Characteristics of tropical rainforests
Tropical rainforests have distinct characteristics that support a wide variety of different species. This means that they have a high biodiversity. The biotic or living components of the ecosystem and the abiotic or non-living components of the ecosystem depend on one another - a change in one leads to a change in the other.
Climate
- Very wet with over 2,000 mm of rainfall per year.
- Very warm with an average daily temperature of 28°C. The temperature never drops below 20°C and rarely exceeds 35°C.
- The atmosphere is hot and humid.
- The climate is consistent all year round. There are no seasons.
Soil
- Most of the soil is not very fertile.
- A thin layer of fertile soil is found at the surface where the dead leaves decompose.
- It is red in colour because it is rich in iron.
- Due to heavy rainfall the nutrients are quickly washed out of the soil.
Plants and animals
- The warm and very wet climate provides perfect conditions for plant growth.
- The wide range of plant species supports many different animals, birds and insects.
- Species have adapted to the conditions of the rainforest, eg trees and plants have shallow-reaching roots to absorb nutrients from the thin fertile layer in the soil.
Structure of a tropical rainforest
A tropical rainforest is made up of the following layers:
A tropical rainforest is made up of the following layers:
- ground level
- shrub layer
- under canopy
- (main) canopy
- emergents
TASK
Use the information above and your own online research to answer the questions.
1. What is meant by "high biodiversity"?
2. Explain why the climate of a rainforest is consistent all year round.
3. Why is soil in rainforest regions not very fertile?
4. If soil is not very fertile, why do rainforests have such dense and vibrant vegetation?
5. Explain why a warm and wet climate provides perfect conditions for plant growth.
6. Give an example of a specific species of vegetation and animal for each of the rainforest layers shown in the diagram above.
Use the information above and your own online research to answer the questions.
1. What is meant by "high biodiversity"?
2. Explain why the climate of a rainforest is consistent all year round.
3. Why is soil in rainforest regions not very fertile?
4. If soil is not very fertile, why do rainforests have such dense and vibrant vegetation?
5. Explain why a warm and wet climate provides perfect conditions for plant growth.
6. Give an example of a specific species of vegetation and animal for each of the rainforest layers shown in the diagram above.
TASK
7. Name three continents with tropical rainforests.
8. Name 5 countries with tropical rainforest coverage.
9. Describe the distribution of tropical rainforests.
7. Name three continents with tropical rainforests.
8. Name 5 countries with tropical rainforest coverage.
9. Describe the distribution of tropical rainforests.
Threats to tropical rainforests and the need for their management
TASK
Watch the video and note down what you consider to be the 5 most important pieces of information discussed.
Choose one and explain why it is the biggest issue of the video. Do some further research on the issue chosen in order to add some depth to your explanation.
Watch the video and note down what you consider to be the 5 most important pieces of information discussed.
Choose one and explain why it is the biggest issue of the video. Do some further research on the issue chosen in order to add some depth to your explanation.
Amongst other things, tropical rainforests have extraordinarily highs level of biological diversity or “biodiversity”. Scientists estimate that about half of Earth's terrestrial species live in rainforests. Rainforests provide a critical ecosystem services at local, regional, and global scales, including producing oxygen (tropical forests are responsible for 25-30 percent of the world's oxygen turnover) and storing carbon (tropical forests store an estimated 229-247 billion tons of carbon) through photosynthesis; influencing precipitation patterns and weather; moderating flood and drought cycles; and facilitating nutrient cycling.
In spite of this, they are under threat as never before.
Every year an area of rainforest the size of New Jersey is cut down and destroyed, mostly the result of human activities. We are cutting down rainforests for many reasons, including:
In recent decades there has been an important shift in deforestation trends. Today export-driven industries are driving a bigger share of deforestation than ever before, marking a shift from previous decades, when most tropical deforestation was the product of poor farmers trying to put food on the table for their families. There are important implications from this change. While companies have a greater capacity to chop down forests than small farmers, they are more sensitive to pressure from environmentalists. Thus in recent years, it has become easier—and more ethical—for green groups to go after corporations than after poor farmers.
