Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
Photosynthesis of a tree canopy is driven or influenced by
the total leaf area (LAI).
air temperature (T).
photosynthetically active solar radiation (PAR).
air humidity (VPD).
soil moisture (REW).
As plants respire, they release
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.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
What is the source of carbon that is assimilated in photosynthesis?
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
To transform atmospheric CO2 into organic molecules, plants can use the energy from
Photoinhibition means the decrease in photosynthesis due to
exposure to shortage of soil moisture.
exposure to excess of CO2.
exposure to high temperature.
exposure to excess of light.
exposure to high temperature
exposure to excess of CO2
exposure to shortage of soil moisture
exposure to excess of light
In some part of the stems, some photosynthesis may also occur.
Transpiration decreases as air becomes drier.
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
Carbon becomes locked as part of the accumulating plant biomass as plants grow.