desertification desertification

DefinitionDefinition• Desertification is a process of turning the produc

tive land into desert.

• A definition of desertification should recognize that it is a land degradation process that involves a continuum of change, from slight to very severe degradation of the plant and soil resource, and is due to man's activities.

• Desertification is also a situation on the desert expansion. That means desert is continuously expanding to the surrounding area.

Where?Where?

• Sub-Saharan Africa, the Middle East, western Asia, northern Mexico and south-eastern South America, western United States, prairies of Canada, and eastern Australia. Scientists estimate that 60,000 square kilometers of new desert are now annually created worldwide.

Causes on desertificationCauses on desertificationdesertification

High pop. Poor / poverty

Climatic change

Over cropping

deforestation

Over grazing

Global warming

Less R”

↓ Soil fertility ,↓ soil degradation &↓ Soil aridity

Human factors

+Impropriate irrigation

-salinization

CauseCauseHuman factors:High population

-Deforestation--- demand∵ more land and timber for cropping & building, cutting down to tree extensively

-Over cropping—- demand∵ for food crops↑ & the cash crops demanded by MCDs ↑, ↑shifting cultivation, ↓soil fertility, secondary growth

Poverty / poor

-Over grazing--- LDCs have a large international debts, ∵the cheap labours & the extensive land in LDCs used by MDCs, in order to pay the debts, →the extensive is suitable for grazing (i.e., cattle )

CauseCauseImpropriate irrigation

∴infiltration >E underground water table rises salinization (鹽鹼化 )

Climatic change -Global warmingCO2↑, T ↑, ice cap melt, flooding in

coastal area , ↓ rainfall, drought , veg. die

-Less rainfalldrought , veg. die

“If the climatic factors are said to be the main causes of desertification ,then human activities are going to intensify it.”

Effects on desertificationEffects on desertificationdesertificationdesertification

Atmosphere

-local climate

↓R”

drought

-macro climate

global warming

Hydrosphere

-water cycle

breaks down

Lithosphere

-loss of arable

salinization

-land intensify the

soil erosion

Biosphere

-extinction of plants & animals

-↓biodiversity

Upset the balance of ecosystem

EffectsEffectsAtmosphere1) Micro (i)↓R”+↑T° ↑T in day time &↓ T in night time↑ET/reflection ↑diurnal range of T° (ii) ↑wind speed no veg cover / shelter ∵ (iii) ↓relative humidity

2)Macro (i)Global warming (ii)Sandstormexpanding of desert

EffectsEffectsLithosphere

1)loss of arable land

soil texture change to sandy ↓cohesive

power (cannot hold water) not suitable for veg growth

2)intensify the soil erosion

1.↑ deforestationno root to bind the soil

↑ soil erosion↑ silting

EffectsEffectsHydrosphere1)Water cycle breaks down ↓∵ R” & ↑ evaporation( no shelter)∵ rivers and wells dried up

Biosphere1)lower the bio-diversity ↓∵ R” & unevenly dis.+deforestation scattered veg. (veg. Is shorter, few species, less luxuriant)extinction

EffectsEffects

Others1)lower the income

∵R” ↓ crops productivity ↓,

2)use a large amt of $ for soil protection & recovery

(i.e. UNCED us$1,060m per yr to recover the deserted land)

How to solve???How to solve???LDCs1.Control the pop. growth / natural increase

by using family planning, in order to decrease the land use capacity

2.The number of grazing and the rate of cultivation should not over the carrying capacity of land

How to solve???How to solve???

3. improve i)farming & ii)grazing methods, in other to reduce soil erosion and

salinization

i) suitable timing and amount to carry out irrigation

plant the halophytes (which can adapt salty &

droughted soil) e.g, Chenopodiaceae

ii)sufficient fallowing period

Animal welfare (e.g, Kenya)

How to solve???How to solve???

4.Legislation: band the deforestation and over grazing, etc. , in order to balance the ecosystem of desert.

5.afforestation i.e. plant the wind break trees & drought resistant plants

6.stone lines (e.g, in Burkina Faso)

7. Building reservoir and canal , (e.g, The Indira Gandhi Canal)

How to solve???How to solve???

MDCs

1) international aid(e.g.,Green Peace)

technology, low interest rate of loan &

education

2) scientific research e.g World Association of Soil and Water Conservation (WASWC) 

How to solve???How to solve???

Both citizens in MDCs & LDCs have

Responsibility

i) Don’t buy valuable halophytes (e.g,Fat choi)

ii) 5R(reuse, reduce, renew, recycle, rethink)

iii) Fund raising

EffectivenessEffectivenessLDCs1)Money? LDCs are so poor

2)International aid? lack of technology,efficient farming skill

& low education

3)Attitude? X family planning

MDCs1)Exploitation? try to get more raw materials & resources fr

om LDCs

2)Human behaviour?? rapid ↑in living standard

& large amt of wastes are produced

ConclusionConclusion

The effectiveness of preventing desertification

is depended on the cooperation of MDCs &

LDCs.