Topic 8 - Tropical Rainforest Flashcards
Give a description of tropical rainforests
Located in a zone within 20° north and south of the equator
It’s hot all year (27°-30°) never below 20
Wet all year (2000-3000mm)
High biodiversity, the conditions for plant growth is very good, many species have evolved to meet the challenges of the rainforest
Plant adaptations (tree height)
Some trees grow tall (50m+) called emergents, the rest of the canopy at 30-40m, when a gap appears due to old trees dying, light reaches the forest floor and tree sapling race upwards and outwards to capture maximum sunlight
Plant adaptations (leaves)
Almost all plants have drip-tip leaves which means water runs off them quickly. This is important to stop moss and algae growing on the leaf and blocking the light out
Plant adaptations (roots)
Trees have buttress structures at the bottom as nutrients is concentrated at on the top of the soil so only shallow roots are needed, they keep the trees anchored upright
Animal adaptations (monkeys)
Different tree species produce flowers, leaves and fruits at different times so some animals have to travel through the canopy eating them as they appear, monkeys have evolved gripping hands and feet as well as long tails for balance and colour vision to identify ripe fruit
Animal adaptations (birds)
Hundreds of bird species live in the canopy including eagles who have evolved powerful legs and clawed talons to grab monkeys from the trees.
Animal adaptations (camouflage)
Many species use different forms of camouflage to avoid predators, some insects mimic sticks while birds develop colouring that makes them hard to see
Explain the nutrients cycle in TRF
- 3 compartments: soil, litter and biomass
- nutrients is transferred between them, they differ in size depending on the ecosystem
- in TRF the biggest store is biomass
- when leaves and branches become litter, the quickly decompose releasing nutrients in the soil, plants absorb quickly
- rainwater takes the nutrients and minerals with it through the soil (leaching)
Threats to TRF (commercial agriculture)
- Crops and herds grown and sold for profit, leading cause of TRF deforestation
- most of TRF deforestation in Brazil was for cattle farming as beef is one of Brazils key exports, more recently TRF is being cleared for sugarcane
- In SE Asia RF deforestation has been rapid and replaced for palm oil plantations as these crops are in high demand as biofuels
- biofuels are in demand to reduce fossil fuel use and is now called deforestation diesel
Threats to TRF (subsistence agriculture)
- crops and herds grown to feed families
- trees are cut down on small plot and the underground burned known as slash and burn method, nutrients in soil is quickly leached out and weed take over
- rapid population growth in developing counties means this is being done more
Threats to TRF (commercial hardwood logging)
- there is high demand for tropical hardwood timber especially rosewood. Chinese buyers will pay high prices for it which encourages illegal logging
- people who live near the RF are very poor and illegal logging pays well
- police and government officials often let illegal logging happen in return for money
Threats to TRF (mining)
- some RF are on top of valuable minerals, the cheapest way to extract them is to use open cast mining, affecting large areas of RF
- roads are built to access the mines and farmers and loggers are encouraged to use them
- 15% of deforestation is linked to mining
Threats to TRF (climate change)
- this is indirect
- warmer global temps shift the weather systems pole wards so there so there is less rain in the RF
- conditions are likely to become hotter and drier, with more droughts
- species are not adapted to heatwaves, new species would move in and out compete TRF species
- ecosystems stress could mean plants and animals would have lower resistance to new pets disease
