Kysymys:
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
Vastaus:
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.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
Photoinhibition means the decrease in photosynthesis due to
exposure to excess of light.
exposure to excess of CO2.
exposure to shortage of soil moisture.
exposure to high temperature.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
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.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
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.
What is the source of carbon that is assimilated in photosynthesis?
Atmospheric CO2
Soil water
Soil nutrients
Solar radiation
Photosynthesis of a tree canopy is driven or influenced by
soil moisture (REW).
air temperature (T).
photosynthetically active solar radiation (PAR).
atmospheric CO2.
air humidity (VPD).
the total leaf area (LAI).
Almost half of the total biomass of a tree may be allocated to the roots.
In some part of the stems, some photosynthesis may also occur.
Carbon becomes locked as part of the accumulating plant biomass as plants grow.
As plants respire, they release
carbon dioxide.
oxygen.
Photosynthesis releases oxygen whereas respiration releases CO2.