Abstract
Branch bags were used to expose branches on mature Sitka spruce trees to either ambient [CO 2 ] (A) or elevated [CO 2 ] (E) for 4 yr. This paper reports the effects of this treatment on the growth, development and phenology of the branches, including shoot expansion, shoot numbers, needle dimensions, needle numbers and stomatal density. The effect of elevated [CO 2 ] on the relationship between leaf area and sapwood area was investigated. Exposure to elevated [CO 2 ] doubled photosynthetic rates in current‐year shoots and, despite some down‐regulation, 1‐yr‐old E shoots also had higher rates of photosynthesis than their A counterparts. Thus, the amount of assimilate fixed by E branches was substantially more than that fixed by A branches; however, this increase in the local production of assimilate did not lead to an increase in non‐structural carbohydrate or stimulate growth or meristematic activity within the E branches. There was a very consistent relationship between leaf area and stem cross‐sectional area that was not influenced by [CO 2 ]. However, unbagged branches had thicker stems than bagged branches, resulting in a slightly lower ratio of leaf area to cross‐sectional area. The implications of the results for the modelling of growth and allocation and the potential utility of the branch bag technique are discussed.
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 8
Claim · model-written summary
Elevated carbon dioxide doubled photosynthesis in current-year shoots.
- Taxon
- Sitka spruce
.jpg?width=60)
Picea sitchensise1 - Organ / stage
- current‐year shootse0
- Treatment
- elevated [CO 2 ]e0
- Outcome
- photosynthetic ratese0
- Direction
- doublede0
- Value
- doublede0
- Comparator
- ambient [CO 2 ]e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“Exposure to elevated [CO 2 ] doubled photosynthetic rates in current‐year shoots”
e1“mature Sitka spruce trees”
e2“either ambient [CO 2 ] (A) or elevated [CO 2 ] (E)”
Claim · model-written summary
One-year-old elevated CO2 shoots photosynthesized faster than ambient shoots despite down-regulation.
- Taxon
- Sitka sprucePicea sitchensise1
- Organ / stage
- 1‐yr‐old E shootse0
- Treatment
- elevated [CO 2 ]e2
- Outcome
- rates of photosynthesise0
- Direction
- highere0
- Qualifier
- despite some down‐regulatione0
- Comparator
- ambient [CO 2 ]e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“despite some down‐regulation, 1‐yr‐old E shoots also had higher rates of photosynthesis than their A counterparts.”
e1“mature Sitka spruce trees”
e2“either ambient [CO 2 ] (A) or elevated [CO 2 ] (E)”
Claim · model-written summary
Elevated branches fixed substantially more assimilate than ambient branches.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- elevated [CO 2 ]e2
- Outcome
- amount of assimilate fixede0
- Direction
- moree0
- Comparator
- ambient [CO 2 ]e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the amount of assimilate fixed by E branches was substantially more than that fixed by A branches”
e1“mature Sitka spruce trees”
e2“either ambient [CO 2 ] (A) or elevated [CO 2 ] (E)”
Claim · model-written summary
Elevated carbon dioxide did not increase non-structural carbohydrate.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- elevated [CO 2 ]e2
- Outcome
- non‐structural carbohydratee0
- Direction
- did not lead to an increasee0
- Comparator
- ambient [CO 2 ]e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this increase in the local production of assimilate did not lead to an increase in non‐structural carbohydrate or stimulate growth or meristematic activity within the E branches.”
e1“mature Sitka spruce trees”
e2“either ambient [CO 2 ] (A) or elevated [CO 2 ] (E)”
Claim · model-written summary
Elevated carbon dioxide did not stimulate growth or meristematic activity.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- elevated [CO 2 ]e2
- Outcome
- growth or meristematic activitye0
- Direction
- did not lead to an increasee0
- Comparator
- ambient [CO 2 ]e2
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“this increase in the local production of assimilate did not lead to an increase in non‐structural carbohydrate or stimulate growth or meristematic activity within the E branches.”
e1“mature Sitka spruce trees”
e2“either ambient [CO 2 ] (A) or elevated [CO 2 ] (E)”
Claim · model-written summary
Leaf area and stem cross-sectional area had a consistent relationship unaffected by CO2.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- [CO 2 ]e0
- Outcome
- relationship between leaf area and stem cross‐sectional areae0
- Direction
- not influencede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“There was a very consistent relationship between leaf area and stem cross‐sectional area that was not influenced by [CO 2 ].”
e1“mature Sitka spruce trees”
Claim · model-written summary
Unbagged branches had thicker stems than bagged branches.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- unbagged branchese0
- Outcome
- stemse0
- Direction
- thickere0
- Comparator
- bagged branchese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“unbagged branches had thicker stems than bagged branches, resulting in a slightly lower ratio of leaf area to cross‐sectional area.”
e1“mature Sitka spruce trees”
Claim · model-written summary
Unbagged branches had a slightly lower leaf-area-to-cross-sectional-area ratio.
- Taxon
- Sitka sprucePicea sitchensise1
- Treatment
- unbagged branchese0
- Outcome
- ratio of leaf area to cross‐sectional areae0
- Direction
- lowere0
- Comparator
- bagged branchese0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“unbagged branches had thicker stems than bagged branches, resulting in a slightly lower ratio of leaf area to cross‐sectional area.”
e1“mature Sitka spruce trees”
The same questions in other papers
co2 · growth · Picea sitchensis (Sitka spruce)Results differ
3 papers in the same direction as this paper · 4 in the opposite direction
- positive
- positive
- positive
4 papers more in this group
See all 8 papers →co2 · physiology: photosynthesis · Picea sitchensis (Sitka spruce)Results agree
2 papers in the same direction as this paper
- positive
- positive
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.