Grassland Habitats SS2 Biology Lesson Note

GRASSLAND [SAVANNA]

This is a plant community in which grass species are dominant, but trees and shrubs may be present.

Characteristics Of Grassland

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

Types Of Savanna

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

1. Southern Guinea savanna
2. Northern Guinea savanna
3. Sudan savanna
4. Sahel savanna
5. The Southern Guinea savanna is the largest biome in Nigeria

Plant Distribution And Adaptation In Grasslands

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 with underground stems to escape fire and drought.
3. Leaves with waxy surface in addition to cuticle covering to reduce transpiration.
4. Reduced or small leaves to reduce transpiration.
5. Presence of curly leaves to conserve water.
6. Leaves fall (deciduous) in the drying season to conserve water.
7. Baobab trees have broad and succulent leaves to conserve water.

Animals Distribution And Adaptation In A Forest

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

1. Termites lived in air-conditioned nests called anthills for cooling the animals.
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 and also have pockets of flesh to shield their young ones from hot weather and attacks.
6. Elephants and lions move in groups or herds to achieve strength in numbers.

Food Chains In Grassland

There are several food chains due to numerous animals:

Grass → grasshoppers→ lizards → snakes

Grass → grasshoppers → toads → birds

Grass → zebras → lions

ARID LANDS [DESERTS]

These are areas of very low rainfall and high evaporation rates. They are the driest habitats, receiving less than 25 cm of annual rainfall. Arid lands are of two types;

1. Hot deserts e.g. Sahara desert (North Africa), Kalahari desert (South Africa)
2. Cold deserts e.g. desert in North America

Characteristics Of A Desert

1. Water is very scarce.
2. Temperature is very high during the day and very low at night.
3. Vegetation is very scanty.
4. The soils are sandy or rocky.
5. Strong winds occur frequently and sunshine is very intense
6. Presence of drought-resistant plants (xerophytes)

Plant Distribution And Adaptation In Deserts

Desert plants include thorny bushes, cacti, scattered dwarf acacia, date palms, wiring grasses, baobab trees and euphorbia species. They adapt to this habitat in the following ways:

1. Plants have thin leaves to reduce transpiration.
2. Cacti leafless have thorns to reduce transpiration and thick succulent stems to store water.
3. Acacia (drought resistant) has deep roots which absorb underground water.
4. Baobab trees have waxy leaves which can be hairy or needle-shaped to reduce the rate of transpiration.
5. Wiring grass has narrow and slender leaves to reduce transpiration.

Animal Distribution And Adaptation In Deserts

The Desert animals include camels, rodents, lizards, snakes, zebras, desert tortoises, grasshoppers, wasps, ants etc. They survive in the following ways:

1. Most desert animals excrete solid wastes to conserve water.
2. Kangaroos and rats remain in burrows during the day to avoid excessive heat.
3. Reptiles have scales to reduce water loss.
4. Camels can survive several days without drinking water. They can withstand a wide range of body temperature up to 40°c.

5. Locusts have water-proof bodies and impervious cuticles.

Food Chains In Arid Lands

Plants → desert rats → snakes

Plants → ants → scorpions → snakes