The EcosystemUnit 2

Ecosystem FactorsAbiotic Factors

Non-living factors in an ecosystem

Include water, air, light, minerals, soil, temperature, and climate.

Biotic Factors

All living factors in an ecosystem

Include all living organisms, such as plants, animals, fungi, bacteria, and algae.

Trophic Levels

The position an organism occupies in a food chain as a result of its feeding habits.

All organisms in an ecosystem are interlinked by their source of food and the organisms that on them.

Producers are organisms which convert simple abiotic factors into living matter. Most producers are plants which convert water, CO2, and minerals into organic matter using the sun’s energy (Photosynthesis).

This new organic material is called biomass.

Parts of an ecosystem

Consumers

Cannot make their own food and must feed on other

organisms.

Food Chains

•Show the flow of nutrients and food•Arrows point in the direction of the flow

ProducerPrimaryConsumer

SecondaryConsumer

TertiaryConsumer

1. Make a food chain for a pond ecosystem.

2. Make a food chain for an ocean

ecosystem.

3. Make a food chain for a desert ecosystem.

4. Make a food chain for a forest ecosystem.

5. Make a food chain for a mountain

ecosystem.

Practice Problems

Food Webs

Inter-related feeding habits for all organisms in an ecosystem.

Provide a useful snapshot of the relationships in an ecosystem.

Used to predict feeding habits and relationships.

Pyramids!!!!

Pyramids of numbers

•Constructed by counting the

number of organisms at each trophic

level.

•Each level is drawn to scale.

•Samples are used and are

multiplied to represent the entire

ecosystem.

•Give a good representation of the

ecosystem, but do not account for

size.

•One large tree would count the

same as one single-celled diatom in

a pond.

Pyramids of biomass

•Biomass is the measure of mass of all

the organisms at each trophic level.

•Recorded by determining the dry mass

of an organism multiplied by the number

of organisms.

•Organisms must be killed in order

to measure dry mass.

Pyramids of productivity

•The most accurate way to model an ecosystem.•Each level represents energy per unit area per unit time and is measured in mass or energy per square meter.•Show the flow of energy over time.•Each trophic level has a smaller bar than the previous one.•Only about 10% of energy is passed from one level to the next.

Type of pyramid

Advantages Disadvantages

numbers•Quick overview•Comparing numbers in different seasons

•No account for size, so pyramids with large producers are inverted.

biomass•Takes size of organisms into account

•Difficult to measure•Kills organisms•Seasonal variation leads to inverted pyramids•Bone or shell can distort numbers

productivity•Shows energy transfer over time•Easy to compare ecosystems•Never inverted

•Data is difficult to collect over time.•Many species feed at more than one trophic level.

On a large sheet of poster paper, construct three food chains, a food web, a pyramid of numbers, and a pyramid of productivity for one of the following ecosystems. You may need to research some information.

Warm-water ocean Temperate Forest MountainArctic ocean Jungle PrairiePond River DesertLake Tundra Savannah

Assignment

Populations and Ecosystems

Commensalism

One benefits, the other is unaffected.

A species is a group of organisms that can interbreed to produce fertile offspring.

A population is a group of organisms in the same species living in the same area at the same time and are able to interbreed.

Habitat is the environment in which a species usually live.

Key Terms

A niche is the particular environment and lifestyle that a species has.

It includes factors such as the place where it lives, its feeding habits, and its activity patterns and interactions with other species.

A niche is unique to a species.

Two different species cannot occupy the same niche.

A community is a group of populations which live in the same habitat and interact with each other.

Interactions between populations

Competition

Occurs when resources such as food and space are scarce.

HerbivoryHerbivores feed on plants.

One plant may provide food for many organisms.

PredationAn interaction between species in which one species, the predator, kills and eats the other, its prey.

Usually leads to a negative

feedback relationship.

ParasitismA relationship in

which one organism, the

parasite, benefits from another, the

host, which may be harmed.

MutualismTwo organisms that interact in such a

way that both benefit from the

relationship.