Flashcards in chapter 20 Deck (64)
provides energy to the ecosystem.
The movement of energy depends on
the efficiency of energy flow.
Most energy that moves through ecosystems originates as
solar energy that powers photosynthesis.
Where sunlight is not available (e.g., deep ocean thermal vents), producers rely on
on chemosynthesis as their source of energy.
Producers use energy for
respiration, growth, and reproduction.
the rate at which solar or chemical energy is captured and converted into chemical bonds by photosynthesis or chemosynthesis.
The difference between gross primary productivity (GPP) & NPP (Net PP) is due to
the energy lost to respiration.
the biomass of producers present in a given area of an ecosystem at a particular moment in time
the rate at which energy is captured and assimilated by producers in an area.
Gross primary productivity (GPP):
the rate of energy that is assimilated by producers and converted into producer biomass in an area; includes all energy that is not respired:
Net primary productivity (NPP
net primary productivity equation
NPP = GPP - Respiration
gross primary productivity equation
GPP = NPP + Respiration
Respiration = GPP - NPP
is photosynthesis an efficient process
can be measured as the change in producer biomass over time
Substantial amounts of herbivory or tissue mortality will lead to
an underestimation of NPP.
Since producers take up CO2 during photosynthesis and produce CO2 during respiration
we can measure NPP by recording the rate of CO2 exchange from the leaf
what happens When a leaf is concealed in the dark
only CO2 respiration occurs.
Other techniques used to measure CO2 uptake and release
-place a leaf into a sealed container with added CO2 that contains trace amounts of a rare carbon isotope
- researchers measure CO2 uptake and release by using towers that sample CO2 concentrations at different heights above the ground.
measuring CO2 does not provide a good estimate of NPP because CO2 is rapidly converted into bicarbonate ions in what systems?
Since producers release O2 during photosynthesis and take up O2 during respiration
we can estimate NPP and GPP by measuring changes in concentrations of O2.
In a bottle exposed to light, the net increase in O2 is the combined result of photosynthesis and respiration by
In a dark bottle, the decrease in O2 is a result of
a technique that allows measurement of conditions on Earth from a distant location, typically using satellites or airplanes that take photographs of large areas of the globe.
high absorption of blue and red light, and high reflectance of green light indicate
ecosystems with high standing crops.
the portion of consumed energy that is excreted or regurgitated.
the portion of energy that a consumer digests and absorbs; analogous to GPP for producers.
the portion of assimilated energy a consumer uses for respiration
the rate of consumer biomass accumulation in a given area
Net secondary productivity