Abstract
A model was developed that simulated photosynthesis, growth and allocation in tree seedlings. The model was parameterized with data from experiments on seedlings of sycamore (Acer pseudoplatanus L.), Sitka spruce (Picea sitchensis (Bong) Carr.) and young birch trees (Betula pendula Roth.). In these experiments, CO2 concentration ([CO2]) and nutrient addition rate were varied. Parameters quantifying nutrient uptake, translocation and starch synthesis were fitted, based on data from control treatments. Elevated [CO2] and low-nutrient treatments were then used to test the predicted response of growth and allocation against observations. The model accurately predicted total seedling growth in the elevated [CO2] treatments. A response of growth to elevated [CO2] was seen in the birch and sycamore experiments, but not in the Sitka spruce, because of photosynthetic down-regulation. Predictions of allocation were reasonably accurate in the birch and Sitka spruce experiments, but were notably poorer in the sycamore experiments, possibly because of differences in sink strength between root and shoot. In the birch and sycamore experiments, little change in allocation with elevated [CO2] was observed or predicted. This was ascribed to the relative values of K(Tc) and K(Tn), the translocation coefficients that determine the sensitivity of allocation to carbon and nitrogen uptake rates, respectively. Growth and allocation in the low-nutrient treatments were poorly predicted by the model. In Sitka spruce, it was suspected that the photosynthetic parameters measured in August 1994 had been higher earlier in the season, before nutrients became depleted. In sycamore, the discrepancies were thought to relate to differences in sink strength between root and shoot that could not be described by the model.
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Claims 10
Claim · model-written summary
The model accurately predicted total seedling growth under elevated carbon dioxide.
Not reportedTaxonValue
Verbatim
e0“The model accurately predicted total seedling growth in the elevated [CO2] treatments.”
Claim · model-written summary
Elevated carbon dioxide increased growth in birch.
Not reportedComparator
Verbatim
e0“A response of growth to elevated [CO2] was seen in the birch and sycamore experiments, but not in the Sitka spruce, because of photosynthetic down-regulation.”
Claim · model-written summary
Elevated carbon dioxide changed growth in sycamore.
Not reportedComparator
Verbatim
e0“A response of growth to elevated [CO2] was seen in the birch and sycamore experiments, but not in the Sitka spruce, because of photosynthetic down-regulation.”
Claim · model-written summary
Sitka spruce growth did not respond to elevated carbon dioxide.
- Taxon
- Sitka spruce
.jpg?width=60)
Picea sitchensise0 - Treatment
- elevated [CO2]e0
- Outcome
- growthe0
- Direction
- note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“A response of growth to elevated [CO2] was seen in the birch and sycamore experiments, but not in the Sitka spruce, because of photosynthetic down-regulation.”
Claim · model-written summary
Allocation predictions were reasonably accurate for birch.
Verbatim
e0“Predictions of allocation were reasonably accurate in the birch and Sitka spruce experiments, but were notably poorer in the sycamore experiments”
Claim · model-written summary
Allocation predictions were reasonably accurate for Sitka spruce.
- Taxon
- Sitka sprucePicea sitchensise0
- Outcome
- allocatione0
- Direction
- reasonably accuratee0
- Comparator
- sycamoree0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Predictions of allocation were reasonably accurate in the birch and Sitka spruce experiments, but were notably poorer in the sycamore experiments”
Claim · model-written summary
Allocation predictions were poorer for sycamore.
Verbatim
e0“Predictions of allocation were reasonably accurate in the birch and Sitka spruce experiments, but were notably poorer in the sycamore experiments”
Claim · model-written summary
Birch showed little allocation change under elevated carbon dioxide.
Not reportedComparator
Verbatim
e0“In the birch and sycamore experiments, little change in allocation with elevated [CO2] was observed or predicted.”
Claim · model-written summary
Sycamore showed little allocation change under elevated carbon dioxide.
Not reportedComparator
Verbatim
e0“In the birch and sycamore experiments, little change in allocation with elevated [CO2] was observed or predicted.”
Claim · model-written summary
The model poorly predicted growth and allocation under low nutrient supply.
Not reportedTaxon
Verbatim
e0“Growth and allocation in the low-nutrient treatments were poorly predicted by the model.”
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
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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.