human factors (not in Specified)

Question 1

what state do systems unaffected by human activity act in?

Answer 1

dynamic equilibrium

in the ST, inputs, outputs + stores of water or carbon will fluctuate from year to year

Question 2

how do flows + stores maintain a balance?

Answer 2

negative feed back loops eg in CC. burning fossil fuel;s increases atmospheric CO2 but stimulates photosynthesis also -> negative feedback response should remove excess Co2 from the atmosphere + restore equilibrium

Question 3

what is urbanisation?

Answer 3

conversion of land use from rural to urban eg farmland + woodland are replaced by housing, offices etc natural surfaces eg vegetation give way to concrete

Question 4

how does urbanisation affect the water cycle?

Answer 4

• artificial surfaces = largely impermeable so allow little or no filtration + provide minimal water storage capacity to buffer run off
• urban areas have draining system eg pitched roofs, gutters thus high proportion of water from precipitation flows quickly into streams + rivers leading to rapid rise in water table
• urban development on flood plains reduces water storage capacity in drainage basins, increasing river flow + flood risks

Question 5

how does farming affect the carbon cycle?

Answer 5

• clearance of forest for farming reduces carbon storage in ground biomass. soil carbon storage is reduced by ploughing + the exposure of soil organic matter to oxidation. further losses occur through harvesting as only small amounts organic matter return to the soils
• changes to CC less apparent on pasture land. eg NA the NPP of annual crops eg wheat exceeds that of the original prairie grasslands
• carbon exchanges through photosynthesis are lower than in natural systems (bc lack of biodiversity + growth cycle is compressed into 4 or 5 months)