Hot Deserts

Climate

Less than 250mm per year

When it rains varies - might only rain once every two/three years

Temps extreme - v/ hot in day (45 degrees C) to v/ cold at night (5 degrees C)

Soil0

Shallow with a coarse, gravelly texture

Hardly any leaf fall so soil isn't very fertile

Often dry

Plants

Pretty sparse due to lack of rainfall

Most quite short but cacti can grow fairly tall

Short life cycle - when it rains

Animals

Mammals tend to be small and nocturnal

Most birds leave the desert during the harshest conditions

People

Many people living in the desert grow a few crops where there are natural springs or wells to supply water, usually in desert fringes

Indigenous people are often nomadic

Hot Deserts - Biodiversity

Fragile, Interdependent Ecosystems

Plants gain nutrients from the soil and provide nutrients to animals that eat them - animals spread seeds through their dung, helping the plants to reproduce

Hot and dry climate affects the soil in deserts. Soils are salty due to high evaporation and relatively low in nutrients because there is little decomposition of dead plant material by fungi and bacteria

Sparse vegetation limits the amount of food available, so desert has low-density populations of animals

Water supplies in deserts can be extremely scarce

Biodiversity is higher in areas with water

Small areas around ephemeral (temporary) pods or rivers or along the desert margins have the highest biodiversity

Development around desert margins also means that habitats are being divided up by roads, this threatens animals that migrate over large distances to find food and water

Global warming is generally making deserts hotter and drier. This is forcing some species to move to cooler areas to cope, however species that are already at the limits of their environment don't have anywhere else to go, so are at risk of decline

Hot Deserts - Adaptations

Plants

Animals

Plant roots are very long or very wide to catch as much water possible

Many plants are succulents, large, fleshy stems for storing water and thick waxy skin to reduce water loss

Some have small leaves/spines - low surface area, reducing transpiration

Nocturnal animals sit in shade in heat and stay cool - lose less energy

Lizards and snakes are able to tolerate high body temps

Some bigger animals store large amounts of fat that they can break down into water when needed

Development in Hot Deserts

Development opportunities in Sahara

Mineral resources

Oil and gas

Solar energy

Tourism

Farming

Extreme climate and inaccessibility makes development challenging

Extreme temps - range from 40 to below freezing

Inaccessibility - people and materials have to travel long distances

Water Supply - low annual rainfall, so providing rainfall for workers is extremely hard

Desertification

Desertification is caused by Human and Physical factors

Degradation of land so it becomes more desert-like

Third of world's land surface at risk of desertification

Soil erosion is key - soil that is exposed is easily removed by wind/water

Climate Change

Human Activities

Rainfall - expected to reduce, plants die, so nothing to hold soil together

Removal of fuel wood - removal of trees leave soil exposed

Temperatures - increase, more water evaporates from land and makes soils drier and plants die

Overgrazing - too many cattle eat plants faster than they can re-grow, leads to more erosion

Over-cultivation - if crops are planted continually in the same place, all the nutrients in the soil are drained, so no more plants

Population growth - pressure on land, leading to more deforestation, overgrazing and over-cultivation

Risk of Desertification can be reduced

Water Management - growing crops that don't need much water

Tree Planting - planted to act as windbreaks to protect soil from wind erosion

Soil Management - leaving area of land to rest in between grazing or planting

Appropriate Technology - involves cheap, sustainable and easily available materials that are easy for locals to maintain