Tropical rainforest
What is the temp & rainfall of Equatorial climate (2)
- High temp all year / low temp range
- High annual rainfall
- No seasons
Explain why equatorial climates have low temp range. (3)
- Low temp range: small difference between highest & lowest
- Near equator
- Overhead sun with solar radiation concentrated over a small area is constant
- (Diurnal) Cloud cover trap heat at night
Explain why equatorial climates have large amounts of rainfall. (4)
Convectional rainfall
- Overhead sun cause large amounts of evaporation & transpiration
- Lead to high humidity
- Air cools as it rises to upper atmosphere
- Lots of condensation occur
- Cumulus & cumulonimbus clouds form
- Air mass cannot hold any more water
- Heavy rain occurs
- Repeated each day
Explain why some places have an equatorial climate. (4)
- Near Equator
- Overhead sun
- Convectional rainfall
- Low pressure (coz air is hot & rises)
- Large amounts of evaporation & transpiration
Explain relationship between climate & natural vegetation in TRF. (5)
- Lots of vegetation & rapid growth, evergreen coz high temp & constant rainfall all year, continuous growing season
- Tall (eg emergent trees) reach for sun
- Drip tip leaves – shed water
- Large leaves – absorb more sunlight
- Buttress roots (in emergent) – support tree & prevent it from falling over
Explain why there are many different types of plants & animals in TRF. (4)
- High rainfall, temp
- No seasons
- Optimum growing condition
- Variety of habitats for different species
- Large supplies of food
- Rapid nutrient cycling
- Little human disturbance
Explain how nutrients are cycled in TRF ecosystem. (3)
- Leaves fall to ground
- Decomposed by bacteria rapidly in hot & wet climate to form humus
- Humus mixed with soil & provides nutrients
- Nutrients absorb by plants
Deforestation
Give 3 reasons why deforestation has occurred. (3)
- Timer (make paper / logging)
- Agriculture / cattle ranching to meet demand
- Urban development (settlements, roads, dams)
- Mining
Explain how deforestation affects TRF ecosystem. (5)
- Destruction of vegetation
- Loss of habitats – loss of food sources – disrupt food chain – threat species extinction
- Leads to soil infertile & erosion
- Soil exposed by removal of trees
- Roots of plants no longer hold soil in place
- When rains, ↓ interception, large amounts of surface run off remove soil
- Reduce nutrient cycle
- ↓ decomposition from plants, ↓ humus bind soil, ↓ nutrients returned to soils
Explain how deforestation leads to flooding of local rivers in areas of TRF. (5)
- ↓ interception by vegetation
- Rain falls directly on to ground
- No trees roots absorb water
- Soil soon becomes saturated
- Surface of soil becomes impermeable
- Large surface run off occur
- Soil erosion occurs coz soil isn’t held by roots & washed into rivers
- River channel fills & overflow
Explain why protecting rainforest from deforestation is important for local natural environment & for ppl who live in rainforest. (5)
- Prevent extinction of species, loss of habitat, soil erosion, desertification, flooding
- Maintain biodiversity
- Not destroy valuable medicines
- Attract tourists
Explain why tropical rainforest is important globally. (5)
- Create O2 & reduce CO2
- Reduce global warming, flooding risk
- Source of medicine & raw materials
Explain why it’s difficult for LEDCs to reduce rate of deforestation. (3)
- Source of income
- Lack of gov legislation
- Exploitation by MNCs
Explain how tropical rainforests could be used sustainably. (4)
- Restrict logging
- Selective logging
- Afforestation
- Rubber tapping – latex collected used to make rubbery goods eg balls
- Education – ppl understand value of TRF
- Ecotourism – encourages tourism that creates jobs for local while ensuring money earned is used to protect TRF
Deserts
Define desert
- Area with annual precipitation < 250mm
Describe the climate of hot desert. (3)
- The annual precipitation is < 250mm
- High annual temp range
- Hot in summer (30-40°C)
- Cold in winter (15-20°C)
- Large diurnal temp range
- Low humidity
Explain why temp in tropical deserts vary during the year. (2)
- Angle of sun changes
- Overhead sun (Sept – March)
Suggest reasons why temp are high in Dec & January. (3)
- Near Tropic of Capricorn
- Overhead sun
- Inland location
- Small amount of cloud over
Explain why deserts have high diurnal range of temperature. (3)
- High daytime but cold night temp
- Lack of clouds allow high insolation during day & allows heat to escape at night
- Inland so no moderating influence of sea
Ocean currents
Explain how ocean currents result in formation of tropical deserts. (4)
- Winds blow across a cold ocean current
- Cold temp prevent air hold moisture
- Air cools above ocean and condensation occur at sea
