Question:
What is the source of carbon that is assimilated in photosynthesis?
Soil nutrients
Atmospheric CO2
Soil water
Solar radiation
Response:
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
Photosynthesis of a tree canopy is driven or influenced by
the total leaf area (LAI).
air humidity (VPD).
photosynthetically active solar radiation (PAR).
soil moisture (REW).
air temperature (T).
atmospheric CO2.
High soil moisture leads to decreased photosynthesis.
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
As plants respire, they release
carbon dioxide.
oxygen.
Photosynthesis releases oxygen whereas respiration releases CO2.
Carbon capture is performed by the green parts of plants via photosynthesis.
The effect of light on photosynthesis has a clear saturating pattern: more light results in more photosynthesis but eventually leaves cannot take full advantage of all the extra light.
Leaf area increases with stand age, resulting in a decreasing rate of photosynthesis in the stand.
An increment in leaf area increases also the photosynthesis of a tree stand. However, the relationship is saturating.
Transpiration decreases as air becomes drier.
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
Photoinhibition means the decrease in photosynthesis due to
exposure to shortage of soil moisture.
exposure to excess of light.
exposure to high temperature.
exposure to excess of CO2.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
Almost half of the total biomass of a tree may be allocated to the roots.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
