2.2 HL, 2.3, 2.4, 2.5

not done

Photosynthetic autotroph

Autotrophic energy from carbon dioxide, processed through photosynthesis e.g. plants, algae, some bacteria

Chemosynthetic autotroph

autotrophic energy from chemicals, processed through chemosynthesis e.g. some bacteria

Productivity

production of biomass per unit area per unit time

Primary productivity

gain by producers (autotrophs) in energy or biomass per unit area per unit time

• Units: kg carbon/m^2/yr

• Depends on: 

  • amount of sunlight

  • ability of producers to convert energy into biomass

  • The availability of other factors needed for growth e.g. minerals and nutrients 

Secondary productivity

biomass gained in heterotrophic organisms, through feeding and absorption, measured in units of mass or energy per unit area per unit time

Gross primary productivity (GPP

the mass of glucose created by photosynthesis per unit area per unit time in primary producers GPP=NPP+R

Net primary productivity equation

NPP= GPP - R

What is NPP?

represents the amount of energy converted to new biomass that becomes available to the next trophic level

Gross secondary productivity (GSP)

the gain in biomass by consumers using carbon compounds that are absorbed and assimilated from ingested food GSP= food eaten - faecal loss

note: Not considering respiration and other bodily functions

Net secondary productivity equation

NSP= GSP - R

Sustainable yield

the rate of increase in natural capital (i.e. natural income) that can be exploited without depleting the original stock or its potential for replenishment

Maximum sustainable yield equation

MSY= NPP or NSP

Ecological efficiency

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

Ecological efficiency equation

(energy used for growth (new biomass)/ energy supplied)x 100

Entropy

the disorder of energy in a system

• Entropy in a system increases as biomass passes through ecosystems

• Increase in entropy reduces the energy available to do work

Entropy in an isolated system where there is no new input of energy

tends to increase spontaneously

Second law of thermodynamics

In an isolated system entropy tends to increase spontaneously/ in any transformation there is a net increase in entropy/ dissipation of energy

Nutrients are circulated and re-used frequently

Unlike energy which flows through ecosystems (enters as light energy and leaves as heat), matter (nutrients) cycles between the biotic and abiotic environment

Stores (storages)

remain in equilibrium with the environment

Sinks

indicate a net accumulation of the element

Sources

indicate a net release of the element

Carbon cycle

natural process where carbon moves between different stores and flows

Carbon cycle before the industrial revolution

Pre-industrialisation carbon cycle was in a dynamic equilibrium; amount of carbon absorbed into the stores is balanced by the amount of carbon released

residence time

The length of time that one atom of carbon remains in a specific store

Affect of humans on residence time

Humans have affected residence time in many ecosystems, we release carbon into the atmosphere that would have otherwise remained locked away through our production of energy

Organic stores of carbon

• organisms

• crude oil

• natural gas

• coal

Inorganic carbon stores

• oceans

• soils

• atmosphere

Sequestration

natural capture and storage of CO2 from the atmosphere by physical/ chemical processes

Ecosystem as a sink

Young forest acts as a sink because they are actively absorbing carbon

Ecosystem as a store

Mature forests act more as stores because their growth rates are slower but they hold the carbon they absorbed in the past

Ecosystem as a source

If deforestation or fires are occurring, forests can be sources of carbon

Rules about storage in ecosystems

• Wet, colder soil stores carbon better

• Plants cannot have greater storage than soil

fossil fuel formation

formed from organic material that has been preserved for millions of years

Fossil fuel residence time

Very long residence time: they continue functioning as storages for many thousands or millions of years naturally

Atmospheric concentration of CO2

• atmosphere is currently at nearly 412 parts per million (ppm) and rising -> 47% increase since the beginning of the Industrial Age(280 ppm)

• 11% increase since 2000, when it was near 370 ppm

Regenerative agricultural practices

practices that aim to promote soil health and carbon sequestration by imitating natural ecosystems

Examples of regenerative agricultural practices

Crop rotation, cover crop, no till periods

Length of time that a crop is grown can also influence soil carbon dynamics

• Short-term cropping: Growing crops for short periods, such as annual grains, often leads to increased soil erosion and carbon loss

• Long-term cropping (e.g., timber production): Growing perennial crops, such as trees, provides extended cover and reduces soil disturbance, promoting carbon sequestration over a longer period

Physical dissolution

when CO2 molecules in the atmosphere dissolve in seawater, forming carbonic acid

Biological uptake

• marine organisms such as phytoplankton and algae use carbon dioxide for photosynthesis, incorporating it into their biomass