Desertification And Sandstorms (1B) Flashcards
How does desertification occur?
Dry land is the start of desertification. It is places with low precipitation and high evaporation rate. Dry land only support particular vegetation covers: grass, shrubs and scattered trees. Examples are grassland and savanna.
Then leads to persistent soil degradation. Topsoil, without vegetation covers, are exposed to erosion by wind and water. There will then be loss of soil fertility, which lead to loss of vegetation covers. This causes an unstoppable loop around losing vegetation.
This results in desertification. Lands loses its productivity and support less vegetation.
Where are the major desertified areas in the world?
Desertification occurs usually at the fringe of Sahara Desert and Turkestan Desert (because of the large areas of dry land)
Areas of china facing desertification
Northern side
Example: Nei Mongol
How does the physical factor — low precipitation and strong wind cause desertification in the northern China?
During summer, not much moisture brought by the onshore monsoon (travelling from south to north) can reach the inland as wind gradually lose moisture as they move inland
During winter, the cold and dry offshore winter monsoon (travelling from north to south) doesn’t favour the formation of rain.
During winter and spring, the frequently strong wind cause soil erosion to happen, causing them to break down and move away.
How does the physical factor — presence of deserts and poor soil form desertification in the northern Chinas?
The relief of the northern and western-northern part of China is rugged. There are many mountains, and large and small desert also exist. (Like Gobi Desert)
The drylands at the edge of deserts have sandy, poor and dry soil, and they have a dry climate.
These lead to low productivity to the land, causing less vegetation covers, and set off desertification to occur.
How does physicals factor lead to desertification in northern China?
Firstly, low precipitation and strong winds. During the summer, not much moisture is brought by the onshore monsoon, which is travelling from south to north, into the inland as the moisture gradually reduces. During the winter, the dry and cold offshore winter monsoon doesn’t favour the formation of rain. During winter and spring, the frequently strong winds causes soil erosion to occur.
Secondly, presence of desert and poor soil. The relief of the land located at the northern and NW of China is rugged, and many mountains, small deserts and large deserts are located there. (Like Gobi desert). The dryland of the edge of the desert has soil that are dry, sandy and poor. Dry climate is also seen there, which both leads to spare vegetation.
This causes the productivity of the land to be low, which causes the soil fertility to be low, and therefore, cause desertification to happen, leading to land degradation.
How does the human factor — population growth cause land degradation to occur in the northern China?
Due to the rapid population increase in drylands, the demand for food, water and resources increase. As a result, humans have to use the land more intensively, which can lead to misuse of the dryland resources, like overgrazing. This then sets off the process of land degradation.
How does the human factor — misuse of land resources lead to land degradation in the northern China?
- Overgazing — herders are rearing too many livestock at once, and pastures are being used up faster than it can regrow
- Over-cultivation — farmers are growing crops on poor soil year after year. This uses up the soil moisture and nutrients very quickly, leading to crops unable to grow. The land then loses its productivity and farmers will abandon the land
- Over-irrigation
— tapping too much groundwater for irrigation causes the water table to drop. Soil moisture then decreases, and the soil become dry
— applying too much irrigation water increases the salt level in the soil. The land then become salty and loses its productivity - Over-cutting of trees and shrubs — cut more trees and shrubs for cooking and building materials will lead to deforestation
How does the human factor — human-induced climate change lead to land degradation in the northern China?
When the air temperature in a region is increasing, this decreases the relative humidity, which hinders with the formation of rain. Precipitation then decreases, leading to land productivity decreasing, and chances of droughts happening more frequently. Vegetation cover then decreases, which leads to increase in the chances of soil erosion, and land degradation.
Also, when the air temperature is increasing, the evaporation rate increases, which increases the loss of soil moisture. This will also lead to decrease in vegetation cover, and due to the higher chance of soil erosion, land degradation happens.
Loss of vegetation cover will lead to a decrease in evapotranspiration, which goes back and causing the relative humidity to decrease. This forms an unstoppable loop around this climatic change.
How do all the human factor lead to land degradation in the northern China?
Firstly, population growth. When there is a rapid growth in population in places like drylands, the demand for food, water and other resources increases. Humans then have to use the land intensively in order to get enough recourses, which leads to misuse of dryland resources. This starts the process of land degradation.
Secondly, misuse of land resources.
- Firstly, over-grazing: herders are rearing too many livestocks at once, which causes pastures to be used up faster than it can grow back.
- Secondly, over-cultivation: farmers are growing crops on poor soil year after year, causing the soil moisture and nutrients to be used up quickly. This causes crops unable to grow, causing the land to lose its productivity and farmers abandoning the land.
- Thirdly, over-irrigation: tapping too much groundwater for irrigation causes the water table to drop. Soil moisture then decreases, causing the soil to be dry. Also, applying too much irrigation water can increase the salt levels. This makes the land to become salty, and loses its productivity.
