Grassland – SS1 Biology Lesson Note (First Term)

Grassland, also called savanna, is a plant community in which grass species are dominant, but trees and shrubs may be present.

Natural mountains and grassland

Behavioural objectives

By the end of the lesson, students should be able to:

1. define grassland (savanna);
2. state the characteristics of grassland;
3. name the four major types of savanna in Nigeria;
4. describe how grassland plants and animals are adapted to their habitat;
5. write examples of food chains in grassland.

What are the characteristics of grassland?

1. Temperature is usually high and sunshine is intense.
2. The relative humidity is low and rainfall is scanty (60 to 150 cm annual rainfall).
3. Grass is abundant, with few short trees sparsely distributed.
4. Bush fire is frequent and the trees are fire resistant.
5. Deciduous plants (plants that shed their leaves in the dry season) are present.
6. Plants possess underground stems and deep roots to search for water.
7. Trees have modified leaves for adaptation to the environment.

What are the types of savanna in Nigeria?

There are four major types of savanna in Nigeria, namely:

1. Southern Guinea savanna
2. Northern Guinea savanna
3. Sudan savanna
4. Sahel savanna

The Southern Guinea savanna is the largest biome in Nigeria.

Which plants grow in grassland and how are they adapted?

The grassland plants include acacia, elephant grass, guinea grass, spear grass, palms, baobab trees, etc. Their adaptive features include:

1. Trees have thick corky barks to resist severe fire.
2. Grasses have underground stems to escape fire and drought.
3. Leaves have a waxy surface in addition to the cuticle covering to reduce transpiration.
4. Reduced or small leaves reduce transpiration.
5. Curly leaves conserve water.
6. Leaves fall (deciduous) in the dry season to conserve water.
7. Baobab trees have broad and succulent leaves to conserve water.

Which animals live in grassland and how are they adapted?

Animals found in grassland include antelopes, elephants, giraffes, zebras, goats, cattle, grasshoppers, lizards, birds, lions, tigers, leopards, rats, snakes, grass cutters, kangaroos, etc. They adapt to this habitat in the following ways:

1. Termites live in air-conditioned nests called anthills, which keep them cool.
2. Rats burrow into the soil to avoid excessive heat and fire.
3. Zebras and giraffes can camouflage using their colours.
4. Lions, tigers and leopards have powerful claws and teeth for attacking animals.
5. Kangaroos have long legs to help them escape from danger. They also have pouches to shield their young ones from hot weather and attacks.
6. Elephants and lions move in groups or herds to gain strength in numbers.

What food chains are found in grassland?

There are several food chains because many kinds of animals live in grassland.

1. Grass → grasshoppers → lizards → snakes
2. Grass → grasshoppers → toads → birds
3. Grass → zebras → lions

Evaluation

1. Define grassland.
2. State four characteristics of grassland.
3. Name the four major types of savanna in Nigeria.
4. Give three ways in which grassland plants are adapted to fire or drought.
5. Write one food chain found in grassland.

Assignment

1. List four grassland animals and state one way each is adapted to its habitat.
2. Explain why many grassland plants have small or curly leaves.