Flashcards in 19: Primary and Secondary Production & Energy Flow Deck (59)
With the exception of a few ecosystems, this fuels life on earth:
primary production through photosynthesis
The flow of energy through a system starts with what?
harnessing energy from sunlight
The total rate of photosynthesis or total amount of energy assimilated by autotrophs.
Gross Primary Production (GPP)
The rate of energy storage or amount of energy stored after respiration.
Net Primary Production (NPP)
Net Primary Production = Gross Primary Production - Respiration
Glucose produced during photosynthesis
Some glucose used to supply energy to drive cellular processes.
Remaining glucose available to be laid down as new material - biomass
Why do we care about NPP at the individual and population levels?
NPP represents plant growth and health
Why do we care about NPP at the community and ecosystem levels?
NPP represents the amount of C (or food) available at the base of the food web, and thus all trophic levels.
Why do we care about NPP at the ecosystem, biome, and biosphere levels?
NPP represents the amount of C that is stored in plant biomass
How do we measure NPP in AQUATIC ecosystems?
Light – dark bottle technique
What processes take place within the light (transparent) bottle?
Photosynthesis + Respiration (R)
What processes take place within the dark (opaque) bottle?
Only respiration (R)
What do we measure in the Light-Dark Bottle Technique?
Measure change in 02 in each bottle over some set time (generally over 24 hrs)
Light-Dark Bottle Technique equation
NPP + R = GPP
Amount of O2 produced in photosynthesis and 02 used in respiration (NPP) + amount of O2 loss (R) = Gross Primary Product (GPP)
In aquatic ecosystems, it is important to get continuous measurements of what?
O2 between day and night
In terrestrial ecosystems, what do we measure to get the NPP & GPP?
What could be done in a terrestrial ecosystem to estimate NPP?
use Standing Crop Biomass
Amount of accumulated primary producer biomass in a given area at a given time
Standing Crop Biomass
What is the problem with using biomass to estimate NPP?
Productivity (or NPP) is the rate or amount of organic matter created by photosynthesis, whereas biomass is the amount of organic matter present at a given time
How could we measure biomass (or NPP) from space?
By using chlorophyll
How was the use of biomass to estimate NPP influence your results?
You would underestimate NPP
What environmental factors influence productivity in terrestrial ecosystems?
Temperature and precipitation
High temperatures reflects high amounts of solar radiation and longer growing seasons
Therefore solar radiation fuels primary productivity
Global limits on primary production
Temperature, Sunlight, and Water
NPP is highest in what zone, with year-round warm temperatures, high precipitation and higher radiation?
The equatorial zone
How does Earth's tilt influence temperature?
23.5° on axis. Energy from the sun does not reach all areas of the earth with equal strength. Areas near the equator receive direct an intense solar energy, which influences temperature.
Why is NPP reduced as you move north or south on the globe?
Cooler temperatures, and higher seasonal variation in temperatures and precipitation, less direct radiation