EcosystemsBiological Life Science

What is an ecosystem?System = regularly interacting

and interdependent components forming a unified whole

Ecosystem = an ecological system;= a community and its physical environment treated together as a functional system

Ecosystem Unit of biosphere consisting of

interacting biotic and abiotic factors. Biotic Factors: Living physical factors of

an environment. Organisms, parasites, predation, etc.

Abiotic Factors: Non-living physical factors of an environment. Air, sunlight, water, pressure, etc.

Habitat: The physical location in which an organism lives.

Niche: The way of life of an organism (species). Includes: Habitat, feeding

habits, reproductive behavior, etc.

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Parts of the Biosphere

1. Species – a group of organisms that can reproduce (Ex – humans).

2. Population – The number of a species in a given area (Ex – all the humans living in Dresden).

3. Community – All the species in a given area (Ex – the humans, trees, grasses, bacteria, squirrels, mice….. Living in Dresden.)

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Parts of the Biosphere4. Ecosystem – The community and all

the nonliving things in an area (Ex – all the plants, animals, bacteria, fungi and protists, plus the air, water, and climate of Dresden).

5. Biosphere – The area on the Earth that supports life (includes the bottom of the oceans to the upper atmosphere).

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Parts of the Ecosystem

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Competition Since resources will eventually run out,

organisms have to compete for it.

Can be between members of the same species (Ex – Polar Bears have to compete for fish to eat). Intraspecific competition

Can be between members of a different species (Ex – a robin and a woodpecker might compete over a tree to build a nest in.) Interspecific competition

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Niche Niche – the role an organism plays in

the environment (Ex – The Great White Shark is the top consumer in some marine ecosystems.)

If two organisms occupy the same niche they will compete for resources until one species is forced out.

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Carrying Capacity The maximum number of individuals an

ecosystem can support is the carrying capacity.

Once the carrying capacity is met, limiting factors (such as space, food, shelter) keeps the population size near this carrying capacity.

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Carrying Capacity

Time

# Of Individuals

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Predator – Prey RelationshipsPredators Can Control the Prey

Population Predators help control the prey

population (Since there are few predators of Deer left in New York State, their population size is out of control).

If there are no natural predators the prey become overpopulated.

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Predator – Prey RelationshipsPrey Populations Can Control the

Size of Predator Populations If there are few prey in an area, a small

number of predators can survive. If there are many prey in an area, more

predators can survive.

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Predator-Prey RelationshipsThe Predators and Prey May Have No

Relationship If the predators rely on many sources of

food, one disappearing may have little effect (Ex – If cows go extinct we might have to eat more chicken, but humans would still survive.)

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Predator-Prey Relationship Example

Moose Wolves

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Food ChainsParts of the Food Chain

1. Producers – (Autotrophs) make their own food from abiotic factors (Ex – Green plants make glucose by photosynthesis.)

2. Herbivores – Consumers that eat only plants. (Ex – rabbits eat crops and other plants)

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Food Chains3. Carnivores – Eat only other

consumers (Ex – lion). 4. Omnivores – Eat plants and animals

(Ex – Humans).5. Detrivores – (Decomposers) Feed off

of and break down dead organisms. These are usually bacteria and fungi.

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Energy Pyramid

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Food Pyramid Relationships

Biomass Pyramid Measures the amount of material at

each trophic level.

Like the Energy Pyramid, the larges biomass is at the base (producers) and it decreases as you move up the pyramid.

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Biomass Pyramid

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Food Pyramid RelationshipsPyramid of Population Size

The third pyramid shows the number of individuals at each trophic level.

Life the other two pyramids, the largest population is at the base (producers) and decreases as you move up the pyramid.

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Pyramid of Population Size

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Energy PyramidShows the relative amount of energy available at each trophic level. Organisms use about 10 percent of this energy for life processes. The rest is lost as heat.

Pyramid of NumbersShows the relative number of individual organisms at each trophic level.

Biomass PyramidRepresents the amount ofliving organic matter at each trophic level. Typically, thegreatest biomass is at the base of the pyramid.

