Upon completion of this unit you will be able to:
1. Compare and contrast ecology, conservation
and environmentalism.
2. Distinguish between an ecosystem
and a biome, noting both the
similarities and differences between
them.
3. List several terrestrial ecosystems.
4. List several biotic and abiotic
factors which constitute the environment.
5. Discuss the Law of Limiting Factors
as it was proposed by Justis von Liebig.
6. Provide definitions for each of
the following:
species population
community habitat
symbiosis environment
niche autotroph
ecology disclimax
heterotroph ecosystem.
7. Identify the groups in a typical
food chain: distinguish between a food chain
and a food web in terms of complexity
or numbers of potential interactions.
8. Relate the second law of thermodynamics
to the events in a food chain.
9. State the three Principles of Ecosystem
Functioning.
10. Provide several examples of symbiotic
relationships.
11. Distinguish between intraspecies
and interspecies competition.
12. Describe how competitive exclusion
and coexistance result from interactions between
populations.
13. Provide a list of climatic factors
which influence plant distribution.
14. Discuss the events which occur during
ecological succession.
15. Distinguish between primary and
secondary ecological succession.
16. Discuss the development of a climax
community.
17. Define carrying capacity.
18. List and describe factors contributing
to the carrying capacity of any system.
19. Appreciate that humans alter and interfere
with natural ecological processes.
Unit References:
Text Chapters 15, 16, 17
http://www.mhhe.com/enger12
(Objective #1)
ECOLOGY- (Text
pg 304) branch of biology that studies the relationships between
organisms and
their environment.
ENVIRONMENT- anything that affects
an organism during its lifetime (broad)
Ecologist vs. Environmentalist
(Ecology not in danger, environment is)
"Environmental Issues"; "Ecological Concerns"
**We are an integral part of
our environment!!!
Unfortunately we tend to
exploit rather than coexist.
Organization of Living Systems
I. Biosphere - largest biological
system, thin skin of life on planet;
intersection or air, water
and land; bottom of ocean to the
tops of the highest mountains
*if Earth were the size of an
apple, the biosphere would be about the thickness
of its skin.
Closed system
II. Biosphere divided into distinct
regions called Biomes (Objective #2, 3,
13)
text
pgs 334-340
Biome- characterized by
a distinct climate and characteristic assemblage of plants
and animals adapted to it,
plants usually determine the other kinds of plants and
animals present (temperature,
moisture biggest physical factors)
North America: Tundra
Taiga
Temperate deciduous forest
Temperate Grassland
Semidesert, arid grassland
Desert
Mountain (complex zonation)
Check out: Deserts- Geology and Resources
Prairies in the Prairie State
Arctic Studies Center
National Estuary Program
Major Biomes
Ecosystem (Objective
#2)- System consisting of organisms and their environment
(biotic and abiotic) and all of the
interactions that exist between these components
Environment of any organism is complex and
interrelated, everything influenced or modified
by other factors:
(Objective #4)
text pg 304- 306; 311-316
Abiotic Factors - Physical:
gravity, light, heat, humidity
Chemical: water,
nutritional elements, minerals
Temporal: Normal
changes throughtout life gradual environmental changes
Justus von Liebig- Law of limiting factors (Objective #5) 308-316
Range of Tolerance; Zones of Physiological Stress; Zones of Intolerance
Check Out:
What is the Carbon Cycle?
Watersheds: Phosphorus
Water On The Web- Understanding Lake Ecology
Biotic Factors (Objective#7) text pg 305-306- living things that affect organisms
1. Producers- (Autotrophs)-
produce own food.
2. Consumers- (Heterotrophs)-
"other" feeders
Primary consumers- herbivores
Secondary consumers- carnivores,
omnivores
3. Decomposers/ detritivores
- bacteria, fungi- use dead organisms as energy
4. Omnivores
ECOSYSTEM FUNCTIONING ( Objective #7) text pg 306-311
*Food and Energy flow through food
chains that are generally part of much larger food
webs in ecosystems
Food Chain- series of organisms, each feeding on the organism preceding it.
Food Web- more complex
network of feeding interactions; several food chains
interacting together.
