3.6 human impact Flashcards
(30 cards)
what do scientists believe the background extinction rate is?
1 per 1,000,000
rate of 10-6 yr-1
how many periods of mass extinction have there been been?
what one are we in now and what is it due to?
there have been 5 periods
we’re in the 6th due to human activity rather than catastrophic changes
causes of extinction
- natural selection
- non-contiguous populations
- loss of habitat
- overhunting by humans
- competition and introduced species
- pollution (oil disasters and PCBs)
define conservation
the management of Earth’s natural resources in such a way that maximum use of them can be made in the future
conservation methods
- spermbanks
- whaling
- ecotourism
- education
- rare breed
- seedbanks
- genebanks
- SSSI’s
- legislation
reasons for species conservation (4)
- ethical
- plant breeding
- avoiding extinctions
- potential for medicinal use
what is there a conflict between?
the need for conservation of species and the demand for increased food production
what is deforestation?
removal of trees to use as timber or fuel or to repurpose the land use for agriculture or building
problems with deforestation
- disrupts water cycle
- water balance, flooding and drought
- loss of biodiversity
- destroys habitats
- infertility and soil erosion
- contributes to global warming
what is humus? what does it do?
dead decaying matter
starts to disappear when trees are cut down - reduce soil quality
management of deforestation
coppicing
re-planning
legislation
what is overfishing?
rate at which fish are harvested exceeds the rate at which they can reproduce
what is trawling?
what is drift netting?
dragging a large net through the water catching whatever is in the way
suspend a net between 2 boats and it catches fish on upper surface
problems with overfishing
- reduce genetic diversity due to the reduction in the size of fish
- fish population has fewer individuals and cannot replace harvested fish
management of overfishing
- larger mesh like nets to allow small fish to escape and reproduce
- quotas
- exclusions zones
- restricted fishing seasons to allow reproduction
what do planetary boundaries do?
regulate the stability of the land, atmosphere and the sea
what is caused if the boundaries are crossed?
irreversible damage
what can a small change in the planetary boundaries have?
a larger and unpredictable effect on the environment and it doesn’t give a linear response
what are the crossed planetary boundaries?
climate change
biosphere integrity
land system change
biogeochemical flows
problem and solution to climate change
- Earth’s temperer is largely controlled by greenhouse gases in atmosphere; higher CO2 = higher average global temperature
- use biofuels instead of fossil fuels as they are carbon neutral
problem and solution to biosphere integrity
- habitat destruction has occurred; populations of living organisms are reduced; species may become extinct
- monitor biodiversity; species conservation; limit use of agricultural chemicals
problem and solution to land system change
- natural ecosystems have been used for urban development, raising livestock and farming including biofuel crops
- more efficient crop plants should be grown; no more than 15% of ice free land should be used for crop growing and human habitation
problem and solution to biogeochemical flows
- natural cycles have been disrupted; fertilisers used - eutrophication; combustion of fossil fuels and biomass
- transfer nitrogen fixing genes to crop plants
what are the 3 avoidable planetary boundaries?
stratospheric ozone
ocean acidification
fresh water use
