Trees in Savanna habitats usually have thick bark which mainly.

Step 1: Analyze the question The question asks about the main function of thick bark in Savanna trees. Savanna is a tropical grassland with scattered trees and a long dry season.

Step 2: Explain the concept Savanna regions (like the Guinea and Sudan savanna in Northern Nigeria) experience a long dry season. During this time, the grasses dry up and bush fires occur frequently, either naturally or from hunters and farmers clearing land. Plants that survive there show adaptations to fire, drought, and heat.

Step 3: Evaluate each option

• A. Reduces the rate of transpiration: Transpiration happens mainly through the leaves (stomata), not the bark. Savanna trees reduce water loss through small, thick, waxy leaves or by shedding leaves. This is not the main job of bark.
• B. Protect them from scorching sun: Bark does give some protection, but the sun is not the major threat that thick bark evolved to counter.
• C. Protect them from heavy winds: Wind resistance depends on roots and trunk strength, not bark thickness.
• D. Resist bush fires: Thick, corky bark is a poor conductor of heat and insulates the living tissues (cambium and phloem) beneath it. This protects the tree when grass fires sweep through. ✔

Step 4: Answer The correct answer is D. Resist bush fires.

Step 5: Exam tip Remember the link: Savanna → Fire → Thick bark. In questions on savanna adaptations, associate:

• Thick bark → fire resistance
• Small or waxy leaves, leaf shedding → reduced water loss
• Deep roots → reaching underground water