20) Human influences on ecosystems (3.4) Flashcards
1.1.1. Describe how humans have increased food production, limited to agricultural machinery to use larger areas of land and improve efficiency
Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land
Tractors and ploughs prepare land for sowing seeds
Combine harvesters harvest crops
Soil monitoring sensors monitor the soil
Drones monitor fields
1.1.2. Describe how humans have increased food production, limited to chemical fertilisers to improve yields
Chemical fertilisers encourage the growth of crop plants, increasing the yield of the crop.
Fertilisers increase the amount of nutrients in the soil
This lets them grow larger and produce more fruit
1.1.3. Describe how humans have increased food production, limited to insecticides to improve quality and yield
Pesticides kill pests like insects
Less damage is done to the plants and less fruit is lost to insects
1.1.4. Describe how humans have increased food production, limited to herbicides to reduce competition with weeds
Herbicides kill weeds that compete with crop plants for water, light and nutrients
1.1.5. Describe how humans have increased food production, limited to selective breeding to improve production by crop plants and livestock
Selective breeding increases yield and makes crops more resistant to drought + diseases
Animals and crop plants which produce a large yield are selectively bred
This produces breeds that reliably produce high yields
1.2.0. What is monoculture farming?
When only one type of crop is grown on a given area of agricultural land, which does not occur naturally in ecosystems
Usually there are many different species of plants which support many species of animals (high biodiversity)
1.2.1. Describe the advantages of large-scale monocultures of crop plants
Increased machinery means continuous cropping
Decrease in labour costs
Only one crop is grown so it can be selectively bred to increase yield
Selective use of fertilisers and pesticides increases yield
Soil pH can be regulated
1.2.2. Describe the disadvantages of large-scale monocultures of crop plants
Destroying areas of natural vegetation between fields reduces biodiversity of plants and animals
Excess fertilisers can leach into rivers causing eutrophication killing fish and invertebrates
Pesticides may enter the food chain
Unlike organic fertilisers, chemical fertiliser do not improve soil structure
If a particular pest feeds on a crop, farming it in large areas gives it an ample supply of food, causing the population to rise
Harmless insects might be killed due to insecticide
Pests may eventually become resistant if insecticide is used repeatedly
1.3.0. What is intensive livestock production?
Using modern technology to achieve high yields of crop plants and livestock
Crops are grown over large areas at high densities
Livestock is kept in large numbers, their food supply is supplemented and their movement is often restricted by being kept indoors
1.3.1. Describe the advantages of intensive livestock production
Animals reared indoors can be given high-protein diets and additives so they grow as fast as possible
Temperature of housing is kept constant since animals grow well in warmth
Antibiotics can be used to control disease
Keeping animals in cages or pens restricts their exercise so they put on weight faster
1.3.2. Describe the disadvantages of intensive livestock production
Many people think it is more humane for them to be outside
Being caged in overcrowded conditions causes obesity, boredom and frustration
Rearing animals in crowded conditions can lead to a rapid spread of disease
Fish farming can cause pollution, as many fish in one place means animal waste and uneaten food can cause eutrophication
Animals, especially cattle, generate lots of methane, which is a greenhouse gas
2.1. Describe biodiversity
The number of different species that live in an area
2.2.1. Describe why increased area for housing, crop plant production and livestock production has caused habitat destruction
The increasing human population means that there is a higher demand for food
Crops, livestock and housing take up a large amount of space
The amount of land available for these things must be increased by clearing habitats such as forests (deforestation)
2.2.2. Describe why extraction of natural resources has caused habitat destruction
Natural resources such as wood, stone and metals must be gathered to make products
Many trees are cut down, destroying forest habitats
Some resource extraction also takes up lots of space (e.g. mining, as land must be cleared for it first)
2.2.3. Describe why extraction of natural resources has caused freshwater and marine pollution
Oil spills and other waste pollutes the oceans, killing marine life
Eutrophication occurs due to fertilisers from intensively farmed fields entering waterways
Most aquatic species living in these waterways die from lack of oxygen, causing a huge decrease in biodiversity
