AQA GCSE Geography - Ecosystems

What is an ecosystem?

Where organisms, biotic factors and abitoic fators interact within an environment

What does interdependent mean?

Both sides are equally relying on each other

How many major ecosystems are there?

10

Biome

A group of ecosystems that share similar climates and typical organisms

Biotic factor examples

animals, plants, bacteria prevalence

Abiotic factors examples (4)

Temperature

Oxygen availability

Sunlight intensity

PH of soil

Primary producer

an organism that produces its own food

Primary consumer

An organism that eats producers

secondary consumer

An organism that eats primary consumers

Top carnivore

Carnivore on top of the food chain; no one eats it.

What is a food chain

A linear series of steps in which organisms transfer energy by eating and being eaten

What is a food web

a system of interlocking and interdependent food chains.

Trophic level

Each step in a food chain or food web

Why does biomass decrease along a food chain? (3)

● Energy lost in nitrogenous waste (urine) & faeces.

● Some of the organism is not consumed.

● Energy lost to surroundings as heat.

Humus

material formed from decaying leaves and other organic matter

Why are decomposers important?

Break down dead matter to return nutrients to soil for plant uptake

Inputs of an ecosystem (4)

Energy from sun

Animals immigrate

Precipitation

Rock weathering

outputs of an ecosystem (5)

Animals emigrate

Leaching

Evapotranspiration

Surface run off

Groundwater + throughflow

Flows of an ecosystem (4)

Capillary uptake

Decomposition

Weathering

Respiration

Stores in an ecosystem (3)

Soils

Vegetation

Plant litter

Physical factors that disturb an ecosystem (3)

Extreme weather

Climate change

Disease

Human factors that disturb an ecosystem (5)

Eutrophication (leads to aquatic life death in lakes)

Deforestation (removes habitats)

Pollution (CO2 forms carbonic acid when dissolved, animals may ingest toxic chemicals)

Invasive species (will outcompete locals)

Poaching/overhunting (organisms tropic level above can't get the food they need)

Restoring Ecosystems (6)

- reintroducing animals into a tropic level

- quotas on hunting

- afforestation

- selective breeding

- organic farming

- laws

Nutrient cycling

The circulation of chemicals necessary for life, from the environment (mostly from soil and water) through organisms and back to the environment. (Nitrogen, carbon etc)

Tropical forest

These lie along the equator in Asia Africa and South America. The suns rays are concentrated at this latitude heating moist air which rises and leads to heavy rainfall with little seasonal variation. This means there is permanent evergreen rainforest

Desert

Found close to the tropics of cancer and Capricorn. The air that rises over the equator heads poleward after shedding its moisture as rain. The Sun's rays are still highly concentrated at this low latitude. Combined with the dry air this brings desert conditions to places like the Sahara

Savanna

These are found between desert and rainforest. These are dry for half of the year due to the Hadley cell

Temperate grassland

Short tussocks and feather grasses dominate the landscape between 40 to 60° north of the equator. These areas are in the centres of continents

Chaparral (Mediterranean)

Drought resistant small trees and evergreen shrubs grow between 30 to 40° above and below the equator. Only on the west coast of continents

Temperate deciduous forest

These grow in higher latitudes. Found in Western Europe. The Sun's rays are weaker here and there are frequent rain storms

Coniferous forest

Found at 60° north where winter temperatures are extremely low due to lack of solar insolation. Some months have no sunlight. Trees have needles to reduce moisture loss

Tundra

These areas are found in the arctic circle where the Sun provides little energy. Temperatures are below freezing for much of the year. Only tough short grass is survive in boggy soils where the surface ice melts