UNIT 21– human influences on ecosystems Flashcards
why modern tech increased food supply
- agricultural machinery (= + effective)
- chemical fertilisers (improved yields)
- insecticides/herbicides (less damage to plant and less competition)
- selective breeding (large yield of plants that are bred to reliably produce high yields)
what do arable farms use to work large fields (+ example)
large agricultural machines (e.g. tractors)
what do chemical fertilisers do?
encourage growth of crop plants (which then increases the yield of the plant)
what do pesticides do?
kill pests like insects that feed on crops
what do herbicides do?
kill weeds that compete with crop plants for water, light and nutrients
what has selective breeding done to crops?
increased yield and made them more resistant to drought and disease
what has genetic engineering done?
transferred features (e.g. herbicide resistance) to crop plants from unrelated species
what is intensive farming?
using modern technology to achieve high yields of crop plants and livestock.
how is intensive farming done for crops?
involves growing crop plants over large areas at high densities
how is intensive farming done for livestock?
kept in large numbers, given high energy food, given antibiotics, kept in artificially warm temperatures and often restricting movement by keeping them indoors
negative effects of intensive farming systems
- animals (especially cattle) -> lots of methane
- urine & faeces (aka slurry) -> pollute lakes, seas, etc. where can cause eutrophication
- reduction in biodiversity
- overgrazing= soil erosion
consequences of fish farms
- waste food = serious effect on surrounding waters
- high densities of fish= parasites and pathogens can spread easily
- using pesticides can cause issues with resistance to the chemicals
what is a monoculture?
growing same crop over large areas, year after year. this does not happen naturally.
advantages of monoculture
allow farmers to concentrating on growing large quantities of specific crops (e.g. wheat)
negative effects of monoculture on environment
- lower biodiversity
- increase in pest populations (if particular pest feeds on crop grown, monocultures= large food supply for pest= pest population increases)
what does spraying crops with insecticides lead to? (negative)
- harmless insects being killed
- pollution (of land, accumulation inside of organisms)
- pests may become resistant to them
what occurs when people do not receive enough food?
famine
factors for famine
- natural disasters (i.e. drought)
- increasing population
- poverty
- unequal food distribution
what must food production do as global human population increases?
also increase
why is having to increase food production while global population increases a problem?
- more land is required (for crops/animals) -> deforestation
- also, +animals = +methane
what do greenhouse gases cause and what does that lead to?
- global warming
- leads to increased natural disasters (e.g. tropical storms) & rising sea levels which flood homes and decreases amount of habitable land
effects of growing population on habitats
destruction (i.e. of woodlands, marine habitats)
what does habitat destruction lead to
- reduction of biodiversity
- interrupts food chains/ webs, meaning more species may die because their pray = gone
main reasons why habitats = destroyed
- clearing land for farming and housing
- extraction of natural resources
- marine pollution
(habitat destruction) explain why clearing land for farming and housing done
- crops, housing, etc. take up large amount of space
- growing population = increase in demand for food/ housing = need to clear habitats i.e. forests (deforestation)
(habitat destruction) explain why extraction of natural resources done
- natural resources (i.e. wood, metals) = needed to make different products
- therefore i.e. trees = cut down for wood
- other extraction takes up lots of space i.e. mining (where land must be cleared first)
(habitat destruction) explain why marine pollution happen
- pollution = due to human activities
- oil spills and other waste= pollute ocean & kill sea life
- eutrophication can occur when fertilisers from intensively farmed fields enter waterways
- eutrophication leads to decrease in biodiversity as most aquatic species need oxygen to survive
what is deforestation?
clearing of trees usually in large scale
can cutting down trees be done sustainably?
yes, through replacement/replanting after cutting down
generally, is it done sustainably?
no, as land = cleared for cattle grazing, housing, planting monocultures, etc.
