human impact on the environment Flashcards
how does deforestation effect the carbon cycle?
increases the co2 content in the atmosphere
how does climate change effect the carbon cycle?
global and regional climate patterns have been changing noticeably due to the huge rise in atmospheric CO2 and the rise in greenhouse gases.
the two main reasons are combustion, the burning of fossil fuels releases CO2 that was previously locked up and deforestation
how does global warming effect the carbon cycle?
- carbon dioxide is an important greenhouse gas, as it absorbs radiation from the Earth. if it accumulates in excess, it can lead to global warming
- this has resulte in increased frequency of extreme weather conditions, polar ice caps melting and an increased frequency of forest fires
- as a consequence, species distribution may change; plants and animals may be driven to extinction if they cannot find a suitable new habitat fast enough, which reduces biodiversity.
- in some regions, there may be increased crop yields, but pest populations may also increase
how does ocean warming effect the carbon cycle?
oceans can store a lot of heat so there is a time lag between warming of the atmosphere and the warming of the ocean
list some consequences of global warming and climate change on aquatic habitats
- decreases pH of oceans (acidification) - corals die
- eutraphication
- less oxygen dissolved in water at higher temperatures
- fish migrate to cooler waters
state some possible changes in farming practices
- rotating crops to reduce pests and mineral depletion
- salt-tolerant crops to overcome rising sea levels
- feeding cows high-sugar grasses with less cellulose to reduce the release of the greenhouse gas methane
- keeping the soil healthy by using minimal preparation of land for growing crops and cover crops like clover to protect and improve soil
- drought-resistant crops to tackle low and fluctuating water supply
- improving drainage to aerate water-logged and anaerobic soils
what is carbon footprint?
the total amount of carbon attributable to the actions of an individual, a product or service over a period of one year
how can we reduce our carbon footprint?
- recycling packaging material
- driving less
- use less AC and heating
- choosing a diet low in animal protein
- avoiding food waste
- planting trees
why is nitrogen important to all living organisms?
- component of organic molecules
- used for amino acids + DNA
- chlorophyll
by which processes do these ions get taken up by plant roots?
- facilitated diffusion
- active transport
what are the 5 main processes in the nitrogen cycle?
- ammonification
- nitrification
- nitrogen fixation
- assimilation
- denitrification
describe ammonification
decomposers (saprotrophs and detritivores) result in the decay of dead plants and animals, faeces and urine into ammonium ions
describe nitrification
the ammonium ions produced by decomposes are converted into nitrites then nitrates by nitrifying bacteria.
- aerobic conditions are required
- plants can absorb these nitrate ions and incorporate them into amino acids, nucleotides and chlorophyll
what are the key nitrifying bacteria?
NITROSOMONAS - convert ammonium ions into nitrites
NITROBACTER - convert nitrites into nitrates
describe nitrogen fixation
nitrogen fixing bacteria can directly fix nitrogen gas into ammonium ions
what are the key nitrogen-fixing bacteria?
AZOTOBACTER - free living in the soil
RHIZOBIUM - found in root nodules of leguminous plants
describe the relationship between rhizobium and root nodules of legumes
when nitrogen gas diffuses into the root nodule, rhizobium produces nitrogenase enzyme which catalyses the fixation of nitrogen gas into ammonium ions
- these ammonium ions can then be converted into amino acids for use by the plant.
- however, nitrogenase is inhibited by oxygen. therefore, haemoglobin is present in root nodules to bind with the oxygen, giving it a pink colour
why can the relationship between the bacteria in the root nodule and the legume be classed as a symbiotic relationship?
- bacteria gains sugars from photosynthesis
- plants gain nitrogenous compounds
both benefit
describe assimiliation
the formation of organic compounds (e.g amino acids) from inorganic nitrogen compounds present in the environment
describe denitrification
denitrifying bacteria convert nitrate from the soil into nitrogen gas. this is a problem as it removes useful nitrogenous compounds from the soil.
anaerobic conditions are required for this and it occurs in waterlogged soil
what human activities aid the nitrogen cycle?
