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.
What is the source of carbon that is assimilated in photosynthesis?
Photoinhibition means the decrease in photosynthesis due to
exposure to shortage of soil moisture.
exposure to high temperature.
exposure to excess of CO2.
exposure to excess of light.
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
Transpiration decreases as air becomes drier.
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.
In some part of the stems, some photosynthesis may also occur.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
High soil moisture leads to decreased photosynthesis.
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
The rate of respiration decreases with temperature.
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.
As plants respire, they release
Photosynthesis releases oxygen whereas respiration releases CO2.