Abstract
We investigated how leaf hydraulic conductance (K(leaf)) of loblolly pine trees is influenced by soil nitrogen amendment (N) in stands subjected to ambient or elevated CO(2) concentrations (CO(2)(a) and CO(2)(e), respectively). We also examined how K(leaf) varies with changes in reference leaf water potential (Psi(leaf-ref)) and stomatal conductance (g(s-ref)) calculated at vapour pressure deficit, D of 1 kPa. We detected significant reductions in K(leaf) caused by N and CO(2)(e), but neither treatment affected pre-dawn or midday Psi(leaf). We also detected a significant CO(2)(e)-induced reduction in g(s-ref) and Psi(leaf-ref). Among treatments, the sensitivity of K(leaf) to Psi(leaf) was directly related to a reference K(leaf) (K(leaf-ref) computed at Psi(leaf-ref)). This liquid-phase response was reflected in a similar gas-phase response, with g(s) sensitivity to D proportional to g(s-ref). Because leaves represented a substantial component of the whole-tree conductance, reduction in K(leaf) under CO(2)(e) affected whole-tree water use by inducing a decline in g(s-ref). The consequences of the acclimation of leaves to the treatments were: (1) trees growing under CO(2)(e) controlled morning leaf water status less than CO(2)(a) trees resulting in a higher diurnal loss of K(leaf); (2) the effect of CO(2)(e) on g(s-ref) was manifested only during times of high soil moisture.
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Claims 9
Claim · model-written summary
Nitrogen amendment significantly reduced leaf hydraulic conductance.
- Taxon
- loblolly pine
Pinus taedae1 - Treatment
- Ne0
- Outcome
- K(leaf)e0
- Direction
- reductionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We detected significant reductions in K(leaf) caused by N and CO(2)(e)”
e1“loblolly pine trees”
Claim · model-written summary
Elevated CO2 significantly reduced leaf hydraulic conductance.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- CO(2)(e)e0
- Outcome
- K(leaf)e0
- Direction
- reductionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We detected significant reductions in K(leaf) caused by N and CO(2)(e)”
e1“loblolly pine trees”
Claim · model-written summary
Neither nitrogen nor elevated CO2 affected pre-dawn or midday leaf water potential.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- treatmente0
- Outcome
- pre-dawn or midday Psi(leaf)e0
- Direction
- neither treatment affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“neither treatment affected pre-dawn or midday Psi(leaf)”
e1“loblolly pine trees”
Claim · model-written summary
Elevated CO2 significantly reduced reference stomatal conductance and reference leaf water potential.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- CO(2)(e)e0
- Outcome
- g(s-ref) and Psi(leaf-ref)e0
- Direction
- reductione0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“We also detected a significant CO(2)(e)-induced reduction in g(s-ref) and Psi(leaf-ref)”
e1“loblolly pine trees”
Claim · model-written summary
Sensitivity of leaf hydraulic conductance to leaf water potential was directly related to reference conductance across treatments.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- treatmentse0
- Outcome
- sensitivity of K(leaf) to Psi(leaf)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Among treatments, the sensitivity of K(leaf) to Psi(leaf) was directly related to a reference K(leaf) (K(leaf-ref) computed at Psi(leaf-ref))”
e1“loblolly pine trees”
Claim · model-written summary
Stomatal conductance sensitivity to vapor pressure deficit was proportional to reference stomatal conductance.
- Taxon
- loblolly pinePinus taedae1
- Outcome
- g(s) sensitivity to De0
- Comparator
- g(s-ref)e0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“g(s) sensitivity to D proportional to g(s-ref)”
e1“loblolly pine trees”
Claim · model-written summary
Reduced leaf hydraulic conductance under elevated CO2 induced a decline in reference stomatal conductance.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- CO(2)(e)e0
- Outcome
- g(s-ref)e0
- Direction
- declinee0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“reduction in K(leaf) under CO(2)(e) affected whole-tree water use by inducing a decline in g(s-ref)”
e1“loblolly pine trees”
Claim · model-written summary
Elevated CO2 trees controlled morning leaf water status less and lost more leaf hydraulic conductance diurnally.
- Taxon
- loblolly pinePinus taedae1
- Treatment
- CO(2)(e)e0
- Outcome
- morning leaf water statuse0
- Direction
- lesse0
- Comparator
- CO(2)(a) treese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“trees growing under CO(2)(e) controlled morning leaf water status less than CO(2)(a) trees resulting in a higher diurnal loss of K(leaf)”
e1“loblolly pine trees”
Claim · model-written summary
The elevated CO2 effect on reference stomatal conductance appeared only when soil moisture was high.
- Taxon
- loblolly pinePinus taedae1
- Outcome
- effect of CO(2)(e) on g(s-ref)e0
- Qualifier
- only during times of high soil moisturee0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the effect of CO(2)(e) on g(s-ref) was manifested only during times of high soil moisture”
e1“loblolly pine trees”
The same questions in other papers
co2 · physiology: water · Pinus taeda (loblolly pine)Positive and negative results
2 papers in the same direction as this paper · 1 in the opposite direction
- positive
- no effect
- no effect
Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.