human influences on ecosystem Flashcards
describe how humans have increased food production
Agricultural machinery to use larger areas of land & improve efficiency
* farmer can cultivate greater area of land in shorter time then using manual labor and animals.
Chemical fertilizers to improve yields
* add more mineral ions such as nitrate ions to soils nto containing sufficient amounts.
Insecticides to improve quality & yield
* sprayed onto crops to kill insect pests that might reduce yields/make it less appealing.
Herbicides to reduce competition with weeds
* to kill weeds, which would compete w crop plants; reduces their growth.
Selective breeding to improve production by crop plants & livestock
* includes cattles (Cows), fish, poultry, that are larger and produce more meat and crop plants that grow faster and are disease-resistant.
Describe the advantages and disadvantages of large-scale monocultures of crop plants
Advantages
* Efficient; all plants are planted, taken care of, harvested in the SAME way, using SAME chemicals & machinery; makes it easier to manage crops. Cost effective.
- Higher yields from same area of land; more food & profit for farmers.
- Food produced is cheaper for consumers.
Disadvantages
- Reduction in biodiversity ; fewer plant species the natural ecosystem. fewer plant species = no habitats provided for as many organisms.
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increase in pesticide use ; excess pesticides washed into water; pollutes freshwater environment.
kills useful insets, and food chain disruption. - Low genetic variation ; pest/disease affecting plant species = can kill ALL crops being grown.
Describe the advantages and disadvantages of
intensive livestock production
Advantages
- Keeping animals in confined place = easier to monitor & protect from predators.
- Animals use less energy for movement & controlling body temp; more energy available for growth; more meat being produced.
- Greater profit for farmer, cheaper for consumers.
Disadvantages
* Waste from livestock - builds up - diseases easily spread - waste can run into water sources - pollution
- Diseases spread dealt using regular doses of antibiotic - risk of antibiotic resistance
- Welfare issues for livestock; may suffer in crowded conditions
- Unethical
- Large quantities of water may need to be provided; surrounding environment affected.
what is monoculture
area of ground covered by a single crop with almost no other species present.
what is intensive livestock production?
when livestock are farmed intensively; large no of animals kept in a small area. it limits movement of animals.
keeps them in temp controlled environment
define biodiversity
- number of diff species that live in an area
describe the reasons for habitat destruction
- to make land available for growing crops, farming livestock, building houses, factories, roads
- mining for natural resources (metal ores) building materials, fossil fuels.
- cities and factories create wawste thats often dumped in rivers and ends up in seas; causes freshwater and marine pollution that can harm aquatic environments.
how can humans have a negative impact on habitats?
- altering food webs and food chains
negative effects of deforestation
Loss of biodiversity
* when habitats are destroyed, species living in them will die or move away, reducing biodiversity in that area.
Extinction
* species can die out if they can’t find or unable to move to suitable habitats.
Loss of soil
* when trees are removed, there’s no roots to stabilize the soil during heavy rain. Soil is washed away, and nutrients are lost.
* harder for new trees to grow later.
flooding
* trees slow down rain as it falls; without trees, flooding is more likely. destroys habitats and wildlife.
increase of co2 in atmosphere
* increased co2 leads to global warming
Describe the effects of untreated sewage and excess fertiliser on aquatic ecosystems
Untreated sewage
* eutrophication
* microorganisms (decomposers) break down sewage
* microorganisms population increases
* increased respiration of microorganisms decreases oxygen content of water
excess fertilizer
* eutrophication
* extra nutrients (ions and nitrates) enters water.
* cause algae to grow faster and block out light.
* plants cant photosynthesise due to lack of light and start to die
* microorganisms (deocmposers) feed on dead plants increase in number. they respire aerobically, so the amount of dissolved oxygen in water is reduced, as decomposition increases.
* organisms that need oxgen dissolved in water (Fish) die.
Describe the effects of non-biodegradable plastics, in both aquatic and terrestrial ecosystems
Aquatic ecosystems
* eating plastic items; intestinal blockages in organisms
* poisoning from chemicals.
