ECOSYSTEM
An ecosystem is formed by the interactions between all living and non-living things
How do living and non-living things interact in an environment?
The earth can be divided into layers:
Atmosphere:Trophosphere – goes up 11 miles,
greenhouse contains ozone
Stratosphere – ozone layer, filter out harmful UV rays
Hydrosphere: all the ice, H2O, and H2O vapor
Lithosphere: the land (crust/mantle)
What sustains life on earth?
The one-way flow of high-quality energy
The cycling of matter or nutrients
Gravity
Allows the planet to hold onto its atmosphere
Causes the downward movement of nutrients
Ecosystem Function
1. Energy flow in an ecosystem is
represented by a food web.
2. Nutrients are recycled within an ecosystem.
Water * NitrogenCarbon * PhosphorusOxygen * Sulfur
Ecosystems:
Fundamental CharacteristicsStructure:
Living (biotic)
Nonliving (abiotic)
Process:
Energy flow
Cycling of matter (chemicals)
Change:
Dynamic (not static)
Succession, etc.
ABIOTIC components:
Solar energy provides practically all the energy for ecosystems.
– water
– temperature
– wind
– sunlight
– soil
BIOTIC componentsThe biotic components of an ecosystem can be classified according to their mode of energy acquisition.
Ecology is
The study of the distribution and
abundance of organisms,
AND
the flows of energy and materials
between abiotic and biotic
components of ecosystems.
Organism
Organism
PopulationPopulation
• A population is a group of the same
species that lives in one area.
Organism
Organism
Population
Population
Community
Community
• A community is a group of different
species that live together in one area.
Organism
Organism
Population
Population
Community
Community
Ecosystem
Ecosystem
• An ecosystem includes all of the organisms as
well as the climate, soil, water, rocks and other
nonliving things in a given area.
Organism
Organism
Population
Population
Community
Community
Ecosystem
Ecosystem
Biome• A biome is a major regional or global community of
organisms characterized by the climate conditions
and plant communities that thrive there.
Observation is the act of carefully watching something over time.
Observations of populations can be done by visual surveys.
Ecological research methods include
observation, experimentation, and modeling.
– Direct surveys for easy to spot species
employ binoculars or scopes.
– Indirect surveys are used for species
that are difficult to track and include
looking for other signs of their presence.
Modified from: General Ecology, by David T. Krome
Trophic level: All the organisms that are the same number of food-chain steps from the primary source of energy
Niche vs habitat
A habitat is wear an organism lives. The habitat must
provide a source of food, water and shelter for the
organism.
Niche is the role of the organism. This is largely to do
with the trophic level of the organism.
For example: plants produce food for the rest of the
food chain. Tigers keep herbivore populations under
control.
Trophic Levels
A trophic level is the position occupied by an organism in a food chain.
Trophic levels can be analyzed on an energy pyramid.
Producers are found at the base of the pyramid and compromise the first trophic level.
Primary consumers make up the second trophic level.
Secondary consumers make up the third trophic level.
Finally tertiary consumers make up the top trophic level.
Trophic Levels Found on an Energy Pyramid
The greatest amount
of energy is found at
the base of the
pyramid.
The least amount of
energy is found at
top of the pyramid.
BiomassEnergy is sometimes considered in terms of
biomass, the mass of all the organisms and organic
material in an area.
There is more biomass at the trophic level of
producers and fewer at the trophic level of
tertiary consumers. (There are more plants on Earth
than there are animals.)
Bio=life Mass=weight
Bio + Mass = Weight of living things within an
ecosystem.
Food Chains The producers, consumers, and decomposers of each
ecosystem make up a food chain.
There are many food chains in an ecosystem.
Food chains show where energy is transferred and
not who eats who.
Trophic levels in food chains
Be able to give an example of each!
Primary producers (autotrophs)
Primary consumers (herbivores)
Secondary consumers (carnivores)
Tertiary consumers (top carnivores)
Decomposers
Detrivores
Scavengers
Ecosystem Structure:
the living components of an ecosystem
The roles of organisms in an ecosystem:
Producer (autotrophs): make food; plants, algae
Consumer (heterotrophs): eat other organisms
Decomposer: eat dead organic matter; bacteria
and fungi
Role of Organisms
Scavengers – feed on dead organisms (vultures, flies, crows, lobsters)
Detritus feeders – organisms that extract nutrients from fragments of dead organisms into more simple organic waste (termites, earthworms, crabs)
Decomposers – organisms that digest parts of the dead organisms into simplest chemicals (bacteria, fungi)
Role of organisms
Classes of Consumers
Herbivore – primary consumer – eats plants
Carnivores – secondary–meat eaters; eat herbivores
Tertiary – feed on carnivores
Omnivores – eat plants/animals
Keystone species form and maintain a complex web of life.
creation of
wetland
ecosystem
increased waterfowl
Population
increased fish
populationnesting sites
for birds
keystone species
Limiting factors
An abiotic factor can limit the population size if there is too much or too little of it. Even if there is the right amount of other factors
Examples to consider:
Sunlight
Precipitation
Salinity
Nutrients in the soil
Parasitism
Parasitism is the
situation where one
organism benefits
while the other is
harmed.
