chapter 42
ecosystem
all the organisms living in a community
two main processes involved in the dynamics of an ecosystem
energy flow and chemical cycling
energy flows ____ ecosystems while matter cycles ____ them
through, within
law of conservation of mass
matter cannot be created or destroyed
ecosystems are ___ systems
open
how do energy and nutrients pass through the trophic levels
primary producers > primary consumeers> secondary consumers> tertiary consumers
detrivores or decomposers
consumers that derive energy from detritus (nonliving organic matter)
primary production
amount of energy converted to chemical energy by autotrophs during a given time period
the extent of photosynthetic production ___
sets the spending limit for the energy budget of an ecosystem
the amount of solar radiation reaching earths surface _____
limits the photosynthetic output of ecosystems
gross primary production
total primary production of an ecosystem
net primary production
GPP minus the energy used by primary producers for their autotrophic respiration (usually half GPP)
key measurement for production
net primary production
standing crop
total biomass of photosynthetic autotrophs at a given time
most productive ecosystems
rainforests estuaries and coral reefs
marine ecosystems are relatively ____ productive
unproductive per unit area, but very large so contribute a lot
net ecosystems production
measure of the total biomass accumulated during that time
NEP equation
GPP minus the total respiration of all organisms in the system (not just producers)
why is NEP useful
because its value determine whether an ecosystem is gaining or losing carbon over time
what controls primary production in water ecosystems
nutrients and light
limiting nutrient
the element that must be added for production to increase in an area
typical limiting nutrients in aquatic ecosystems
nitrogen and phosphorous
areas of upwelling have ___ productivity
high productivity
eutrophication
result of sewage runoff in lakes
effects on primary production in terrestrial ecosystems
temperature and moisture
actual evapotranspiration
the water annually transpired by plants and evaporated from a landscape
a limit on primary production in terrestrial ecosystems
soil nutrients (nitrogen)
energy transfer efficiency between trophic levels
10%
production efficiency
the fraction of energy stores in food not used for respiration
trophic efficiency
the percentage of productioni transferred from one trophic level to the next (5-20 %)
percent of chemical energy that reaches a tertiary consumer
0.1
biogeochemical cycles
nutrient circuits in ecosystems
restoration ecology two key strategies
bioremediation, biological augmentation
bioremediation
use of living organisms to detoxify ecosystems
biological augmentation
uses organisms to add essential materials to a degraded ecosystem