Testing plant use of mobile vs immobile soil water sources using stable isotope experiments

Vargas, Ana I.; Schaffer, Bruce; Li, Yuhong; Sternberg, Leonel da Silveira Lobo

doi:10.1111/nph.14616

Cited by 153 publications

(236 citation statements)

References 33 publications

Supporting

Mentioning

212

Contrasting

Order By: Relevance

“…In addition, plants can also indirectly promote weathering by secreting bio-signaling molecules to activate their mycorrhizal networks and associated micro-organisms (Deveau et al, 2012;Venkateshwaran et al, 2013). Such secretions initiate a cascade of reactions that then allows them to take up weathering products.…”

Section: Hypothesismentioning

confidence: 99%

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

et al. 2017

View full text Add to dashboard Cite

Abstract. Trees, the most successful biological power plants on earth, build and plumb the critical zone (CZ) in ways that we do not yet understand. To encourage exploration of the character and implications of interactions between trees and soil in the CZ, we propose nine hypotheses that can be tested at diverse settings. The hypotheses are roughly divided into those about the architecture (building) and those about the water (plumbing) in the CZ, but the two functions are intertwined. Depending upon one's disciplinary background, many of the nine hypotheses listed below may appear obviously true or obviously false. (1) Tree roots can only physically penetrate and biogeochemically comminute the immobile substrate underlying mobile soil where that underlying substrate is fractured or pre-weathered. (2) In settings where the thickness of weathered material, H , is large, trees primarily shape the CZ through biogeochemical reactions within the rooting zone. (3) In forested uplands, the thickness of mobile soil, h, can evolve toward a steady state because of feedbacks related to root disruption and tree throw. (4) In settings where h H and the rates of uplift and erosion are low, the uptake of phosphorus into trees is buffered by the fine-grained fraction of the soil, and the ultimate source of this phosphorus is dust. (5) In settings of limited water availability, trees maintain the highest length density of functional roots at depths where water can be extracted over most of the growing season with the least amount of energy expenditure. (6) Trees grow the majority of their roots in the zone where the most growth-limiting resource is abundant, but they also grow roots at other depths to forage for other resources and to hydraulically redistribute those resources to depths where they can be taken up more efficiently. (7) Trees rely on matrix water in the unsaturated zone that at times may have anPublished by Copernicus Publications on behalf of the European Geosciences Union. 5116 S. L. Brantley et al.: Reviews and syntheses: on the roles trees play in building and plumbing the critical zone isotopic composition distinct from the gravity-drained water that transits from the hillslope to groundwater and streamflow. (8) Mycorrhizal fungi can use matrix water directly, but trees can only use this water by accessing it indirectly through the fungi. (9) Even trees growing well above the valley floor of a catchment can directly affect stream chemistry where changes in permeability near the rooting zone promote intermittent zones of water saturation and downslope flow of water to the stream. By testing these nine hypotheses, we will generate important new cross-disciplinary insights that advance CZ science.

show abstract

Section: Hypothesismentioning

confidence: 99%

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

et al. 2017

View full text Add to dashboard Cite

show abstract

“…Some of these biophysical processes may include: effects of evaporative fractionation on xylem isotopic compositions during summer months (Simonin et al, 2014), the potentially longer residence and transit times of water within the xylem (Brandes et al, 2007), or possible 15 fractionation/discrimination of 18 and 2 during root-water uptake (Ellsworth and Williams, 2007;Vargas et al, 2017).…”

Section: Ecohydrologic Controls Of Root-uptake On Soil Watermentioning

confidence: 99%

“…Conceptualization of catchment-scale flow paths in transit-time studies has typically simplified catchment storage into a single compartment with a single input (rainfall) and two outputs (ET and discharge) van der Velde et al, 2012).…”

Section: Feed-forward Sas Functions: Depth-dependent Soil Volumesmentioning

confidence: 99%

“…The SAS function approach tracks water ages in storage using "age-ranked" storage ( ), which is the cumulative sum of water in storage since the time of rainfall ( , absolute age of water) van der Velde et al, 2012;Harman, 2015). Values of represent the youngest cumulative sum of water in storage (e.g.…”

