Ch 20 - (Human influence on ecosystem) Flashcards
What does making food production more intensive mean?
producing food more efficiently with a finite amount of land and other resources
What are the ways in which modern technology has increased food supply substantially?
- Agricultural machinery - replaced humans, improved efficiency due to the ability to farm much larger areas of land
- Chemical fertilizers improve yields - fertilizers increase the amount of nutrients in the soil for plants
- Insecticides and herbicides - these chemicals kill off unwanted insects and weed species, reducing competition from other plant species (herbicides)
- Selective breeding - animals and crop plants which produce a large yield are selectively bred to produce breeds that reliably produce high yields
What happens to the stock in developing countries?
Large numbers of livestock are often kept in an area that would not normally be able to support more than a very small number
What food is fed in highly developed countries?
- high energy foods
- antibiotics
- artificially warm temperatures
- do not allow for much movement
What are the advantages of intensive livestock farming?
- Less land is required to produce large amounts of food
- Food can be produced all year round in controlled environments
- The cost of production is lower
therefore food can be sold at cheaper prices - There is a lower requirement for labor to produce the food
What are the disadvantages of intensive livestock farming?
- Ethical issues associated with cruel treatment of animals
- Natural habitats may be destroyed
- reduction in biodiversity
- soil erosion
- large numbers of cattle produce large amounts of methane,
What do intensive farming tend to sue?
- herbicides which may result in eutrophication
- pesticides which can cause negative effects on the food chain
What is monoculture farming?
on a given area of agricultural land only one type of crop is grown
What happens on large scale growth of single variety of plant in monoculture?
- does not happen naturally
- usually many different species of plants
- support many species of animals
What are the issues in monoculture?
- biodiversity is much lower
- increase in pest populations
What does spraying insecticides onto crops lead to?
- harmless insects being killed as well
- pollution by pesticides (which are often persistent chemicals which accumulate in food chains)
- in many instances where they are used repeatedly for specific pests, the pests may eventually become resistant to them, reducing their effectiveness
Define biodiversity.
number of different species that live in a particular area
What has human activities caused?
- force biodiversity downwards,
- habitat destruction
What are the reasons for habitat destruction?
- The increasing human population
- Many habitats are destroyed by humans to make space for other economic activities
- This interrupts food chains and webs
What is deforestation?
clearing of trees (usually on a large scale)
How are trees being replaced?
- by replanting it can be a sustainable practise
- and to be used in a different way
- particularly severe example of habitat destruction
What are undesirable effects of deforestation ?
- Extinction of species
- Loss of soil
- Flooding
- Increase of carbon dioxide in the atmosphere
What have human activities lead to?
What are the pollutants?
- Untreated sewage
- Chemical waste
- Discarded rubbish
- Fertilizers
- Insecticides & Herbicides
- Nuclear fallout
- Fallout
- Methane
- Carbon dioxide
What is source / cause of untreated sewage?
Lack of sewage treatment
What is source / cause of chemical waste?
mercury chemicals are released from factories
What is source / cause of discarded rubbish?
rubbish consists of plastics that is discarded or buried in landfills
What is source / cause of fertilizers?
runoff from agricultural land if applied in very High concentration
What is source / cause of Insecticides and herbicides?
sprayed on crops from to prevent damage by insects and growth of weeds
What is source / cause of nuclear fallout ?
radioactive particles from explosions of nuclear bomb
What is source / cause of methane?
cattle farming, rice fields, landfills
What is source / cause of carbon dioxide?
- produced when fossil fuels are burnt
- released when trees are burnt
What is the effect of untreated sewage?
- gud source of food for bacteria
- depletes oxygen dissolved in water (respire aerobically)
- cause death of aquatic species (eutrophication)
What is the effect of chemical waste?
- heavy metals are persistent
- don’t break
- can build up in food chains
What is the effect of discarded rubbish?
- non bio degradable
- harms the environment
- animals eat small plastic
What is the effect of fertilizers?
- causes algal bloom
- provides gud source of food which decomposes bacteria
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What is the effect of insecticides and herbicides?
- bioaccumulation
- loss of biodiversity
- damage to beneficial insects
What is the effect of nuclear fallout?