Summary of the Pyramid Relationships

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.

Antarctic Food Web

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.

Trophic Structure Reminder Eltonian pyramids Number of individuals per species Is this pyramid stable?

Trophic Structure Reminder What if we transformed each species

into biomass instead of absolute numbers?

Biomass Energy 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.

Trophic Structure Reminder

•Express trophic structure as energy transfer

•Energy pyramids can never be inverted

•Is there room for anyone else

at the top of this food chain?

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Biological Magnification If a poison is introduced into an ecosystem, it

will affect each level of the food chain more severely.

Each level of the food chain will have more individuals affected.

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Biological Magnification

Accidental IntroductionsZebra Mussel – from Caspian Sea to Great

Lakes (1986) from a ship Now they are everywhere!!! Problem: clogs water pipes, smothers native clams,

consumes plankton, no natural predatorsKiller Bees – genetically altered to make

more honey Africanized bees escaped and took over Brazilian

honeybees Problems arose: they are more aggressive, can

travel longer distances, swarm, attack people The real threat? Agriculture

More Invasive Species Asian Carp

Introduced in 1970s No natural predators Out compete native fish

and mollusks for food Snakehead Fish

Early 2000s No natural predators Eat mostly other fish Can breathe air

4 days out of water

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Nutrient RecyclingWater Cycle - Earth’s water supply is

constantly recycled throughout the biosphere:

Evaporation – water vapor leaves the oceans and joins the atmosphere.

Transpiration – water vapor evaporates off of plant leaves.

Condensation – water vapor in the atmosphere forms clouds.

Precipitation – water vapor in the atmosphere falls to the ground (rain.)

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Nutrient Recycling

CO2 and O2 Cycle Photosynthesis and Cellular Respiration work

together to recycle carbon dioxide and oxygen in the atmosphere.

Photosynthesis – in plants, uses up CO2 and produces O2 as a waste.

Cellular Respiration – in consumers, uses O2

and produces CO2 as a waste.

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Nutrient RecyclingNitrogen Cycle

The Nitrogen in the atmosphere is made usable for living things through Nitrogen Fixation.

Plants use this nitrogen in the soil to make protein. This is assimilation.

Once the plants and organisms that eat the plants die, decomposers break down the remains and return the nitrogen to the soil and the atmosphere.

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Ecological Succession As organisms live in a given area, they

change their environment.

As the environment changes, so do the organisms that can live there.

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Ecological Succession Primary Succession – a pioneer organism first

grows on a bare rock surface (Ex – Hawaiian Islands)

Secondary Succession – after a disaster (fire, drought) succession begins again at an intermediate stage (Ex – Pine Barrens of Long Island).

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Human Effects on the EnvironmentNegative Effects:1. Urbanization2. Industrialization3. Agriculture4. Exploitation of Wildlife5. Deforestation

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Greenhouse Effect

Carbon Dioxide and other Greenhouse gases trap the suns energy in our atmosphere to keep the earth within a range of suitable temperatures for the survival of the present organisms

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Global Warming By burning fossil fuels (use of automobiles,

electricity, home heating) carbon dioxide is released as a waste gas.

At the same time we are cutting down trees which would have used up the Carbon Dioxide.

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Global Warming As a result, Carbon

Dioxide levels increase, trapping MUCH MORE heat from the sun and gradually causing the Earth to warm up.

Global Warming could cause sea level to rise, habitats to be destroyed, draught, and mass extinction.

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Acid Rain Air pollution in the atmosphere

combines with rain water, lowering the pH of the rain.

The resulting acid rain damages freshwater ecosystems, and there is evidence linking it to extinctions of many amphibian species.

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Ozone Layer Depletion The ozone layer is part of the upper

atmosphere and blocks harmful rays of the sun.

The release of CFC’s from aerosol cans and other sources of air pollution interact with the atmosphere and deplete the ozone layer.

If the ozone layer is destroyed, harmful rays from the sun would cause catastrophic mutations and would threaten all life on Earth.

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Positive Human Influences

Conservation of Resources Recycling Pollution Controls Decreasing our dependence on fossil

fuels.