Abstract
To investigate whether nitrogen (N) load affects the ozone (O3) stomatal flux-effect relationship for birch biomass, three-year old birch saplings were exposed to seven different O3 profiles (24 h mean of 35–66 ppb) and four different N loads (10, 30, 50 and 70 kg ha−1 yr−1) in precision-controlled hemispherical glasshouses (solardomes) in 2012 and 2013. Stomatal conductance (gs) under optimal growth conditions was stimulated by enhanced N supply but was not significantly affected by enhanced O3 exposure. Birch root, woody (stem + branches) and total biomass (root + woody) were not affected by the Phytotoxic Ozone Dose (POD1SPEC) after two seasons of O3 exposure, and enhanced N supply stimulated biomass production independent of POD1SPEC (i.e. there were no POD1SPEC × N interactions). There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment, which was not affected by O3 exposure or N load. Enhanced N supply stimulated the stem cross-sectional area at the end of season 2, but not at the end of season 1, which suggests a time lag before tree biomass responded to enhanced N supply. There was no significant effect of POD1SPEC on stem cross-sectional area after either the first or second growing season of the experiment. Contrasting results reported in the literature on the interactive impacts of O3 and N load on tree physiology and growth are likely due to species-specific responses, different duration of the experiments and/or a limitation of the number of O3 and N levels tested.
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Claims 9
Claim · model-written summary
Enhanced nitrogen supply stimulated birch stomatal conductance under optimal growth conditions.
- Taxon
- birch (Betula pendula) saplings
Betula pendulat0 - Treatment
- enhanced N supplye0
- Outcome
- Stomatal conductance (gs)e0
- Direction
- stimulatede0
- Qualifier
- under optimal growth conditionse0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“Stomatal conductance (gs) under optimal growth conditions was stimulated by enhanced N supply”
Claim · model-written summary
Enhanced ozone exposure did not significantly affect birch stomatal conductance.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- enhanced O3 exposuree0
- Outcome
- Stomatal conductance (gs)e0
- Direction
- not significantly affectede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“Stomatal conductance (gs) under optimal growth conditions was stimulated by enhanced N supply but was not significantly affected by enhanced O3 exposure.”
Claim · model-written summary
Phytotoxic ozone dose did not affect birch root, woody or total biomass after two seasons.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- Phytotoxic Ozone Dose (POD1SPEC)e0
- Outcome
- root, woody (stem + branches) and total biomass (root + woody)e0
- Direction
- not affectede0
- Qualifier
- after two seasons of O3 exposuree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“Birch root, woody (stem + branches) and total biomass (root + woody) were not affected by the Phytotoxic Ozone Dose (POD1SPEC) after two seasons of O3 exposure”
Claim · model-written summary
Enhanced nitrogen supply stimulated birch biomass independently of phytotoxic ozone dose.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- enhanced N supplye0
- Outcome
- biomass productione0
- Direction
- stimulatede0
- Qualifier
- independent of POD1SPECe0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“enhanced N supply stimulated biomass production independent of POD1SPEC (i.e. there were no POD1SPEC × N interactions)”
Claim · model-written summary
Stem cross sectional area had a strong linear relationship with tree biomass.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Organ / stage
- steme0
- Outcome
- tree biomasse0
- Qualifier
- strong linear relationshipe0
Not reportedDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment”
Claim · model-written summary
Ozone exposure and nitrogen load did not affect the relationship between stem cross sectional area and tree biomass.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- O3 exposure or N loade0
- Outcome
- relationship between the stem cross-sectional area and tree biomasse0
- Direction
- not affectede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“There was a strong linear relationship between the stem cross-sectional area and tree biomass at the end of the experiment, which was not affected by O3 exposure or N load.”
Claim · model-written summary
Enhanced nitrogen supply stimulated birch stem cross sectional area at the end of season 2.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- Enhanced N supplye0
- Outcome
- stem cross-sectional areae0
- Direction
- stimulatede0
- Qualifier
- at the end of season 2e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“Enhanced N supply stimulated the stem cross-sectional area at the end of season 2”
Claim · model-written summary
Enhanced nitrogen supply did not stimulate birch stem cross sectional area at the end of season 1.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- Enhanced N supplye0
- Outcome
- stem cross-sectional areae0
- Direction
- note0
- Qualifier
- at the end of season 1e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“Enhanced N supply stimulated the stem cross-sectional area at the end of season 2, but not at the end of season 1”
Claim · model-written summary
Phytotoxic ozone dose had no significant effect on stem cross sectional area after either growing season.
- Taxon
- birch (Betula pendula) saplingsBetula pendulat0
- Treatment
- POD1SPECe0
- Outcome
- stem cross-sectional areae0
- Direction
- no significant effecte0
- Qualifier
- after either the first or second growing seasone0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“birch (Betula pendula) saplings”
e0“There was no significant effect of POD1SPEC on stem cross-sectional area after either the first or second growing season”
The same questions in other papers
ozone · physiology: gas exchange · Betula pendula (white birch)Results differ
6 papers in the same direction as this paper · 1 in the opposite direction
- negative
- positive
- negative
4 papers more in this group
See all 8 papers →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.