- increased risk of cancer
What is the effect of methane?
contributes to enhanced greenhouse effect
What is the effect of carbon dioxide?
greenhouse base contributing to climate change
What are the effects of algal bloom?
- blocks sunlight
- water plants and algae die in greater numbers; decomposing bacteria increase in number and use up the dissolved oxygen whilst respiring aerobically
- less oxygen dissolved in water, so aquatic organisms such as fish and insects may be unable to breathe
What are the negative impact of plastic on marine habitats?
- Animals often try to eat plastic or become caught in it, leading to injuries and death
- As the plastic breaks down it can release toxins that affect marine organisms
- Once it has broken down into very small particles, it is commonly ingested by animals and enters the food chain
what are the negative impacts of plastic on land?
- Plastic is generally disposed of by burying in landfills
- As it breaks down, it releases toxins into the surrounding soil and as such the land is no good for growing crops or grazing animals
What gases insulate the earth as a blanket?
Methane and carbon dioxide
What human activity increases levels of methane and carbon dioxide?
- Burning fossil fuels increases carbon dioxide
- Keeping livestock generates methane gas
- Global warming
What are sustainable resources?
resources from the Earth; some, such as food, water and wood,
What is a sustainable resource?
produced as rapidly as it is removed from the environment so that it does not run out
What resources are non - renewable ate conserved and reused?
- reducing the amount we use and finding other, sustainable resources to replace them
- energy source
- raw materials
- products such as plastic, paper, glad or metal can be reused or recycled
- forests and fish stalks maintained by harvesting sustainably
Define sustainable development.
development providing for the needs of an increasing human population without harming the environment
How do we balance conflicting demands in sustainable production?
- the need for local people to be able to utilize the resources
- he needs of large companies to make money from resource
- the need for balancing the needs of humans for resources
- the needs of the animals and plants
- current populations need with what future populations might need -
Describe how sustaining forest is important?
- produce paper products and provide wood for timber
- replant similar trees when mature trees are cut
- introduction of several schemes designed to monitor logging companies
- Education
What are ways in which we sustain fish stalks?
- Controlling the number of fish
- Controlling the size of fish caught
- Controlling the time of year that certain fish can be caught
- Restocking (breeding and keeping offspring until they are large enough to survive in their natural habitat then releasing)
- Educating fishermen as to local and international laws and consumers
Why are endangered species at risk?
the population of the species may fall below a critical level
extinct
What are the reasons why species become endangered?
- hunting
- climate change
- pollution
- loss of habitat
- introduction of non-native specie
What are conservation methods use to save endangered species ?
- education programmes
- captive breeding programmes
- monitoring and legal protection of the species and of their habitats
4.seed banks as a conservation measure for plants
Why may a specie be at risk for becoming extinct?
- if there is not enough genetic variation in the population
- remaining organisms are all very similar and may not have the adaptations to survive such changes
What are some moral, cultural, and scientific reasons for conservation programs?
- reducing extinction rates
- protecting vulnerable ecosystems (eg the rainforests)
- protecting our future food supply
- maintaining nutrient cycles and possible sources of future medical drugs and fuels
what are there numerous reasons on why conservation programs are important?
- Maintaining or increasing biodiversity - allows ecosystems to remain stable
- Reducing extinction -
Helps to retain iconic species and maintain biodiversity
What are ways in which ecosystem functions are maintained?
- Food - making sure we have enough for the population
- Drugs - having access to plants for plant-based remedies
- Fuel - for important activities such as cooking
- Genes - so the gene pool remains wide and variety exists in all species
What are conservation techniques used for?
maintain biodiversity
What are examples of conservation techniques?
- Artificial insemination (AI): in captive breeding programmes
- This allows large numbers of offspring to be produced without the need for conventional sexual intercourse between males and females
- In vitro fertilisation (IVF) in captive breeding programmes
- This allows gametes with known alleles to be used in ensuring the next generation remains biodiverse
What are the risks to a species?
- population size decreases, a species will experience reduced genetic variation
- more susceptible to environmental change
- less resilient and has a greater risk of extinction
