Human influences on ecosystems

• Intensive food production


  Producing food more efficiently with a finite amount of land and other resources
• Modern technology has increased food supply substantially


  • Agricultural machinery has replaced humans and improved efficiency due to the ability to farm much larger areas of land
  • Chemical fertilisers improve yields - fertilisers increase the amount of nutrients in the soil for plants, meaning that they can grow larger and produce more fruit
  • Insecticides and herbicides - these chemicals kill off unwanted insects and weed species, meaning that there is less damage done to plants and fruit lost to insects (insecticides), as well as 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
  • Modern agricultural processes allows for cultivation of much larger areas of land for crop plants
• 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
• 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 labour to produce the food
• Disadvantages of intensive livestock farming


  • Intensive farming techniques tend to use herbicides which may result in eutrophication
  • Intensive farming techniques tend to use 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


  • 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


  Only one type of crop is grown (eg trees for palm oil grown in Indonesian rainforest)
• Monoculture farming does not happen naturally in ecosystems, where there are usually many different species of plants growing which, in turn, support many species of animals (high biodiversity)
• In monocultures, biodiversity is much lower
• Issue with monocultures


  Increase in pest populations - if a particular pest feeds on a crop, farming it in large areas repeatedly means there is an ample supply of food for the pest, causing the population to increase
• Issues with using insecticides in monocultures


  • 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
• Palm oil production has increased rapidly over the last 30 years
• Deforestation refers to the clearing or cutting down of trees from forests, which can have significant impacts on local ecosystems.