Ecology 1

• Modern machinery


  • Positive: Cultivation and harvesting will be quicker, and more land area can be used
  • Negative: More fossil fuels, more CO2, greenhouse gas, pollution
  • Soil is compacted, so difficult for rainwater to penetrate the soil
• Use of artificial fertilisers


  • Positive: Increasing soil fertility by availability of minerals such as nitrates and magnesium to plants
  • Negative: Eutrophication, increase in population of bacteria/decomposers, decomposers respire aerobically, decrease the O2 concentration in water, damage to aquatic life, less food for consumers/loss of biodiversity
• Solutions for use of artificial fertilisers

  1. Control use of fertiliser: Don't spray near rivers and streams, apply only on growing plants, never apply on empty field, don't place when rain forecast

  2. Use animal manure: Heavier so not easily leached by water, release minerals slowly allowing efficient absorption
• Factors/specifications when choosing insecticides and herbicides

  • Weather forecast to avoid being transferred to another nearby places and kill useful insects/plants
  • Number of times need to be applied, cost
  • Herbs/insects are not resistant
  • Biodegradable
• Use of pesticides and herbicides

  • Positive: Insecticides kill insects, so avoid damage of crop, thus increasing crop yield
  • Herbicides kill weeds, so avoid competition on nutrients, light and water, thus increasing crop yield
  • Negative: Non-biodegradable, causing bioaccumulation/biomagnification, disrupt food chain, decreasing biodiversity and increasing risk of extinction, insects/herbs might become resistant, kill useful plants/insects such as pollinators
• Monoculture


  • Positive: Efficient food production, less land area required, mechanical harvesting easier
  • Negative: Increase the risk of spread of disease, use up specific minerals from the soil, decrease soil fertility, use of artificial fertiliser, lead to eutrophication, damage aquatic life, increase pest population, more use of insecticides, kill useful insects/animals such as pollinators, decrease the other pest population, disrupt food chain, decrease biodiversity, increase risk of extinction, deforestation, destruction of habitat, disruption of food chain, decrease biodiversity, increase of extinction, soil erosion, desertification, CO2 concentration increase, enhanced greenhouse effect and global warming
• Solutions for monoculture


  Applying mixed crop rotation: Different crops in same field, reduce pest population by breaking their life cycles, allow mineral balance, so less use of fertiliser
• Modern irrigation system


  • Positive: Provide water to growing plant, therefore removing a limiting factor
  • Negative: Can lead to leaching of minerals from soil
• Selective breeding (intensive farming)


  • Positive: Improvement in the variety of animals and plants, farmers use high energy food to feed their animals so increasing production of milk, meat and wool, regular medications given to animals so they stop developing diseases, animals are kept under controlled temperature to maximize their growth rate
  • Negative: Overcrowded places lead to spread of disease, so they increase dosing of antibiotic so increasing chance that bacteria become resistant to antibiotics, decrease in biodiversity, increase risk of extinction, waste and left overs from animals cause pollution, water borne disease, visual pollution, increase organic content of rivers, increase growth of decomposers, increase plant growth, eutrophication, feed them with high energy food (will increase cost)
• Genetic engineering


  • Positive: Crop plants resistant to herbicide, crop plants modified to contain toxic substance to kill insects, golden rice rich in vitamin A, food can be engineered into more convenient, plants can be modified to be pathogen resistant or resistant to drought
  • Negative: Reduce natural biodiversity, GM seeds are expensive, seeds need to be bought each season, ethical concerns of consumers, creating a super weed if the herbicide resistant plant cross pollinate with a wild relative, bacteria might escape from laboratories resulting in unpredicted consequences
• Deforestation


  • Positive: Increase land area available for food production, agriculture, get wood for buildings and furniture, urbanization, wood as a source of energy
  • Negative: Less plants, less photosynthesis, less oxygen concentration, more CO2 concentration, which is a greenhouse gas, trap more heat, increase temperature of Earth's surface, enhanced greenhouse effect, global warming, melt ice caps, increase/rise in sea level, floods, destruction of habitat, no food, no shelter, no breeding site, disruption of food chain, decrease in biodiversity, increase risk of extinction, less roots to absorb water, water logging, less roots to hold soil in place, so rain/wind can easily hit the soil removing top layer of soil causing soil erosion and desertification, soil washed into rivers, floods