Section: Feed-forward Sas Functions: Depth-dependent Soil Volumesmentioning

confidence: 99%

“…water, this is not apparent in all cases (Ellsworth and Williams, 2007;Vargas et al, 2017), and the source of water for vegetation and their uptake processes needs further methodological development and testing (Rothfuss and Javaux, 2017).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Using StorAge Selection functions to quantify ecohydrological controls on the time-variant age of evapotranspiration, soil water, and recharge

Smith

Tetzlaff

Soulsby

2018

Preprint

View full text Add to dashboard Cite

Abstract. Quantifying ecohydrological controls on soil water availability is essential to understand temporal variations in catchment storage. Soil water is subject to numerous time-variable fluxes (evaporation, root-uptake, and recharge), each with 10 different water ages which in turn affect the age of water in storage. Here, we adapt StorAge Selection (SAS) function theory to investigate water flow in soils and identify soil evaporation and root-water uptake sources from depth. We use this to quantify the effects of soil-vegetation interactions on the inter-relationships between water fluxes, storage, and age. The novel modification of the SAS function framework is tested against empirical data from two contrasting soil-vegetation units in the Scottish Highlands; these are characterised by significant preferential flow, transporting younger water through the soil during 15 high soil moisture conditions. Dominant young water fluxes, along with relatively low rainfall intensities, explain relatively stable soil water ages through time and with depth. Soil evaporation sources were more time-invariant with high preference for near-surface water, independent of soil moisture conditions, and resulting in soil evaporation water ages similar to nearsurface soil waters (mean age: 50 -65 days). Sources of root-water uptake were more variable: preferential near-surface water uptake occurred in wet conditions, with a deeper root-uptake source during dry soil conditions, which resulted in more variable 20 water ages of transpiration (mean age: 56 -79 days). The simple model structure provides a parsimonious means of constraining the water age of multiple fluxes from the upper part of the critical zone during time-varying conditions improving our understanding of vegetation influences on catchment scale water fluxes.

show abstract

A simple greenhouse experiment to explore the effect of cryogenic water extraction for tracing plant source water

2018

View full text Add to dashboard Cite

Stable isotopes of water (2H and 18O) are useful tracers for determining root water uptake depths. In such studies, plant and soil water are extracted most commonly by cryogenic vacuum distillation. However, recent studies have suggested that cryogenic extraction conditions (extraction time, temperature, and vacuum) and soil physicochemical properties affect the isotopic composition of extracted soil water. Here, we perform a simple greenhouse trial with 2 plant species (Taraxacum officinale and Pelargonium spp.) in 2 soil types (clayey loam and sand) to test our ability to match plant water to its putative soil water source(s) by using different extraction conditions (30–240 min, 80–200 °C, 0.1 Pa). We irrigated plants with water of known isotopic composition, sampled root crowns and soils at 2 depths, and varied the cryogenic water extraction conditions. Our isotope results from the sandy soils were unaffected by cryogenic extraction conditions. In contrast, extraction parameters affected the isotope composition of waters recovered from clayey soil. This influenced the estimates of plant water sourcing, where δ2H and δ18O returned different results from each other. With higher extraction temperatures and longer extraction times, we gradually extracted more enriched soil water, which reflected the source water of both plant species. Our results imply that longer extraction times and temperatures for clayey soils are needed to reduce fractionation effects during the extraction procedure. Future studies should explore how these effects apply to natural clay‐rich soils as well as plant tissue isotope composition.

show abstract

Testing plant use of mobile vs immobile soil water sources using stable isotope experiments

Cited by 153 publications

References 33 publications

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Reviews and syntheses: on the roles trees play in building and plumbing the critical zone

Using StorAge Selection functions to quantify ecohydrological controls on the time-variant age of evapotranspiration, soil water, and recharge

A simple greenhouse experiment to explore the effect of cryogenic water extraction for tracing plant source water

Contact Info

Product

Resources

About