De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
Transpiration decreases as air becomes drier.
When there is low soil moisture, plants close its stomata pores which then decreases 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.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
The rate of respiration decreases with temperature.
Photoinhibition means the decrease in photosynthesis due to
exposure to excess of light.
exposure to shortage of soil moisture.
exposure to excess of CO2.
exposure to high temperature.
To transform atmospheric CO2 into organic molecules, plants can use the energy from
The annual cycle of photosynthesis mainly follows
the changes in CO2 concentration.
the changes in soil temperature.
the changes in air temperature.
the changes in light.
In some part of the stems, some photosynthesis may also occur.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
Carbon becomes locked as part of the accumulating plant biomass as plants grow.
Photosynthesis of a tree canopy is driven or influenced by
the total leaf area (LAI).
air temperature (T).
photosynthetically active solar radiation (PAR).
soil moisture (REW).
air humidity (VPD).
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.