ecology 3 (ecosystems ecology) Flashcards
ecosystem
biotic community of organisms in an area plus the abiotic environment affecting that community
trophic structure
the organization of organisms within an ecosystem based on their feeding relationships; how energy flows through a food chain by dividing organisms into different trophic levels
primary producer
organisms that acquire their energy from sunlight and materials from nonliving sources
primary consumer
organism that eats primary producers
secondary consumer
organism that eats primary consumers
tertiary consumer
organisms that eat secondary consumers
detritivore
an animal which feeds on dead organic material
decomposer
an organism that breaks down dead organic material;
detritus
debris; accumulation of non man made/ natural material
trophic level
each of several hierarchical levels in an ecosystem, comprising organisms that share the same function in the food chain and the same nutritional relationship to the primary sources of energy
primary production
the amount of light energy converted to chemical energy by autotrophs (primary producers) during a given span of time
gross primary production
total amount of production of biomass from solar energy
net primary production
amount of production of biomass from solar energy minus the energy the plant uses for respiration
what energy is available to consumers for energy
NPP
biomass
the total mass of living organisms in an ecosystem at a given time
limiting nutrient
limits the rate of production of biomass
ex. nitrogen
production efficiency
a measure of how well a company uses its resources to produce goods or services
trophic efficiency
the percentage of energy that is passed from one trophic level to the next in a food chain or food web; energy loss up tropic levels
top down control
organisms at higher trophic levels in a food web regulate the populations of organisms at lower trophic levels
bottom up control
availability of resources at the base of a food chain, like nutrients, water, or light, regulates an ecosystem
how to calculate net primary production?
NPP = GPP – R(respiration)
tropic cascade
a series of tropic interactions that result in changes in biomass and species composition; indirect effects
secondary produtivity
amount of chemical energy in food converted to new biomass in a particular amount of space during a given period of time
bioaccumulation
chemicals build up in an organism over time, becoming more concentrated than the chemical in the environment
assimilated energy uses
energy used for growth (new biomass) and respiration
not assimilated energy uses
feces/ waste
pool
main reservoirs of elements/nutrients
*organic/inorganic
*avaibale/unavailable
pool size
total amount of nutrient in a component of the ecosystem
mean residence time
amount of time on average that a molecule spends in a pool
turnover
rates of nutrients cycling
global cycles examples
carbon, oxygen, sulfur, nitrogen cycling; atmospheric pool is global
local cycles examples
phosphorus, potassium, calcium; minerals rather than gasses
3 mechanisms for nutrient cycling
biological, geological, chemical
nutrient budget components
- input (decomposition rates)
-mean residence time
-output
carbon cycle: available forms
CO2 gas, organic matter, dissolved C in water
carbon cycle: largest pool
sedimentary rocks
carbon cycle: key processes
*photosynthesis/respiration
-net movement of C to ocean 0> ocean acidification
-fossil fuels -> C in atmosphere
-erosion of organic matter
why does CO2 in the atmosphere increase in the northern hemisphere winter
less photosynthesis is being done to counteract respiration
*more land in northern hemisphere -> more photosynthesis; global pattern reflects northern hemisphere seasonality
nitrogen cycle: major reservoir
atmosphere
nitrogen cycle: available forms
NH3, NO2, NO3
nitrogen cycle: key processes
bacteria break down N2 into available forms; nitrogen fixation
Phosphorus cycle: main reservoir
rocks
Phosphorus cycle: available forms
decomposers release avail form: (PO4) 3-
Phosphorus cycle: key processes
weathering, decomposition
how can phosphorus become unavailable
soluble P combines with Fe, Ca, Al through chemical mechanism -> forms insoluble unavailable nutrients
nutreince limitation for plants: N and P patterns
N starts off all in the atmosphere (N NPP limitation) than rocks break down and P decreases (P NPP limitation)
how to humans add excess nutrients into nutrient cycle
- phosphorus runoff -> eutrophication
-fossil fuels, N fixing crops, N fertilizer -> N fixation adds N to atmosphere
nitrogen saturation
nitrogen additions to an ecosystem lead to losses of the same order of magnitude; trees die
how do humans remove nutrients from environment/cycles
- removing trees/vegetation(logging)
-???