- Lastly, over-cutting of trees and shrubs. Cutting too many trees and shrubs down for cooking and building resources can cause deforestation.
Thirdly, human-induced climatic change. When the air temperature of a place is increasing over time, the relative humidity decreases, which hinders with the formation of rain. Precipitation then decreases, which cause the land productivity to decrease and droughts happening more frequently. Vegetation cover then decreases, leading to soil erosion and land degradation. Also, when the air temperature is increasing, the evaporation rate increases, causing the chances of loss of soil moisture to increase. This also causes vegetation cover loss. The decrease in vegetation cover leads to decrease in evapotranspiration, which then causes the relative humidity decreases. This human-induced climatic change is an unstoppable loop.
How does desertification affect people and natural environment?
Firstly, economic losses. Desertification lowers soil quality, and productive lands reduces. This reduces the crop fields and pastures for livestocks.
Secondly, relocation of people. When the is degraded to a point that it is unsuitable for humans to live, they will have to relocate themselves and leave their homeland
Thirdly, affecting the nature environment. Due to land degradation, the land loses its productivity, and support much less vegetation. The land then turns into a desert-like environment
Lastly, increase in the frequency of sand and dust storms. As more lands desertified, the supply for sand and dusts increase, which cause the chance of the occurance of sand and dust storm to increase, affecting the human’s daily life.
Affection Sahel received from desertification
- crop failure
- loss of livestock
-> food shortages
-> hunger
-> famine
How does native people adapt to the environment to make a living in the Sahel?
The farming system of Nomadic Herding is developed in order to face the harsh environment in the Sahel. Their nomadic lifestyle means they do not stay at one place for long, it instead, they move on from a place frequently. They have herds of livestocks that can adapt to living in desert-like environment (like camel or goats). Their tents are built to allow air to circulate within them, keeping them cool. Animal hair help insulate them, keeping the tent cool during the day and warmer during the night.
How does the native people adapt to Sahel through migration of herds?
Nomadic people move their herds from a place to another for pasture and water. When the pasture and water are exhausted in a place, they migrate to a new pastureland, leaving the old site fallow for the soil to recover their nutrients and water, which also helps the land to regenerate.
When the nomadic people move their herds on a seasonal basis, it is called transhumance.
How does the native people adapt to Sahel through keeping various type of animal species?
Since different animals eat different plants, keeping a variety of animals allows the nomadic people to prevent complete consumption for any one particular plants, and allows the nomadic people to b provided a rich mix of dairy products
How does the native people adapt to Sahel through controlling the size of the herd?
When the rain is inadequate and droughts are occurring, the size of the herd will be small.
When the rain is adequate and vegetation conditions are favourable, the size of the herd will be large.
This allows the rough grasses to grow well, and maintain the ecological balance.
What does the the dry environment give to the nomadic people on the farming side?
Due to the harsh environment, the cultural inputs has to be low, meaning that the average farm output per area is low in Sahel.
What are the points of the farming system: nomadic herding?
Firstly, migration of herds. Nomadic people move their herds from one place to another for pastures and water. When the pastures and water are exhausted in a place, they migrate to another pastureland. They leave the old site fallow so the soil can recover its nutrients and water, which also helps the land to regenerate.
Secondly, keeping a variety of animal species. Since different animals eat different foods, they keep a variety of animals to prevent complete consumption of any particular plant species, and to provide the people with rich mix of dairy products.
Thirdly, controlling the size of the herd. When the rain is inadequate and drought is occurring, the size of the herd will be small. When the rain is adequate and the vegetation condition is favourable, the size of the herd will be large. This helps the rough grasses to grow well and maintain the ecological balance.
Lastly, low farm output. Due to the harsh natural environment and low farm in out, the average farm output per area will be low in Sahel.
Characteristics of nomadic herding
Pastoral farming (mainly focus on animals to farm)
Extensive farming (low input of crops)
Subsistence farming (farming the amount only needed to eat, leaving little amount for selling)
Low-technology farming (using animals to help with farming)
Non-sedentary farming (moving all the time, and dont stay at one place for a long time)
What are the causes of desertification in Sahel?
For the physical factor, the low and unreliable rainfall, frequent droughts and the thin, infertile soil causes scattered vegetation, which causes the topsoil to be easily corroded. This then lead to land degradation, then desertification.
For the human and cultural factor, due to the rapid increase in population in the dryland, the demand for dryland resources have been increasing, which then causes the misuse of dryland resources: over-grazing, over-cultivation, over-cutting for fuelwood and misuse of water resources like over-irrigation. This causes the loss of vegetation cover, so the topsoil will easily corroded. Land degradation then occur, leading to desertification.
