Question:
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
Response:
The annual cycle of photosynthesis mainly follows
the changes in CO2 concentration.
the changes in soil temperature.
the changes in light.
the changes in air temperature.
Photosynthesis of a tree canopy is driven or influenced by
air humidity (VPD).
photosynthetically active solar radiation (PAR).
air temperature (T).
soil moisture (REW).
atmospheric CO2.
the total leaf area (LAI).
What is the source of carbon that is assimilated in photosynthesis?
Soil water
Solar radiation
Atmospheric CO2
Soil nutrients
The rate of respiration decreases with temperature.
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.
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
To transform atmospheric CO2 into organic molecules, plants can use the energy from
sun light.
soil nutrients.
soil heat.
atmospheric oxygen.
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
Almost half of the total biomass of a tree may be allocated to the roots.
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.
Early spring is a tricky time for plants due to the combination of sunny but still quite cold days.
At low air humidity, a plant closes its stomata to prevent transpiration. The action also decreases photosynthesis
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
