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Question:
High soil moisture leads to decreased photosynthesis.
Response:
In boreal upland forests, low soil moisture decreases the rate of photosynthesis.
A complex microbiota lives belowground, releasing carbon dioxide to the soil.
Plants open its stomata to avoid losing too much water.
Plant closes its stomata to avoid losing too much water.
Transpiration decreases as air becomes drier.
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.
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.
Photosynthesis of a tree canopy is driven or influenced by
air humidity (VPD).
soil moisture (REW).
the total leaf area (LAI).
atmospheric CO2.
air temperature (T).
photosynthetically active solar radiation (PAR).
De-hardening in spring involves gradual re-hydration of the cells, recovery of photosynthetic capacity and a tight control of water loss.
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 light.
the changes in CO2 concentration.
the changes in soil temperature.
the changes in air temperature.
When there is low soil moisture, plants close its stomata pores which then decreases photosynthesis.
What is the source of carbon that is assimilated in photosynthesis?
Atmospheric CO2
Soil water
Soil nutrients
Solar radiation
Plant respiration captures CO2.
Unlike photosynhesis, plant respiration captures atmospheric oxygen and releases carbon dioxide.
In general, the more carbon dioxide that is available to the plant, the faster the rate of photosynthesis - if other factors are favourable.
