Question:
Photosynthesis of a tree canopy is driven or influenced by
air temperature (T).
air humidity (VPD).
the total leaf area (LAI).
atmospheric CO2.
photosynthetically active solar radiation (PAR).
soil moisture (REW).
Response:
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
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.
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.
Carbon capture is performed by the green parts of plants via photosynthesis.
High soil moisture leads to decreased photosynthesis.
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
Transpiration decreases as air becomes drier.
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
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.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
As plants respire, they release
carbon dioxide.
oxygen.
Almost half of the total biomass of a tree may be allocated to the roots.
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.
