Lesson 1: Introduction to Ecosystems

The Spheres of the Earth

understand how ecosystems change and how they are sustained

investigate factors that affect ecosystems

analyze issues that affect the sustainability of ecosystems

In this unit, you will be able to

Earth is the only planet in our solar system that is able to sustain life….and such a wide diversity of life.

What allows Earth

to sustain life?

The Spheres of Earth

a thin gaseous layer swirling with clouds that is held near Earth’s surface because of the force of gravity. It is made of about 78% nitrogen and 21% oxygen gas.

The remaining <1% of the atmosphere includes argon, water vapour, carbon dioxide, and a variety of other gases.

The atmosphere acts like a blanket and

moderates surface temperatures.

The atmosphere also blocks some

incoming solar radiation,

protecting Earth’s species.

The Atmosphere

the rocky shell of Earth

The Lithosphere

consists of all the water on,

above, and below

Earth’s surface

Nearly all the water

on Earth (97%)

is contained in the oceans

The Hydrosphere

Together, the atmosphere, hydrosphere and lithosphere make up the biosphere (the locations in which life can exist).

The Biosphere

The 4 Spheres of Earth

Physical Processes

In the 1960’s, scientist James Lovelock

proposed the Gaia hypothesis. He suggested

that the Earth was capable of responding to

changes in its environment and maintaining

relatively consistent internal conditions

over long periods of time…

just like a living cell.

Gaia Hypothesis

An ecosystem is defined as all of the living (biotic) as well as non-living (abiotic) factors in the environment.

Biotic Factors Abiotic Factors

-insects, bacteria, animals, plants -temperature, wind, water, air

Ecosystems

Abiotic factors influence

Abiotic factors affect distribution of species

● Temperature

● Water

● Sunlight

● Wind (increases heat and water loss)

● Rocks and soil

● Amount of oxygen in the water

● Acidity (soil, water)

Non-Living Parts of Your Community (Abiotic)

An ecosystem is formed by the interactions between all living (biotic factors) and non-living things (Abiotic factors) in an area.

An ecosystem may include many communities with different populations.

What is a POPULATION?

• a population is one species living in a specific area

• for example, all foxes living in an area form a population

• another example, all dandelions growing in an area form another population

Ecosystems

What is a COMMUNITY?

A community is formed from all living populations found in an area.

All the foxes, dandelions, grasshoppers, snakes, hawks, deer and skunks living in one area each form their individual populations, but together make up a community.

Ecology: the study of how organisms interact with each other and their environment (the study of ecosystems)

Habitat: the specific region of space in which an organism or group of organisms live

Species: includes only one type of organism (ex: pigeon)

Population: includes all members of one species that live in the same area (ex: all pigeons living in Hamilton)

Community: includes all the different species that live in the same area (ex: all the pigeons, ants, maple trees, dogs, etc… that live in Hamilton)

Ecosystem: includes the community (all the living species or biotic components) as well as the abiotic components (heat, sunlight, minerals, water)

Key Terms

Levels of Organization

What is an Ecosystem?an ecosystem includes all of the living things in an area, plus their surroundings, plus all

the ways in which they interact with each other

Remember that in real life, no ecosystem can truly be isolated from the other ecosystems surrounding it or including it.

For example, a lake’s ecosystem is related to the ecosystem of the stream that feeds it, the stream’s ecosystem is related to the forested mountain side through which it runs, and perhaps the forest’s ecosystem has been influenced by a nearby forest fire...and so on.

Lesson 1 Support Questions

What is an Ecosystem?1. Choose an ecosystem. Create a web of ecosystems that are joined to yours. Put your

chosen ecosystem at the centre, then list the larger ecosystem of which it is a part, and then list two or three smaller ecosystems that occur within your chosen ecosystem.

2. Thinking of your chosen ecosystem list 3-5 biotic factors that influence your ecosystem. List 3-5 abiotic factors that influence your ecosystem.

3. Identify 3 organisms that live on or in the lithosphere, three organisms that live in the hydrosphere and 3 organisms that live in the atmosphere.

4. Do you agree or disagree with Lovelock’s Gaia hypothesis? Support your answer with an explanation.

Lesson 1 Support Questions

• Mountain Forest

• Tundra

• Boreal Forest

• Grassland

• Temperate Deciduous Forest

• Desert

• Coniferous Forest

• Tropical Forest

Terrestrial Biomes

• Freshwater Ecosystemso Wetlandso Watershedso Rivers, streams, lakes

• Intertidal Zone

• Marine Ecosystemso coral reefso estuarieso mangroves

Aquatic Biomes

Tropical Forest: Vertical stratification with trees in canopy blocking light to bottom strata. Many trees covered by epiphytes (plants that grow on other plants).

Desert: Sparse rainfall (< 30 cm per year), plants and animals adapted for water storage and conservation. Can be either very, very hot, or very cold (e.g. Antarctica)

Temperate Grassland: Marked by seasonal drought and fires, and grazing by large animals. Rich habitat for agriculture.

Temperate Deciduous Forest: Mid-latitudes with moderate amounts of moisture, distinct vertical strata: trees, shrubs, herbaceous sub-stratum. Loss of leaves in cold, many animals hibernate or migrate then.