Geography AQA A2 Ecosystems listening notes part 1

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It is a system made up of living things and non-living things, biotic and a biotic

Non living (a biotic) such as:

·         Underlying rock

·         Soil characteristics

·         Water

·         Relief of the land

·         Climate

·         Drainage

Living (biotic) need a biotic to survive such as

·         Plants

·         Animals

·         Micro organisms

·         Decomposers: an organism which takes the remains of dead plants and animals also their excrement and converts it into carbon dioxide and nutrients.

Inputs outputs and stores in a ecosystem

Inputs in to an ecosystem:

·         Photosynthesis, where green plants use light, water and Carbon dioxide to create food for the plant. Plants that do this are called autotrophs

·         Animals migrating into the area

·         Rock weathering, as this helps produce the soil and nutrients

·         Precipitation

·         Soil weathering this helps create nutrients for the plants

Stores in ecosystems:

·         Biomass, this is the living organism within a ecosystems

·         Carbon  in the ground as peat etc

·         Water is stored in the soils, plants and on top of the ground

Outputs in an ecosystem

·         Drainage

·         Transpiration

·         Animal migrate out

Energy flow in an ecosystem

The sun is the main driving force behind all ecosystems  as it provides all the heat for the ecosystem and so heats up plants in their a biotic environment, the sun also drives the flow of the ecosystems such as the water cycle. It also provides the light needed for a plant to photosynthesise to provide food for the plant

The plant then gets consumed by the primary consumer (herbivore) and then secondary consumers (carnivore) and then to other organisms. This is a flow of energy in an ecosystem and is called a food chain, each stage of the food chain is known as a trophic level such as plants are trophic level 1 and primary consumers are trophic level 2 etc. The movement up the trophic level means a loss in energy of 90% through things like movement, reparation etc. This means that as you move up the food chain there is less and less consumers at each trophic level.

The nitrogen cycle

This is needed for the construction of plant and animal matter as it is needed in the making of amino acids which makeup DNA. It is present in the atmosphere as it makes up about 78 percentage of air. Plants get nitrogen from soil or water in which they grow and animals get their nitrogen from eating plants or other animals. When organisms die their bodies decompose bringing nitrogen back into the soil. Bacteria in the soil change the nitrogen to ammonium then to nitrates they can also change it back into nitrogen.

The nutrient cycle

This shows the transfer of nutrients between the stores of nutrients Biomass, litter layer and the soil. They are transferred


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