- ploughing and drainage of soil to improve aeration. this enables nitrifying bacteria to convert ammonium ions into nitrate and prevents denitrifying bacteria from completing denitrification
- cultivation of legumes in soils lacking nitrogen so that rhizobium will carry out nitrogen fixation within the plants and then when the plants die these nitrogenous compounds will enter the soil to be broken down by decomposers in ammonification
- application of artificial fertilisers and manure to soil that will enable a greater yield of crop plants
what do fertilisers contain?
nitrates, phosphate, potassium
why do crops need fertilisers?
nitrates - nitrogen for amino acids, nucleic acids
potassium - stomatal opening
phosphates - nucleic acids + ATP + phospholipids
describe the process of eutrophication`
- fertilisers leach into watercourses, increasing levels of nutrients
- there is a bloom of algae, blocking out the light to plants below. these plants die as they cant photosynthesise
- decomposers such as bacteria and fungi decompose the dead organic matter
- as these bacteria respire aerobically they use most of the available oxygen, this creates a biological oxygen demand
- aquatic animals die due to lack of oxygen
- anaerobic bacteria then flourish
how can high nitrate levels in waterways can be overcome?
- restricting the amount of fertiliser added to soil
- only applying fertiliser when crops are actively growing so that it is readily taken up and does not remain in the soil
- digging drainage ditches for minerals to concentrate in.
what is the problem with digging drainage ditches?
has lead to a drop in invertebrate biodiversity and has reduced species diversity in nearby grasslands
explain how natural selection is a threat to species
humans are changing environments faster than new mutations allow organisms to adapt
explain how non-contiguous populations are a threat to species
if small populations are isolated from each other and are unable to interbreed there may not be enough genetic diversity to ensure a healthy population
explain how a loss of habitat (deforestation) is a threat to species
deforestation - permanent remove of trees removes habitats
explain how a loss of habitat (drainage of wetlands) is a threat to species
wetlands are drained to allow agriculture or building. this destroys habitats
explain how a loss of habitat (hedgerow loss) is a threat to species
removal of hedgerows which have separated fields for centuries removes breeding sites, feeding sites and wildlife corridors which allows animals to move from one area to another
explain how a loss of habitat (crop sowing seasons) is a threat to species
sowing during autumn rather than spring means plants are unsuitable heights for birds to build nests
explain how overhunting is a threat to species
for trophies, traditional medicine, ‘bush meat’, overfishing, agricultural exploitation
explain how competition introduced from other species is a threat to species
domestic animals and accidentally introduced animals predate or outcompete native species
explain how pollution is a threat to species
pollutants kill organisms or make it more difficult for them to survive in their habitat
define conservation
protection, preservation, management and restoration of natural habitats and communities ; enhancing biodiversity whilst still allowing human activity
name 6 examples of conservation
- international cooperation
- gene banks
- legislation
- ecotourism
- protecting habitats
- education
describe international cooperation
restricting trade of endangered species and their parts
e.g. whaling
describe gene banks
conservation of existing gen pools include:
- breeding programmes in zoos & botanic gardens
- re-introduction of species e.g red kites
- sperm banks
- seed banks
describe legislation
national and international laws protecting habitats and wildlife e.g. EU habitats directive preventing overfishing by imposing fishing quotas, preventing overgrazing
describe ecotourism
aims to minimise the negative impacts of tourism by:
- contributing to conservation
- employing local people
- educating visitors
- cooperating with local people to manage areas
describe protecting habitats
protecting a particular area e.g from urban development
this includes :
- national parks
- SSSIs
e.g. dunham park
what does SSSI stand for?
sites of special scientific interest
state 4 reasons for conserving existing gene pools?
- ethical reasons
- agriculture and horticulture
- environmental changes
- potential medical uses
describe ethical reasons as a reason of conserving gene pools
each species is a unique combination of genes and alleles and so is therefore valuable
describe agriculture and horticulture as a reason of conserving gene pools
breeds of animals and plants used in agriculture and horticulture have been selectively bred so may lack rare alleles that could be important in the future (e.g. disease resistance).
- wild plants and animals can act as a gene bank for these alleles which animals and crop plants can be bred with
describe environmental changes as a reason of conserving gene pools
a large, varied gene pool increases the chance of a species surviving environmental change
describe potential medical uses as a reason of conserving gene pools
plants and animals may have the potential to help in the development of new drugs or other medical treatment
- by preserving habitats we allow this potential to be researched in the future
what classifies a site as an SSSI?
