Human influences on ecosystems Flashcards
What are the ways that modern technology has increased food production
Agricultural machinery
Chemical fertilisers
Insecticides
Herbicides
Selective breeding
What is monoculture
When there is just a single type of plant in a given area
What are the effects of monoculture
Few organisms can live in the area
It destroys the natural ecosystem in that area
What happens if there is a large number of livestock in an area
Overgrazing occurs
The plants in the area are eaten faster than they can grow back
The soil becomes exposed to wind and rain which causes erosion of the soil
Faeces from animals may build up, causing disease to spread
Famine
where not enough food is able to be produced in order to feed the population
What are the causes of famine
Extreme weather events - such as flooding, will be more common with global warming
Growth in human population is bigger than the growth of food production
Poverty - prevents people from seeds, fertilisers and machinery to grow crops
Unequal distribution of food
Why are habitats destroyed
to provide land for farming and housing
to extract natural resources
by adding pollutants to the environment, e.g. sewage and oil in the sea
Deforestation
Cutting down large areas of trees
Effects of deforestation
Loss of habitat - plants/ animals have adaptations to live in their environment. When their habitat is gone they may not survive and become extinct
Loss of soil - Plant roots help to hold soil in place, when plants are lost, soil is easily eroded
Flooding - With deforestation, there are less trees. Less trees mean that rain doesn’t hit leaves before the ground. With no leaves to slow the rain it may not be absorbed rather than soaking into the soil. And there are no roots to absorb the water.
More carbon dioxide - less trees means less photosynthesis
What types of pollution are there
Insecticides - can kill beneficial insects, slows food production, reduces food supplies for animals that feed on the insects
Herbicides - washed into bodies of water, may harm aquatic organisms
Nuclear fallout - causes radiation burns, radiation sickness, mutation
Chemical waste - may contain toxins which harm living organisms, discarded rubbish may also contain toxins
Untreated sewage - may contain pathogens and causes disease to spread,
What happens when untreated sewage enters a body of water
- The nutrients increase plant and algal growth which may cause them to cover the waters surface
- This means plants below can’t photosynthesise and die
- Dead plants increase food for decomposers, decomposer numbers increase
- Decomposers respire aerobically, they use up oxygen in the water
- Animals in the water don’t have oxygen and move away or die
Non biodegradable plastic
Cannot be broken down by decomposers
What do female contraceptive hormones cause
feminisation of male aquatic animals
Low sperm counts for men exposed to the water
What do greenhouse gases do?
They trap heat in the earth’s atmosphere
Two common green house gases
Carbon - from burning fossil fuels
Methane - from gas leakages and in the intestines of cows
What do carbon dioxide and methane allow through
Short-wave radiation from the sun to the ground
What happens when the short-wave radiation hits the ground
It is re-emitted as long-wave radiation, this cannot be passed back into space and is absorbed by the carbon dioxide and methane which raises the temperature of the atmosphere
Why does acid rain occur
Fossil fuels are burnt; Releases SO2; This gas dissolves in the water in clouds
What are the effects of acid rain
Ph of bodies of water falls - kills animals and plants
Damages trees - may not be able to absorb minerals from the acidified soil
Sustainable resource
One that is produced as rapidly as it is removed from the environment, so that it does not run out
How to sustainably use forests
replant at least one tree for each one cut down
leaving enough of the trunk for the tree to regrow
selective felling - only cutting one tree down
How to sustainably fish
Draw up international agreements
Limiting the areas allowed to be fished in
imposing quotas
limiting number of people or boats that can fish
ensuring the nets have wide mesh to allow baby fish to grow up and escape
use patrol boats - severe penalties if people not obey the law
Reduce demand for wild fish
Breeding fish - restocking
Reasons for species becoming endangered
climate change
human destruction of planet
hunting
pollution
introduced species
Why do species with a low population find it hard to survive
The variety of alleles in the population is decreased meaning its more difficult to adapt to the changing environment
How to prevent extinction of species
monitoring and protecting species in their environment
education
captive breeding programmes
seed banks
How to set up conservation programmes
Reducing extinction - extinction effects wood webs causing other species to become extinct
Protecting vulnerable environments - communities of organisms adapted to live in these conditions may become extinct
Nutrient recycling and provision of resources
Sustainable development
development providing for the needs of an increasing human population without harming the environment
Problems with sustainable development
conflicting demands - e.g. people need water, but if water is taken from water bodies organisms may die
