Claim · model-written summary
Net photosynthesis was higher at the top of the canopy than within it, because of light limitation.
- Taxon
- vascular plante0
- Outcome
- Net photosynthesise5
- Direction
- highere5
- Qualifier
- because of light limitatione5
- Setting
- the top of the canopye5
Not reportedMaterialGeneCompoundOrgan / stageInteractorInteractor roleSecond interactorSecond interactor roleTreatmentComparatorValue
Verbatim
e0“Total seasonal vascular plant CO_2 uptake ranged from 400—627 g CO_2 m_G ( —2)”
e5“Net photosynthesis is higher at the top of the canopy, in spite of more favorable temperatures within the canopy, because of light limitation”
Title
A Model of Stand Photosynthesis for the Wet Meadow Tundra at Barrow, Alaska
Philip C. Miller; Wayne A. Stoner; Larry L. Tieszen Ecology 1976. doi:10.2307/1936428
Other claims from this paper (15)
- Observation Modelled total seasonal vascular plant CO2 uptake ranged from 400 to 627 g CO2 per square metre of ground.
- Method / resource The model predicted 627 g CO2 per square metre of seasonal vascular plant CO2 uptake in 1971, against 602 from cuvette estimates.
- Observation Individual species incorporated about 4 g CO2 per square metre of ground per day at most.
- Mechanism The authors suggest that soil respiration is a source of CO2 for vascular plants, because daily CO2 incorporation exceeded the downward atmospheric CO2 flux.
- Association Photosynthesis increased with solar radiation, air and ground temperatures and air vapour density in the model.
- Association Photosynthesis decreased with infrared radiation from the sky and with root resistance to water uptake in the model.
- Observation Total accumulated carbon dioxide, after subtracting leaf growth costs, becomes positive late in the season.
- Association Total accumulated carbon dioxide was highest at the lower canopy levels, because of the longer duration of leaf area there.
- Observation The authors suggest that photosynthesis is adjusted to maximise carbon gain under frequent conditions but not under extreme conditions.
- Observation Leaf area indices of the vascular plants varied by species and by year.
- Observation Leaf areas of all vascular plant species were lowest in 1973.
- Observation About 20% of incoming solar radiation is reflected back by the vascular plant canopy.
- Observation The canopy absorbs 32% to 53% of incoming solar radiation, with absorption increasing with leaf area index.
- Association In the canopy, five to ten times more heat is lost by convection than by evaporation.
- Association The authors suggest that factors increasing transpiration without directly affecting photosynthesis decrease photosynthesis through water stress.