ESS: 2.3 - Flows of energy and matter

pathways of energy through an ecosystem

conversion of light energy to chemical energy

transfer of chemical energy from one trophic level to another

conversion of ultraviolet and visible light to heat energy

re-radiation of heat energy to the atmosphere

ecological efficiency

the percentage of energy transferred from one trophic level to the next

ecological efficiency equation

ecological efficiency = new biomass/energy supplied x 100

how is energy lost from one trophic level to the next?

through respiration, movement, faeces, inedible part

Gross Productivity (GP)

The total gain in energy or biomass per unit area per unit time

Net Productivity (NP)

The gain in energy or biomass per unit area per unit time after respiratory losses

Primary productivity

the gain by producers in energy or biomass per unit area per unit time

Secondary productivity

the biomass gained by consumers through feeding and absorption, per unit area per unit time

Gross primary productivity (GPP)

The total gain in energy or biomass per unit area per unit time from photosynthesis in green plants

Net primary productivity (NPP)

The gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses

NPP = GPP - R

Gross secondary productivity (GSP)

The total gain by consumers in energy/biomass per unit area per unit time through absorption

GSP = food eaten - faecal loss

Net secondary productivity (NSP)

The gain by consumers in energy/biomass per unit area/per unit time remaining after respiratory losses

NSP = GSP - R

Sustainable yield

the highest rate of harvesting that does not diminish/reduce the natural capital

explain the role of consumers in ecosystems

they pass energy and biomass through a food chain

explain the role of producers in ecosystems

they make their own food (glucose) and convert inorganic molecules into organic molecules

explain the role of decomposers in ecosystems

they are essential for recycling matter, including elements such as nitrogen and carbon, in ecosystems

organic storages in the carbon cycle

organisms and forests

inorganic storages in the carbon cycle

the atmosphere, soil, fossil fuels, the ocean

transfers in the carbon cycle

feeding on plants by herbivores

feeding on herbivores by carnivores

feeding on dead organisms by decomposers

CO2 from atmosphere dissolving in rainwater and oceans

transformations in the carbon cycle

photosynthesis (CO2 into glucose)

respiration (organic matter into CO2)

combustion (organic matter into CO2)

decomposition

fossilisation

organic storages in the nitrogen cycle

organisms

inorganic storages in the nitrogen cycle

soil, fossil fuels, atmosphere, water bodies

bacteria in the nitrogen cycle

nitrogen fixing

nitrifying

denitrifying

decomposers

nitrogen fixing bacteria (nitrogen fixation)

atmospheric nitrogen is converted into ammonium ions

nitrifying bacteria (nitrification)

ammonium ions are converted into nitrite and then nitrate

denitrifying bacteria (denitrification)

nitrates are converted into nitrogen

decomposers (deamination)

break down organic nitrogen into ammonia

transfers in the nitrogen cycle

feeding on plants by herbivores

feeding on herbivores by carnivores

feeding on dead organisms by decomposers

absorption of nitrates by plants

transformations in the nitrogen cycle

nitrogen fixation

lightning

nitrification

denitrification

deamination

assimilation

lightning

causes nitrogen and water in the atmosphere to combine to form ammonia and nitrates

assimilation

plants absorb nitrogen from the soil in the form of nitrates and ammonium ions

human activities that impact the carbon cycle

urbanisation

deforestation

agriculture

fossil fuel use

how does urbanisation affect the carbon cycle?

• increases the need for energy; increased use of fossil fuels

• leads to decreased land; reduces photosynthesis

• increases food requirements; reduces land and increases agricultural use

• increased transport; greater energy requirement and greater use of fossil fuels

how does deforestation affect the carbon cycle?

• reduces carbon storages

• worsens soil erosion

• reduction in photosynthesis → less CO2 removed from atmosphere

how does agriculture affect the carbon cycle?

• increased land use for agriculture → alters the nature of carbon storages

• carbon storage present in crops transported to new locations

how does fossil fuel use affect the carbon cycle?

• releases CO2 into atmosphere → entails direct burning of carbon store locked up in geological deposits

• mining and burning of fossil fuels → increases carbon in atmosphere

• increased greenhouse gases → increased temperature

how does agriculture affect the nitrogen cycle?

• increased nitrogen via fertilisers

• nitrate fertilisers → surface runoff into bodies of waters which causes eutrophication

• eutrophication leads to low oxygen in aquatic ecosystems → habitat degradation

how does deforestation affect the nitrogen cycle?

• trees store nitrogen in the form of amino acids and protein → this storage is lost

• increases atmospheric nitrogen

• decreased land-based storages

how does fossil fuel use affect the nitrogen cycle?

• burning of fossil fuels releases nitrogen oxides into the atmosphere → contributes to smog

• releases nitrogen from storages in geological deposits and increases nitrogen in atmospheric, land and water storages

• increases nitrogen available in the ecosystem

how does human population growth affect the nitrogen cycle?

• increases in human population → increased food needs → fertilisers have been used to meet this demand and increase crop yield

• increased sewage output → increased quantities of ammonium and nitrates in water bodies