Grassland – SS1 Biology Lesson Note (First Term)

Grassland, also called savanna, is a plant community in which grasses are the dominant plants, with scattered trees and shrubs.

Behavioural objectives

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 key terms used in the study of grassland?

These eight terms are used throughout the topic.

• Habitat: the place where a plant or animal lives.
• Producer: a green plant that makes its own food by photosynthesis.
• Consumer: an organism that feeds on plants or other animals.
• Grazer: an animal that feeds mainly on grass, such as the zebra and cattle.
• Deciduous plant: a plant that sheds its leaves in the dry season.
• Transpiration: loss of water vapour from the leaves of a plant.
• Camouflage: colour or pattern that helps an animal blend into its background.
• Adaptation: a feature that helps an organism survive in its habitat.

What are the characteristics of grassland?

Grassland has high temperatures, a long dry season, a shorter rainy season and grass as the main vegetation.

1. Temperature: usually high, and sunshine is intense.
2. Humidity and rainfall: relative humidity is low and rainfall is scanty (60 to 150 cm a year).
3. Seasons: rain falls in one season and the rest of the year is dry.
4. Vegetation: grass is abundant, with a few short trees sparsely distributed.
5. Bush fire: frequent in the dry season, so the trees are fire resistant.
6. Deciduous plants: plants that shed their leaves in the dry season are present.
7. Roots and stems: plants have underground stems and deep roots that reach water far below the surface.
8. Leaves: trees have modified leaves that help them survive dry conditions.
9. Food supply: grass is the main producer of food, so the habitat supports many grazing animals and the animals that feed on them.

What are the types of savanna in Nigeria?

There are four major types of savanna in Nigeria: Southern Guinea, Northern Guinea, Sudan and Sahel.

• Arrangement: the four types lie in belts across the country.
• Direction: from the south of the savanna region towards the north, the savanna becomes drier and more open.

Which plants grow in grassland and how are they adapted?

Grassland plants are mainly grasses and a few hardy trees, with features that help them survive fire and drought.

Examples of grassland plants

• Grasses: elephant grass, guinea grass and spear grass.
• Trees: acacia, palms and baobab.

Adaptive features of plants

1. Thick, corky bark: protects trees from severe fire.
2. Underground stems: grasses survive fire and drought, so new shoots grow when the rains return.
3. Thick, waxy cuticle: reduces water loss by transpiration.
4. Reduced or small leaves: a small surface area means less water is lost.
5. Curly or rolled leaves: expose less surface to the sun and wind, which conserves water.
6. Leaf shedding: deciduous trees drop their leaves in the dry season to conserve water.
7. Swollen trunk of the baobab: stores water for use in the dry season.
8. Deep roots: reach water far below the soil surface.

Which animals live in grassland and how are they adapted?

Grassland animals include grazers, predators, small animals and domestic animals, each with features that suit open, dry land.

Examples of grassland animals

• Grazers and browsers: antelopes, elephants, giraffes, zebras and grass cutters.
• Predators: lions, leopards, snakes and birds.
• Small animals: grasshoppers, termites, lizards and rats.
• Domestic animals: goats and cattle, kept by herders.

Adaptive features of animals

What food chains are found in grassland?

A food chain shows how energy passes from one organism to another through feeding.

Meaning of a food chain

• Start of the chain: a producer (green plant), followed by consumers.
• Arrow: means “is eaten by”.
• Number of chains: many kinds of animals live in grassland, so there are several food chains.

Examples of grassland food chains

1. Grass → grasshopper → lizard → snake
2. Grass → grasshopper → toad → bird
3. Grass → zebra → lion

Feeding levels in the first chain

• Grass: the producer.
• Grasshopper: the primary consumer, because it eats plants.
• Lizard: the secondary consumer.
• Snake: the tertiary consumer.

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 and name the producer in it.

Assignment

• Task: list four grassland animals and state one way each is adapted to its habitat. Then explain why many grassland plants have small or curly leaves.