The vegetation of savannah consists of grassland with scattered small trees, but extensive areas have no trees. The forest development in such areas is generally kept in check by one or more or a combination of some conditions. Which of the following are such conditions? Select the correct answer using the codes given below:

Answer: (c) 2, 3 and 4

Fire, grazing and seasonal rainfall together keep trees in check.

Statement by statement

1. ✗ NOT a main check Termites and burrowers are common in savannas, but they don’t control tree cover.

2. ✓ YES Dry-season fires kill young trees; grasses re-sprout from their roots.

3. ✓ YES Grazers and browsers (and elephants) eat saplings before they grow.

4. ✓ YES A long dry season gives trees too little water all year.

5. ✗ NOT the main check Soils vary; the general control is climate and disturbance.

The idea

Savannah lies between the rainforest and the desert. Rain is enough for trees in the wet season but not in the long dry season. Dry grass then burns easily, and large herds eat what the fire spares. A tree seedling must survive drought, fire and grazing together, and few do.

Wet summer: grass grows tall → Long dry winter: grass dries → Fires sweep through → Grazing animals eat the saplings → Grass re-sprouts from its roots; trees stay scattered

The trap

Termite mounds are iconic in savannah pictures, so they feel important.

Also know

Savannah trees are built for this: thick fire-resistant bark, water stored in the trunk (baobab), flat umbrella crowns (acacia). Local names: llanos in Venezuela, campos in Brazil.