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?
- 1.Burrowing animals and termites
- 2.Fire
- 3.Grazing herbivores
- 4.Seasonal rainfall
- 5.Soil properties
Select the correct answer using the code given below.
Answer & explanation
Answer: (c) 2, 3 and 4
Why not the tempting option · UPSC's key is (c). The general checks on tree growth in savannas are fire, grazing and browsing animals, and the long dry season of a seasonal-rainfall climate — a university biome guide puts it as frequent fires and large grazing mammals killing seedlings, with climate the most important factor. Soil does shape the tree–grass balance locally (thin or poorly drained soils carry no trees in some East African savannas), but the question asks for the general conditions and no option pairs soil with fire and grazing; termites build the mounds on which trees grow rather than checking them. In the exam, pick the option that holds the two universal controls, fire and grazing, together.
Fire, grazing and browsing animals, and the long dry season of a seasonal-rainfall climate are the recognised checks that keep savannas open and stop them turning into forest, so 2, 3 and 4 is the answer.
- ✗ 1. Termites are decomposers that break down about 30 per cent of dead organic matter; in parts of East Africa trees grow only on termite mounds, so termites aid rather than check tree growth. Burrowing animals are not a recognised control.
- ✓ 2. Wildfire is an important part of savanna ecosystems in all regions; annual burning of dry grass and litter helps keep woody plants from taking over.
- ✓ 3. Browsing and grazing animals alter the balance between trees and grass. Rising elephant numbers in Virunga National Park, for example, destroyed woody plants and turned a heavily wooded savanna into grass savanna with very few trees.
- ✓ 4. Savanna is a vegetation type of hot, seasonally dry climates: a long dry season each year limits tree growth and keeps the grass cover open.
- ✗ 5. Soil shapes the tree–grass balance only locally — thin or poorly drained soils carry no trees in some savannas — so it is not one of the general checks, and no option pairs it with fire and grazing.
Remember · Savannas stay open through fire, grazing and browsing animals, and a long dry season; without these, woody plants tend to spread and the savanna turns to forest.
Sources
- Encyclopaedia Britannica: Savanna (Population and community development and structure) ↗ · reference work “Wildfire is an important ingredient in savanna ecosystems in all regions. … led to an increase in the destruction of woody plants and transformed a heavily wooded savanna into a grass savanna with very few trees.”
- Encyclopaedia Britannica: Savanna ↗ · reference work “savanna , vegetation type that grows under hot, seasonally dry climatic conditions and is characterized by an open tree canopy (i.e., scattered trees) above a continuous grass understory”
- Encyclopaedia Britannica: Savanna (Environment) ↗ · reference work “An unusually large proportion of dead organic matter—approximately 30 percent—is decomposed through the feeding activities of termites.”
- University of California Museum of Paleontology: The grassland biome (Savanna) ↗ · reference work “Frequent fires and large grazing mammals kill seedlings, thus keeping the density of trees and shrubs low. … Climate is the most important factor in creating a savanna. Savannas are always found in warm or hot climates”
Question and answer: UPSC's official GS Paper I (2021, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 1 Oct 2026 (how we verify). ·