In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
The rate of respiration decreases with temperature.
Almost half of the total biomass of a tree may be allocated to the roots.
Photosynthesis of a tree canopy is driven or influenced by
photosynthetically active solar radiation (PAR).
the total leaf area (LAI).
soil moisture (REW).
air temperature (T).
air humidity (VPD).
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
As plants respire, they release
Photosynthesis releases oxygen whereas respiration releases CO2.
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.
Transpiration decreases as air becomes drier.
The annual cycle of photosynthesis mainly follows
the changes in CO2 concentration.
the changes in air temperature.
the changes in light.
the changes in soil temperature.
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.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
In some part of the stems, some photosynthesis may also occur.
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.