Fragile Environment

Fragile Environments

• Abiotic Factors:
• Non-living things
• e.g Sun, water, gas temperature, soil
• Biotic Factors:
• Living things in an ecosystem
• e.g plants, animals, bacteria

Erosion

• Soil Erosion:
• -Removal of top soil faster than the soil forming process can replace it.
• Consequences: Infertile Land/Soil
• Sheet Erosion:
• -Removal of thin layers of surface materials by continuous sheets of running water.
• Gully Erosion:
• -Removal of soil along the drainage lines by the surface water run off.
• Continue to move by headward erosion
• Slumping
• Wind Erosion:
• The erosion of topsoil by wind and a lot of the time, dust storms.

Desertification

• The term used to describe how once productive land gradually changes into desert-like landscape.
• The process is not necessarily irreversible and it usually takes place in semi-arid land on the edges of hot deserts.
• There are both natural and human causes of desertification.

Cause of Desertification

• Natural:
• Changing Rainfall Patterns
• -vegetation can die and leave soil bare
• Soil Erosion
• -less support for the vegetation
• Intensity of the Rainfall
• -Rain becomes difficult for the soil to hold.
• Human:
• Population Growth
• - more pressure on the land
• Overgrazing
• -destruction of vegetation
• Over cultivation
• -Exhaust soil and therefore crops will not grow
• Deforestation
• -trees cut down for fuel, fencing and housing

Consequences of Soil Erosion

• Soil Erosion
• ↓
• Food Shortages
• ↓
• Malnutrition
• ↓
• Famine/Starvation
• ↓
• Migration
• ↓
• Food Aid

CASE STUDY- Desertification: Sahel, Africa

• The Sahel is a narrow belt of land in central Africa. There is a semi-arid climate with high temperatures. The region is classified as a Savannah. The natural vegetation is a mixture of grasslands, trees and shrubs.
• In the Sahel there are many grazing animals.
• -Large herds of buffalo
• -Zebra and antelope
• Rain fall is unpredictable.
• -trees have been dying and less vegetation is growing.
• Over 100,000 people have died, even more have migrated and it has caused the loss of millions of animals.

Management of Soil Erosion in the Sahel

• Catching Rainfall
• -Stone walls are built following the slope of the land. Act as a dam and stops surface water run-off.
• Contour Ploughing
• -ploughing along the line