Tropical Rainforests Flashcards
All 33 cards in this deck
Describe the climate of a tropical rainforest.
Hot and wet all year: around 26–28°C with a small annual temperature range, and over 2000 mm of rain a year with high humidity.
Name the four layers of tropical rainforest vegetation, tallest first.
Emergent layer, canopy, under canopy (understorey), shrub layer/forest floor.
True or false? Most of the nutrients in a tropical rainforest are stored in the plants, not in the soil.
True. Fallen leaves decompose quickly and the nutrients are taken straight back up by plants, while heavy rain leaches the rest, so the soil itself is infertile.
How do drip tips help rainforest plants survive?
The pointed leaf tips let heavy rain run off quickly, so leaves do not rot or grow fungi and algae.
How do buttress roots help rainforest trees survive?
Large roots above the ground support very tall trees that are growing in thin soils, and help absorb surface nutrients.
Give one way animals are adapted to life in the rainforest canopy.
Strong limbs, gripping claws or prehensile tails for climbing and moving between trees, e.g. spider monkeys.
Why do tropical rainforests have such high biodiversity?
Hot, wet conditions all year allow continuous plant growth, and the layered structure provides many different habitats and food sources.
What has happened to the annual rate of deforestation in the Amazon since 2004?
It fell sharply from a peak in 2004 to a low around 2012, then rose again (about 13 000 sq km in 2021).
Give one reason why rates of deforestation have decreased in some countries.
Stricter government laws and international agreements (also consumer pressure to buy certified timber).
True or false? Rates of deforestation are rising in every rainforest country.
False. Rates vary — some countries have slowed deforestation through laws, agreements and debt relief, while others have increased.
Give two ways tropical rainforests are valuable to people.
They supply medicines, timber, foods and jobs/tourism income, and are home to indigenous people.
Give two ways tropical rainforests are valuable to the environment.
They act as a carbon sink that helps regulate global climate, and they store huge biodiversity while maintaining the water cycle and local rainfall.
Give one consequence of biodiversity loss in a tropical rainforest.
Species become extinct, so possible sources of new medicines and foods are lost forever.
How does subsistence farming cause deforestation?
Local families clear small plots of forest by slash and burn to grow food for themselves.
What are the steps of slash-and-burn (shifting cultivation)?
e.g. a farming family clearing a plot in the Amazon
- Cut down and burn a small area of forest — the ash fertilises the soil.
- Grow crops for about 3–5 years until soil fertility falls.
- Move to a new plot and let the old one regrow.
How does commercial farming cause deforestation?
Huge areas are cleared for cattle ranching and soya plantations to sell for profit — the biggest cause in the Amazon.
How does logging cause deforestation?
Trees are felled for valuable hardwoods such as mahogany, and clear felling plus logging roads destroys large areas.
How does road building cause deforestation?
Roads such as the Trans-Amazonian Highway are cut through the forest and open up the interior to loggers, miners, farmers and settlers.
How does mineral extraction cause deforestation?
Forest is cleared for mines such as the Carajás iron ore mine and for gold mining, which also pollutes rivers.
How does energy development cause deforestation?
Hydro-electric dams, e.g. Belo Monte, flood large areas of forest, and oil and gas extraction clears more land.
How do settlement and population growth cause deforestation?
A growing population and government resettlement schemes need land for homes, farms and towns, which is cleared from the forest.
Why does deforestation lead to soil erosion?
With no canopy to intercept rain and no roots to bind the soil, heavy rainfall washes the thin topsoil away.
How does deforestation contribute to climate change?
Burning and decaying trees release stored carbon dioxide, and the lost carbon sink absorbs less CO2 — adding to the greenhouse effect.
Give one way deforestation can bring economic development.
It creates jobs and export earnings from timber, minerals, beef and soya, providing tax income to pay for schools, roads and hospitals.
How does selective logging manage the rainforest sustainably?
Only a few chosen (usually older) trees are cut down, so the forest structure stays intact and recovers quickly.
True or false? Selective logging means no trees are cut down at all.
False. Trees are still felled, but only a small number of selected mature trees so the forest can recover.
How does replanting manage the rainforest sustainably?
New trees are planted to replace those felled, so the forest resource is maintained for the future.
How does conservation manage the rainforest sustainably?
National parks and protected reserves are set up where logging, mining and farming are banned or strictly controlled.
How does education manage the rainforest sustainably?
Local people, businesses and tourists are taught the value of the forest and sustainable alternatives, so less forest is destroyed.
How does ecotourism manage the rainforest sustainably?
Small-scale tourism with little environmental impact gives local people an income from conserving the forest rather than clearing it.
How does debt reduction help make tropical rainforests more sustainable?
In debt-for-nature swaps, some of a poorer country's debt is written off in return for a guarantee to spend money protecting its rainforest.
Give one limitation of ecotourism as a way of managing tropical rainforests.
It involves only small numbers of visitors in small areas, so it earns far less than logging or mining and cannot stop large-scale deforestation.
True or false? Sustainable management of a rainforest means stopping all human use of the forest.
False. It means using the forest so people benefit now without damaging it for future generations, e.g. selective logging and ecotourism.