Check Out
:
From the Top of the World to the Bottom of the Food Web
Primary Production- Key Element to the Status of San Francisco Bay
**Chains provide avenues for
the flow of energy and the cycling of nutrients through
the environment.
**Organisms of a food chain exist on different trophic levels.
Trophic level ("feeding
level")
Ex. producer, primary
consumer, secondary consumer. . .
(Objective #8)
ENERGY FLOW- 2nd law of
Thermodynamics; energy conversions
are never 100%,
there will always be a loss of useful energy as heat
1935, Charles Elton: Animal Ecology
"The animals at the
base of a food-chain are relatively abundant, while those
at the end are relatively few in numbers,
and there is a progressive decrease in between
the two extremes. . . . This arrangement
of numbers in a community, the relative decrease
in numbers at each stage in a food-chain,
is characteristically found in animal communities
all over the world, and to it we have applied
the term 'pyramid of numbers'."
Pyramid of Energy
Pyramid of Mass
Pyramid of Numbers
Principles of Ecosystem Functioning
(objective #9):
1. Resources are supplied and wastes
are disposed of by recycling all elements
(Carbon cycle, nitrogen cycle,
etc.)
2. Ecosystems run on solar energy,
which is exceedingly abundant, nonpolluting,
relatively constant, and everlasting.
3. Large biomasses cannot be supported
at the end of long food chains. Increasing
population means moving closer
on the food chain to the source of production.
Organism Interactions/ symbiosis (Objective #10, 11) text pgs. 324-3334
Symbiosis- biotic interactions within a community; "living together"
Population- group of organisms of the same species occupying a specific region
Community- several populations existing together
Habitat- description of the place where an organism lives
Niche- how
an organism "fits" into its habitat and all of its relationships in the
environment.
-niche not always constant,
complex sets of items inventory of influences, activities
and impacts.
**many organisms have the same
habitat but occupy a different niche and therefore don't
compete for resources.
**niches do overlap somewhat, this leads to competition
Competitive Exclusion
Principle (Objective #12)
-find something else
to do
-move
-die
Animals competing with man
for resources
Specific Symbiotic Relationships in Ecosystems (Objective#10, 11) text pgs 326-334
Mutualism - two species, both
benefit from association
Lichens; termites; pollination
Predation - benefit to one
at the expense of another
*In predation, individual harmed
but population may benefit by the elimination of old, sick,
injured or poorly adapted
individuals. Predation prevents overpopulation
Parasitism - organism living
on or in another to obtain nourishment
Commensalism - one organism
benefits, other not affected
Competition - competitive
exclusion; winner loser; limited resource
Intraspecies- within same species; Elk vs. Elk
Interspecies- between two different species; Tomato vs. Weeds
Amensalism - one member harmed
but other unaffected; Penicillium and bacteria; off
road driving
Neutralism - hard to come
by; impossible to prove, one cannot assert positively that there
is no relation whatsoever between
two organisms.
Ecological succession (
Objective #14, 15, 16) text pg 340-350
: Process of changing from
one type of community to another
-Intermediate stages leading to climax community are known as seres.
PRIMARY SUCCESSION- plants
and animals develop where none existed before.
Major step is formation of
soil
*difficult to observe because
few places on earth lack communities of organisms
Ex. mountain tops, volcanic
islands
SECONDARY SUCCESSION-
organisms disturbed by a natural or human related
event (hurricane, fire, forest
harvest) and start over at a previous stage.
*Abandoned field, Yellowstone,
(farming expense to prevent)
CLIMAX COMMUNITY-
stable, long lasting community, dependent on physical
environment. (EX. Why
is Western Nebraska primarily grassland? What would it take
to change our grassland
into a temperate forest?)
Successional rates variable
DISCLIMAX COMMUNITY
- succession disturbed or misdirected due to changes in
environmental pressures
Ex. Grassland---> over grazing ---> sagebrush disclimax
CARRYING CAPACITY
(Objective #17, 18)
text pgs 368-374 - maximum # of
consumers which can
be supported by the producers. Limiting factors determine
population size.
-raw materials, energy
available, waste, interactions
Environmental Problems
-industrialized nations
-mother nature
-introduction of foreign species
-Humans ---> naive manipulators