The Terrestrial environment

1. The Terrestrial environment Soils, soils, soils

2. The terrestrial environment

3. Objectives • Discuss the formation of soils • Compare different soil types • Relate soil fertility to physical & chemical properties of soil. • Discuss soil erosion and its preventative methods • Compare farming methods

4. Objectives • Discuss food chains & food webs found in the terrestrial environment • Describe the oxygen, carbon, nitrogen & water cycles.

5. Soils

6. Soil formation • Soil formation begins with weathering. • This is the process by which rocks are broken up into small particles over long periods of time. • There are various ways in which weathering may occur.

7. Weathering • Physical weathering is caused by changes in temperature and water pressure. • Chemical weathering is caused by rainwater in cracks of rock dissolving away some of the substances. • Biological weathering is caused by growth of roots through rocks.

8. Components of soil

9. Soil components These include: • Humus • Mineral particles • Rock particles • Air • Water • Living organisms *Discuss the functions of each

10. Soil types • Clay soils have mainly clay particles with small air spaces. • Sandy soils have mainly sand particles with large air spaces. • Loam soils are a mixture of sand & clay particles with medium size air particles.

11. Size of particles • The size of the particles affects the following physical characteristics of the soil: 1) Air content 2) Water-holding capacity 3)Drainage

12. Soil fertility • Soil fertility is determined by • Particle size • Mineral content • Organic content • pH Nb. Soil which possesses the conditions needed for optimum plant growth of a plant are fertile with respect to that plant.

13. Soil Erosion • Erosion is a natural process, whereby the topsoil is removed by action of wind and water. • It has been increased dramatically by human land use, especially industrial agriculture, deforestation, and urban sprawl.

14. Causes of soil erosion • Careless farming methods • Deforestation • Overgrazing • Over cropping • Loss of soil structure

15. Reducing soil erosion • Contour ploughing • Terracing • Planting trees • Strip cropping *Please check text for various farming techniques

16. Feeding relationships

17. Feeding relationships • An ecosystem is a system formed by the interaction of a community of organisms with their physical environment. • Forests, deserts, grasslands & savannas have their own terrestrial ecosystems.

18. Feeding relationships • All organisms interact with each other and their surroundings within an ecosystem. • One of these main interactions involve the various feeding relationships.

19. Feeding relationships • A food chain shows the feeding sequence of organisms in an ecosystem. • The 1st member is called the producer. It is a plant, and it produces its own food. • All of the other members of the food chain are called the consumers. These acquire their food otherwise.

20. Food chain A food chain always starts with the producer. The arrows shows the direction of energy from consumption. The consumers follow thereafter and are classified primary, secondary, tertiary etc.

22. Consumers can be: *Herbivores: feed only on plant material *Carnivores: feed only other animals *Omnivores: feed on both plants & animals *Decomposers: feed on dead organic matter Can you give examples of these?

23. Food web • A food web is a network of inter-related food chains. • If the number of one organism in a food web changes, it can affect the numbers of all the others.

27. The natural cycles

28. The Carbon cycle

29. The Nitrogen cycle

30. The water cycle