2.3. How can humans have a negative impact on habitats?
Through altering food webs and food chains
2.4. Explain the undesirable effects of deforestation as an example of habitat destruction, to include: reducing biodiversity, extinction, loss of soil, flooding and increase of carbon dioxide in the atmosphere
Extinction/loss of biodiversity: forest habitats, especially tropical rainforests, have a huge range of biodiversity and its destruction causes the loss of large numbers of plant and animal species. Many species are only found in these areas and become extinct
Soil erosion: tree roots stabilise soil, preventing it from being eroded by rain, and usually take up nutrients and minerals from soil. Without trees, they remain unused and they will be washed away by rain (leaching), which is permanent and makes it difficult for trees to regrow
Flooding: the topsoil will be loose so it will be easily washed away by rain, increasing the risk of flash flooding and landslides
Increase of carbon dioxide in the atmosphere: less carbon dioxide is being removed from the atmosphere and less oxygen is released. Trees are also often burned, which releases carbon dioxide (an example of combustion)
3.1. Describe the effects of untreated sewage and excess fertiliser on aquatic ecosystems (note use point 4 for to explain details of the eutrophication process)
Untreated sewage and the deaths of algae from algae blooms caused by excess fertiliser provides a good source of food for bacteria
Bacteria depletes oxygen dissolved in water as they respire aerobically, causing aquatic organisms such as fish to die (eutrophication)
3.2. Describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystems
Marine animals try to eat plastic or get caught in it, leading to injuries and deaths
Plastic releases toxins as it breaks down, which may affect marine organisms
Tiny plastic particles enter the food chain through animals consuming them
Plastic in landfills release toxins into the surrounding soil, so the land becomes bad for growing crops or grazing animals and can only be used for building on decades after burial
3.4. Explain the process of eutrophication of water
4.1. Describe a sustainable resource
A resource that is produced as rapidly as it is removed from the environment so that it does not run out
4.2. What are some resources that can be conserved and managed sustainably?
Forests and fish stocks
4.2. What are some resources that can be conserved and managed sustainably?
Forests and fish stocks
4.3. Explain why organisms become endangered or extinct, including: climate change, habitat destruction, hunting, overharvesting, pollution and introduced species
Climate change: forces species to adapt to new climate patterns, so many species must migrate to new areas that meet their needs. Species that cannot adapt quickly enough die, leading to extinction (e.g. loss of ice from the Arctic reduces hunting sites for polar bears)
Habitat destruction: more land is being used for agriculture, including previously unusable land that has been drained. The carrying capacity for indigenous plants, animals, and other organisms is reduced, so populations decline, removing habitats for many species, such as wading birds and amphibians
Hunting: pests have been hunted ruthlessly, such as the red deer (which damages trees), predators such as cheetahs, and scavengers such as vultures
Overharvesting: reduces valuable living resources to such low levels that their exploitation is no longer sustainable
Pollution: ponds and rivers may be polluted by fertilisers and sewage, so many oxygen-requiring species can be lost
Introduced species: predators such as stoats and weasels introduced to offshore islands can eliminate ground-nesting birds
4.4.1. Describe how endangered species can be conserved through monitoring and protecting species and habitats
Monitoring and protecting species will ensure that they have the best conditions to survive
Problems can be removed before they cause too much harm
4.4.2. Describe how endangered species can be conserved through education
The more people aware of the importance of conservation, the more will be inclined to do something about it
More people will know what species face endangerment, so they’ll be better protected
4.4.3. Describe how endangered species can be conserved through captive breeding programmes
Ensures the population will rise again, and eventually the species can return to the wild
4.4.4. Describe how endangered species can be conserved through seed banks
Seeds of endangered plant species are carefully stored so that new plants may be grown in the future, ensuring the population will eventually rise again
4.5. Explain how forests can be conserved using: education, protected areas, quotas and replanting
Forests are needed to produce paper products and provide wood for timber
Much of the world’s paper is now produced from forests which replant similar trees when mature trees are cut, ensuring that there will be adequate supply in the future
Tropical hardwoods such as teak and mahogany take many years to regrow but are highly desirable for furniture
Using these types is more sustainable due to the introduction of several schemes designed to monitor logging companies and track the wood produced
Education ensures logging companies are aware of sustainable practices and consumers know the importance of buying products made from sustainable sources
4.6. Explain how fish stocks can be conserved
Educating fishermen as to local and international laws, and educating consumers as to types of fish not produced sustainably and to buying avoid them
Controlling the time of year certain fish can be caught (to prevent large scale depletion when fish come together in large numbers in certain areas to breed)
Controlling the number of fish caught each year
Controlling the size of fish caught (ensures there are enough fish of suitable age for breeding remaining)
Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
4.7. Describe the reasons for conservation programmes
Maintaining or increasing biodiversity: allows ecosystems to remain stable
Reducing extinction: retains iconic species and maintain biodiversity
Protecting vulnerable ecosystems: they would be lost to human activity without intervention
Maintaining ecosystem functions: nutrient cycling eg. carbon cycling to hold back climate change. Resource provision, such as making sure we have enough food for the population, having access to plants for plant-based remedies, fuel for important activities such as cooking and genes so the gene pool remains wide and variety exists in all species
4.8. Describe the use of artificial insemination (AI) and in vitro fertilisation (IVF) in captive breeding programmes
Certain conservation techniques can be used to maintain biodiversity
Artificial insemination (AI): allows large numbers of offspring to be produced without the need for conventional sexual intercourse
In vitro fertilisation (IVF): allows gametes with known alleles to be used in ensuring the next generation remains biodiverse
4.9. Explain the risks to a species if its population size decreases, reducing genetic variation (knowledge of genetic drift is not required)
Reduced genetic variation makes a species more susceptible to environmental change, increasing the risk of extinction
