Question:
Leaf area increases with stand age, resulting in a decreasing rate of photosynthesis in the stand.
Response:
An increment in leaf area increases also the photosynthesis of a tree stand. However, the relationship is saturating.
Carbon becomes locked as part of the accumulating plant biomass as plants grow.
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
What is the source of carbon that is assimilated in photosynthesis?
Soil water
Solar radiation
Soil nutrients
Atmospheric CO2
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
As plants respire, they release
carbon dioxide.
oxygen.
Photosynthesis releases oxygen whereas respiration releases CO2.
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.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
Transpiration decreases as air becomes drier.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
Almost half of the total biomass of a tree may be allocated to the roots.
To transform atmospheric CO2 into organic molecules, plants can use the energy from
soil nutrients.
atmospheric oxygen.
soil heat.
sun light.
In some part of the stems, some photosynthesis may also occur.
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
