Energy transfer in ecosystems Flashcards
Secondary production =
production in secondary consumers
Gross secondary production
GSP - total energy taken in minus excretion
Net secondary production
NSP - amount of energy in a consumers food that is converted to biomass (GSP minus respiration)
How can we calculate production efficiency?
As the percentage of energy assimilated from food that is used for growth
Production efficiency =
NSP divided by GSP
Why do inefficiencies occur?
Not all of what an organisms eats can be digested and organisms use energy
Efficiency variable between what?
Taxonomic groups
What is trophic efficiency?
Estimation of the efficiency of transfer between trophic levels
the percentage production transferred at each trophic step
Trophic efficiency is always less or more than production efficiency?
Less - some portion of each trophic level is not consumed
Where does all the energy go?
Most of the energy available at one level is not transferred to the next
What do decomposers do ?
break down dead organic matter externally and subsequently absorb nutrients
What do detritivores do?
eat/consume dead organic matter
What are coprovores?
organisms that consume and re-digest the waste produced by others
Global terrestrial NPP is roughly?
6x10 to the power of 10 metric tons per year
Herbivores consume less than 20%
What is the green world hypothesis?
- Top-down control of herbivores by predators allows plant biomass to accumulate
- Kelp + Urchins + Otters
