booklet 1b Flashcards
what is a dryland and what vegetation does its conditions support
dryland: areas with low precipitation and a high evaporation rate
the dry condition only supports vegetation such as grass, shrubs and scattered trees
eg. grassland, savannas
cycle of vegetation loss
the topsoil, w/o vegetation cover, is exposed to erosion by wind and water → loss of soil fertility → loss of vegetation cover (vegetation roots bind the soil together)
what is desertification
land loses its productivity and supports less vegetation
drylands most vulnerable to desertification
drylands at the fringe of the sahara + turkestan desert
physical factors for desertification in northern china
low precipitation and strong winds
presence of deserts and poor soil
explain how low precipitation and strong winds lead to desertification
most areas in inland n china have low precipitation because
summer: not much moisture from onshore monsoons can reach the inland (distance from sea)
winter: cold and dry offshore monsoons do not favour the formation of rain + frequent strong winds in spring + winter facilitate soil erosion
explain how the presence of deserts and poor soil leads to desertification
relief of n/nw china is rugged with many mountains, containing many small / large deserts (gobi)
drylands at the edge of deserts have dry sandy and poor soil (ie. doesn’t contain much minerals / nutrients / organic matter → infertile) + dry climate → sparse vegetation → low land productivity (low vegetation cover) → sets off the vicious cycle of land degradation
human / cultural factors leading to desertification in northern china
population growth
misuse of dryland resources
human induced climate change
explain how population growth can lead to desertification
rapid increase in population in drylands → increased demand for food / water / other resources (exceed the carrying capacity of the local natural resources) → intensive use of land → misuse of dryland resources → sets off process of land degradation
explain how the misuse of dryland resources can lead to desertification
overgrazing (herders rearing too many livestock → pasture used up faster than it can regrow)
over-cultivation (farmers growing too many crops in poor soil for years → using up soil moisture + nutrients quickie → crops cannot grow, land loses productivity and the land is abandoned by farmers
over-irrigation (tapping too much groundwater for irrigation: water table drops → soil moisture decreases → soil becomes dry // applying too much irrigation water: increase of salt levels in soil → land becomes salty, loses pH value (level becomes unsuitable for farming))
over-cutting of trees and shrubs (cut more trees + shrubs for cooking + building materials (deforestation))
explain how human induced climate change leads to desertification
as the air temperature in n china increased over the past decades —> low precipitation in the region
leads to decrease of relative humidity, hindering the formation of rain and leading to decreased precipitation (due to the lack of moisture —> little condensation)
also leads to higher evaporation rate, leading to a loss of soil moisture —> vegetation cover decreases, erosion of topsoil increase and results in land degradation
decrease in precipitation leads to decrease in land productivity (ie. soil becomes infertile) + increase in frequency of droughts —> decrease in vegetation cover, leading to increase of erosion of topsoil resulting in land degradation
decrease in land productivity also leads to decrease in evapotranspiration for plants
explain how desertification impacts people
economic losses (for farmers, as farming is a source of stable income for them)
desertification lowers soil quality + fertility —> loss of productive land, which reduces crop yields + pastures for livestock —> decreased income for farmers
relocation of people (especially affects LDCs + elderly)
when land is degraded to a level where it is unsuitable for people to live in, people have to leave their homeland
however it may be inconvenient + unsuitable for the elderly, as they have strong social ties in their homeland —> unwilling to leave, prefers to adapt instead
affects natural environment
persistent land degradation —> decreased land productivity, land can no longer support vegetation, resulting in a desert like environment (high temp + low rainfall + high evap rate)
increase in the frequency of sand and dust storms
as more dry lands become desertified, there is an increase in supply of sand and dust for sand/dust storms (bc of soil erosion)
increased frequency of sand and dust storms —> decreased visibility (leading to more traffic accidents) + decrease in air quality (leading to an increased chance of developing respiratory illnesses, ie. increasing medical burden)
what is the sahel region and what issues is it facing
a dry land area located at the southern edge of sahara desert w/ serious desertification issues —> crop failure, loss of livestock, resulting in food shortages —> hunger + famines in the region
what lifestyle + farming system do those living in the sahel region lead and why
extremely arid conditions in the sahel —> nomadic lifestyle, moving on frequently (not settling in one area for long)
nomadic herding farming system
how do the nomads in the sahel region adapt to the environment to make a living (provide factors)
their herds of livestock are adapted to live in desert conditions (camels / goats / sheep / livestock) // tents are built to allow for air circulation, insulation with animal hair allows the tent to be kept cool during the day and warmer during the night
migration of herds
keeping a variety of animal species
controlling herd size
low fam output
