Chapter 42 Ecosystem and Energy Notes
Ecosystem – sum of all the organisms living in a given area and the abiotic factors with which they
interact.
 Includes energy flow and chemical cycling
 Energy enters most ecosystems as sunlight.
 Energy and matter are transformed in ecosystems through photosynthesis and
feeding relationships.
 1% of the visible light that strikes photosynthetic organisms is converted to
chemical energy yet, Earth’s primary producers create about 150 billion metric tons
of organic material each year.
Ecosystem ecologists – study how energy and matter are transformed within a system and
measure the amounts of both that cross the system’s boundaries.
1st law of thermodynamics – energy cannot be created or destroyed but only transferred or
transformed.
2nd law of thermodynamics – every exchange of energy increased the entropy of the universe.
Law of conservation of mass – Matter, like energy, cannot be created or destroyed.
Figure 42.4 – Overview of energy and nutrient dynamics in an ecosystem
 Primary producers
 Primary consumers
 Secondary consumers
 Tertiary consumers
 Detritivores or decomposers
o Detritus – nonliving organic material such as the remains of dead organisms, feces,
fallen leaves and wood
Gross and Net production: NPP = GPP – Ra
Gross primary production (GPP) – amount of energy from light (or chemicals) converted to
chemical energy of organic molecules per unit time.
Net primary production (NPP) – equal to gross primary production minus the energy used by
the primary producers fro their autotrophic respiration
To ecologists, NPP is key measurement because it represents the storage of chemical energy that
will be available to consumers in the ecosystem.
Primary production in aquatic ecosystems is controlled by light and nutrients.
Terrestrial ecosystems: temperature and moisture controls primary production.
Secondary production – amount of chemical energy in consumers’ food that is converted to new
biomass during a given period
Production efficiency – figure 42.10, 10% rule for each link in food chain.
Biological and geochemical processes cycle nutrients and water in ecosystems

Biogeochemcial cycles – nutrient cycles that involve biotic and abiotic components.
Figure 42.13 (pages 874 – 875)
 Water cycle
 Carbon cycle
 Nitrogen cycle
 Phosphorus cycle
Restoration ecologists help return degraded ecosystems to a more natural state

Bioremediation – using organisms (prokaryotes, fungi or plants) to detoxify polluted
ecosystems

Biological augmentation – uses organisms to ADD essential material to a degraded
ecosystem.
Chapter 43 – Global Ecology and conservation Biology – need to read but will not go over
Conservation Biology – integrates ecology, evolutionary biology, molecular biology, genetics and
physiology to conserve biological diversity.
3 levels of biodiversity:
 genetic diversity
 species diversity
 Ecosystem diversity
Threats to biodiversity:
 Habitat loss
 Introduced species
 Overharvesting
 Global change
Earth is changing rapidly as a result of human actions
 Nutrient enrichment
 Toxins in the environment
o biological magnification
 greenhouse gases and climate change
The human population is not longer growing exponentially but is still growing rapidly
Sustainable development can improve human lives while conserving biology
o economic development that meets the needs of people today without limiting the ability of
future generations to meet their needs.