Limitation of plant water use by rhizosphere and xylem conductance: results from a model

Sperry, John S.; Adler, Frederick R.; Campbell, Gaylon S.; Comstock, Jonathan P.

doi:10.1046/j.1365-3040.1998.00287.x

Cited by 677 publications

(742 citation statements)

References 43 publications

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“…The convergence on a 'risky' hydraulic strategy exhibited by many species can be understood as the result of a trade-off that balances growth with protection against risk of mortality in a given environment 17,21,25 . Thus, a low safety margin to Y 50 also indicates that stomatal regulation takes full advantage of the range of xylem pressures that are within the tolerance of the hydraulic system of that species.…”

Section: Letter Researchmentioning

confidence: 99%

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Global convergence in the vulnerability of forests to drought

Choat

Jansen

Brodribb

et al. 2012

Nature

2,026

1,987

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Shifts in rainfall patterns and increasing temperatures associated with climate change are likely to cause widespread forest decline in regions where droughts are predicted to increase in duration and severity. One primary cause of productivity loss and plant mortality during drought is hydraulic failure. Drought stress creates trapped gas emboli in the water transport system, which reduces the ability of plants to supply water to leaves for photosynthetic gas exchange and can ultimately result in desiccation and mortality. At present we lack a clear picture of how thresholds to hydraulic failure vary across a broad range of species and environments, despite many individual experiments. Here we draw together published and unpublished data on the vulnerability of the transport system to drought-induced embolism for a large number of woody species, with a view to examining the likely consequences of climate change for forest biomes. We show that 70% of 226 forest species from 81 sites worldwide operate with narrow hydraulic safety margins against injurious levels of drought stress and therefore potentially face long-term reductions in productivity and survival if temperature and aridity increase as predicted for many regions across the globe. Safety margins are largely independent of mean annual precipitation, showing that there is global convergence in the vulnerability of forests to drought, with all forest biomes equally vulnerable to hydraulic failure regardless of their current rainfall environment. These findings provide insight into why drought-induced forest decline is occurring not only in arid regions but also in wet forests not normally considered at drought risk

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Section: Letter Researchmentioning

confidence: 99%

“…In drying soil, stomata initially regulate water loss from the leaves to maintain xylem pressure (Y x ; measured as water potential below 0) within a range that will protect the xylem from extensive embolism 17,21 . As drought continues, stomatal closure slows but does not halt the decline of xylem pressure and hydraulic capacity.…”

mentioning

confidence: 99%

Global convergence in the vulnerability of forests to drought

Choat

Jansen

Brodribb

et al. 2012

Nature

2,026

1,987

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“…This requires adjustment of the plant's conducting system to maximize water uptake and to reduce water deficits (Sperry et al 1998(Sperry et al , 2002Maseda and Fernández 2006). Trees adapt to changes in water availability either with long-term plastic responses in the size of the absorbing root system and in the evaporating leaf surfaces or by modifications in the hydraulic system and adjustment of the cavitation risk along the flow path (Sperry et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance

Köcher

Horna

Beckmeyer

et al. 2012

Annals of Forest Science

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Abstract& Context It has been estimated that about half of a plant's total hydraulic resistance is located belowground, but it is not well known how temperate tree species differ in root hydraulic properties and how these traits vary with the species' drought tolerance. & Aims We examined root anatomical and hydraulic traits in five broad-leaved tree species with different drought tolerance, analyzed the relation between root anatomy and hydraulic conductivity and root embolism, and investigated the relation of these traits to the species' drought tolerance. & Methods In small-diameter roots (2-6 mm), we measured vessel diameters and vessel density, specific hydraulic conductivity, and the percental loss of conductivity ("native" embolism) during summer in a mixed forest. & Results Specific conductivity was positively related to vessel diameter but not to vessel density. Drought-tolerant Fraxinus showed the smallest mean vessel diameters and drought-sensitive Fagus the largest. Specific conductivity was highly variable among different similar-sized roots of the same species with a few roots apparently functioning as "high-conductivity roots". & Conclusion The results show that coexisting tree species can differ largely in root hydraulic traits with more droughtsensitive trees apparently having larger mean vessel diameters in their roots than tolerant species. However, this difference was not related to the observed root conductivity losses due to embolism.

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“…This is reflected in the tendency of models to overestimate stomatal conductance in the afternoon (Martin et al 1997), and the need to use timeof-day as a variable to account for the overestimation (Körner 1993). As a result, the assumption of small and constant root-soil resistance is only partially correct, even under conditions of low transpiration rates, or where plants with high root-to-leaf surface area ratios are monitored while absorbing water from moist, fine soils (Carbon et al 1980;Sperry et al 1998). However, under flooded conditions, the assumption of invariable resistance to water uptake from the soil is satisfied.…”

Section: Introductionmentioning

confidence: 99%

“…For example, several studies have suggested that the absence of stomatal regulation would cause excessive xylem cavitation and failure of water transport (Tyree and Sperry 1988;Sperry et al 1993;Tyree et al 1993;Saliendra et al 1995;Cochard et al 1996;Lu et al 1996). This "hydraulic constraint" may be particularly important for species adapted to constant and high Ψ S (Sperry et al 1998), such as T. distichum.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity of mean canopy stomatal conductance to vapor pressure deficit in a flooded Taxodium distichum L. forest: hydraulic and non-hydraulic effects

et al. 2001

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We measured the xylem sap flux in 64-yearold Taxodium distichum (L.) Richard trees growing in a flooded forest using Granier-type sensors to estimate mean canopy stomatal conductance of the stand (G S ). Temporal variations in G S were investigated in relation to variation in vapor pressure deficit (D), photosynthetic photon flux density (Q o ), and the transpiration rate per unit of leaf area (E L ), the latter variable serving as a proxy for plant water potential. We found that G S was only weakly related to Q o below 500 µmol m -2 s -1 (r 2 =0.29), but unrelated to Q o above this value. Above Q o =500 µmol m -2 s -1 and D=0.6 kPa, G S decreased linearly with increasing E L with a poor fit (r 2 =0.31), and linearly with lnD with a much better fit (r 2 =0.81). The decrease of G S with lnD was at a rate predicted based on a simple hydraulic model in which stomata regulate the minimum leaf water potential. Based on the hydraulic model, stomatal sensitivity to D is proportional to stomatal conductance at low D. A hurricane caused an ~41% reduction in leaf area. This resulted in a 28% increase in G S at D=1 kPa (G Sref ), indicating only partial compensation. As predicted, the increase in G Sref after the hurricane was accompanied by a similar increase in stomatal sensitivity to D (29%). At night, G Sref was 20% of the daytime value under non-limiting light (Q o >500 µmol m -2 s -1 ). However, stomatal sensitivity to D decreased only to ~46% (both reductions referenced to prehurricane daytime values), thus having more than twice the sensitivity expected based on hydraulic considerations alone. Therefore, non-hydraulic processes must cause heightened nighttime stomatal sensitivity to D.

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Limitation of plant water use by rhizosphere and xylem conductance: results from a model

Abstract: ABSTRACT

Cited by 677 publications

References 43 publications

Global convergence in the vulnerability of forests to drought

Global convergence in the vulnerability of forests to drought

Hydraulic properties and embolism in small-diameter roots of five temperate broad-leaved tree species with contrasting drought tolerance

Sensitivity of mean canopy stomatal conductance to vapor pressure deficit in a flooded Taxodium distichum L. forest: hydraulic and non-hydraulic effects

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