Transcript G2 Ecosystems & Biomes DAA

Option G: Conservation Ecology
G2 Ecosystems & Biomes (pg 328-338)
Gross productivity - the amount of energy trapped in
organic matter during a specified interval at a given
trophic level.
Interesting Link:
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/NetProductivity.html#Net_Productivity
Net productivity – gross
productivity minus that lost
by the respiration of the
organisms at that level.
GP – R = NP
One problem with calculating
NP is that some animals
are omnivores and can
affect more then one
trophic level. Also there is
seasonal variation, and
unknown feeding habits.
Ex: Humans, rats
A food web is often used
to show these multiple
interactions.
Ex: A coyote is both a
secondary and tertiary
consumer.
10% of energy is passed from one trophic level to the next.
This means there is 90% less energy to make the next level
resulting in fewer members and less biomass.
Pyramid of Energy (units: kJ m-2yr-1)
Ecosystems have a lifecycle that usually ends with a
natural “disaster” such as a forest fire. The result is
a clear fertile area for plants to colonize with
different abiotic and biotic factors then the preceding
forest.
Primary succession involves pioneer species developing
and stabilizing the ecosystem. Slowly they change the
abiotic & biotic factors of the ecosystem. Secondary
succession involves a change in the dominant species of
the area over time.
During primary succession gross productivity rises as small
plants are replaced by larger plants, productivity
increases, biomass increases, diversity increases, soil is
built, minerals accumulate, erosion is reduced
A biome is an ecological region dominated by a certain
type of ecosystem characterized by certain
precipitation and temperature conditions leading to a
distinctive biological community adapted to these
conditions. The biosphere includes all of the earth’s
biomes.
Homework: outline the characteristics of the Earth’s
six major biomes. Description should be limited to
temperature, moisture and characteristics of
vegitation.
Use the climograph on page 331 to help you explain
how rainfall and temperature affect the distribution
of biomes on Earth.