Ecology
Succession Succession – the stages a land area
goes through
Primary Succession Starting from rock Happens after a volcanic eruption,
glacier movement or over a rocky area Takes A LONG TIME
Primary Succession - stages Starts with small plants like lichen or moss
that have very little nutrient requirements Slightly more complex plants start to grow
which break apart the rock and release nutrients into the rock, eventually forming soil
small plants start to grow Medium plants start to grow Larger plants including large trees start to
grow
Primary succession Primary Succession
Secondary Succesion Regrowth – occurs after a forest fire or
other disturbance that leave the soil in place
Takes much less time than primary succession
Secondary Succession animation
Food Webs
ProducersAn organism that uses solar energy (green plant) or chemical energy (some bacteria) to make its food.
Primary Consumer (herbivore)An organism that feeds directly on all or parts of plants.
Secondary Consumer (carnivore)An organisms that feeds only on primary consumers. Most are animals, but some are plants (Venus fly-trap).
Tertiary Consumer (carnivore)Animals that feed on animal-eating animals. Ex. hawks, lions, bass, and sharks.
Quaternary Consumer (carnivore)An animal that feeds on tertiary consumers. Ex. humans.
Decomposer (scavenger, detritivore)An organism that digests parts of dead organisms, cast-off fragments, and wastes of living organisms. Ex. bacteria and fungi.
Rule of 10 10% of the energy is transferred from
one tropic level to the next trophic level. Example:
A plant has 30 J. of energy A cow eats the plant The cow gets only 10 % of the plant’s
energy which is 3 J.
Rule of 10 practice A plant has 100 J. of energy. A prairie
dog eats the plant. A fox eats the prairie dog. How much energy does the fox get from the original energy in the plant?
Answer: Plant to prairie dog: 100J. X .10 = 10 J Prairie dog to fox: 10J x .10 = 1 J
The fox has to eat many animals to get it’s energy. This is why animals higher up in the food chain are often the largest.
Roles in the ecosystem Some plants and animals serve specific
roles in the ecosystem.
Keystone species Foundation species Indicator species
Keystone Species A species that the entire ecosystem
depends on If this species disappears the entire
ecosystem will changes Example: Sea Otter
Foundation Species Species that changes the ecosystem
Foundation species Elephant: When elephants move into an area they
stomp down much of the vegetation This changes the habitat of the entire
ecosystem A new ecosystem replaces what used to
be there.
Indicator species A sensitive species that shows the
evidence of change early than other members of the ecosystem
Amphibians are classic examples of indicator species
Life Cycle of a Frog
Rivers and Dams Dams severely impact aquatic
ecosystems
Fig. 14-13a, p. 317
Provides water for year-round irrigation of cropland
Flooded land destroys forests or cropland and displaces people
Large losses of water through evaporation
Provides water for drinking Downstream
cropland and estuaries are deprived of nutrient-rich silt
Reservoir is useful for recreation and fishing
Risk of failure and devastating downstream flooding
Can produce cheap electricity (hydropower)
Downstream flooding is reduced
Migration and spawning of some fish are disrupted
Fig. 14-13b, p. 317
Powerlines
Reservoir
Dam
PowerhouseIntake
Turbine
These are dams & reservoirs that feed from the Colorado River all the way to San Diego, LA, Palm Springs, Phoenix & Mexico.
Colorado River Basin
The Colorado River Basin
Figure 14-14Figure 14-14
Fig. 14-14, p. 318
Dam
Aqueduct or canal
Upper Basin
LOWER BASIN
0 100 mi.
0 150 km
Lower BasinUPPER BASIN
IDAHO
WYOMING
Salt Lake City
Grand JunctionDenver
UTAH
NEVADACOLORADOLake
Powell
Las Vegas
Grand Canyon Glen
Canyon Dam
Boulder CityNEW MEXICO
ARIZONALos Angeles
Albuquerque
PhoenixSan Diego
MexicaliYuma
Tucson
All-American Canal Gulf of
CaliforniaMEXICO
CALIFORNIA
Palm Springs
Col
orad
o R
iver
The Colorado River has so many dams and withdrawals that it often does not reach the ocean. 14 major dams and reservoirs, and canals. Water is mostly used in desert area of the U.S. Provides electricity from hydroelectric plants for
30 million people (1/10th of the U.S. population).
Case Study: The Colorado Basin – an Overtapped Resource