- No rain falls along coast coz air mass warms up and decreases relative humidity, resulting in lack of clouds
- Dry air mass when reaches land
Rain shadow
Explain why some tropical deserts are located in areas of rain shadow. (4)
- Prevailing wind blow from across land
- Air contains water vapour rises on windward side of mountain range
- Air cools
- Water vapour condenses & form clouds
- Precipitation on mountains
- Cool air sinks & warm up at leeward side
- No condensation takes place coz no moisture in air by the time it reaches desert
Hadley cell
Explain why many tropical deserts are located in areas close to Equator. (4)
- Air rises at Equator coz overhead sun
- Air cools as it rises
- High altitude air spends to north/south from Equator
- Cool air sinks & create high pressure at surface
- Air heats as it descends – so no condensation
Explain why desert doesn’t receive much rainfall. (5)
- Close to Tropic of Capricorn
- (Ocean current, rain shadow, Hadley cell)
Explain why wind direction & distance from sea are important influences on desert climates. (4)
- Deserts are inland – so wind are dry by the time they reach them
- Trade winds blow over large areas of land before reaching desert – less moisture in air
Explain how plants & wildlife are able to survive in hot desert. (5)
Plants eg Joshua trees
- Low precipitation results in spares vegetation
- Waxy, narrow leaves – reduce transpiration
- Thorns – protect from predators
- Deep tap / wide shallow roots – access water supplies
- Light colours – reflect sunlight
- Thick stems – store water
- Plants remain dormant when no rain
Animals eg Gila monster
- Shelter in underground burrows – avoid heat
- Only come out to hunt at night – avoid heat
- Camouflage – protect from predators
- Fat accumulated for nutrition in tail – survive during hibernation
- Urinary bladder store water – prevent dehydration
Both TRF & TD
Explain how latitude & atmospheric pressure influence characteristics of equatorial & hot desert climates. (3)
- Both equatorial & desert is hot & doesn’t have seasons coz low latitude & overhead sun at all times
- Equatorial – High rainfall coz low pressure & rising air
- Desert – low rainfall coz high pressure & falling air
Desertification
Define desertification (1)
- Process of land turning into desert as quality of soil declines over time
Explain how desertification occurs. (5)
- Less rainfall / long period without rain
- Overcultivation
- Less humus to bind soil
- Soil erosion
- Overgrazing
- Pop growth – larger desert area being farmed
- Herders have more animals stay in an area for longer, soil becomes compacted, restrict plant growth & root development
- Removal of water from underground for industry
- Leads to death of vegetation
- Deforestation
- Less roots to bind soil
- Soil erosion
- Global warming
- Droughts & less precipitation occur more often
- Over-exploited land can’t recover
Ecosystem
Describe ways in which natural vegetation, soil & wildlife are dependent on each other. (3)
- Vegetation needs soil for growth
- Primary producers eat & get energy from plants
- Predators eat & get energy from animals
- Nutrients returned to soil from rotting vegetation / animals excretion
Clouds
Describe the processes which result in large amounts of cloud forming in areas of Equatorial climate (5)
- Heating
- Evaporation
- Transpiration
- Water vapour rises
- Cooling
- Condensation
- Saturation
- Convection
Explain why there are usually more clouds in areas with an equatorial climate than in areas with a hot desert climate. (5)
- More convectional rainfall at Equator
- Low pressure at Equator but higher at deserts
- Large amounts of evaporation & transpiration at Equator but less at deserts
- Deserts more distant from water bodies
- Winds to deserts are more likely to have blown over large areas of land
Explain why more clouds forms in tropical rainforest areas than in tropical deserts. (5)
- High humidity, pressure / more evaporation, vegetation, transpiration, condensation in TRF
- Air rises in TRP / sinks in desert
Explain why very few clouds form in tropical deserts. (5)
- Distance from oceans
- Winds blow over large areas of land
- Winds don’t blow from sea hence no source of moisture
- Low humidity
- Lack of evapouration
- Sparse vegetation
- Lack of transpiration
- High air pressure
- Descending airCase studiesTropical rainforest – Ecuadoran rainforest, Ecuador, South America
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| Ecosystem
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| Why deforestation has taken place?
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| Impacts of deforestation
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Tropical deserts – Mojave desert, south west USA
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| Human activities
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