The Water Relations of Allosyncarpia ternata (Myrtaceae) at Contrasting Sites in the Monsoonal Tropics of Northern Australia

Fordyce, I. R.; Duff, GA; Eamus, Derek

doi:10.1071/bt96016

Cited by 26 publications

(14 citation statements)

References 49 publications

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“…The effect of water stress on maximum G S due to the variation in f M , normalised to the maximum G S for an unstressed leaf, is shown in Figure 2. We concur with Jones that it is D (or E) and soil water potential that control G S , but the direct mechanistic link is through leaf (xylem) water potential [38]. This model does not attempt to incorporate mechanisms by which changes in soil water availability influence Gs; this model does explicitly deal with how changes in D control G S .…”

Section: Methodssupporting

confidence: 54%

“…For well watered leaves, Gs declined curvilinearly as D increased. Such responses are well-documented [2,9,17,25,30,37,38]. The cause of this decline in Gs was a decline in the volume of the guard cell because water supply to the guard cell became reduced as cuticular transpiration became an increasingly large fraction of total transpiration.…”

Section: Discussionmentioning

confidence: 99%

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A rate equation model of stomatal responses to vapour pressure deficit and drought

Eamus

Shanahan

2002

BMC Ecol

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BackgroundStomata respond to vapour pressure deficit (D) – when D increases, stomata begin to close. Closure is the result of a decline in guard cell turgor, but the link between D and turgor is poorly understood. We describe a model for stomatal responses to increasing D based upon cellular water relations. The model also incorporates impacts of increasing levels of water stress upon stomatal responses to increasing D.ResultsThe model successfully mimics the three phases of stomatal responses to D and also reproduces the impact of increasing plant water deficit upon stomatal responses to increasing D. As water stress developed, stomata regulated transpiration at ever decreasing values of D. Thus, stomatal sensitivity to D increased with increasing water stress. Predictions from the model concerning the impact of changes in cuticular transpiration upon stomatal responses to increasing D are shown to conform to experimental data.Sensitivity analyses of stomatal responses to various parameters of the model show that leaf thickness, the fraction of leaf volume that is air-space, and the fraction of mesophyll cell wall in contact with air have little impact upon behaviour of the model. In contrast, changes in cuticular conductance and membrane hydraulic conductivity have significant impacts upon model behaviour.ConclusionCuticular transpiration is an important feature of stomatal responses to D and is the cause of the 3 phase response to D. Feed-forward behaviour of stomata does not explain stomatal responses to D as feedback, involving water loss from guard cells, can explain these responses.

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Section: Methodssupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

A rate equation model of stomatal responses to vapour pressure deficit and drought

Eamus

Shanahan

2002

BMC Ecol

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“…Although numerous studies show that g max is correlated with soil and/or plant water status, for both non‐arid plants (e.g. Küppers, Küppers & Schulze 1988; Reich & Hinckley 1989; Fordyce, Duff & Eamus 1997; Myers et al . 1997) and semi‐arid and arid species (largely Eucalyptus spp., e.g.…”

Section: Discussionmentioning

confidence: 99%

Desert dogma revisited: coupling of stomatal conductance and photosynthesis in the desert shrub, Larrea tridentata

Ogle

Reynolds²

2002

Plant Cell & Environment

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The success of the desert shrub Larrea tridentata (creosotebush) has been largely attributed to temperature acclimation and stomatal control of photosynthesis ( A ) under drought stress. However, there is a paucity of field data on these relationships. To address this void, we conducted a joint field and modelling study that encompassed a diverse set of environmental conditions. At a Larrea -dominated site in southern New Mexico we manipulated soil moisture during the growing season over a 2-year period and measured plant pre-dawn water potential ( Ψ Ψ Ψ Ψ pd ), stomatal conductance ( g ) and A of individual shrubs. We used these data to develop a semi-mechanistic photosynthesis model (ASeason) that explicitly couples internal CO 2 ( C i ) and g . Vapour pressure deficit ( VPD ) and Ψ Ψ Ψ Ψ pd affect instantaneous g in a manner that is consistent with a biophysical model of stomatal regulation of leaf water potential. C i is modelled as a function of g , derived from a simplification of a typical A -C i curve. After incorporating the effects of growing temperature on stomatal behaviour, the model was able to capture the large diurnal fluctuations in A , g and C i and the observed hysteresis in g versus C i dynamics. Our field data and application of the A-Season model suggest that dogma attributed to Larrea 's success is supported with regard to stomatal responses to VPD and Ψ Ψ Ψ Ψ pd , but not for mechanisms of temperature acclimation and CO 2 demand.

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“…In recent years, a number of studies have examined the interactions of savanna vegetation with the environment of northern Australia. These studies have been conducted at leaf Fordyce et al 1997;Myers et al 1997;Prior et al 1997aPrior et al , 1997b, tree (O'Grady et al 1999) and stand (Cook et al 1998; scales. Such studies have contributed significantly to our understanding of the interactions of plant communities with the tropical monsoonal environment.…”

Section: Introductionmentioning

confidence: 99%

Monsoonal influences on evapotranspiration of savanna vegetation of northern Australia

Hutley¹,

O'Grady²,

Eamus³

2001

Oecologia

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Data from savannas of northern Australia are presented for net radiation, latent and sensible heat, ecosystem surface conductance (G ) and stand water use for sites covering a latitudinal range of 5° or 700 km. Measurements were made at three locations of increasing distance from the northern coastline and represent high- (1,750 mm), medium- (890 mm) and low- (520 mm) rainfall sites. This rainfall gradient arises from the weakened monsoonal influence with distance inland. Data were coupled to seasonal estimates of leaf area index (LAI) for the tree and understorey strata. All parameters were measured at the seasonal extremes of late wet and dry seasons. During the wet season, daily rates of evapotranspiration were 3.1-3.6 mm day and were similar for all sites along the rainfall gradient and did not reflect site differences in annual rainfall. During the dry season, site differences were very apparent with evapotranspiration 2-18 times lower than wet season rates, the seasonal differences increasing with distance from coast and reduced annual rainfall. Due to low overstorey LAI, more than 80% of water vapour flux was attributed to the understorey. Seasonal differences in evapotranspiration were mostly due to reductions in understorey leaf area during the dry season. Water use of individual trees did not differ between the wet and dry seasons at any of the sites and stand water use was a simple function of tree density. G declined markedly during the dry season at all sites, and we conclude that the savanna water (and carbon) balance is largely determined by G and its response to atmospheric and soil water content and by seasonal adjustments to canopy leaf area.

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The Water Relations of Allosyncarpia ternata (Myrtaceae) at Contrasting Sites in the Monsoonal Tropics of Northern Australia

Cited by 26 publications

References 49 publications

A rate equation model of stomatal responses to vapour pressure deficit and drought

A rate equation model of stomatal responses to vapour pressure deficit and drought

Desert dogma revisited: coupling of stomatal conductance and photosynthesis in the desert shrub, Larrea tridentata

Monsoonal influences on evapotranspiration of savanna vegetation of northern Australia

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