* large quantities of buildup in ocean
* loss of biodiversity
* disrupts food chain
Terrestial ecosystems
* plastics can give out poisonous toxins and chemicals that causes land pollution; can kill
* toxic gasses released into atmosphere when plastic disposed by burning; CO2 produced.
* landfills take up valuable space.
Describe the sources and effects of pollution of the air by methane and carbon dioxide
Sources of pollution by CO2
* fossil fuels (coal, oil, natural gas)
* when fossil fuels are burnt, they release co2.
* fossil fuels burnt in power stations, transport
* deforestation also increases amount of co2
Sources of pollution by methane
* methane gas naturall produced: rotting plants
* man-made: growing rice and raising cattle
enhanced greenhouse effect
* increasing lvl of CO2 and methane are causing an increased green house effect; causing earth to heat up; this is global warming.
whata sustainable resource
- one which is produced as rapidly as it is removed from the environment
- so that it doesn’t run out
Explain how forests can be conserved
Education
* ppl understand value of biodiversity in forests; they’ll want to protect them from deforestation
protected areas
* deforestation banned in areas by law
quotas
* limits applied to no. of trees that can be cut down in forests
replanting
* replace trees that are removed (reforestation)
* no. of trees can be maintained
Explain how fish stocks can be conserved
Education
* knowing abt improtance of conserving fish stocks means that ppl shopping for them can make better choices.
closed seasons
* some areas of the sea can be closed for certain times of the year such as breeding szn. allows fish stocks to replenish
protected areas
* areas of sea can be completely closed to fishing
* fishes can live and breed safely.
controlled net type and mesh size
* using bigger mesh size allows unwanted species to escape
* younger fish able to slip through net, allowing them to reach breeding age
quotas
* limit on number & size of fish that can be caught
* helps prevent certain species from being overfished
monitoring
* inspectors enforce rules, check catches brought to land
Explain why organisms become endangered
or extinct
- climate change
- habitat destruction
- hunting
- overharvesting
- pollution
- introduced species
describe how endangered species can be conserved
Monitoring & protecting species & habitats
* monitoring species’ no. helps identify species most under threat.
* protected areas set up to protect organisms & habitats from hunting/deforestation.
Education
* teaching ppl about natural world helps them under abt conservation
Captive breeding programmees
* bred in captivity. set up to prevent extinction of endangered species.
* easier for animals to increase numbers in captivity. less infant mortality more offspring can reproduce.
Seed banks
* seeds of endangered plant species can be kept in a seed bank
* protects and saves plant genetic diversity.
Describe the reasons for conservation
programmes
maintaining or increasing biodiversity
* conserving species means that ecosystem functions like nutrient cycling will be maintained
* helps increase/maintain biodiversity.
reducing extinction
* conserving one species may stop others from being extinct
* if 1 species extinct = affects food chain/web
protecting vulnerable ecosystems
* organisms can continue to live in their natural habitat
maintaining ecosystem functions
* resources can be used by humans e.g animals for food, plants for drugs, wood for fuel, and genes from organisms.
* conservation programmes ensure resource provision from environment can continue
Describe the use of artificial insemination (AI) in captive breeding programmes
- sperm collected from male inserted into female’s cervix to allow fertilization to take place.
- helps individuals who are unable to breed together naturally.
- helps increase genetic variation
Describe the use of In Vitro Fertilization (IVF) in captive breeding programmes
- egg is removed from female’s ovaries
- fertilized using sperm in laboratory
- embryo is planted into female
- helps individuals breed together if aren’t able to naturally
- collected eggs placed in sterile petri dish
- necessary to wait ovulation day to take eggs.
Explain the risks to a species if its population size decreases
- Fewer individuals
- Reduces genetic variation in population
- Less genetic variation can lead to inbreeding
- Less able to breed and produce healthy offspring
- Less able to adapt to changing conditions
