IAS Prelims Geography GQ-8 – 2021 | Savannah Biome & Vegetation Controls
Authentic Classroom Explanation by IAS Monk
📍 The Question
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?
- Burrowing animals and termites
- Fire
- Grazing herbivores
- Seasonal rainfall
- Soil properties
Select the correct answer using the code given below:
(a) 1 and 2
(b) 4 and 5
(c) 2, 3 and 4
(d) 1, 3 and 5
✅ Correct Answer: (c) 2, 3 and 4
🎯 Theme of the Question
World Geography | Biomes | Savannah Ecosystems | Climate–Vegetation Interaction
This question tests understanding of why savannas remain grass-dominated despite being climatically capable of supporting trees.
🧠 Classroom Explanation
Savannahs are not forests in transition. They are stable ecosystems, where tree growth is actively suppressed by a combination of climatic and ecological controls.
🔥 Fire (Statement 2)
- Seasonal dry periods make grasses highly flammable.
- Frequent fires kill tree saplings before they mature.
- Grasses regenerate faster than woody plants after fires.
🐄 Grazing Herbivores (Statement 3)
- Large herbivores (zebras, antelopes, cattle) consume young tree shoots.
- Continuous grazing prevents forest thickening.
- Grazing favours grasses over trees.
🌧️ Seasonal Rainfall (Statement 4)
- Rainfall is highly seasonal, with long dry spells.
- Water availability supports grasses but limits deep-rooted tree survival.
- This creates an open canopy system.
✔️ Together, fire + grazing + seasonal rainfall maintain the savannah structure.
❌ Why other statements are not the best answer
🐜 Burrowing animals & termites (Statement 1) ❌
- Termites often enhance soil fertility locally.
- They may promote tree growth near mounds rather than suppress it.
- Hence, not a primary controlling factor at biome scale.
🌱 Soil properties (Statement 5) ❌
- Savannas exist on varied soils, including fertile ones.
- Soil alone does not explain the absence of forests.
📊 Concept Snapshot
| Factor | Role in Savannah |
|---|---|
| Fire | Suppresses tree regeneration |
| Grazing | Removes saplings |
| Seasonal rainfall | Limits woody growth |
| Termites | Local nutrient enhancement |
| Soil | Secondary influence |
🧩 Prelims Memory Hook
“Savanna survives on three S’s:
Seasonal rain, Stock grazing, and Sparks (fire).”
🧭 IAS Monk Whisper
Where rain hesitates,
fire repeats,
and grazers rule —
trees learn restraint.