Biosphere to Ecosystems, Grade 10: Biomes of South Africa and Ecotourism

A glass beaker on a school lab bench with a layer of blue salt water at the bottom and clear fresh water floating on top, modelling an estuary

This page covers the first part of the Grade 10 topic Biosphere to ecosystems: the biosphere, the biomes of South Africa, people and the environment, and ecotourism. It ends with a short classroom demonstration of how river water and sea water meet in an estuary.

Subject Life Sciences
Grade and term Grade 10, Term 3
Topic Biosphere to ecosystems, part 1 of 3: the biosphere, biomes and ecotourism
Practicals Classroom demonstration: a model estuary. The fieldwork for this topic is on the study an ecosystem page
Time Demonstration about 15 minutes

The biosphere

The biosphere is the part of the Earth, including its atmosphere, where living organisms are found. It is the largest ecosystem there is, and it depends on three non-living parts that overlap with it:

Diagram of three overlapping circles labelled atmosphere, hydrosphere and lithosphere, with the biosphere where all three meet

Component What it is Examples
Atmosphere The layer of gases around the Earth Oxygen, nitrogen, carbon dioxide, water vapour
Hydrosphere All the water on Earth Oceans, rivers, lakes, groundwater, ice
Lithosphere The rocky outer layer of the Earth, with the soil on it Rocks, soil, mountains

The three are connected. Water evaporates from the hydrosphere into the atmosphere and falls back as rain onto the lithosphere, and organisms take gases, water and minerals from all three.

Levels of organisation

Diagram of the levels of organisation from largest to smallest: biosphere, biome, ecosystem, community, population, organism

Level Meaning
Biosphere All the parts of the Earth where life is found
Biome A large area with a particular climate, soil and vegetation, and the animals that live there
Ecosystem A community of organisms interacting with each other and with their non-living environment
Community All the populations of different species living in one area
Population All the organisms of one species living in one area
Organism A single living thing

The living parts of an ecosystem are its biotic factors, and the non-living parts, such as light, water, soil and temperature, are its abiotic factors. Both are covered in detail on the biotic and abiotic factors page.

Terrestrial biomes of South Africa

Climate, especially how much rain falls and in which season, decides which plants can grow in a place. The soil and the plants then decide which animals can live there. South Africa has seven main terrestrial biomes. The national vegetation map (2006) recognises nine, adding the Desert biome in the far north-west and the Indian Ocean Coastal Belt along the KwaZulu-Natal and northern Eastern Cape coast.

Chart of the seven terrestrial biomes of South Africa showing the rainfall and typical vegetation of each

Biome Climate Vegetation Animals Where
Savanna Summer rain A grass layer with scattered trees and shrubs, called bushveld Giraffe, elephant, zebra, lion The lowveld and the Kalahari region, including Limpopo, Mpumalanga, North West and the Northern Cape. The largest biome, over a third of the country. The Kruger National Park is in it
Grassland Summer rain, frost in winter Grasses, with almost no trees Black wildebeest, blesbok The high central plateau (the Highveld), and inland KwaZulu-Natal and the Eastern Cape
Fynbos Mainly winter rain Shrubs, with proteas, ericas and restios (Cape reeds) Cape sugarbird, Cape grysbok Mainly the Western Cape, and east into the Eastern Cape
Forest High rainfall, no frost Tall evergreen trees such as yellowwood and stinkwood Knysna turaco Small patches, the largest along the Garden Route. The smallest biome, well under 1% of the area
Thicket Too dry for forest, but protected from fire Dense, often spiny shrubs and succulents such as spekboom Elephant, kudu, bushbuck The Eastern Cape
Nama-Karoo Low summer rain, 100 to 520 mm a year Low shrubs and grasses Springbok The central plateau in the western half of the country
Succulent Karoo Low winter rain, 20 to 290 mm a year, summers often over 40 °C Small succulent shrubs such as vygies, with mass flowering of daisies in spring Bat-eared fox, steenbok, golden moles The west, including Namaqualand

Plants in the dry Karoo biomes are adapted to save water. Many are succulents that store water in thick leaves or stems, and in spring, after the winter rain, annual plants flower in huge numbers.

