Topic 12- Ecosystem Energetics Flashcards
what is ecosystem energetics?
the study of how energy is fixed by autotrophs and made available to heterotrophs
how is energy measured in ecosystems?
measured as the dry weight of organic matter in an organism or ecosystem
what is gross primary production?
the total amount of energy fixed into organic molecules in an ecosystem.
what is primary production?
the rate at which energy is fixed
what is net primary production?
the amount of energy available for growth (Eproduction) tells how much energy is available to other trophic levels
how does the ecosystem affect NPP?
rainforests have high NPP because of high amounts of standing carbon. Deserts have high amounts of land but low biomass and produce biomass very slowly. Open oceans have very high amounts of surface area but very low PP in lots of areas, but because of how big oceans are they account for a lot of the NPP on earth.
primary production in terrestrial ecosystems
driven by precipitation and temperature. the transition from winter to summer causes an increase in productivity
primary production in aquatic ecosystems
majority of oceans have low PP but near shores and coasts productivity is much higher. open ocean current bring in ocean nutrients off of coasts into open ocean causing a peak in productivity in mid ocean ridges. floods can also cause the uplift of ocean floor, causing peaks in productivity. Productivity away from coasts mainly caused by open ocean circulation.
how does light affect PP?
amount of light an ecosystem recieves plays a very important role in PP. the amount of light reaches a peak where it is ideal for an ecosystem, afterwards as light keeps being added it can be considered radiation and start to damage plants.
how does temperature affect PP?
enzymatic rates are temperature dependent. as an increase in annual temperature occurs, productivity generally increases.
how does precipitation affect PP?
generally as precipitation increases, PP increases but it is very dependent on region. for example in Hawaii since the climate is very wet as is, when precipitation passes a peak it can start to damage PP.
how does nitrogen affect PP?
certain environments are nitrogen limited and react when more N is added. N is soluble so areas with high rainfall will have it be more limiting. N is more limiting in terrestrial environments than aquatic.
how does phosphorous affect PP?
P is insoluble so it doesn’t wash away with rainfall, and it does not enter aquatic systems as easily. P is more limiting in aquatic environments than terrestrial.
What are primary consumers? what trophic level are they?
Primary consumers are in the second trophic level. they consume the organic matter of primary producers. use the energy to support their energy budgets. can be used to produce biomass, called secondary production.
what are secondary/tertiary consumers? what trophic level are they?
they are in the third and fourth trophic level. organisms that consume organic matter of the consumers in the lower trophic levels.
what are decomposers and detritivores?
organisms that consume organic matter of the other trophic levels. they recycle nutrients through the system.
decomposers= single cell (bacteria)
detritrivores= multicellular (worms, etc.)
what is bottom up control?
resource abundance regulates the trophic structure. the energy in each trophic level is determined by the energy available in the trophic level below. can result in eutrophication.
what is top down control?
predation regulates the trophic structure. organisms in each trophic level are limited by the predators in the next higher trophic level. can remedy eutrophication.