Rainforests are also threatened by climate change, which is contributing to droughts in parts of the Amazon and Southeast Asia. Drought causes die-offs of trees and dries out leaf litter, increasing the risk of forest fires, which are often set by land developers, ranchers, plantation owners, and loggers.
- wood for both timber and making fires;
- agriculture for both small and large farms;
- land for poor farmers who don’t have anywhere else to live;
- grazing land for cattle (the single biggest driver of deforestation in the Amazon);
- plantations, including wood-pulp for making paper, oil palm for making palm oil, and rubber;
- road construction; and
- extraction of minerals and energy.
In recent decades there has been an important shift in deforestation trends. Today export-driven industries are driving a bigger share of deforestation than ever before, marking a shift from previous decades, when most tropical deforestation was the product of poor farmers trying to put food on the table for their families. There are important implications from this change. While companies have a greater capacity to chop down forests than small farmers, they are more sensitive to pressure from environmentalists. Thus in recent years, it has become easier—and more ethical—for green groups to go after corporations than after poor farmers.
Rainforests are also threatened by climate change, which is contributing to droughts in parts of the Amazon and Southeast Asia. Drought causes die-offs of trees and dries out leaf litter, increasing the risk of forest fires, which are often set by land developers, ranchers, plantation owners, and loggers.
Even though rainforests are disappearing very quickly, the good news is there are a lot of people who want to save rainforests. The bad news is that saving rainforests will be a challenge as it means humanity will need to shift away from business-as-usual practices by developing new policies and economic measures to creative incentives for preserving forests as healthy and productive ecosystems.
Over the past decade there has been considerable progress on several conservation fronts. Policymakers and companies are increasingly valuing rainforests for the services they afford, setting aside large blocks of forests in protected areas and setting up new financial mechanisms that compensate communities, state and local governments, and countries for conserving forests. Meanwhile, forest-dependent people are gaining more management control over the forests they have long stewarded. Large international companies are finally establishing policies that exclude materials sourced via deforestation. People are abandoning rural areas, leading to forest recovery in some planes.
But the battle is far from over. Growing population and consumption means that rainforests will continue to face intense pressures. At the same time, climate change threatens to dramatically alter temperatures and precipitation patterns, potentially pushing some forests toward critical tipping points.
Over the past decade there has been considerable progress on several conservation fronts. Policymakers and companies are increasingly valuing rainforests for the services they afford, setting aside large blocks of forests in protected areas and setting up new financial mechanisms that compensate communities, state and local governments, and countries for conserving forests. Meanwhile, forest-dependent people are gaining more management control over the forests they have long stewarded. Large international companies are finally establishing policies that exclude materials sourced via deforestation. People are abandoning rural areas, leading to forest recovery in some planes.
But the battle is far from over. Growing population and consumption means that rainforests will continue to face intense pressures. At the same time, climate change threatens to dramatically alter temperatures and precipitation patterns, potentially pushing some forests toward critical tipping points.
TASK
Answer the following questions.
1. Explain the impacts of deforestation.
2. Explain why deforestation can contribute towards climate change.
3. Explain how tropical rainforests are valuable for medicines, climate and energy.
4. Define the term ‘sustainable management’ in relation to tropical rainforests.
5. ‘Countries that need money to develop should be allowed to use the tropical rainforest resource however they want’. Do you agree with this statement? Justify your view.
Answer the following questions.
1. Explain the impacts of deforestation.
2. Explain why deforestation can contribute towards climate change.
3. Explain how tropical rainforests are valuable for medicines, climate and energy.
4. Define the term ‘sustainable management’ in relation to tropical rainforests.
5. ‘Countries that need money to develop should be allowed to use the tropical rainforest resource however they want’. Do you agree with this statement? Justify your view.