- rare species
- rare habitats
- wide variety of species
define the re-introduction of species
reintroduction of an organism to its native habitat, an area from which it has been previously lost.
what does reintroduction aim to do?
aims to re-establish a viable population of the species within its native habitat
name examples of re-introduction of species
- introduction of beavers into UK
- wolves in Yellowstone national park
- siberian tigers
what are the factors that need to be considered for re-introduction to be successful?
- habitat : the receiving habitat is suitable, the effect of species introduction on habitat or effect on biodiversity
- research : the resources and expertise are available for the establishment and protection of the reintroduced species
- consultation : this would occur between neighbouring landowners and local stakeholders, to make sure that the majority of these consulted do not oppose reintroduction
- correct individuals: a suitable disease free donor population is identified and the correct species is re-introduced
why re-introduction into not well established population?
- there are fewer predators
- less intraspecific competition for food / nest sites / habitats
- less likely to pass on disease as fewer numbers (initially)
why might illegal or unregulated re-introduction be concerning?
- introduction of disease
- destruction or loss of habitat and other effects on ecosystem
- the wrong species would be not adapted
name 3 ways of agricultural exploitation
- removal of hedgerows to make larger fields
- monoculture
- overgrazing
why does agricultural exploitation take place?
farmers were encouraged to cultivate more land to maximise food crop yields
therefore, a number of farming method were introduced with wide environmental implications
how is the removal of hedgerows a method of agricultural exploitation?
allows farmers to use larger machinery to plough the soil and harvest crops
- reduces biodiversity by removing breeding sites, feeding sites and wildlife ‘corridors’ which allows animals to move from one area to another
how is monoculture a method of agricultural exploitation?
single crops e.g maize, wheat and barely are grown in large fields
- this will have an effect on biodiversity as it only provides one habitat, reducing the number of different microhabitats that would be available in an area with mixed crops
- roots grow to the same length and extract the same minerals from the same depth of the soil, reducing the concentrations of nutrients in the soil and increasing the use of inorganic fertilisers
how is overgrazing a method of agricultural exploitation?
overgrazing occurs when plants are exposed to intensive grazing for extended periods of time
- can lead to soil erosion and desertification
- hooves of cattle compact soil, driving out air and preventing water drainage
- roots cannot penetrate the soil and grass for grazing cannot grow
define deforestation
removal of trees in an unsustainable way
what are the reasons for deforestation ?
- demand for timber as a construction material
- wood used for fuel
- to make paper and cardboard packaging
- to clear the land for farming
- to improve transport infrastructure by building new roads
- targeting high value trees e.g teak and mahogany
what are the consequences of deforestation?
- global climate change
- destruction of habitats
- soil erosion
expand on global climate change as a consequence of deforestation
- trees cut down = less co2 removed from atmosphere by photosynthesis
felled trees will also increase the concentration of co2 in the atmosphere because:
- combustion of trees releases carbon dioxide from biomass
- logs decompose and decomposers release co2
- fossil fuels burnt in transport of logs
expand on the destruction of habitats as a consequence of deforestation
in tropical rainforests:
- reduces biodiversity - 50% of earth’s species live in rainforests so loss of this habitat is damaging
- rainforests have undiscovered medical properties
expand on soil erosion as a consequence of deforestation
the removal of topsoil which contains valuable nutrients
- increase in soil erosion as trees are removed due to lack of roots holding soil together and the soil can easily be washed away
- top soil is fertile (high level of nutrients), soil below is not suitable for crop growth
name some things that happen as a result of deforestation
- increased evaporation compared to transpiration
- decreased oxygen in soil
- soil temperatures reduce
- denitrifying bacteria increase
why is there increased evaporation compared to transpiration after deforestation?
increased evaporation from soil, evaporation returns water more slowly to the atmosphere than transpiration does.
