ch. 55 Flashcards
ecosystem
consists of all organisms living in an area as well as the abiotic factors with which they interact
2 main processes for dynamics of ecosystem
- energy flow
- chemical cycling
what do ecologists study
transformations of energy and matter in an ecosystem and map the movements of chemical elements
first law of thermodynamics
energy cannot be created or destroyed, only transferred or transformed
how does energy enter and leave an ecosystem
- enters as solar radiation
- conserved
- lost from organisms as heat
second law of thermodynamics
every exchange or energy increases entropy of the universe
where is some energy lost in energy conversions
heat
law of conservation of mass
matter cannot be created or destroyed
chemical elements are ____________ ____________ within ecosystems
continually recycled
open systems
absorb energy and mass and release heat and waste products
what happens if a nutrient’s outputs from an ecosystem exceed its inputs
the nutrient will limit production
autotrophs
build molecules themselves using photosynthesis or chemosynthesis as an energy source to connect carbon together
heterotrophs
depend on biosynthetic output of other organisms
where do energy and nutrients pass
- primary producers (autotrophs)
- primary consumers (herbivores)
- secondary consumers (carnivores)
- tertiary consumers (carnivores that feed on other carnivores)
detritivores/decomposers
heterotrophs that derive their energy from detritus
detritus
nonliving organic matter
main detritivores
prokaryotes and fungi
what connects all trophic levels
decomposition
primary production
amount of light energy converted to chemical bond energy by autotrophs during a given time period
gross primary production (GPP)
total primary production
how is GPP measured
conversion of energy from light (or chemicals) to the chemical bond energy of organic molecules per unit time
net primary production (NPP)
GPP - Ra
- Ra = energy used by autotrophs for respiration
- amount of new biomass added in a given time period
on average, NPP is ________ GPP
one-half
how is primary production expressed
- energy per unit area per unit time
- bio mass added per unit area per unit time
only what is available to consumers
NPP
most productive ecosystems per unit area
- tropical rain forests
- estuaries
- coral reefs
why do marine ecosystems contribute much to global net primary production if they are unproductive
because of their size
what limits primary production in marine/freshwater ecosystems
light and nutrients
what affect primary production in the photic zone of oceans/lakes
depth of light penetration
limiting nutrient
element that must be added for production to increase in an area
nutrients that most often limit marine production
nitrogen and phosphorus