ecosystems, rainforests

Question 1

distribution of ecosystems

Answer 1

biomes usually form belts parallel to lines of latitude because global atmospheric circulation determines their climate and characteristics

variations occur because of factors such as ocean currents, winds, distribution of land/sea

rainforest- typically around equator
tropical grassland- 15-30 south and north of equator
deciduous/coniferous forests- 50-60 north
tundra- 60-70 north

Question 2

characteristics of tropical rainforests

Answer 2

between tropics of capricorn/cancer

• hot and humid, high rainfall
• high biodiversity
• soils infertile

Soils
- cycle nutrients rapidly to support new growth

shrub/ground layer(0-10m)
- ferns, woody plants, younger trees
- lack of light
-thick buttress roots spread weight of towering trees above

lower canopy(10-20m)
- shaded
- less substantial trees waiting to take advantage of next available light space
- interlocking branches, lianas form green corridors along which light animals can travel

middle canopy(20-30m)
- most productive layer
- mushroom shaped crown has enormous photosynthetic surface
- drip tips help them shed water quickly/efficiently

top canopy(35-50m)
- hardly exposed emergent trees with straight branchless trunks receive the most light

Question 3

deforestation in Malaysia

Answer 3

67% tropical rainforest

logging
- 1980s- became world’s largest exporter of high value wood
- replaced by selective logging of mature trees only

road building
- constructed to provide access

energy development
- HEP projects boost Malaysia’s energy supplies

mineral extraction
- tin mining
- drilling for oil/gas

population pressure
- poor people from urban areas encouraged to move to countryside

commercial farming
- largest exporter of palm oil in the world

subsistence farming
- traditional short-term clearance is sustainable
- fires can grow out of control which destroys large areas

Question 4

impacts of deforestation in Malaysia

Answer 4

• reduces biodiversity- loss of plant species with medicinal potential
• exposes ground to soil erosion
• impacts local/global climates

Question 5

rainforests vs economic development

Answer 5

gains
- job creation
- tax revenue used to supply public services
- improved transport infrastructure benefits development/tourism
- plantation products support processing industries
- HEP is cheap and plentiful
- minerals are valuable

losses
- water pollution in dry climate limits supplies
- fires pollute/destroy large areas
- rising temps devastate farming
- plants that could form profitable medicines go extinct
- climate change has economic costs
- rainforest tourism could decrease

Question 6

how can rainforests be managed sustainably?

Answer 6

• felling
• selective logging and replanting
• conservation and education
• ecotourism introduces people to natural world and provides income
• international agreements to recognise global importance of rainforests in combating climate change