Chapter 19: Effects of human activity on the ecosystem

Deforestation

Is the cutting of trees.

• Reasons:

  • Urban development

  • Cultivation

  • Grazing

  • Timber

  • Fibres

• Effects of deforestation:

  • Soil erosion

  • Flooding

  • Desertification:

    • Loss of habitats.

    • Extinction of species.

    • Loss of robust wild species of plant.

    • Imbalance b/w O2 and CO2 concentration in air.

    • Climatic changes.

Pollution

• Pollutants:

  • Sulphur dioxide and nitrogen oxides - leads to acid rain and smog.

  • Lead - is poisonous if accumulated with consumed food.

  • Carbon monoxide - forms carboxyhemoglobin in blood.

  • Carbon dioxide - greenhouse effect.

  • Chlorofluorocarbons (CFC’s) - damage ozone layer.

• Causes

  • Exhaust fumes from motor vehicles.

  • Chimney fumes.

  • Burning of garbage.

• Ways of reducing

  • Use catalytic converters in cars.

  • Less use of cars.

  • Use filters or scrubbers on chimneys to remove sulphur dioxide.

  • Use of less fossil fuels in factories.

  • Use of alkalis to neutralize acidic waste products from factories before they are released to environment.

  • Use ozone - friendly products.

• Water pollution

  • Causes:

    • Sewage

    • Inorganic waste

    • Fertilizers - eutrophication

    • Pesticides

    • Insecticides

    • Herbicides

Conservation

• reasons

  • Ensure protection of plant and animals.

  • Maintenance of stable and balanced ecosystem.

  • Ensure conservation of marine life + tropical forests + natural scenery.

  • Scientific value.

• Measures

  • Laws that prevent tree hunting and human activities that harm ecosystem.

  • Educate youth.

  • On fishing grounds - ban use of large nets + regulating size of ships + limiting period of fishing + banning harvesting endangered species + harvesting months.

• Why is recycling necessary

  • Reduces waste disposal.

  • Reduces pollution.

  • Treatment of sewage saves water.

  • Saves energy and money.