B13 - Human influences on ecosystems Flashcards
How has modern technology increased food supply? (4)
- Agricultural machinery
- Chemical fertilisers improve yields
- Insecticides and herbicides
- Selective breed
Intensive livestock farming
Large numbers of livestock are often kept in an area that would not normally be able to support more than a very small number
* fed high energy foods, medicated to prevent disease, kep in artificially warm temperatures, not allowed much movement
Advantages of intensive livestock farming (name 3)
- 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 labour to produce the food
Disadvantages of intensive livestock farming (name 3)
- Intensive farming techniques tend to use
- herbicides which may result in eutrophication
- pesticides which can cause negative effects on the foodchain
- Ethical issues associated with cruel treatment of animals in intensive farms
- Natural habitats may be destroyed to maximise land available
- Ecological issues with intensive farming include:
* reduction in biodiversity in areas where large amounts of land are used to graze cattle (as only grass is grown so in effect it becomes a monoculture)
* overgrazing can lead to soil erosion
* large numbers of cattle produce large amounts of methane, a greenhouse gas
Monoculture farming
Monoculture farming means that on a given area of agricultural land only one type of crop is grown
The carbon cycle
- Carbon is taken out of the atmosphere in the form of carbon dioxide by plants for photosynthesis
- Passes onto animals by feeding
- Returned to the atmospher as CO2 by plants, animals and micoorganisms through respiration
- Animals and plants die and do not docompose, the carbon in their bodies can be converted (over millions of years) into fossil fuels
- When fossil fuels are burnt (process called combustion), carbon combines with oxygen and CO2 is released into atmosphere
1. Increased use of fossil fuels increases carbon emmissions
2. Mass deforestation and the reducing number of producers also increases carbon dioxide in the atmosphere
Biodiversity
The number of different species that live in a particular area
* human activity tends to force it downwards
* habitat destruction puts pressure on it
Reasons for habitat destruction (3)
- Clearing land for farming and housing
- Extraction of natural resources
- Marine pollution
How does the clearing of land lead to habitat destruction?
- Crops, livestock and housing take up a large amount of space
- An increase in population and demand for food means available land must be increased by clearing habitats such as forests
How does the extraction of natural resources lead to habitat destruction?
- Natural resources need to be gathered to make different products
- Many trees are cut down for wood and quarries are formed for mining minerals
How does marine pollution lead to habitat destruction?
- Human activities lead to pollution of marine habitats
- In many place oil spills and other waste pollutes the ocean, killing sea life
- Eutrophication can also occur
Deforestation
Deforestation is the clearing of trees (usually on a large scale)
Negative consequences of deforestation (4)
- Extinction of species
- Loss of soil
- Flooding
- Increase of carbon dioxide in the atmosphere
How does deforestation lead to extinction?
- Forest habitats have a huge range of biodiversity and as habibats are destroyed is causes the loss of animals and plants
- Many of these species are only found in these areas and will becom extinct
How does deforestation lead to soil erosion?
- Tree roots help stabilise the soil, preventing erosion by rain
- Trees will also take up nutrients and minerals through their roots
- Without trees, nutrients and minerals will be unused and the soil will be washed away into rivers and lakes by rain (leaching)