negative effects of deforestation
- extinction of species
- loss of soil
- flooding
- increase of CO2 in atmosphere
explain how extinction/ loss of biodiversity = consequences of deforestation
- forest habitats = lots of biodiversity, so when the are destroyed, it causes loss of many species
- many of these species= only found in these areas and so will become extinct
explain how soil erosion = consequence of deforestation
- tree roots help stabilise soil, preventing it from being eroded by rain
- trees = take up nutrients/minerals from soil through roots
- without trees, minerals/ nutrient stay in soil and as soil = washed away into bodies of water (leaching)
- loss of soil nutrients = permanent and makes it difficult for trees to regrow
explain how flooding = consequence of deforestation
- without trees, topsoil = loose and unstable
- this means it is easily washed away by rain
- this means risk of flooding and landslides = increased
explain how increased CO2 in atmosphere = consequence of deforestation
- trees = photosynthesis
- removal of trees = less removal of CO2 from atmosphere (+ less O2 released)
- when trees = removed for land use, they are usually burned (not cut down) which releases CO2 into atmosphere (contributing to increasing CO2 levels in atmosphere and global warming)
source and effect of untreated sewage as a pollutant
- lack of sewage treatment plants or money (meaning sewage runs/ is pumped into bodies of water)
- EUTROPHICATION
source and effect of chemical waste as a pollutant
- released from factories into bodies of water/ leach into land surrounding factory
- many chemicals/ heavy metals = persistent and so accumulate in food chains (bioaccumulation), poisoning top predator
source and effect of discarded rubbish as a pollutant
- much rubbish = plastic that is discarded or buried in landfills
- non-biodegradable= stays in environment for many years
- animals may accidentally eat it (and it can accumulate in food chains)
source and effect of fertilisers as a pollutant
- runoff from agricultural land if applied in too high concentrations
- EUTROPHICATION through algal blooms
source and effect of insecticides/ herbicides as a pollutant
- sprayed on crops to prevent damage
- bioaccumulation, loss of biodiversity, damage to beneficial insects, can build up in soil to toxic concentrations and harm other organisms
source and effect of nuclear fallout as a pollutant
- accidental leakage from nuclear power plants or explosion of a nuclear bomb
- some particles = remain in environment for many years
- can cause increased risk of cancer and wind can carry these particles very far away
source and effect of methane as a pollutant
- cattle farming, rice fields, landfills
- methane = greenhouse gas= enhanced greenhouse effect = climate change
source and effect of CO2 as a pollutant
- burning of fossil fuels, trees, etc.
- like methane, is greenhouse gas = enhanced greenhouse effect = climate change
why are plastics harmful?
- non-biodegradable
- animals eat or get caught up in it
- as it breaks down, it releases toxins (affecting marine animals, land)
- enters food chains once small
- disposed of by burying landfills
problem with contraceptive pill (because contains estrogen)
- excreted in urine and make way into water supply (as not filtered out by sewage treatment
- if reach male aquatic organisms, cause feminisation
- male organism begins to produce eggs and lose ability to reproduce
- smaller amount of offspring is produced (affects population and food chains)
- can also reduce sperm count in human males, leading to fertility problems
explain eutrophication from fertilisers
- fertilisers from land runoff into water and cause increased growth of algae and water plants
- this algal bloom blocks sunlight so plants at bottom start to die. as does algae when competition becomes too intense
- decomposing bacteria increase in number and use dissolved oxygen while respiring aerobically
- lack of oxygen kills aquatic organisms
how is acid rain formed?
