define dryland & give 3 examples
- climate:
areas with low precipitation
high evaporation rate(implying high temperature) - vegetation cover:
dry condition supports vegetation like grass, shrubs and scattered trees - examples: grassland, savannas
describe process of land degradation
cause: decrease in vegetation cover
1. the topsoil, without vegetation, is exposed to erosion by wind and water
2. loss of soil fertility (lack of nutrients and organic matter)
3. loss of vegetation cover
* vicious circle of losing vegetation «persistent land degradation
what happen to the land when desertfication occurs?
land loses its productivity & supports less vegetation
how does desertification occur?
drylands
1. in drylands, the precipitation is low and teh evaporation rate it high. There is also little vegetation cover as the low precipitation only supports the growth of grass, shrubs and scattered trees.
persistent land degradation
2. when there is a decrease in vegetation cover
3. the topsoil, without vegetation cover, is exposed to erosion by wind and water.
4. loss of soil fertility (lack of organic matter and nutrients)
5. loss of vegetation cover, creating a vicious circle of losing vegetation(persistent land degradation)
5. desertification occurs: land loses productivity, supports less vegetation
where are the major desertified areas in the world?
- large areas of drylands
* most vulnerable: drylands at the fringe of the Sahara Desert & Turkestan Desert
what places are affected/ facing risk of desertification in China?
locate the deserts and provinces
- northern China: vast areas affected
- largest desertified areas : Nei Mongol
- high risk provinces: Xinjiang, Ningxia, Nei Mongol, Shaanxi
* due to the presence of Takla Makan Desert and Gobi Desert
explain how low precipitation and strong winds lead to desertification in china
- most of Northern China: inland.
«_space;low annual precipitation
DISTANCE FROM THE SEA
a. in summer, not buch moisture brought by onshore monsoons can reach the inland
b. in winter, cold and dry offshore winter monsoon does not fabour the formation of rain
c. in winter & spring, frequent strong winds facilitate soil erosion
what are the physical factors contributing to the desertification in northern china
- low precipitation & strong winds
- presence of deserts & poor soil
explain how presence of deserts and poor soil lead to desertification
RELIEF of N&NW China
a. rugged
b. many mountains(hilly)
c. many small and large deserts (Gobi & Takla Makan)
dryland at the FRINGE of deserts
a. soil is sandy, dry and poor
b. dry climate
«_space;sparse vegetation
RESULT
1a. the drylands located on the leeward side of teh mountain is in the rain-shadowed area.
b.The annual mean rainfall is low, resulting in low precipitaiton.
«_space;sparse vegetation.
2a. sandy dry and poor soil and dry climate
«_space;sparse vegetation
2. sparse vegetation
3. land productivity in N China is low
when there is loss of vegetation
4. set off the process of land degradation
list the human/cultural factors leading to desertification
- population growth
- misuse of dryland resources
- human-induced climate change
how does growth in population lead to desertfication?
- rapid increase in population in drylands
- increase in demand for food, water and other natural resources
- people have to use the land more intensively
- misuse of dryland resources(2)
- set off the process of land degradation
how does misuse of land resources lead to land degradation?
OVERGRAZING
1. herders rear too many livestock
2. pasture is used up faster than it can regrow
OVER-CULTIVATION
1. farmers grow too many crops in poor soil year after year
2. use up soil moisture and nutrients quickly
3. crops cannot grow
4. land loses productivity & farmers abandon the land
OVER-IRRIGATION
1a. tapping too much groundwater for irrigation
b. water table decreases
c. soil moisture decreases
d. soil becomes dry
2a. Apply too much irrigation water
b. increase salt levels in the soil
c. land becomes salty and loses productivity
OVER-CUTTING OF TREES AND SHRUBS
1. cutting more trees and shrubs for cooking and building materials (deforestation)
«<loss of vegetation cover < increase soil erosion < land degradation
how does human-induced climate change lead to land degradation in N china?
draw a diagram to explain the inter-relationships
- air temperature in N China has been increasing over the past decades
«LOW PRECIPITATION - relative humidity decreases
- hinder formation of rain
- precipitation decreases
4a. frequent droughts
b. land productivity decreases - vegetation cover decreases
6a. evapotranspiration decreases
b. relative humidity decreases …
«_space;EVAPORATION RATE increases - loss of soil moisture increases
- vegetation cover decreases
««soil erosion increases«< land degradation
impact of desertification
ECONOMIC LOSSES
1. desertification lowers soil quality
2. loss of productive land
3. reduce crop yields and pastures for livestock
RELOCATION OF PEOPLE
1. when land is degraded to a level where it is unsuitable for people to live in
2. people have to leave their homeland
AFFECTING NATURAL ENVIRONMENT
1. persistent land degradation
2. land productivity decreases
3. land no longer support vegetation
4. land turns into a desert-like environment
INCREASE IN FREQUENCY OF SAND AND DUST STORMS
1. more drylands become desertified
2. supply of sand and dust for sand and sand ad dust storms increases
3. frequency of sand and dust storms increases
«_space;affect people’s daily life
(air quality decreases, hinder traffic visibility and cause respiratory diseases)
how does desertification affect Sahel?
Sahel: dryland area located at the S edge of the Sahara Desert in Africa
impact: crop failure, loss of livestock
«_space;food shrtages, hunger, famine
how do native people adapt to the environment with nomadic herding?
NOMADIC HERDING(farming system)
1. nomatic lifestyle: do nt settle in one area for long
2. move on frequently.
3. herd of livestock adapted to living in desert conditions ( camels, goats)
4. living condition: tents that allow air to criculate within them, keeping them cool
5. animal hair used to insulate them, keep the tent cool during the day and warm at night. (high daily range of temperature)
list of adaptations of people in Sahel
- nomadic herding
- migration of herds
- variety of livestocks
- controlling size of the herd
- low farm output
explain how migration of herds helps Sahel people
- nomadic people move their herds form one place to another for pastures and water.
- when the water and pasture are exhausted, they migrate to a new pastureland.
- old site left fallow for soil to recover its nutrients and water «_space;help the grassland regenerate
- transhumance: nomadic people move their herds on seasonal basis
how does keeping a variety of animal species help sahel people?
- different animals eat different types of plants
a. camel: branches and leaves of trees and shrubs
b. goat: leaves of trees and shrubs
c. cattle: grass - preent the complete consumption of any one particular plant species
- provide nomadic people with a rich mix of dairy products at different times.
why do Sahel people control the size of the herd?
- when rainfall is inadequate/drought occurs, size: small
- when rainfall is adequate & vegetation condition is favourable, size: large
- rough grasses can grow well, ecological balance maintained
why does sahel people have low farm output
- harsh natural environment & low cultural nputs
- average farm output per unit area is low
other characteristics of the farming system
- pastoral farming: focused on raising of animals
- extensive farming: large area of land with low input and output
- substitence farming: grow food for own consumptions
- low tech farming
- non-sedentary farming: move around to search for pasture and water (migration of herds)
