CONSERVATION

1. vegetation

2. nature's defence

2.1. laws

3. Circulation

3.1. rapid run-off

3.1.1. frequent flood

3.1.2. leave little dry water

3.2. hydro-electric dams

4. deforestation

4.1. disappearance

4.1.1. variety of plants and animals

4.2. destruction

4.2.1. the habitat of animals