What is ecology? Ecology is the study of interactions between
living things and between living and non living things
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What are abiotic factors? Abiotic factors include all the non
living things that living things interact with For example the sun
provides energy, carbon dioxide and water are needed for
photosynthesis. Oxygen is required for cell respiration. Sun,
water, carbon dioxide, oxygen are all abiotic factors.
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What are biotic factors? Biotic factors include all the living
things and once living things.
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What are the levels of Ecological organization? Populations-A
group of organisms of the same species that can mate, produce
fertile offspring, and live in same location. Community-A group of
interacting populations living in the same area (includes only
biotic factors). Ecosystems-Community (all the living) plus all
abiotic factors in a particular location.
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Energy flow in an ecosystem All organisms require energy Solar
energy provides practically all the energy for ecosystems. Living
things in an ecosystem can be classified according to how they
obtain energy- autotrophs or heterotrophs. Autotrophs convert
energy from the sun into chemical energy stored in the bonds of
organic molecules (photosynthesis).
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Energy Flow continued Heterotrophs cant produce their own food
directly from sunlight and inorganic compounds. They require energy
previously stored in organic molecules. Autotrophs are called
primary producers Heterotrophs can be grouped as consumers or
decomposers Consumers can be herbivores, carnivores, omnivores or
detritvores-invertebrates that feed on organic wastes and dead
organisms. Energy flow is one directional moving from sun to
producers to consumers to decomposers and eventually lost as heat
(cant be reused).
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What is a food chain? A food chain is a simple model that shows
how energy and nutrients move through an ecosystem. A food chain is
composed of feeding levels called trophic levels
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What are the trophic levels? First trophic level are the
primary producers- make their own food Second trophic level are the
primary consumers- obtain food by eating producers. They are
considered herbivores because they eat only plants. Third trophic
level- are the secondary consumers- obtain food by eating primary
consumers. They are considered carnivores if they eat meat or
omnivores if they eat meat and plants.
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What are the trophic levels-continued Fourth trophic level-are
the tertiary consumers-obtain their food by eating secondary
consumers. Decomposers are considered a trophic level but have no
number because they feed on other trophic levels. Break down dead
material into inorganic material. Bacteria and fungi are the main
decomposers.
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Energy flow in an ecosystem
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Food chains
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What is the amount of energy available at each trophic level?
90% of energy lost in each trophic level Producers (1 st trophic
level) get 100% of energy available. Primary consumers (2 nd
trophic level) get 10% of available energy. Secondary consumers (3
rd trophic level) get 1% of available energy. Tertiary consumers (4
th trophic level) get 0.1% of energy available.
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Energy available continued Thus the amount of energy available
limits the food chain to 4-5 links. The greatest amount of energy
is in the first trophic level and the least amount of energy is in
the higher trophic levels More efficient to feed at lower trophic
levels
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Ecological pyramids Ecological pyramids are models that show
amounts at each trophic level and the change from level to level.
Energy pyramids show the amount of energy at each trophic level.
Biomass pyramids show the amount of biomass (dry weight of living
tissue) at each trophic level Numbers pyramid shows the number of
organisms at each trophic level.
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Energy pyramid Shows that each higher trophic level must have
less energy than lower levels due to loss of energy as heat (via
cell respiration) at each level.
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Numbers pyramid Numbers pyramid indicates the number of
individuals in each trophic level. Sometimes get inverted numbers
pyramid. For example one tree can support many consumers. Energy
pyramids can never be inverted.
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Biomass pyramid Pyramid of biomass shows amount of biomass at
each trophic level. Cant be inverted.
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What is a food web? A group of interconnecting food chains.
Shows all the possible feeding relationships in an ecosystem. More
realistic than a food chain since most organisms feed on more than
one thing.
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FOOD WEB
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Nutrients also move through ecosystems Nutrients move through
ecosystems vias trophic levels Unlike energy, nutrients are
recycled Nutrient cycles include the water cycle, carbon cycle,
nitrogen cycle, and phosporus cycle
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Water Cycle Evaporation Transpiration-Leaf sweating
Condensation Precipitation Runoff
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Carbon Cycle Atmospheric carbon dioxide (burning fossil fuels
and cell respiration) Death and decay result in fossil fuel
formation Photosynthesis (remove carbon dioxide from air and move
carbon to glucose housed in living things).
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Carbon Cycle
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Nitrogen cycle Bacteria capture nitrogen and bring it into
living things Different bacteria return nitrogen back to
atmosphere.
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Community ecology focuses on interactions between organisms
Types of interactions include Competition Predator-prey
Symbiotic
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Competition Increases between specie swhen resources are scarce
Niche is the role in plays in an ecosystem (how does it meet its
food need?, Shelter? How and where it survives? how and when it
reproduces?) Habitat is location that it lives. Habitat is one
small part of an organisms niche.
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Competitive exclusion principle States that no two species can
occupy the same niche at the same time. Possible outcomes include
extinction of one species or resource partitioning-splitting up of
niche
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Predator-Prey Relationships A predator eats prey Since no
community can carry more organisms than its food, water, and
shelter can accommodate it must stay in balance. Ecosystems will
fail if they do not stay in balance. To stay in balance predators
and prey develop adaptations-any inherited behavior or structure
that provides a survival advantage in a particular
environment.
