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Chapter 7: Fragile environments

Ecological footprint: measure of the mark that we humans make on the natural world. It considers how much land and sea are required to provide us with the energy for our lifestyles.

Sustainability: actions and forms of progress that meet the needs of the present reducing the ability of future generations to meet their needs.

Soil erosion and desertification

Soil erosion
* The washing or blowing away of top soil.
* There are three types:
* Sheet erosion – occurs in parts with moderate rainfall * Gully erosion – occurs where there’s intense rainfall and little vegetation cover. Force of water cuts gullies in slopes :O! * Wind erosion – occurs in dry parts of world

* What makes soil erosion worse?
* Deforestation and removing vegetation. As a result of this soil gets exposed to wind/rain * Overgrazing by animals. Result is same as above
* Over cultivating the soil! Especially monoculture which weakens the soil and structure and removed minerals from soil * Compacting the soil by use of heavy machinery. This encourages more run off which encourages soil erosion * Ploughing fields in the same direction as the slopes. Encourages gullying :P Desertification

* The process of how once productive land gradually changes into a dessert-like landscape * Natural causes of desertification:
* Changing rainfall patterns
* Soil erosion
* Intensity of rain: because when rainfall falls only a little does so it makes it hard for the soil to capture and store the water * Human causes of desertification:
* Population growth: more population = more food needed = more pressure on land * Overgrazing
* Over cultivation: intensive use of marginal land = soil exhausted and so crops wont grow * Deforestation: which leads to soil erosion

Consequences and management of soil erosion

Consequences
* Fall in food production
* Malnutrition = rise in morality rate
* Famine and starvation
* Migration
* Food aid

Management
* Terracing and tree planting (esp. for wind and gully erosion) * Mulching
* Contour-ploughing slopes
* Strip cropping
* Maintaining water in the soil by building small dams across streams, building earth walls along contours, planting trees/protecting them from grazing animals

All the above reduces run off and allows time for infiltration * Organic farming – relies on crop rotation
Type of organic farming is permaculture: particularly suited for LICs

Causes of deforestation
Deforestation – cutting down of trees

Why are trees being cut?
* Commercial logging/ timber extraction – when valuable trees are chopped they damage others as well * Road building
* Land for peasants
* Agriculture (directly linked to population growth)
* Mining
* HEP (hydroelectric power) – rivers are dammed and huge areas of forest are flooded as a result

Consequences of deforestation
* Loss of biodiversity (variety of phona and flora)
* Contributes to global warming
* Sometimes it stimulates much needed economic growth in LICs (eg:- Brazil, Guyana, Indonesia, Thailand, Philippines)

Managing rainforests in a sustainable way
Sustainable management should:
* Respect environment and cultures of local people
* Use traditional skills and knowledge
* Give people control over their land and lives
* Use appropriate technology
* Generate income for local communities
* Protect biodiversity

Sustainable management of forests:
* Protection of forests
* Selective logging
* Carefully planned and controlled logging in forests
* Replanting of forested areas that have been cut
* Restrictions on number of logging licenses given out
* Heli-logging (eg:- in Sarawak)
* Developing alternative energy supples (biogas,...
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