Deserts & Desertification

Some examples of man-land relationship in deserts

Nomadic herding – The Bedouin The Bedouin

- A community of Arabic-speaking - desert nomads of the Middle East and North Africa e.g. Morocco- traditionally living by animal husbandry-social rank among them is determined by the animals that they herd e.g. - camel nomads (the greatest status)

- sheep and goat herders (~for meat) - cattle nomads

Nomadic herding – The Bedouin Surviving the dry conditions (i) Seasonal movement with herds

- they migrate into the desert during the rainy season e.g. The Atlas in summer from October to April

- return to cultivated areas during the dry season e.g. up hill areas in summer between April and October

- this kind of seasonal movement is called transhumance

Nomadic herding – The Bedouin Surviving the dry conditions (ii) Wandering for pasture and water

- moving most of the time- nomadic nature of life

(iii) Using camels for different purposes- they ride on camels and as a main means of transport- for the camels adapt well to the arid environment- camels provide milk, hair (cloth)

Nomadic herding – The Bedouin Surviving the dry conditions Changing way of life

- but since World War II (1939 – 45) the governments of many countries have nationalized their range lands, and conflicts over land use have arisen.

- many Bedouin have since adopted sedentary ways of life- most, however, retain pride in their nomadic heritage

Nomadic herding – The Bedouin Characteristics 1. extensive grazing

- practised in the semi-arid areas / fringe of deserts- only scattered and little pasture found

2. nomadic & seasonal in nature - permanent & intensive grazing activity not supported

- transhumance

3. self-subsistence- low production- the carrying capacity of the soil is extremely low

Nomadic herding – The Bedouin Characteristics 4. balance use of the grazing land

- time is given for the land to recover

5. base camps on wadis (i.e. river courses in the desert) - greater chance of finding pasture along valleys / depressions

6. consuming pasture in base camps sector by sector- to ensure long fallow period for recovering the grazing land,

e.g. the fertility and vegetation cover

Nomadic herding – The Bedouin Characteristics 7. keeping different animal species

e.g. camels, cattle, goats, sheep- to make the best use of the pasture - eating different parts / species of plants- evenly spread of animal pressure on land e.g. cattle kept near water holes vs camels far from them

8. mobility as a response to physical conditions - vegetation can recover before another cycle of grazing during the fallow period

Nomadic herding – The Bedouin Characteristics Summing up

Nomadic hearing is well adapted to the tropical desertenvironment by

(a) making use of the limited environmental opportunities, AND(b) avoiding environmental constraints by behaving sensibly

i.e. respond to physical conditions by mobility

Nomadic herding – Why destructive Why does it become ecologically destructive?

1. Demographic / Population explosion - high birth rate (3 – 3.5 %o p.a.) - shorter population doubling period: 20-25 years - larger population pressure on land - but the carrying capacity: very low

2. Greater demand for food / firewood - increase: no. of livestock / intensity of agr / cutting woody veg. - resulted in: overgrazing / over-cultivation / overcutting of wood - effect on soil: extending farming into marginal land w irrigation,

resulting in salinization of soil

OvergrazingReasons & Impacts

Reasons of overgrazing1. rapid population growth2. migration into marginal land3. disturbance to regeneration

e.g. rotation of grazing land (X)4. restriction by artificial boundaries

e.g. restriction on movt of nomads5. encouragement by governments6. reluctant to reduce stock

(a sign of wealth & social status)

Reasons of overgrazing7. higher food crops price for exchange

due to growing of cash crops for overseas markets8. more farmland for food & cash crops under irrigation, forcing grazing into more fragile

marginal land9. prevailing ranches of western ranches, more

private ownership of pasture * Concentration of more animals in much smaller area.

Impacts of overgrazing1. damage of vegetation cover lower regeneration capacity exposure of loose, sandy soil micro-climatic change (e.g.?)

2. over-trampling on the soil around water holes

soil compaction, lower infiltration damage of vegetation surface runoff & velocity: higher

Soil erosion

(wind & water)

Desertification!!

Impacts of overcultivation1. higher farming intensity Shorter fallow period Expansion of cash crop farming

2. overcultivation Soil nutrients and moisture: decrease damage of vegetation surface runoff & velocity: higher

3. damage of vegetation difficult to recover

Soil erosion

(wind & water)

Desertification!!

Impacts of misusing irrigation water1. practice with no drainage Top soil: waterlogging Excessive inflitration Low-lying areas: death of vegetation

2. Not under proper manage Higher actual evapotranspiration Capillary action of water Salts built up in the soil on evaporation Salination of soil (a salt crust / salt pan) Death of vegetation

Soil erosion

(wind & water)

Desertification!!

Impacts of Overcutting of firewood1. rapid decrease of vegetation cover

Excessive inflitration Low-lying areas: death of vegetation

2. Not properly managed Hard crust in the harsh sun Rainwater / wind to cause erosion on the to

p Soil becomes more unproductive

Soil erosion

(wind & water)

Desertification!!