Geography IGCSE - Hot Desert

Mojave Desert location

southeastern California and portions of Nevada, Arizona, and Utah, U.S.A

Area of Mojave Desert

occupies more than 25 thousand square miles.

BP1 (wildlife)

Camel:

• Fat stored in hump → helps reduce insulation over rest of body → keeps it cooler

• Long eyelashes + closable nostrils → protect eyes + nose from blowing sand during sandstorms

• Thick lips → allow camels to eat thorny desert plants without injury

• Wide, padded feet → spread their weight to prevent sinking in soft, sandy terrain.

• Can survive without water for days → tolerate dehydration + rehydrate quickly → important where water is scarce.

BP2 (wildlife)

Kangaroo rat:

• Does not drink water → gets all moisture from dry seeds + food

• Highly efficient kidneys → produce very concentrated urine + dry feces → conserve water

• Nocturnal → only active at night when temperatures are cooler → avoids extreme daytime heat

• Lives in burrows → underground homes protect from daytime temperatures + predators

• Light fur → reflects heat → helps it blend into sandy environment

BP3 (wildlife)

Fennec fox:

• Large ears → radiate heat to cool body → improve hearing to detect prey underground

• Thick fur on feet → acts like built-in “sand shoes” → protect against hot sand + prevent slipping

• Light-coloured fur → reflects sunlight and → provides camouflage against sand.

• Nocturnal → hunts at night to avoid heat + dehydration → rests in burrows during day

• Burrow system → cools body → offers protection from predators + sun

BP1 (vegetation)

Saguaro cacti:

• Succulent stem → stores large amounts of water during rare rainfalls → survival through dry periods

• Pleated skin → expands like an accordion when it rains → hold more water → contracts as it uses up stored moisture

• Widespread shallow roots → extend far near surface to absorb water quickly after rain

• Spines instead of leaves → reduce water loss through transpiration → protect against herbivores.

• Waxy skin (cuticle) → helps reduce evaporation in extreme heat

BP2 (vegetation)

Creosote bush:

• Small, waxy leaves → minimise water loss → reduces transpiration

• Leaves can close their pores → during hottest parts of day → conserve moisture

• Extensive root system (deep taproots + shallow surface roots) → allows access water from different soil layers

• Produces chemicals in soil → reduce competition from other plants → allelopathy

• Drop leaves in extreme drought → further reduce water loss

BP3 (vegetation)

Joshua tree:

• Thick, waxy leaves → retain moisture + reflect sunlight

• Extensive root system → deep taproots → helps find underground water sources

• Slow - growing → uses limited water efficiently over long periods

• Grows in areas with slightly more rainfall + cooler desert climates → e.g. Mojave Desert

• Can survive in poor, dry, sandy soils → tough + drought-tolerant structure

BP1 (causes + effects of desertification)

Urbanisation → Expanding cities → e.g. Las Vegas + Los Angeles push into the desert → removes vegetation + compacting soil → off-road vehicle use → recreational use damages fragile desert plants → exposes dry soil to wind erosion → over-extraction of groundwater for irrigation + golf courses → drys out sol → climate change increases temperatures → reduces rainfall → speeds up evaporation + soil degradation

BP2 (causes + effects of desertification)

Loss of native vegetation → e.g. Joshua trees → reduces biodiversity → disrupts ecosystems → soil erosion increases due to lack of plant roots → causes dry, loose soil to be blown away → more frequent dust storms → worsen air quality → leads to more land degradation → habitat loss affects wildlife → e.g. desert tortoise → pushes some species toward endangerment

BP3 (causes + effects of desertification)

Water shortages → groundwater levels in parts of the Mojave → e.g. Las Vegas Valley → dropped by over 30 meters in past 50 years → leads to water use restrictions → higher water bills → health issues → dust storms increase → asthma + respiratory hospital visits → Clark County, Nevada, dust-related ER visits spiked by 15% during peak dry periods → urban pressure → desert land becomes unproductive → rural families migrate to urban centres like Las Vegas → increases housing demand → strain on public services