The Living World: Hot Deserts Flashcards Preview

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Flashcards in The Living World: Hot Deserts Deck (22):

Characteristics of HOT DESERTS

-Roughly 30 degrees north and south of the equator

-Cover 1/5 of the world's surface

-Sinking air stops prevents clouds from forming

-This causes high daytime temps, low nighttime temps and low rainfall

-Plants and animals have to be well adapted to survive in these conditions


What are desert soils like?

-Sandy, stony with little organic matter due to lack of leafy vegetation

-Dry but can soak up water rapidly after rainfall

-Evaporation draws salts to the surface, often leaving white powder on ground

-NOT very fertile


How are plants adapted?

E.g. cactus

-thin, spiky or glossy leaves (avoid water loss)

-deep roots (to tap underground water)

-thick, waxy skin (avoid water loss, reflect heat)

-spikes (protects from animals)

-lies dormant for years until rain falls

E.g. cactus


How are animals adapted?

E.g. camels

-long eye lashes, hairy ears, closing nostrils (keep sand out)

-thick eyebrows (shade eyes from sun)

-wide feet (don’t sink in sand)

-store fat in humps (can go months without food)

-body temp. can change (avoid water loss through sweating)

-thick fur (warm at night)

-leathery knees (can kneel in hot sand)


How is human activity and climate change threatening the biodiversity?

-development and high pop. contaminate water supplies

-drier weather means animals migrate to cooler areas

-some don’t have anywhere to go, leading to extinction


Plants in the desert: SUCCULENCE

-store water in fleshy leaves, stems or roots

-can quickly absorb large amounts of water through widespread, shallow roots and can store this water for long period of time

-metabolism slows during drought so stomata stays closed, water loss almost stops


Plants in the desert: DROUGHT TOLERANCE

-photosynthesise with low leaf moisture level

-shed leaves to prevent water loss through transpiration

-become dormant during drought

-deep roots penetrate soil and rock to tap underground water


Plants in the desert: DROUGHT AVOIDANCE

-annuals (survive one season, have rapid life cycle, then die after seeding)

-seeds last for years and germinate when soil moisture is high

-some germinate in autumn after rain and before winter cold sets in, seedlings survive winter frost and flower in spring



Process in which land becomes dry and degraded as a result of climate change or human activities or both


Opportunities in the Thar Desert: SUBSISTENCE FARMING

-although a good deal of farming in the desert is subsistence farming, some crops are sold at local markets

-hunter-gatherers survived in desert by hunting animals and gathering fruit and natural products (Khali’s tribe), most basic form of subsistence farming

•climate presents huge challenge: unreliable rain, frequent droughts


Opportunities in the Thar Desert: IRRIGATION AND COMMERCIAL FARMING

-main form is Indira Ghandi Canal, total length of 650km

-canal provides drinking water to many people in desert

-commercial farming in form of crops now flourishes in area that used to be scrub desert

•mainly benefits cities on Jodhpur and Jaisalmer


Opportunities in the Thar Desert: MINING AND INDUSTRY

-Rajasthan is rich in various minerals and valuable reserves of stone:

-at Jaisalmer, Sanu limestone is main source of limestone for India’s steel industry

-valuable reserves of rock marble quarried near Jodhpur for construction industry

•Quarrying could effect landscape, bad for tourism


Opportunities in the Thar Desert: TOURISM

-has beautiful landscapes, popular tourist destination

-In Jaisalmer, desert safaris on camels is popular

-local people benefit from being guides and looking after camels

-Thar Desert national park protects rare wildlife that has adapted


Opportunities in the Thar Desert: SOLAR ENERGY

-plenty of solar radiation

-lots of barren land to put down solar panels on to make lots of energy for energy companies and the country

•expensive for locals to pay for farmland and solar panels



The deposition of toxic salts on the ground surface following the evaporation of water



The destruction of the protective vegetation cover by having too many animals grazing upon it



The excessive use of farmland to the point where productivity falls due to soil erosion or land degradation


Causes of desertification in the Thar desert: EXTREME TEMPERATURE, INACCESSABILITY

-extreme weather and vast barren areas mean limited road network

-high temp. can cause tarmac to melt and strong winds blow sand over roads


Causes of desertification in the Thar desert: WATER SUPPLY

-difficult to travel in blistering heat to fetch water

-water directly connected to agriculture:

-without water, impossible to grow crops so severe impact on economic situations of farmers and their families

-also affects variety of food available, people forced to live on minimal diet

-increased drought leads to water scarcity

-excessive irrigation leads to salinisation, making land unusable


Managing desertification sustainably in the Sahel: ACACIA TREES PROJECT IN SENEGAL

-run by UN FAO, who gave the community seedlings and taught them how to plant them and extract gum from them

-provides nutrients for soil, preventing soil erosion, enabling plants to grow

-feeds soil, shelter for crops, food for community and livestock

-they can sell products (e.g. peanuts) at market so they can invest in a windmill to improve their quality of life


Managing desertification sustainably in the Sahel: STONE LINES

-rows of tightly packed stones built along contour lines

-sediment builds up along stone line instead of being washed away

-soil absorbs water and nutrients, prevents soil erosion, vegetation can grow


Managing desertification sustainably in the Sahel: THE GREEN WALL

-9mile wide band of trees, stretching through 11 countries, occupying total area of 11.6 million hectares

-WorldBand giving $2 million to help build it

-will prevent desert from advancing

-will take a long time and is open to corruption

-people could cut some trees down for firewood or to sell for profit