Abstract
A long-term free air ozone fumigation experiment was conducted to study changes in physiological ozone responses during tree ontogeny and exposure time in ozone sensitive and tolerant clones of European white birch (Betula pendula Roth), originated from south and central Finland. The trees were grown in soil in natural microclimatic conditions under ambient ozone (control) and 1.4-1.7 x ambient (elevated) ozone from May 1996 to October 2001, and were measured for stem and foliage growth, net photosynthesis, stomatal conductance, stomatal density, visible injuries, foliar starch content and bud formation. After 6 years of exposure, the magnitude of ozone-induced growth reductions in the sensitive clone was 12-48% (significant difference), levels similar or greater than those reported earlier for 2- and 3-year-old saplings undergoing shorter exposures. In the tolerant clone, growth of these larger trees was reduced by 1-38% (significant difference in stem volume), although the saplings had previously been unaffected. In both clones, ozone stress led to significantly reduced leaf-level net photosynthesis but significantly increased stomatal conductance rates during the late summer, resulting in a lower carbon gain for bud formation and the onset of visible foliar injuries. Increasing ozone sensitivity with duration of exposure was explained by a change in growth form (relatively reduced foliage mass), a lower photosynthesis to stomatal conductance ratio during the late summer, and deleterious carry-over effects arising from the reduced number of over-wintering buds.
Abstract from the paper’s OpenAlex record, shown for indexing and research. Copyright remains with the authors or the publisher. Read at the source ↗
The text the model read, with the source record’s inline markup (italics, sub- and superscripts) rendered and its character entities decoded; quote offsets refer to the raw text.
Claims 10
Claim · model-written summary
In the sensitive clone, ozone reduced growth by 12–48% after 6 years of exposure, a significant difference.
- Taxon
- Betula pendula
Betula pendulae0 - Material
- sensitive clonee1
- Treatment
- ozonee1
- Outcome
- growthe1
- Direction
- reductionse1
- Value
- 12-48%e1
- Comparator
- ambient ozone (control)e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e1“After 6 years of exposure, the magnitude of ozone-induced growth reductions in the sensitive clone was 12-48% (significant difference)”
e2“under ambient ozone (control) and 1.4-1.7 x ambient (elevated) ozone”
Claim · model-written summary
In the tolerant clone, ozone reduced growth by 1–38% in larger trees, a significant difference in stem volume.
- Taxon
- Betula pendulaBetula pendulae0
- Material
- tolerant clonee3
- Treatment
- 1.4-1.7 x ambient (elevated) ozonee2
- Outcome
- growthe3
- Direction
- reducede3
- Value
- 1-38%e3
- Comparator
- ambient ozone (control)e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e2“under ambient ozone (control) and 1.4-1.7 x ambient (elevated) ozone”
e3“In the tolerant clone, growth of these larger trees was reduced by 1-38% (significant difference in stem volume), although the saplings had previously been unaffected”
Claim · model-written summary
Saplings of the tolerant clone were previously unaffected by ozone in growth.
- Taxon
- Betula pendulaBetula pendulae0
- Material
- tolerant clonee3
- Organ / stage
- saplingse3
- Outcome
- growthe3
- Qualifier
- previously been unaffectede3
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e3“In the tolerant clone, growth of these larger trees was reduced by 1-38% (significant difference in stem volume), although the saplings had previously been unaffected”
Claim · model-written summary
Ozone stress significantly reduced leaf-level net photosynthesis in both clones during the late summer.
- Taxon
- Betula pendulaBetula pendulae0
- Treatment
- ozone stresse4
- Outcome
- leaf-level net photosynthesise4
- Direction
- reducede4
- Setting
- late summere4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e4“In both clones, ozone stress led to significantly reduced leaf-level net photosynthesis but significantly increased stomatal conductance rates during the late summer”
Claim · model-written summary
Ozone stress significantly increased stomatal conductance rates in both clones during the late summer.
- Taxon
- Betula pendulaBetula pendulae0
- Treatment
- ozone stresse4
- Outcome
- stomatal conductance ratese4
- Direction
- increasede4
- Setting
- late summere4
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e4“In both clones, ozone stress led to significantly reduced leaf-level net photosynthesis but significantly increased stomatal conductance rates during the late summer”
Claim · model-written summary
Ozone stress led to a lower carbon gain for bud formation.
- Taxon
- Betula pendulaBetula pendulae0
- Treatment
- ozone stresse4
- Outcome
- carbon gain for bud formatione5
- Direction
- lowere5
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e4“In both clones, ozone stress led to significantly reduced leaf-level net photosynthesis but significantly increased stomatal conductance rates during the late summer”
e5“resulting in a lower carbon gain for bud formation and the onset of visible foliar injuries”
Claim · model-written summary
Ozone stress led to the onset of visible foliar injuries.
- Taxon
- Betula pendulaBetula pendulae0
- Treatment
- ozone stresse4
- Outcome
- onset of visible foliar injuriese5
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e4“In both clones, ozone stress led to significantly reduced leaf-level net photosynthesis but significantly increased stomatal conductance rates during the late summer”
e5“resulting in a lower carbon gain for bud formation and the onset of visible foliar injuries”
Claim · model-written summary
Increasing ozone sensitivity with exposure duration is explained by a change in growth form.
- Taxon
- Betula pendulaBetula pendulae0
- Outcome
- Increasing ozone sensitivity with duration of exposuree6
- Qualifier
- a change in growth form (relatively reduced foliage mass)e6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e6“Increasing ozone sensitivity with duration of exposure was explained by a change in growth form (relatively reduced foliage mass), a lower photosynthesis to stomatal conductance ratio during the late summer, and deleterious carry-over effects arising from the reduced number of over-wintering buds”
Claim · model-written summary
Increasing ozone sensitivity with exposure duration is explained by a lower photosynthesis to stomatal conductance ratio in late summer.
- Taxon
- Betula pendulaBetula pendulae0
- Outcome
- Increasing ozone sensitivity with duration of exposuree6
- Qualifier
- a lower photosynthesis to stomatal conductance ratio during the late summere6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e6“Increasing ozone sensitivity with duration of exposure was explained by a change in growth form (relatively reduced foliage mass), a lower photosynthesis to stomatal conductance ratio during the late summer, and deleterious carry-over effects arising from the reduced number of over-wintering buds”
Claim · model-written summary
Increasing ozone sensitivity with exposure duration is explained by deleterious carry-over effects from fewer over-wintering buds.
- Taxon
- Betula pendulaBetula pendulae0
- Outcome
- Increasing ozone sensitivity with duration of exposuree6
- Qualifier
- deleterious carry-over effects arising from the reduced number of over-wintering budse6
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“European white birch (Betula pendula Roth)”
e6“Increasing ozone sensitivity with duration of exposure was explained by a change in growth form (relatively reduced foliage mass), a lower photosynthesis to stomatal conductance ratio during the late summer, and deleterious carry-over effects arising from the reduced number of over-wintering buds”
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
- positive
- negative
- negative
4 papers more in this group
See all 8 papers →ozone · molecular: metabolites · Betula pendula (white birch)Positive and negative results
1 paper in the same direction as this paper · 1 in the opposite direction
- negative
- positive
ozone · physiology: photosynthesis · Betula pendula (white birch)Results agree
4 papers in the same direction as this paper
- negative
- negative
- negative
1 paper more in this group
See all 5 papers →ozone · growth · Betula pendula (white birch)Results agree
8 papers in the same direction as this paper
- negative
- negative
- negative
5 papers more in this group
See all 9 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.