- this leads to reduced local rainfall and accelerates desertification
why is there a decreased oxygen level in soil after deforestation?
as the soil becomes wetter water fills the soils’ airspaces and the oxygen available for roots decreases
why does the soils temperature decrease after deforestation?
it takes wet soil longer to warm up than dry soil (due to the specific heat capacity of water), this means these soils are cold
- this reduces germination and root activity (active transport of nitrates)
- reduces the rate of the nitrogen cycle
why is there an increase in the denitrifying bacteria after deforestation?
cold, damp soil favours the growth of denitrifying bacteria so soils lose inorganic nitrogen compounds and so is less fertile
(conditions are anaerobic)
what is forest management?
sustainable replanting and regeneration of forests
why is forest management important?
to remove timber without destroying the forest’s ecosystem, especially if a small number of trees are removed each year, leaving the habitat intact.
list 4 techniques are used to manage forests?
- coppicing
- selective cutting
- long rotation times
- planting trees optimum distances apart
- controlling pests and diseases
describe coppicing
- a tree trunk is cut but a ‘stool’ a few cm high is left.
- new shoots emerge from the stool and grow into ‘poles’
- the ‘poles’ can be cut on rotation to produce timber of different widths.
- coppiced plants can regenerate over long periods of time
describe selective cutting
- some of the larger trees are felled whilst others are left in place
- this is particularly useful on steep slopes and near rivers because on steep slopes the total removal of trees would leave soil vulnerable to soil erosion
- this helps maintain nutrients in the forest soil and minimise the amount of soil which is washed into rivers and other waterways.
describe long rotation times
letting trees grow for a long period of time before cutting them down
- habitat diversity increases as it provides more stable, long term habitat
describe planting trees optimum distances apart
reduces intraspecific competition which can lead to trees growing tall and thin and so produced poor quality timber
describe controlling pests and diseases
ensures trees grow well and produce high quality timber, this then means that fewer trees need to be felled and the best use is made of the land
why is it important that native woodlands are preserved?
maintain and enhance biodiversity by preserving very old habitats
why is over fishing a problem?
increases intensity and efficiency of modern fishing is having a highly negative effect on the populations of some marine organisms
what are the effects of fishing on other wildlife?
- drift nets can catch non-target species such as turtles or dolphins
- trawling damages the sea floor habitat of organisms such as some molluscs
- can catch organisms that are prey of other species e.g catching capelin which is eaten by cod or krill, which is eaten by some whales, seals, penguin squid and fish, which can affect whole food webs
comment on the use of smaller mesh sizes
- smaller juvenile fish which are not sexually mature are unable to escape nets.
- this reduces the future breeding population, over time this leads to fewer offspring and reduces genetic diversity
what controls can be used to reduce the impact of overfishing?
- impose quotas on catches so only a certain mass of fish can be landed
- ensure mesh sizes of nets are large enough to let young fish escape
- enforcement of exclusion zones
- legislate size of fishing fleets and number of days at sea
- encourage consumers to eat sustainably sourced fish
what additional problems can imposing quotas leas to?
too many fish drawn out, those over quota are discarded back into the sea
why is ensuring large enough mesh sizes important?
young fish can escape and can grow and reproduce after becoming sexually mature
what areas and at what times of year should fishing boats be unable to fish?
breeding sites and breeding seasons to allow fish to reproduce
what are the advantages of farming fish rather than traditional livestock?
- fish convert their food into protein more efficiently
- a greater proportion of a fish’s body is edible
- fish farming has a lower carbon footprint
what is fish farming used for?
used to overcome the problem of overfishing
what are some problems with fish farming?
- diseased fish
- pollution
- resource use
- environmental toxins
- environmental degration
explain diseased fish as a problem of fish farming
- salmon farms often have a high density so can easily transmit disease.
- large amounts of antibiotics and pesticides have to be used to keep the fish healthy
- the pesticides used can cause harm to other organisms such as marine invertebrates.
- escaped fish can also pass parasites and other infections to wild populations
explain pollution as a problem of fish farming
- pollution effects the ecological balance of waterways
- waste from fish farming can get into water around the fish pens and lead to eutrophication
explain resource use as a problem of fish farming
farmed fish can eat a large amount of food, which is often other fish
- this is inefficient
explain environmental toxins as a problem of fish farming
environmental toxins such as PCBs and pesticides are more concentrated in farmed fish than wild fish
explain environmental degration as a problem of fish farming
local environment can be damaged
- e.g. shrimp industry leading to salinisation of soil and groundwater leading to destruction of mangroves
explain what the term ‘planetary boundary’ means
- a threshold value for a global process that is affected by human activity
-crossing these boundaries could generate abrupt o irreversible environmental changes
how many earth system processes are there?
