Abstract
Exchange of water vapour and CO2 was measured on a small group of trees in a 12-year-old regenerating forest dominated by Eucalyptus spp. in Kioloa State Forest, south-eastern New South Wales. The trees were growing in a weighing lysimeter (10.3 m2 ground area) with the dominant tree about 10 m high. A 12 m high enclosure made of polyethylene film was erected to enclose the trees on the lysimeter. Air was impelled in from the bottom of the enclosure by four fans at a total flow rate of 4.6 m3 s-1. Air samples for infrared gas analysers were taken 1, 4, 7 and 10 m above the ground. Pure CO2 (up to 100 litres min-1) was injected to obtain the response of rates of photosynthesis and transpiration at various levels of CO2 in the enclosure environment. At normal ambient partial pressure of CO2, the photosynthetic rate of the canopy (28 µmol m-2 ground area s-1) was found to be saturated at about half of full sunlight. At midday, the foliage in the layers 1-4 m, 4-7 m and 7-10 m from the ground level contributed 20.7, 44.3 and 35% of the total carbon assimilated by the canopy, respectively. Canopy conductance was reduced with increasing vapour pressure difference between leaves and the air on the basis that internal partial pressure of CO2 was decreased. Light intensity required to saturate photosynthesis increased with increasing ambient partial pressure of CO2. At 680 µbar ambient partial pressure of CO2 and at saturating light intensity, there was a 50% increase in photosynthetic rate and a 30% reduction in transpiration rate, resulting in a reduction in transpiration ratio of about 80%. The apparent quantum yield derived at 340 and 680 µbar CO2 was 0.049 and 0.071, respectively. The light compensation point also decreased at higher ambient partial pressure of CO2.
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Claims 12
Claim · model-written summary
At ambient CO2, canopy photosynthesis saturated at about half of full sunlight with a rate of 28 µmol m-2 ground area s-1.
- Taxon
- Eucalyptus spp.
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Eucalyptuse1 - Outcome
- photosynthetic rate of the canopye0
- Value
- 28 µmol m-2 ground area s-1e0
- Qualifier
- about half of full sunlighte0
- Setting
- Kioloa State Foreste1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
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Verbatim
e0“At normal ambient partial pressure of CO2, the photosynthetic rate of the canopy (28 µmol m-2 ground area s-1) was found to be saturated at about half of full sunlight.”
e1“dominated by Eucalyptus spp. in Kioloa State Forest, south-eastern New South Wales.”
Claim · model-written summary
The 1-4 m foliage layer contributed 20.7% of midday canopy carbon assimilation.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Organ / stage
- foliagee0
- Outcome
- total carbon assimilated by the canopye0
- Value
- 20.7e0
- Qualifier
- 1-4 me0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At midday, the foliage in the layers 1-4 m, 4-7 m and 7-10 m from the ground level contributed 20.7, 44.3 and 35% of the total carbon assimilated by the canopy, respectively.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
The 4-7 m foliage layer contributed 44.3% of midday canopy carbon assimilation.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Organ / stage
- foliagee0
- Outcome
- total carbon assimilated by the canopye0
- Value
- 44.3e0
- Qualifier
- 4-7 me0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At midday, the foliage in the layers 1-4 m, 4-7 m and 7-10 m from the ground level contributed 20.7, 44.3 and 35% of the total carbon assimilated by the canopy, respectively.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
The 7-10 m foliage layer contributed 35% of midday canopy carbon assimilation.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Organ / stage
- foliagee0
- Outcome
- total carbon assimilated by the canopye0
- Value
- 35%e0
- Qualifier
- 7-10 me0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At midday, the foliage in the layers 1-4 m, 4-7 m and 7-10 m from the ground level contributed 20.7, 44.3 and 35% of the total carbon assimilated by the canopy, respectively.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
Canopy conductance fell as leaf-air vapour pressure difference increased.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Organ / stage
- leavese0
- Outcome
- Canopy conductancee0
- Direction
- reducede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Canopy conductance was reduced with increasing vapour pressure difference between leaves and the air”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
The light intensity needed to saturate photosynthesis increased with ambient CO2 partial pressure.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Outcome
- Light intensity required to saturate photosynthesise0
- Direction
- increasede0
- Setting
- ambient partial pressure of CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Light intensity required to saturate photosynthesis increased with increasing ambient partial pressure of CO2.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
At 680 µbar CO2 and saturating light, photosynthetic rate increased 50%.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Treatment
- 680 µbar ambient partial pressure of CO2e0
- Outcome
- photosynthetic ratee0
- Direction
- increasee0
- Value
- 50%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 680 µbar ambient partial pressure of CO2 and at saturating light intensity, there was a 50% increase in photosynthetic rate”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
At 680 µbar CO2 and saturating light, transpiration rate decreased 30%.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Treatment
- 680 µbar ambient partial pressure of CO2e0
- Outcome
- transpiration ratee0
- Direction
- reductione0
- Value
- 30%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 680 µbar ambient partial pressure of CO2 and at saturating light intensity, there was a 50% increase in photosynthetic rate and a 30% reduction in transpiration rate”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
At 680 µbar CO2 and saturating light, transpiration ratio decreased about 80%.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Treatment
- 680 µbar ambient partial pressure of CO2e0
- Outcome
- transpiration ratioe0
- Direction
- reductione0
- Value
- about 80%e0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“At 680 µbar ambient partial pressure of CO2 and at saturating light intensity, there was a 50% increase in photosynthetic rate and a 30% reduction in transpiration rate, resulting in a reduction in transpiration ratio of about 80%.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
Apparent quantum yield was 0.049 at 340 µbar CO2.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Outcome
- apparent quantum yielde0
- Value
- 0.049e0
- Qualifier
- 340e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent quantum yield derived at 340 and 680 µbar CO2 was 0.049 and 0.071, respectively.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
Apparent quantum yield was 0.071 at 680 µbar CO2.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Outcome
- apparent quantum yielde0
- Value
- 0.071e0
- Qualifier
- 680 µbar CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The apparent quantum yield derived at 340 and 680 µbar CO2 was 0.049 and 0.071, respectively.”
e1“dominated by Eucalyptus spp.”
Claim · model-written summary
The light compensation point decreased at higher ambient CO2.
- Taxon
- Eucalyptus spp.Eucalyptuse1
- Outcome
- light compensation pointe0
- Direction
- decreasede0
- Setting
- higher ambient partial pressure of CO2e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The light compensation point also decreased at higher ambient partial pressure of CO2.”
e1“dominated by Eucalyptus spp.”
The same questions in other papers
co2 · physiology: photosynthesis · EucalyptusPositive and negative results
2 papers in the same direction as this paper · 2 in the opposite direction
- positive
- negative
- negative
1 paper more in this group
See all 5 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.