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.
High soil moisture leads to decreased photosynthesis.
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
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.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
As plants respire, they release
The annual cycle of photosynthesis mainly follows
the changes in light.
the changes in soil temperature.
the changes in CO2 concentration.
the changes in air temperature.
In some part of the stems, some photosynthesis may also occur.
The rate of respiration decreases with temperature.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
Photosynthesis of a tree canopy is driven or influenced by
soil moisture (REW).
the total leaf area (LAI).
air humidity (VPD).
photosynthetically active solar radiation (PAR).
air temperature (T).
Carbon becomes locked as part of the accumulating plant biomass as plants grow.
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.