Exam 1 Study Guide: Ecosystems I - Flow of Energy Flashcards
Connect the trophic pyramids to ecological efficiencies between aquatic and terrestrial systems.
Aquatic systems have higher production efficiency but similar or lower trophic efficiency than terrestrial. Aquatic biomass pyramids can be inverted due to small, fast growing producers.
At what ecological level do we typically focus on the flow of energy?
At ecosystem level because energy flows through individuals and populations. At the ecosystem level there is a more complete picture of the energy moving through the trophic levels and exiting.
Explain what primary productivity is, including GPP and NPP.
NPP is net primary productivity - the amount thats available to consumers (total energy captured by plants)
GPP is gross primary productivity - total amount of CO2 that is fixed by plants through photosynthesis.
What is the source of virtually all energy flowing through ecosystems?
the sun
How do we find GPP and NPP? Include formulas and explain how ecologists might take measurements.
NPP measured through biomass and CO2 uptake
GPP measured by total amount of CO2 that is fixed by plants through photosynthesis.
NPP= GPP - respiration
What is secondary productivity?
The productivity of consumers, the rate of biomass produced from consumers eating.
What drives terrestrial NPP and Aquatic NPP?
Terrestrial NPP is driven by temp, precipitation, and nutrients.
Aquatic NPP is driven by temp, light, and nutrients
How do humans use NPP?
By harvesting biomass for fuel or food. Humans use 25% of the worlds NPP.
Compare NPP to standing crop (biomass).
standing crop is the biomass on producers present at any given time. NPP is change in biomass producers, change in movement of CO2 or O2.
how to calculate the efficiencies of energy transfers across trophic levels
how much is respired (R) = assimilated energy - net production
consumption efficiency (CE) = (energy consumed by the next trophic level/energy at the lower level)*100%
net production efficiency (NPE) = (net production/assimilated energy)*100
assimilation efficiency (AE) = (energy assimilated/energy ingested)*100
ecological efficiency (EE or TE) = (energy available the trophic level above/energy available at current level)*100
Think about what each formula tells us. How do the formulas differ? How do they relate to one another?
CE, AE, and NPE describe sequential steps in energy processing (eating, digesting, growing).
TE measures the overall energy transfer between trophic levels. TE is a product of the other efficiencies, reflecting the cumulative energy losses at each step.
Interpret trophic pyramids, comparing energy and biomass in aquatic and terrestrial ecosystems.
- Energy pyramids are always upright, showing energy decrease with trophic level.
- Biomass pyramids can be upright (terrestrial) or inverted (aquatic) due to differences in producer size, turnover, and consumption rates.
- Comparing energy and biomass pyramids reveals differences in how ecosystems function. Aquatic systems can support a larger consumer biomass with a smaller producer biomass due to rapid producer turnover and efficient energy flow.
Why do aquatic systems have a large biomass of consumers?
Aquatic systems have large consumer biomass despite potentially small producer biomass because producers (like phytoplankton) reproduce very quickly and are eaten almost immediately. This rapid turnover means energy flows quickly, supporting many consumers, even though producer biomass at any one time is low.
Connect the trophic pyramids to ecological efficiencies between aquatic and terrestrial systems.
- Trophic pyramids visualize energy flow and biomass distribution.
- Ecological efficiency measures energy transfer between levels.
- Aquatic systems often have higher production efficiency but similar or lower trophic efficiency compared to terrestrial systems.
- Biomass pyramids can be inverted in some aquatic systems due to high producer turnover rates.