9
what are the planetary boundaries?
- biodiversity boundary
- climate change boundary
- nitrogen boundary
- land use boundary
- fresh water boundary
- chemical pollution boundary
- aerosol boundary
- ocean acidification boundary
- ozone boundary
- what classification is the biodiversity boundary?
- explain this
CLASSIFICATION: crossed
EXPLANATION:
- human activity has caused environmental changes to happen too fast for natural selection to produce organisms that are adapted to this changing environment. as a result many species have become extinct
- habitat changes in regions such as tundra (temperature rises) and marine environments (pollution of oceans w acid, oil and sewage). this has caused concern and biodiversity has been significantly reduced in these regions
- coral reef bleaching and coastal plain submission due to rising sea levels are also reducing biodiversity
what can we do to help the biodiversity boundary?
monitoring biodiversity, collecting materials for gene banks, raising public awareness to reduce human behaviour that has generated biodiversity loss
- what classification is the climate change boundary?
- explain this
- what can we do to help?
CLASSIFICATION: crossed
EXPLANATION:
- greenhouse gases are continually being added to the atmosphere. this causes an increase in global temperature, climate change, rise in sea levels
HELP:
- the production of biofuels - produced by biological processes
- as the growth of biofuel crops takes in co2 from atmosphere, the co2 when they are burnt has less impact
- can be made by anaerobic digestion of plant material
- what classification is the nitrogen boundary?
- explain this
- what can we do to help?
CLASSIFICATION: crossed
EXPLANATION:
- denitrification due to waterlogged soil
- use of agricultural fertilisers leading to eutrophication
HELP:
planting fields of legumes to increase nitrogen fixation
- ploughing soil to improve aeration and prevent anaerobic condition
- what classification is the land use boundary?
- explain this
- what can we do to help
CLASSIFICATION : crossed
EXPLANATION:
deforestation to allow for farming and urban development has led to a conflict between the need to grow food and the need to grow biofuels and protect natural habitats
HELP:
- changing farming practices to concentrate it in the most productive areas
- reducing consumption of meat would reduce land being cultivated
- what classification is the fresh water boundary?
- explain this
- what can we do to help?
CLASSIFCATION: avoidable
EXPLANATION:
- organisms need fresh water to live
- decrease in supply of freshwater is due to changing landscapes, agriculture, increased demand from humans, water pollution and climate change
HELP:
- water conservation, water efficiency, waste water reclamation, irrigation
- desalination
- what classification is the
chemical pollution boundary? - explain this
CLASSIFICATION: unquantified
EXPLANATION :
organic pollutants, radioactive materials, nanomaterials and micro-plastics
- these could all interact with each other and produce harmful effects
- what classification is the aerosol boundary?
- explain this
CLASSIFICATION : unquantified
EXPLANATION:
- atmospheric aerosols are the microscopic particles put into the atmosphere by combustion of fuels and by creating dust from digging and quarrying. these can lead to respiratory problems and cause death from lung disease
- sulphates in aerosols reflect sunlight, providing a cooling effect, but other particulates reradiate it, increasing warming
- what classification is the ocean acidification boundary?
- explain this
- what can we do to help?
CLASSIFICATION: avoidable
EXPLANATION:
- the pH of the oceans is decreasing due to dissolving carbon dioxide forming carbonic acid which releases hydrogen ions. low pH leads to mollusc, coral shells and arthropod exoskeletons softening, making them vulnerable
- gill structure in fish is also affected by low pH and their functioning is damaged
HELP:
reduction in the burning of fossil fuels
- what classification is the ozone boundary?
- explain this
CLASSIFICATION: avoided
EXPLANATION:
- CFCs favour the breakdown of the ozone
- resulted in the thinning and development of a ‘hole’ in the ozone layer
- the use of CFCs in spray cans was banned in 1978
- the ozone is now recovering naturally
