desertification

Definition Desertification is a process of turning the productive 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? 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 desertification Climatic change Human factors Impropriate irrigation -salinization + High pop. Poor / poverty Global warming Less R” Over grazing deforestation Over cropping ↓ Soil fertility ,↓ soil degradation &↓ Soil aridity

Cause Human 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 )

Cause Impropriate irrigation ∴infiltration >E underground water table rises salinization (鹽鹼化) Climatic change -Global warmingCO2↑, T ↑, ice cap melt, flooding in coastal area , ↓ rainfall, drought , veg. die -Less rainfalldrought , 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 desertification 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

Effects Atmosphere 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)Sandstormexpanding of desert

Effects Lithosphere 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.↑ deforestationno root to bind the soil  ↑ soil erosion↑ silting

Effects Hydrosphere 1)Water cycle breaks down ∵↓R” & ↑ evaporation(∵ no shelter)  rivers and wells dried up Biosphere 1)lower the bio-diversity ∵↓R” & unevenly dis.+deforestation scattered veg. (veg. Is shorter, few species, less luxuriant)extinction

Effects Others 1)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??? LDCs 1.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??? 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??? 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??? 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??? 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

Effectiveness LDCs MDCs 1)Money? LDCs are so poor 2)International aid? lack of technology,efficient farming skill & low education 3)Attitude? X family planning MDCs 1)Exploitation? try to get more raw materials & resources from LDCs 2)Human behaviour?? rapid ↑in living standard & large amt of wastes are produced

Conclusion The effectiveness of preventing desertification is depended on the cooperation of MDCs & LDCs.

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