Energy Flow Flashcards
Why are food chains only 3-4 trophic levels?
- longer chains tend to be unstable (lower population)
- increasingly less energy reaches higher trophic levels
because most energy is excreted or respired
energy balance equation
eaten = tissues + excreted + respired
solve this to figure out how much energy leaves and in what way
amount of energy reaching each trophic level depends on + equation
net primary product
energy transfer efficiency
consumption a trophic level n / production at level (n-1)
(or multiplied, idk)
when are biomass pyramids inverted
when the biomass of producers is consumed rapidly and is replaced rapidly
rate at which biomass is produced may be very large
*** energy pyramids are never inverted
production
change in biomass per unit time
change in energy per unit area per unit time
Allen’s Paradox
populations can reproduce many times during year
measurements at a given sampling time doesn’t always show full picture
Gross Primary Production
amount of CO2 fixed in plants by plant through photosynthesis
Respiration
amount of CO2 lost (by going out) through metabolic activity
Net Primary Production
rate of accumulation of plant biomass
net amount of PP after the cost of plant respiration
= GPP - Rp
Net Ecosystem Production
NEP = GPP - Rp - Rhet
NEP = NPP - Rhet
respiration of plants and heterotrophs
= net C storage in ecosystem
Sinks, sources, equal rate
sink when biomass accumulates NEP > 0
sources when disturbed by fire, newly-tilled field, NEP less than )0
NEP = 0, C transferred to the ecosystem and atmosphere at equal rates
Limited by water?
when water is scarce, photosynthesis stops
in terrestrial systems PP is water limited
Effects of deforestation on C cycling
- removal of forests removes a CO2 sink
stored C is released as CO2 - increases rate of decomposition of soil 3. organic mater
land use change, - potential to become a source