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Predator-prey continued Predator adaptations include teeth,
claws, fangs, poison, heat sensing organs, speed and agility
Outcomes of predator-prey interactions include offset oscillations
in the population sizes of the predator and prey-as the predator
population increases the prey population decreases, as the prey
population decreases the predator population decreases, as the
predator population the prey population increases causing the
predator population to increase.
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Predator-prey continued Another outcome may be co-evolution of
predator prey. Each acts as a selective pressure on the other for
adaptations. Each adapts to changes in the other.
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Symbiosis (living together) A close and permanent relationship
between two organisms of different species Three types of symbiotic
relationships- mutualism, commensalism, and parasitism
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Mutualism AAAAA symbiotic symbiotic relationship where both
species benefit e.g. 1. Clown fish and sea anemone 2. Humans and
pets 3. Ants & Peony flowers 4. Lichens algae and a fungus
MUTUALISM - a symbiotic relationship where both species
benefit
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Commensalism A symbiotic relationship in which one species
benefits and the other is neither helped nor harmed.
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Parasitism A symbiotic relationship where one organism benefits
and the other is harmed.
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Succession
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Both the biotic or living and the abiotic or non- living
components of an ecosystem change over time. Will this landscape of
rocks remain this way forever?
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The answer is, NO! Over the years, one kind of community is
replaced by another kind of community until eventually, a stable
community develops. The gradual change in a community is known as
succession.
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Two Types of Succession Primary Succession: The process of
creating life in an area where no life or soil previously existed.
Secondary Succession: The process of re- rebuilding a previously
existing community after being destroyed by some disaster like
fire. Soil exists.
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Primary succession The development of an ecosystem in an area
that has never had a community living within it occurs by a process
called PRIMARY SUCCESSION. An example of an area in which a
community has never lived before, would be a new lava or rock from
a volcano that makes a new island.
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Primary Succession Begins in a place without any soil Sides of
volcanoes Receding Glaciers Starts with the arrival of living
things such as lichens that do not need soil to survive. Called
PIONEER SPECIES Lichen is a classic Pioneer species
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Pioneer Organisms Primary succession on land begins in an area
where there are no living things and no soil. The first plants or
plant-like organisms that arrive are called pioneer organisms. They
can grow on bare rock without soil eventually breaking it up and
helping soil to form. These include lichens and algae.
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Modification of the environment Soil starts to form as lichens
and the forces of weather and erosion help break down rocks into
smaller pieces. When lichens die, they decompose, adding small
amounts of organic matter to the rock to make soil
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Creation of New Soil Creation of soil allows plants to
grow.
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Primary Succession Simple plants like mosses and ferns can grow
in the new soil
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Primary Succession The simple plants die, adding more organic
material. The soil layer thickens, and grasses, wildflowers, and
other plants begin to take over. Then These plants die, and they
add more nutrients to the soil. Shrubs and tress can now survive
now.
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Primary Succession Insects, small birds, and mammals have begun
to move in. What was once bare rock now supports a variety of
life.
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Pictures of Succession One sequence of plant succession in New
Jersey might be lichens----then----grasses--- shrubs----conifers
(pine trees)----deciduous forests(beech and maple trees).
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Climax Community Succession ends with the development of a
climax community. Here, the plants and animals exist in balance
with each other and the environment. For example, in New Jersey a
hemlock-beech-maple forest is a climax community. Animals that
reside here include, chipmunks, deer, bear, turkeys, rabbits,
squirrels, fox, birds, to name a few!
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Typical New Jersey State forest
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Animals in a hemlock, beech, maple forest
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Animals found in a TYPICAL New Jersey State forest
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Climax communities are stable The climax community will exist
indefinitely without further change, unless something catastrophic
occurs. A volcanic eruption or a forest fire, will alter and
possibly destroy the climax community. Then, ecological succession
begins again and after many years, a new climax community will
develop.
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Secondary Succession Begins in a place that already has soil
and was once the home of living organisms Occurs faster and has
different pioneer species than primary succession Example: after
forest fires
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Secondary succession SECONDARY SUCCESSION begins in habitats
where communities were entirely or partially destroyed by some kind
of damaging event. When an existing community has been cleared by a
disturbance such as a fire, tornado, etc...and the soil remains
intact, the area begins to return to its natural community. Because
these habitats previously supported life, secondary succession,
unlike primary succession, begins on substrates that already bear
soil. In addition, the soil contains a native seed bank. Since the
soil is already in place, secondary succession can take place five
to ten times faster than primary succession.
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Why Does Ecological Succession Occur? Organisms alter their
environment Organisms become less suitable for environment New
organisms better adapted to changes in the environment come in and
out compete original organisms
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A Summary of Changes That occur During Succession Pioneer
species colonize a bare or disturbed site. Soil building. Changes
in the physical environment occur (e.g., light, moisture). New
species of plants displace existing plants because their seedlings
are better able to become established in the changed environment.
Newly arriving species alter the physical conditions, often in ways
that enable other species to become established. Animals come in
with or after the plants they need to survive. Eventually a climax
community that is more or less stable will become established and
have the ability to reproduce itself. Disturbances will start the
process of succession again.
Slide 62
Does Ecological Succession Ever Stop? No Do Humans Affect
Ecological Succession?
