ENVS10011 Lecture Notes - Lecture 8: Overgrazing, Water Table, Eutrophication

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WEEK 8: LAND DEGRADATION
Degradation: reduced capacity or diminished ability of a resource, to a lower quality
state, as compared to a healthy/sustainable state
43% of Earth’s vegetated land degraded (lowered capacity to provide benefits)
o Causing a 10% decrease in value + benefits
Types of Land Degradation
Desertification
About
Desert type conditions
Drylands: arid, semi-arid + dry sub-humid areas
Degraded drylands have diminished control over limiting resources
Causes
Overgrazing by livestock
Over cultivation
Fuel gathering
Deforestation
Why Care?
Drylands cover 4% land surface, home to 38% population
Severe degradation of up to 20% of Earth’s drylands
When occurs past threshold, requires extensive external intervention
Restoration
Goal: restoring vegetation cover
Wadi Hanifah Restoration Project:
Goal: recover ecological integrity + reduce dust storms
Action: restore strip between 2 patches, expand protected dunes + trial
planting techniques
Salinisation (Secondary)
About
‘Concentration of salts in surface soil caused by human activity’
Types: dryland or irrigated land
Causes
Water table rises
associated with
surface-water
irrigation systems
Why Care?
Rural land affected: 10% (WA) + 5% (SEA)
$millions production lost each year
Principal cause of soil + water degradation in Victoria
Restoration
Goal:
Northern United Forestry Group Kamarooka Project:
Goal: provide commercially viable forest products, environmental
services + community benefits by rejuvenating the area
Action: restore strip between 2 patches, expand protected dunes + trial
planting techniques
Tropical Forest Degradation
About
‘Negative change in the structure, biodiversity + functioning of
undisturbed (primary) tropical forest
50% worlds closed canopy forest cleared, creating edge effects, as
population of tropical countries grows
Leads to:
Decreases in vegetation cover
Loss of soil (wind + water erosion)
Low water retention
Leads to:
Changes in landscape
Changes in hydrological processes associated
with major vegetation changes
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Document Summary

Causes: desert type conditions, drylands: arid, semi-arid + dry sub-humid areas, degraded drylands have diminished control over limiting resources, overgrazing by livestock, over cultivation, fuel gathering, deforestation, decreases in vegetation cover. Why care: drylands cover 4% land surface, home to 38% population, severe degradation of up to 20% of earth"s drylands, when occurs past threshold, requires extensive external intervention. Wadi hanifah restoration project: goal: recover ecological integrity + reduce dust storms, action: restore strip between 2 patches, expand protected dunes + trial planting techniques. Concentration of salts in surface soil caused by human activity": types: dryland or irrigated land, water table rises. Leads to: associated with surface-water irrigation systems: changes in landscape, changes in hydrological processes associated with major vegetation changes. Why care: rural land affected: 10% (wa) + 5% (sea, production lost each year, principal cause of soil + water degradation in victoria.

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