🌴 Tropical rainforests
Where: either side of the Equator, between the Tropics of Cancer and Capricorn. The largest areas are the Amazon basin in South America, the Congo basin in Africa and parts of South East Asia such as Indonesia.
Fragile Environments Under Threat » The World's Fragile Environments
What you'll learn this session
Study time: 30 minutes
Edexcel spec: 7.1 Fragile environments are under threat from desertification, deforestation and global climate change (a)
- What a fragile environment is and why it is easily damaged
- Where the world's main fragile environments are found
- The key characteristics of each one
- How to describe their locations on a world map
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Unlock This CourseWhat is a fragile environment?
This lesson starts Topic 7, Fragile Environments and Climate Change. It is one of three global issues in Paper 2 Section C. Edexcel students answer ONE of the three, so your teacher may choose which ones to study.
Some places can cope with a lot of change. Others cannot. A small change, such as a few years of drought or the cutting down of some trees, can harm them badly, and they may take a very long time to recover, or never recover at all. These places are called fragile environments.
Key terms:
- Fragile environment: a place where the plants, animals, soil and climate are in a delicate balance, so it is easily damaged by natural change or human activity.
- Distribution: where something is found on the Earth's surface and how it is spread out.
- Characteristics: the features that make a place what it is, such as its climate, soil, plants and animals.
- Desertification: the process by which land becomes drier and turns into desert-like conditions. You will study its causes in the next lesson.
Where are the world's fragile environments?
The spec does not give a fixed list, so you should know the main examples and where they are. You already know about biomes from the lessons on the world's biomes, so this lesson only picks out the ones that are under threat.
🏜 Hot deserts and their edges
Where: mainly around 15 to 30 degrees north and south of the Equator. Examples are the Sahara in North Africa and the Australian deserts. The dry land on the southern edge of the Sahara, called the Sahel, is especially fragile.
❄️ Polar and tundra regions
Where: around the Arctic Ocean (northern Canada, Alaska, Greenland, northern Russia) and around Antarctica in the far south.
⛰️ Mountain areas
Where: high ranges such as the Himalayas in Asia, the Andes in South America and the Alps in Europe.
Skill: describing a location on a world map
Use more than one clue. Give the continent or country, the line of latitude (for example "on the Equator" or "north of the Tropic of Cancer") and a nearby ocean or neighbouring region. For example: "The Amazon rainforest is in the north of South America, on the Equator, and stretches from the Atlantic coast towards the Andes."
Characteristics of each environment
Each fragile environment has its own features. These features explain why it is easily damaged.
🌴 Rainforest
Hot and wet all year. Very high biodiversity. Tall trees form a thick canopy. Most nutrients are held in the plants and the top layer of soil, not deep in the ground.
🏜 Hot desert margins
Hot and dry, with little and unreliable rainfall. Thin soils and sparse plants such as grasses and shrubs. Plant roots help to hold the soil together.
❄️ Polar and tundra
Very cold with a short, cool summer. Low-growing plants, few animal species, slow plant growth. Ground below the surface may be frozen all year.
Mountain areas are cold and windy at the top, with steep slopes and thin soils. Plants and animals change with height, and they are adapted to a narrow range of conditions.
Why are they fragile?
The environments above look very different, but they share some features that make them easy to damage.
- Delicate balance. Plants, animals, soil and climate depend on each other. If one part is lost, the others suffer.
- Slow recovery. Plant growth is slow in cold or dry places, and rainforest soils are thin, so damage can last for many years.
- Limited resilience. Many species are adapted to a narrow range of conditions, so they cannot survive if the climate or land use changes.
These environments face three main threats, which you will study in this topic: desertification, deforestation and global climate change.
Worked example
Question: Describe the distribution of tropical rainforests. [3 marks]
Rainforests are found close to the Equator, between the Tropics of Cancer and Capricorn. (1) The largest areas are in the Amazon basin in South America and the Congo basin in Africa. (1) There are also areas in South East Asia, such as Indonesia. (1)
Common mistakes
- Saying "it is in Africa" with no more detail. Always add a country, a line of latitude or a feature.
- Mixing up distribution (where it is) with characteristics (what it is like).
- Thinking only rainforests are fragile. Deserts, polar regions and mountains can be fragile too.
- Saying that fragile means weak and useless. It means easily damaged and slow to recover.
Exam-style question
(a) What is meant by a fragile environment? [2 marks]
(b) Name one fragile environment and describe where it is found. [2 marks]
(c) Explain why hot desert margins are easily damaged. [3 marks]
Model answer
(a) It is a place where plants, animals, soil and climate are in a delicate balance. (1) It is easily damaged and slow to recover. (1)
(b) Tropical rainforest. (1) It is found near the Equator, for example in the Amazon basin in northern South America. (1)
(c) Rainfall is low and unreliable, so plants grow slowly. (1) The soils are thin and plant roots help to hold them together. (1) If the plants are removed, the soil is exposed and the land can become drier, so it is slow to recover. (1)
Exam tip
For a "describe the distribution" question, give at least two location clues, such as a continent plus a line of latitude, and name a specific example.