- combustion of fossil fuels that contain sulfur impurities creates sulfur dioxide
- this is released into atmosphere where combines with oxygen and makes sulfur trioxide
- sulfur trioxide dissolves in water droplets in clouds and forms acid rain
causes of acid rain
sulfur dioxide, oxides of nitrogen
sources of sulfur dioxide, oxides of nitrogen
burning of fossil fuels, combustion of petrol in car engines
effects of acid rain
- damage to cuticles in leaves, killing plants
- acidification of lakes, killing organisms
- increased risk of asthma attacks and bronchitis in humans
- corrosion of stonework on buildings
- release of aluminium from soil into lakes that are toxic to fish
acid rain_ possible solutions
- changing power stations from coal and oil to renewable energy sources
- using “scrubbers” in power station chimneys (against SO2)
- using catalytic converters in car exhausts to convert oxides of nitrogen to harmless nitrogen
what is a greenhouse gas?
a gas that absorbs infrared radiation from the Sun so it remains trapped in the Earth’s atmosphere
why are greenhouse gases important?
- make earth a liveable temperature
why too many greenhouse gases bad?
increase temperature too much, causing enhanced greenhouse effect
name 4 greenhouse gases
- CO2
- methane
- water vapour
- CFCs
how does the greenhouse effect work?
- sun emits rays that enter the Earth’s atmosphere
- heat bounces back from earth’s surface
- some heat reflected into space
- some heat absorbed by greenhouse gases and trapped within earth’s atmosphere (=normal)
- however, rising levels of greenhouse gases due to human activities are causing earth’s temperature to rise beyond normal (= enhanced greenhouse effect), = global warming
consequences of global warming due to enhanced greenhouse effect
- ocean temp increase = polar ice caps melt, flooding occurs, sea levels rise
- extreme weather (e.g. super storms) which can then lead to loss of habitats -> loss of biodiversity
- increase in migration of species to new places, increased spread of pests/ disease
what is a sustainable resource?
one that is produced as fast as it is removed from the environment so it does not run out
what is a non-renewable resource?
one that cannot be replaced, once used cannot be produced anymore = need to be conserved
how can we conserve resources?
- reducing amount used
- finding replacements
what does recycling do?
reduces waste in the environment and reduces the amounts of raw materials and energy needed to make new products
how can we conserve i.e. forests and fish stocks?
these can be maintained. we can harvest them sustainably so they wont run out in future
sustainable development definition
development providing for the needs of an increasing human population without harming the environment
types of conflicts we have to balance in regards to sustainable development
- what current populations need with what future populations might need
- need for local people to be able to utilise the resources they have in their immediate environment with the needs of large companies
- need for balancing the needs of humans for resources with the needs of the animals and plants
what do we need to happen for development to occur sustainably (cooperation-wise)
For development to occur sustainably, people need to cooperate at local, national and international levels in the planning and management of resources
how to sustainably use forests
- re-planting trees when mature ones are cut
- legal quotas
- education
what does managing fish stocks sustainably include?
- quotas (controlling size, amount and when fish caught)
- restocking ( breeding and keeping offspring until large enough to survive in natural habitat then releasing)
- education
sewage treatment steps
- pipes carry sewage and water to treatment plants
- passes through screen, where large materials are filtered and then disposed of
- passed through channels slowly where grit and other heavy particles can settle at bottom (grit= later washed and returned to land)
- sedimentation tanks (solid material settles at bottom as sludge and liquid part called effluent at top)
- pumped into tanks where anaerobic bacteria decompose sludge (bacteria-> methane-> used as energy)
- liquid = treated with aerobic bacteria to remove organic waste
- treated with chlorine to remove bacteria
- now can be introduced to environment or sent to other treatment plant
what is an endangered species at risk for?
becoming extinct
reasons for species becoming endangered?
- hunting
- climate change
- introduction of non-native species
- habitat destruction
- pollution
conservation measures for endangered species
- education programmes
- captive breeding programmes
- monitoring and legal protection
- seed banks
why might species be at risk of extinction? (genetic)
- not enough genetic variation in the population
- small change in environment = extinction as all remaining organisms = similar and not adapted to survive
reasons for. conservation programmes
- reducing extinction rates
- stopping damage to food chains and protecting vulnerable ecosystems
- protecting future supply of food, medicine, fuels
- maintaining nutrient cycles
