Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
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.
The rate of respiration decreases with temperature.
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.
Photosynthesis of a tree canopy is driven or influenced by
air temperature (T).
photosynthetically active solar radiation (PAR).
soil moisture (REW).
the total leaf area (LAI).
air humidity (VPD).
The annual cycle of photosynthesis mainly follows
the changes in air temperature.
the changes in light.
the changes in soil temperature.
the changes in CO2 concentration.
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 some part of the stems, some photosynthesis may also occur.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
Almost half of the total biomass of a tree may be allocated to the roots.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
Transpiration decreases as air becomes drier.
What is the source of carbon that is assimilated in photosynthesis?