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