Hot Desert

• Arid- dry, sandy, hot
• high temperatures (can be 50^oC in day, 0^oC at night)
• low rainfall (less than 250mm)
• low biodiversity

Why hot and dry?

• Due to global atmospheric circulation of air
• air rises at equator, because of high temps
• as rises it cools, forms precipitation at equator
• air then moves 30^o north & south of equator, where it sinks, forming high pressure area
• sinks but air is dry, so no precepitation

• Biotic (living) and abiotic components all closely related and many dependant on eachother
• Climate, plants, soil, animals & people all depend on one another

Climate- hot & dry

Plants- sparsely grow (not much rain), adapted to not need water, short life cycle

Soil- little leaf litter, soil can be infertile, very dry, very salty (lots of evapouration)

Animals- low biodiversity, adapted animals, usually small & nocturnal

People- indigenous people (nomadic farmers*) travel to find water & food for livestock, as there's a low supply

*- nomadic farmers are farmers that travel with their livestock and keep moving to find food

Less rainfall = less plants = less leaf litter prodiced = lower soil quality = less plants for animals to eat = livestock would overgraze = less plant coverage = exposed soil = soil erosion = unable to grow crops = famine

Cacti-

• spines- lose less water than leaves would, more efficient in hot climates
• thick waxy skin- less water lost through transpiration
• succulents (thick fleshy bodies)- allow water to be stored in plant & used in times of no rain

Animals in the desert are usually:

• nocturnal (cooler at night)
• live in underground burrows
• store fat (e.g. camel hump)
• triple eyelids, keep sand out of eyes

Fennec fox-

• big ears- heat escape from bodies, can keep cool, hear prey underneath sand
• soles of feet are hairy- can walk on hot sand
• nocturnal

• Farming & irrigation:
  • mostly subsistence farming, more & more commercial farming
  • grow lots of seeds & maze
  • use irrigation to water crops
• Energy:
  • coal- built a power station in Giral
  • wind- Jaisalmer wind park, India's largest
  • oil- large oil field found
  • solar- used in water treatment
• Tourism
  • annual desert fesitival in winter
  • desert safaris on camels, sandboarding, ect.
  • locals provide food, accomodation, work as guides for 10,000's that visit a year
• Mineral extraction
  • gypsum- used to make plaster & cement
  • feldpar- make ceramics
  • reserves of stone- e.g. limestone

• Extreme temperatures
  • Thar +50^oC in summer, hard to work outside in heat
  • plants & animals need to adapt, lots of evapouration & transpiration, water shortage
• Water security
  • Population has increased, high demand for water
  • drinking water in ponds evapourates, use underground sources e.g. aquifer, poor quality
  • few rivers & streams- River Luni, sometimes dry 
  • Strategies:
    • Indra Ghandi Canal, water comes from mountains 
    • can grow crops, clean drinking water
• Inaccessabitlity
  • limited road network, sand cover roads, tarmac may melt, mostly use camels to transport
  • little public transport
  • limited electricity & communication network
• Salinisation- deposition of solid salts on ground surface, after evapouration of water
  • irrigation of land- water brought to land for crops, usually dry, more salt
  • salts toxic to plants, land unusable, low yields

• Population increase
  • due to natural increase, lots born, people live longer 
  • due to migration, people move due to drought/ in from conflict areas 
• Overcultivation
  • higher population, more crops needed, drain aquafers to irigate
  • soil becomes infertile due to same crops being planted, same nutrients taken from soil
  • trees are biggest source of energy, burn wood to cook
• Overgrazing
  • too many goats/cattle too long on one site, vegetation not given chance to recover
  • no longer allow nomadic farmers, as people own land and femce it off
• Soil erosion
  • caused by overcultivation & overgrazing, less plants covering land
  • exposed topsoil becomes hard under sunlight
  • when rains, washes over instead of soaking in,soil carries away, vegetation can't regrow
• Desertification (Bodia, Jordan)
  • sheep came from Iraq after war, ate all vegetation = soil erosion, more migration
• Darfur,Sudan
  • 1 in every 5 years: droughts, crop failure
  • can't produce enough food

• Aforestation- large scale planting trees
  • roots bind soil, less likely to wash away, gives shade so water evapourates slowly
  • firewood source, grazing for animals
  • Great Green Wall- acts as a barrier between desert and other countries
    • spreads across Africa, from Sengal to Ethiopia, will span across 11 countries, 15km wide
    • acacia trees (drought resistant)
    • new economy, women able to work, don't have to travel for firewood, more in school
    • not all money goes to right place
• Ponding banks- areas of land with low walls that collect water
• Contouring- build mounds, traps soil, stops from running after heavy rain
• National parks- limits population that can live here, e.g. one in Thar, stops overgrazing&cultivation
• Drip fed irrigation- no overwatered plants, prevent waste of water
• Bunds- mounds of earth/stone to contour land
• Terrace farming- farming over steps, conserve water & reduce surface run off
• Education- farmers know different methods of farming, e.g. crop rotation
• Plant more GMOs that are drought- resistant
• Raise marine fish

• abiotic - non-living
• biotic - living
• ecosystem - community of plant/animals that depend on eachother
• nutrient cycling - process in which plants get nutrients
• comercial farming - farm for profit, large scale
• subsistence farming - farm for self & family
• mineral extraction - taking materials from the ground
• soil erosion - waring away of soil, removal of top soil
• desertification - land getting dryer, desert growth
• hunter gatherer - basic subsistence farming, hunting animals & gathering fruits/nuts
• irigation - artificial watering of land
• salinisation - deposition of solid salts on ground surface after water has evapourated