Introduction to EcosystemsAims

• To understand what an ecosystem is.

• To learn about a small scale ecosystem (a pond ecosystem)

DefinitionEcosystems are the interaction between the living and the non-

living environment. Ecosystems are the interaction between

plants, animals or people and things such as local relief (shape of

the land), climate, soils and vegetation (plants and trees).

Ecosystems can be identified at different scales. A local

ecosystem may be as small as a pond or a hedge. Larger

ecosystems include lakes or woodlands. Ecosystems found on a

global scale (also called biomes) include tropical rainforests and

deciduous woodlands.

Global ecosystems are known as biomes. The dominant type of vegetation cover usually defines a biome.

There are many different ecosystems in the world. We are going to study 3:• Temperate Deciduous Woodlands • Tropical Rainforests• Hot deserts

The main factor that influences the distribution (where they are found) of each ecosystem is climate.

Each ecosystem has a different soil depending on the climate and vegetation.

The Climate of the World’s Major Ecosystems

Ecosystem Climate description

Temps

winter + summer

Rainfall winter + summer

TRF Hot and wet all year.

27–30oC. Wet all year. TAP = 2000-3000mm.

Hot Desert Very hot most of the year.

Above 30oC. TAP below 250mm.

Mediterranean Hot summers. Mild/warm winters.

Summers about 25oC. Winters about 10oC.

Dry in summer. Wet in winter. TAP = 750mm.

TemperateDeciduous Woodland

Warm summers. Mild/cold winters.

Summer about 18oC. Winter about 5oC.

Precipitation all year. TAP = 1000mm.

Coniferous Woodland

Warm summers. Very cold winters.

Summer 16-20oC. Winter = below freezing.

Mainly in summer. TAP = low (below 500mm).

Savanna Grasslands

Hot all year. 25-35oC. Variable rainfall totals but always a drought period. TAP =500-1000mm.

Location of the global ecosystems

A Food Chain

A food chain is a line of linkages between producers and

consumers. It always begins with a plant.

A Freshwater Pond Food Chain

Heron

Fish

Great Diving Beetle

Midge Lava

Detritus (decaying leaves)

Con

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sPro

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A Food Web

A food web is more complex than a food chain. It is a diagram that

shows the linkages between producers and consumers in an

ecosystem.

Food chains and food webs both show the transfer of energy

through an ecosystem.

A Freshwater Pond Food Web

Heron

Worms

Algae and microscopic plants

Mayfly

Great diving beetle

Stonefly

Fish

Kingfisher

Midge larva

Caddis

Dragonfly

Detritus

Blackfly

The Impact of Change on the Freshwater Pond Ecosystem

The number and the types of species in an ecosystem can change

over time and these changes often have impacts in other parts of

the ecosystem. Changes can be caused by natural or human

factors.

Natural Factors• Changes in the environment may occur through floods, fires and

drought.

Human Factors• Changes in drainage basins• Depletion of fish stocks• Deforestation• Increased human use for timber and land for settlements and

farmland (e.g. in the Tropical Rainforests).