human influences on ecosystems

Food production

  • Most of the supply of food on the world is from crops or keeping animals

    • Even though we still harvest fish in large quantities

  • Quantity of food produced has increased in the past few hundred years

    • Such as rice, wheat, grains

  • Increasing because the world's population is increasing

  • Many ways the increase has been successful

Agricultural machinery

  • Animals have helped greatly

  • Machines have helped greatly

    • Farmers cultivate larger areas in a shorter time now

  • Few examples

    • Tractors

      • Plough deep

      • Quick

    • Ploughing with oxen

      • Not too deep

      • Wooden plough

      • Slow

Agricultural chemical

  • Help improve growth of crops

  • Chemical fertilisers

    • Add more mineral ions

      • If the soil does not contain enough

  • Insecticides

    • Kill insect pests

    • Reduce yields

    • May make crops look less appealing to buyers

  • Herbicides

    • Kill weeds

      • Compete with the crop plats and reduce their growth

Selective breeding

  • Carefully selected

  • Increases world food production

  • Produced plants that can grow in poor soil conditions

    • Resistant to diseases

  • Cattle produce more meat and milk

  • Hens lay more eggs

Monocultures

  • Area of ground covered by one, single crop

    • No other types of plants

  • Make _____ easier and more efficient

    • Sowing

    • Tending

    • Harvesting

    • Selling

  • Likely to grow the same height

  • Ripen around the same time

  • Harvested at once using specialised machines

  • You can cultivate a large area and can be done quicker and efficiently that small several different fields

  • Can be treated with the same herbicides

    • In the same way etv333

    • Increases efficiency

  • Produce larger quantity of seeds and fruit and harvestable parts

    • Uniform in size and quantity

    • Easier for farmer to market

Reduction in biodiversity

  • Number of different species that live in one area

  • In a natural ecosystem there are different species of plants

  • Different types of animals

  • In a monoculture, biocultural is low

Increase in pests

  • Can lead to increase of organisms

  • If a large area of land is covered by one crop, pests that attack that crop will increase and grow to large sizes

  • Can be reduced by insecticide

    • You could use predatory insects

      • Some spiders too

    • Expensive

    • Pests can gain resistances and can no longer be killed by the

Reduction of soil quality 

  • Over time minerals from the soil get removed because of constant planting on the same area, even if it is the same plant

    • Usually needs the same nutrients and minerals

  • Fertilisers are added to replace the minerals

  • Yield will reduce year by year

  • Changing the crop and particular area or ground helps

    • Maintains better balance of minerals

  • Soil becomes toxic to other plants because it gets used to one plant that if you decide to try and change to another crop you may not receive anything.

Intensive livestock production

  • Cattle and livestock usually kept outdoors in some countries

    • They graze on grass

  • They don't take too much from the environment

    • Don't do much damage

  • In developed countries

    • They are farmed intensively

    • Large numbers kept in an area that would support a smaller number

  • Do this to increase

    • Milk meat

    • Wool

  • Use of high energy food for the animals

  • Regular medicine given

    • To prevent diseases (duh)

  • Kept in temperature controlled buildings

    • Maximises growth

  • Advantages

    • Provide more food

      • Provided cheaply

      • Fewer people go hungry

    • Less land needed

      • More land left to natural state

        • Other habitats for other animals and plants

  • Disadvantages

    • Welfare issues

      • Suffer from crowded environment

    • Diseases spread easier

      • Some countries try giving antibiotics but the bacteria can grow a resistance

    • Waste from the unit can pollute land and waterways nearby

    • Food for the animals is sometimes food we eat ourselves

      • For example, soya

      • Wasteful because the beans could give us the energy we need rather than cattle

    • Energy used to transfer cattle feed over long distances

    • Energy used to keep buildings for the livestock regulated

    • Large amount of water needed

Habitat destruction

  • If humans destroy habitat, the species may find it difficult to adapt to a new area

  • Cutting down native vegetation

    • For growing other plants

    • For farming livestock

    • Building houses

    • Buildings factories

  • Mining

    • Removes soil and vegetation

    • Toxic run-off

      • Can enter rivers

  • Add pollutants to land and water

    • Kill plants that normally live there

      • Changing the habitat

  • Removing key species

    • Collecting live corals

    • Endangering hundreds of species that may depend on the habitat you removed

    • Damage food webs

Deforestation

  • Cutting down of trees

  • Wood is great for fuel and building materials

  • Happening in many countries

  • Happens a lot in rainforests especially

    • Area of perfect condition for growing plants

      • High and constant temperature

      • High rainfall

    • High biodiversity

    • More different species in a small area of a rainforest than any other area

    • When cut down, exposing soil under the trees is exposed

      • To the rain

      • This soil is thin

        • Easily and quickly washed away

          • Soil erosion

          • Washed into rivers

            • Water overflows (flooding occurs)

      • Roots were there to bind it together

    • Difficult for the soil to grow back

    • Lots of animals live there

      • Can cause extinction

        • The complete loss of a species from Earth

Pollution by greenhouse gases

  • Gases such as carbon dioxide and methane that trap heat within the atmosphere

  • Addition to the environment of something that harms it

  • Some gases act like a blanket to keep the earth warm

  • Carbon dioxide

    • Allows shortwave radiation from the sun

    • Passes freely though

      • Reaches the ground

    • Warms the atmosphere

    • Carbon dioxide does not allow this

  • Greenhouse effect is caused

    • Heating of the Earth  by trapping of heat by greenhouse gases

    • Without it, the world will be cold

 

Eutrophication

Non-biodegradable plastics

Conserving forests

Endangered species

Conserving endangered species