Aquatic biomes

Aquatic biomes are described by the water rather than the soil, especially by how salty it is.

Aquatic biome Examples
Marine (salt water) Rocky shores, sandy beaches, kelp forests, coral reefs, the open ocean
Freshwater Rivers and streams, lakes and dams, wetlands such as vleis and pans
Estuaries (brackish water) Where a river meets the sea. South Africa has about 290 of them

Estuaries mix fresh and salt water, so they belong to both groups. They are nursery areas where the young of many fish and other sea animals feed and shelter.

Diagram of a river from its source in the mountains to its mouth at the sea, showing a narrow channel of cold water near the source and a wider channel of warmer water carrying more sediment lower down

A river changes gradually from its source to its mouth. Near the source the channel is narrow and the water is usually cold. Cold water holds more dissolved oxygen than warm water. Further down, the river becomes wider, and the water is warmer and carries more sediment.

People and the environment

The environment is everything around an organism, living and non-living. People change it all the time.

Human activity Effect on the environment
Farming Natural vegetation is cleared, and fertilisers and pesticides can wash into rivers
Mining Land is dug up, and rivers can be polluted
Building towns and roads Habitats are destroyed or cut into small pieces
Bringing in alien plants and animals Alien species compete with indigenous species
Conservation Parks and reserves protect biomes and the species in them

Ecotourism

Ecotourism is responsible travel to natural areas that conserves the environment, sustains the well-being of the local people, and involves interpretation and education. A project that protects wildlife but brings nothing to the people living around it is not ecotourism.

Economics

  • Visitors pay entrance, permit and accommodation fees, and part of the money can go to conservation and to local communities.
  • Local people are employed guiding visitors, and as trackers, rangers, cooks and lodge staff.
  • Local businesses sell crafts, food, transport and accommodation to visitors.

Ethics: how a responsible tourist behaves

  • Stay on paths and roads, and do not drive off-road in sensitive areas.
  • Take all litter away.
  • Do not pick plants or take shells, eggs or animals.
  • Do not feed or disturb wild animals.
  • Respect local customs, and ask before photographing people.

Opportunities in South Africa

Example How the community benefits
Makuleke, Pafuri area of the Kruger National Park The Makuleke community won back their land in a land claim in the late 1990s. It stays part of the park as a contractual park, managed with SANParks, and the community earns income from lodges built with private partners

Classroom demonstration: a model estuary

Aim

To show how fresh river water and salty sea water meet in an estuary.

What you need

Method

  1. Measure 300 ml of tap water into the 600 ml beaker.
  2. Stir in 1½ level teaspoons of salt (about 9 g) until it dissolves. This is about as salty as sea water.
  3. Add 3 drops of blue food colouring and stir. This is the sea water.
  4. Measure 200 ml of tap water into the 250 ml beaker. This is the river water.
  5. Hold the tablespoon just above the blue water, back side up, and pour the river water slowly onto the back of the spoon so it runs gently down the side of the beaker.
  6. Look at the beaker from the side.
  7. Stir the beaker gently a few times and look again.

What you should see

Step What you see
After pouring The clear fresh water floats on top of the blue salt water, with a fairly sharp boundary between them
After stirring The two mix into one pale blue layer

Why it happens

Salt water is denser than fresh water, so it sinks and the fresh water floats on top of it. In an estuary the river water flows out over the top while the heavier sea water pushes in underneath. Tides and waves stir the two together, which makes the brackish water of the estuary. Organisms living there must cope with saltiness that changes with every tide.

Safety

  • Wipe up spills straight away so nobody slips.
  • Food colouring stains clothes and skin.
  • Do not taste the water.

Free worksheet and marking memo

Related practicals

References