A + / - relationship.
Think of a friendship
where you might feel
used by your friend. Parasitic Isopod on fish
Bedbugs Bedbugs are small,
nocturnal parasites that come out of hiding at night to feed on unsuspecting humans. They feed exclusively on blood! Their bites often result in an allergic reaction.
Parasitism: one benefits, one is harmed
Taenia worm in human eye
Worm infects
human blood
stream
Human may go
blind
Commensalism
Commensalism is whereone species benefits whilethe second speciesremains unaffected.
A + / 0 relationship
Think of a friendship where one of the friends benefits while the other doesn’t change.
Barnacles adhering to the skin of a whale
Commensalism: one benefits, one is unaffected
Cattle with cattle egrets
Cattle stir up
insects as
they eat
grass
Egrets hang
around and
eat insects
Neutralism is the situation where both species remain unaffected.
A 0 / 0 relationship.
Think of someone you sit beside but never show any emotional either positive or negative.
Neutralism
Neutralism the most common type of
interspecific interaction. Neither population
affects the other. Any interactions that do occur
are indirect or incidental.
Example: the tarantulas living in a desert and
the cacti living in a desert
Competition is where neither species benefits.
A - / - relationship.
Think of someone whom you are constantly at battle with.
COMPETITION: Scramble (Indirect) vs. Contest (Direct)
Scramble: mutual use of limited resource
-Most plant competition is of this form
Contest: interact directly (direct aggression or display)
Competition can be defined as an interaction
between organisms or species, in which
the fitness of one is lowered by the presence of
another.
Limited supply of at least one resource (such
as food, water, and territory) used by both is
required. Competition is one of many interacting
biotic and abiotic factors that
affect community structure
intraspecific competition -
Competition among members of
the same species
interspecific competition.
competition between individuals of
different species is known as
Amensalism between two species involves one
impeding or restricting the success of the other while the other
species has no effect on it.
Do you know that there are organisms that may live
together only for sometime
because one species secrete a toxic or lethal substance that
could kill the other species?
Are you familiar with some of them? A certain species of
Artemisia (damong maria) secrete
a substance that can kill the grasses that may grow around
them. This is an example of
amensalism.
It is a type of symbiosis. Usually this occurs when
one organism exudes a chemical compound as part of its
normal metabolism that is detrimental to another organism.
The bread mold Penicillium is a common example of this;
penicillium secrete penicillin, a chemical that kills bacteria.
A second example is the black walnut tree (Juglans
nigra), which secrete juglone, a chemical that harms or
kills some species of neighbouring plants, from its roots.
This interaction may still increase the fitness of the non-
harmed organism though, by removing competition and
allowing it access to greater scarce resources. In this
sense the impeding organism can be said to be negatively
affected by the other's very existence, making it a +/-
interaction.
A third simple example is when sheep or cattle make
trails in grass that they trample on, and without realizing,
they are killing the grass.
Since one of the characteristics of fungi is that
they are unable to produce their own food by
photosynthesis, due to the lack of choloroplasts,
they obtain their food from other organisms. They
also do not have mouths to take in food as
animals do, therefore they absorb food through
their plasma membranes and cell walls. One of
the types of such heterotrophic food intake
methods is saprophytism
Saprophytism
Effects and examples
They break down wastes from dead organic matter
and thereby enabling the constituent materials to be
available for reuse by other organisms within the
ecosystem.
dry rot, which occurs in wooden houses, and other
wooden structures, causing the wood to deteriorate
and the structure to fall apart
Cooperation Helping same kind of organisms or organisms of different
kind to get food.
Example: Ants in a colony
honeybee colony where the member
carry out and follow specific task
rigidly and work together for benefit
of the group
X
Y Type of interaction
0 0 Neutralism
- 0 Amensalism
+ 0 Commensalism
- - Competition
+ + Mutualism
+ - Predation orParasitism