The Living World: Tropical Rainforests

Question 1

Why does convectional rainfall happen in rainforests?

Answer 1

Some rainforests lie on the equator. This means that the sun’s rays are more concentrated in these regions and this produces convectional rain.

Question 2

What is leaching and how does it apply to soils in TRFs?

Answer 2

The soils in TRFs are not very fertile because so many of the nutrients are dissolved and washed out of the soil by the heavy rainfall. This is called leaching and it leaves the upper soil layers lighter in colour because of the lack of nutrients.

Question 3

Where are most nutrients found in the soil in TRFs?

Answer 3

Most nutrients are found in thin fertile surface layers of the soil where dead leaves decompose rapidly in the hot humid conditions.

Question 4

Why are tropical soils some of the deepest soils in the world?

Answer 4

Because the rocks beneath the rainforest have been weathered by the hot, wet conditions for millions of years, forming a deep soil - up to 30m deep in some places!

Question 5

Why does TRF soil have a thick layer of litter?

Answer 5

Because of the constant growing season so leaves are always falling to the forest floor.

Question 6

Why do the relatively infertile soils only support lush vegetation?

Answer 6

Because the nutrients are stored in the upper soil layers are quickly recycled and taken up by the growing plants.

Question 7

Why are the lower layers of the soil usually red in colour?

Answer 7

Because they are rick in iron from the weathered rock beneath the soil.

Question 8

Why do roots not extend very deeply through the soil?

Answer 8

Because the nutrients are all held in the upper soil layers.

Question 9

How are the leaves in the canopy and emergent layer of a TRF adapted?

Answer 9

They have a large surface area to catch as much sunlight as possible.

Question 10

Why is the canopy like an umbrella?

Answer 10

To maximise absorption of sunlight and allow photosynthesis so plants can grow continuously all year round.

Question 11

Why is there little undergrowth in a TRF?

Answer 11

Because less than 5% of the sun’s rays reach this layer.

Question 12

Why are the roots shallow in a TRF?

Answer 12

Because the water and nutrients needed by the plants are all close to the surface in the upper layers of the soil.

Question 13

Why do dead trees rot quickly in a TRF?

Answer 13

Because of the large amounts of heat and water available to speed up decomposition. This adds nutrients to the surface which are quickly used by other plants to grow.

Question 14

What are lianas and what do they use to reach sunlight?

Answer 14

They are vines which use other trees to reach the canopy and sunlight because there is not much light at ground level and they wouldn’t survive otherwise.

Question 15

What is biodiversity?

Answer 15

The variety of organisms living in a particular area p both plants and animals.

Question 16

Why do TRFs have so many different species (biodiversity)?

Answer 16

• Perfect growing conditions all year mean lots of different plants can survive.
• Different plant layers create different environmental conditions (niches).
• It is always hot and wet, so species don’t need to cope with changing conditions.
• TRFs are ancient, plants and animals have been evolving there for thousands of years.
• Large numbers of plant species support similarly large numbers of animal species.

Question 17

What is deforestation?

Answer 17

The permenant removal of trees to make room for something besides forest.

Question 18

Describe the projected global TRF loss.

Answer 18

An area with predicted high TRF cover is Australia with a loss of 3.4 million square hectors. An area with projected low loss of TRF cover is North South America with 34-48 million square hectors. However, Australia is predicted to have its whole rainforest wiped out by 2030.

Question 19

What is cattle ranching, why is it a growing industry and how does it cause deforestation in the Amazon rainforest?

Answer 19

• Cattle ranching - 70%
  Cattle ranching is a growing industry because Brazil is the world’s largest exporter of beef. it also has the largest commercial cattle herd of around 180-190 million. The governemtn of Brazil offers loans of billions of dollars to support the expansion of its beef industry.

Question 20

Where is the Amazon rainforest?

Answer 20

In South America and it is north of the continent. Two countries that the Amazon rainforest is in are Colombia and Ecuador.

Question 21

What % of deforestation comes from logging?

Answer 21

2%.

Question 22

Why is population growth causing deofrestation in the Amazon?

Answer 22

• Human activities.
• Population growth - increases in food demand.
• Humans reuqire more land.
• We have to produce more crops because of demand for food.

Question 23

How has population gorwth grown in the city of Brazil?

Answer 23

I has grown massively, 23% between 2000 and 2010. This is a threat because more of the rainforest surrounding the city is being cut down to accommodate more people moving in.

Question 24

How is road building a cause of deforestation in Brazil?

Answer 24

Roads are needed in the rainforest so that equipment and transport can be brought in and products can be brought back out. However, huge numbers of trees need to be cut down to make space for them.

Question 25

How is mineral extraction a cause of deforestation in Brazil?

Answer 25

In the Amazon, gold is a highly sought after mineral. Today, the area of land beig used is over 50,000 hectares.

because gold is a valuable and popular mineral, Brazil gains a lot of interest and profit from selling it.

This impacts the TRF ecosystem because the gold is mined by clear0felling which means cutting down huge portions of TRF in one go.

Question 26

How is logging a cause of deforestation in Brazil?

Answer 26

It is the first step of conversion of forest land to other uses. However, to do this vast areas are cleared in one go (clear felling).

This impacts the TRF ecosystem because vast areas of rainforest are cut down in one go, leaving the land damaged and unable to grow back quickly/if at all.

Question 27

What are the impacts of deforestation?

Answer 27

Soil erosion - once the tree canopy is removed, the soil is easily washed away by the heavy convectional rain. The rain can now reach the ground and easily erode.
Economic development - Brazil benefits financially from the profits of mineral extraction and logging. This money can be spent on improving the quality of life of Brazil’s population.
Climate change - The loss of trees reduces the rainforest’s capacity to absorb carbon dioxide.
Loss of biodiversity - Clearing raindforest means that biodiversity will be reduced and individual species will become endangered and then extinct.

Question 28

Why should TRFs be protected?

Answer 28

• TRFs provide employment for thousands of people.
• Tourism - attracts tourists which provides jobs for people and income for the country.
• Water - important source of clean water.
• People - home to many indigenous tribes.
• Food - 80% of the world’s diet originated from rainforest plants.
• Medicine - 25% of all medicines come from TRFs.
  Rescources - Trees and plants provide wood, rubber etc.
• Climate - They prevent the climate from becoming to hot and dry.
• Climate change - nTRFs absorb and store 20% of the world’s CO2 emmissions.
• Biodiversity - TRFs contain 50% of all known plants and animals.
• Inherent value
• Protection - reduce flooding and erosion.

Question 29

What is interdependance?

Answer 29

All parts of the ecosystem: climate, water, soil, plants, animals and people are dependant on one another. If one changes, everything else is affected.