Tropical Rainforests Flashcards
(42 cards)
Describe the distribution of tropical rainforests across the earth
•Unevenly distributed
•Can be found between Tropic of Cancer 23 ½ degrees N
•and Tropic of Capricorn 23 ½ degrees S
•Mainly concentrated near the Equator / along the Equator 0 degrees
Continent: Asia, South America, Africa
Region: Southeast Asia, Northern areas of South America, Central Africa
Countries: Malaysia, Indonesia; Brazil, Columbia; Congo, Cameroon
What is a climograph?
A graph that shows how mean monthly temperature and mean monthly precipitation vary throughout the year for a particular place.
•The temperature is shown using a line graph while the precipitation is shown using a bar graph.
How do you describe the temperature pattern shown on a climograph?
Are there variations in the temperatures? Are they slight or large?
If there are seasonal variations, when are the summer and winter months?
What is the highest/lowest mean monthly temp recorded? Which months did they occur in?
What is the annual temperature range? Calculate, showing your working.
How do you describe the precipitation pattern shown on a climograph?
Is the mean monthly rainfall evenly distributed throughout the year?
What is the highest / lowest mean monthly rainfall recorded? Which months did they occur in? Are they seasonal?
What is the total annual rainfall received?
Define a water table
The line marking the boundary between saturated and unsaturated soil
Define confluence
The point where two rivers merge
Define percolation
The downward movement of water within the soil, usually entering the ground water
Define infiltration
The process by which water on the ground surface enters the soil
Define water shed
The boundary/divide between two drainage basins
Define overland flow
The flow of water over the earth’s surface; fastest process of water movement
Define groundwater
Water stored underground in the soil or in pores of rocks
Define tributaries
A smaller river or stream flowing into a larger river
Define mouth
Where the river flows into a lake or ocean
Define through flow
Water moving downslope through the soil
Define base flow
Flow of groundwater into the riverbed; the slowest flow of water movement
Define source
Original point from which the river flows/the place where a river originates
Define evapotranspiration
The sum of evaporation of water from the land surface plus transpiration from vegetation
Why are tropical rainforests important to the indigenous people?
Homes for indigenous people Source of timber Medicinal properties Water catchment Habitat for plants and animals Carbon sink
How do tropical rainforests protect the soil layer from erosion?
During heavy downpours, the mass of vegetation in the rainforest catches and holds much of the rain, which is then lost via evaporation and does not reach the ground
The layers of vegetation also break the force of the rain, protecting the top soil layer from direct force
Roots also help to hold the soil together
Where trees are cut down in large numbers, this natural protection is removed, soil erosion increases and minerals are washed away
Define deforestation
Large scale removal of trees; intentional clearing of large areas of forest for human purposes
Why are tropical rainforests important?
The Amazon is home to the world’s largest river by volume. The Amazon River discharges five times the quantity of water of any other river. •Its catchment area encompasses a whopping 2.72 million square miles, which is roughly 40% of the entire continent of South America.
Rainforests play a key role in adding water to the atmosphere through the process of transpiration
Water vapour released contributes to the formation of rain clouds, which release water back onto the rainforest
In the Amazon, 50-80% of moisture stays locked within the ecosystem’s water cycle
What are the main causes of deforestation?
Increased demand for land for agriculture
> Cattle grazing
- Trees are cleared and the land converted to pasture
for cattle to graze
- Cattle ranching is an important revenue-generating
activity –beef is exported to other countries (e.g.
USA, Canada, Japan, France)
> Growing crops
- For commercial purpose (large scale) E.g. Multi-
national companies clear the forest for plantations
to grow cash-crops (pepper, sugarcane, bananas,
coffee)
- For subsistence purpose (small scale) –over a
period of time the land area required will increase
when there is an increase in population
- E.g. Small holding farmers in Indonesia –need land
for cultivation of crops for food, sell surplus to earn
income
Increased demand for natural resources (timber and mineral ores)
> Timber logging
- Due to increased demand for hardwoods from
other countries (e.g. Japan, Germany, USA)
- Use of mechanical, modern equipment such as
bulldozers, chain-saws
> Mining
- Mining for large deposits of gold, bauxite, iron, tin
and diamonds
- Forests are cleared in order to extract these
minerals
- More than 1/6 of the Amazon forest has been
cleared for extraction of iron
What are some minor causes of deforestation?
Increased demand for land for development of the area •To build settlement, transportation networks, transport infrastructure, railway, roads, airports
•Increased demand for land as a result of growing population
•Need land for housing to cater to needs of the growing population
What are some environmental impacts of deforestation?
Loss of biodiversity
•Unique environment of tropical rainforest
•Over a million species of plants and animals, and many not classified
•Animals forced to migrate, may not be able to adapt
•Plants species are lost before being discovered, such
plants could have been medicinal
• Extinction of plants and animals
Enhanced Greenhouse Effect
•Greenhouse gases in the atmosphere trap heat and
keep the Earth warm
rise in the Earth’s average temperature
•Deforestation > less carbon dioxide absorbed > more stored carbon released
Increase in soil erosion and frequency of landslides
- no trees and leaves to intercept rain, which may wash away soil
- no tree roots to hold soil
- topsoil contains minerals and nutrients essential for plant growth
- loosened slopes will cause landslides
Increased sedimentation and flooding
•Eroded soil washed into rivers > affects water quality > threaten survival of aquatic plants and animals
•Increases chances of flooding as water level rises by the large amount of soil particles deposited in it > destruction to property and lives
