao et al, 2018). Meanwhile, at the global scale, Evaristo et al (2015) suggest that the ecohydrological separation occurs at 80 % of the sites, and Good et al (2015) report that 38 % of surface water comes from the plant accessible soil water pool.…”

Section: Introductionmentioning

confidence: 99%

“…For those previous studies on the ecohydrological separation, bulk soil water that includes both mobile and immobile (matric-bound) water was sampled with the cryogenic vacuum distillation. In addition to bulk soil water sampling, some studies also extracted mobile soil water using suction lysimeters Hervé-Fernández et al, 2016), centrifugation (Geris et al, 2015), or wick samplers (Gierke et al, 2016). As most studies on the ecohydrological separation assume that plants rely on the immobile soil water, it should be reasonable to investigate isotope composition of immobile water to reflect the isotopic composition of water used by plants.…”

Section: Introductionmentioning

confidence: 99%

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Examination of the ecohydrological separation hypothesis in a humid subtropical area: Comparison of three methods

Luo

Guan

Zhang

et al. 2019

Journal of Hydrology

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The ecohydrological separation between soil water sources for plant water uptake and groundwater recharge has been recently examined in various climate zones primarily based on isotopic composition of water. The existence of the ecohydrological separation has profound implications for mechanistic ecohydrological modeling and water resource management. However, it is still unclear when and where the ecohydrological separation occurs, especially in humid regions. In this study, high frequency sampling of precipitation, bulk soil water, groundwater and twig xylem water for hydrogen and oxygen isotope composition measurement was conducted in a humid subtropical site in the central southern China from March 2017 to April 2018. We examined evidence of the ecohydrological separation with three methods (dual-isotope space, line-conditioned excess (lc-excess), and the piecewise isotope balance (PIB) method). The results show that the isotope compositions of plant xylem and bulk soil water are not distinguishable from those of precipitation water on the dual-isotope space due to a weak evaporation effect at the study site, indicating that there is no evidence of the ecohydrological separation.However, the other two methods support the ecohydrological separation in this humid area, with the results from the PIB method revealing more temporal details. The present study suggests that the ecohydrological separation can happen in subtropical humid climate. It is more likely to occur in spring and winter at the study site when plant-accessible water pool has been replenished by antecedent precipitation, while ecohydrological connection seems to occur during winter snowmelt. With the limitations of three methods, the caution should be taken when only one method is 3 applied in examining the ecohydrological separation in such an environment. Highlights Two commonly used methods for assessing the ecohydrological separation show inconsistent results. A new method based on root zone isotope mass balance supports the ecohydrological separation at the studied humid site. The ecohydrological connection occurs during snowmelt at the site.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Examination of the ecohydrological separation hypothesis in a humid subtropical area: Comparison of three methods

Luo

Guan

Zhang

et al. 2019

Journal of Hydrology

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“…Several studies (Liu et al, 2013;Mathieu and Bariac, 1996;Allison and Barnes, 1985) have shown that transpiration do not cause isotopic fractionation of soil water. The isotopes δD and δ 18 O can be a powerful tool to determine the water sources utilized by plants in the field, since δD and δ 18 O values of xylem water reflect those of the water sources utilized (Gierke et al, 2016;Yang et al, 2011;Lu et al, 2011). The naturally occurring vertical gradients of δD and δ 18 O in soil water provide similar information about plant water uptake depth from soils.…”

Section: Introductionmentioning

confidence: 99%

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

Yang

2017

Hydrol. Earth Syst. Sci.

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Abstract. Soil water is an important driving force of the ecosystems, especially in the semiarid hill and gully region of the northwestern Loess Plateau in China. The mechanism of soil water migration in the reconstruction and restoration of Loess Plateau is a key scientific problem that must be solved. Isotopic tracers can provide valuable information associated with complex hydrological problems, difficult to obtain using other methods. In this study, the oxygen and hydrogen isotopes are used as tracers to investigate the migration processes of soil water in the unsaturated zone in an arid region of China's Loess Plateau. Samples of precipitation, soil water, plant xylems and plant roots are collected and analysed. The conservative elements deuterium (D) and oxygen ( 18 O) are used as tracers to identify variable source and mixing processes. The mixing model is used to quantify the contribution of each end member and calculate mixing amounts. The results show that the isotopic composition of precipitation in the Anjiagou River basin is affected by isotopic fractionation due to evaporation. The isotopic compositions of soil waters are plotted between or near the local meteoric water lines, indicating that soil waters are recharged by precipitation. The soil water migration is dominated by piston-type flow in the study area and rarely preferential flow. Water migration exhibited a transformation pathway from precipitation to soil water to plant water. δ 18 O and δD are enriched in the shallow (< 20 cm depth) soil water in most soil profiles due to evaporation. The isotopic composition of xylem water is close to that of soil water at the depth of 40-60 cm. These values reflect soil water signatures associated with Caragana korshinskii Kom. uptake at the depth of 40-60 cm. Soil water from the surface soil layer (20-40 cm) comprised 6-12 % of plant xylem water, while soil water at the depth of 40-60 cm is the largest component of plant xylem water (ranging from 60 to 66 %), soil water below 60 cm depth comprised 8-14 % of plant xylem water and only 5-8 % is derived directly from precipitation. This study investigates the migration process of soil water, identifies the source of plant water and finally provides a scientific basis for identification of model structures and parameters. It can provide a scientific basis for ecological water demand, ecological restoration, and management of water resources.

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“…This fundamental understanding of water uptake and transport from roots to shoots underlies the utility of stable isotopes in plant water uptake investigations17. While many site-based studies have now been completed18192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114…”

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confidence: 99%

Prevalence and magnitude of groundwater use by vegetation: a global stable isotope meta-analysis

Evaristo

McDonnell

2017

Sci Rep

130

111

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The role of groundwater as a resource in sustaining terrestrial vegetation is widely recognized. But the global prevalence and magnitude of groundwater use by vegetation is unknown. Here we perform a meta-analysis of plant xylem water stable isotope (δ2H and δ18O, n = 7367) information from 138 published papers – representing 251 genera, and 414 species of angiosperms (n = 376) and gymnosperms (n = 38). We show that the prevalence of groundwater use by vegetation (defined as the number of samples out of a universe of plant samples reported to have groundwater contribution to xylem water) is 37% (95% confidence interval, 28–46%). This is across 162 sites and 12 terrestrial biomes (89% of heterogeneity explained; Q-value = 1235; P < 0.0001). However, the magnitude of groundwater source contribution to the xylem water mixture (defined as the proportion of groundwater contribution in xylem water) is limited to 23% (95% CI, 20–26%; 95% prediction interval, 3–77%). Spatial analysis shows that the magnitude of groundwater source contribution increases with aridity. Our results suggest that while groundwater influence is globally prevalent, its proportional contribution to the total terrestrial transpiration is limited.

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Soil-water dynamics and tree water uptake in the Sacramento Mountains of New Mexico (USA): a stable isotope study

Cited by 33 publications

References 24 publications

Examination of the ecohydrological separation hypothesis in a humid subtropical area: Comparison of three methods

Examination of the ecohydrological separation hypothesis in a humid subtropical area: Comparison of three methods

Soil water migration in the unsaturated zone of semiarid region in China from isotope evidence

Prevalence and magnitude of groundwater use by vegetation: a global stable isotope meta-analysis

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