This is a classic 'Biotic Climax' question derived from the core logic of GC Leong and NCERT Ecology. While standard texts explicitly list Fire, Grazing, and Rainfall as the 'Holy Trinity' of Savannah formation, 'Burrowing animals' and 'Soil' act as distractors. The key was to identify the *active* disturbances that arrest succession, rather than static or niche factors.
How this question is built
This question can be broken into the following sub-statements.
Tap a statement sentence to jump into its detailed analysis.
Statement 1
Do burrowing animals and termites inhibit tree establishment and thereby limit forest development in savannah vegetation?
Origin: Weak / unclear
Fairness: Borderline / guessy
Indirect textbook clues
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > UPSC Prelims 2021] 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? > p. 437
Strength: 4/5
β[UPSC Prelims 2021] 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?
β’ 1) Burrowing animals & termitesβ’ 2) Fireβ’ 3) Grazing herbivoresβ’ 4) Seasonal rainfallβ’ 5) Soil propertiesβ
Why relevant
The UPSC-style item lists 'Burrowing animals & termites' alongside fire, grazing and seasonal rainfall as conditions that can keep forest development in check in savannahs.
How to extend
A student could take this as a hypothesis to investigate locally (e.g., map termite/burrow density vs. tree recruitment) or look for field studies linking soil disturbance by these organisms to seedling mortality.
FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > BIOLOGICAL ACTIVITY AND WEATHERING > p. 41
Strength: 4/5
βBiological weathering is contribution to or removal of minerals and ions from the weathering environment and physical changes due to growth or movement of organisms. Burrowing and wedging by organisms like earthworms, termites, rodents etc., help in exposing the new surfaces to chemical attack and assists in the penetration of moisture and air. Human beings by disturbing vegetation, ploughing and cultivating soils, also help in mixing and creating new contacts between air, water and minerals in the earth materials. Decaying plant and animal matter help in the production of humic, carbonic and other acids which enhance decay and solubility of some elements.β
Why relevant
Explains that burrowing organisms (earthworms, termites, rodents) actively alter soils by exposing surfaces, changing moisture and aeration β a general mechanism by which they can affect plant establishment.
How to extend
One could extend this by reasoning that soil disturbance and altered moisture regimes might reduce seed survival or root establishment for tree seedlings in savannahs.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Explanation: > p. 438
Strength: 4/5
ββ’ Fires destroy seeds, large herds of grazing herbivores trample small plants and sprouting seeds, and seasonal rainfall leads to a long dry season that causes forest fires (mostly initiated by dry grasses which dominate the savannah ecosystem). So (c) 2, 3 and 4 is the answer.
β’ A definite dry winter and wet summer Tropical Savannah (there are a few very small regions in the world where the savannah climate is characterised by dry summers and wet winters).β
Why relevant
Gives a pattern: fires, large herds trampling seedlings, and seasonal drought are recognised mechanisms that prevent forest development in savannahs β showing the class of biotic/abiotic processes that limit tree establishment.
How to extend
Use this pattern to compare with burrowing/termite activity (another biotic process) to assess plausibility that they could play a similar limiting role.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
Strength: 3/5
βIt is one of the major biomes containing large expanses of grassland interrupted by trees and shrubs; a transitional area between the humid rainforest and tropical deciduous forests and the drier, semi-arid tropical deserts. Te savannah biome also includes treeless tracts of grasslands. Te trees of the savannah grasslands are characteristically fat-topped (Fig. 3.4). Savannah covered more than 40 per cent of Earth's land surface before human intervention but were especially modifed by humanβcaused fre. Fires occur annually throughout the savannah biome. According to ecologists, the savannah biome is the result of deforestation, frequent forest fres and overgrazing. Te Indian savannah are dominated by shrubs instead of grasses.β
Why relevant
States that savannahs result from factors like frequent fires and overgrazing and that they include treeless tracts β supporting the general idea that multiple disturbance agents maintain treeless conditions.
How to extend
Combine this with the notion that termites/burrowers are disturbance agents to justify field checks (e.g., whether areas with intense termite activity coincide with reduced tree cover).
Statement 2
Does fire (recurring wildfires) prevent forest development and maintain grassland in savannah ecosystems?
Origin: Direct from books
Fairness: Straightforward
Book-answerable
From standard books
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > 3.3.4. Role of fire > p. 27
Presence: 5/5
βFire plays an important role in the management of grasslands.
β’ * Under moist conditions fire favours grass over trees, whereas in dry conditions fire is often necessary to maintain grasslands against the invasion of desert shrubs. β’ Burning increases forage yields.β
Why this source?
- Explicitly states that under moist conditions fire favours grass over trees and that fire is necessary to maintain grasslands against woody invasion.
- Directly links fire regime to maintenance of grassland composition.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Role of fre in terrestrial succession > p. 29
Presence: 5/5
βIn ecology, fre has been recognised as a dynamic ingredient in community succession. Controlled fre secures plant reproduction and prevents the accumulation of forest litter and brush; widely regarded as a wise forest management. In terrestrial succession, successional stages may be interrupted by fre. Earth's land area experiences fre each year. Today, fre is recognised as a natural component of most ecosystems and not the enemy of nature it once was popularly considered. In fact, in many forests, undergrowth is purposely burned in controlled 'cool-fres' to remove fuel that could enable a catastrophic and destructive 'hot fre'. In contrast, when fre prevention strategies are rigidly followed, they can lead to abundant undergrowth accumulation, which allows total destruction of forest by a major fre.β
Why this source?
- States that fire can interrupt terrestrial successional stages, preventing progression to later (forest) stages.
- Describes controlled and recurring fires as a dynamic component that can halt or reset succession.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
Presence: 4/5
βIt is one of the major biomes containing large expanses of grassland interrupted by trees and shrubs; a transitional area between the humid rainforest and tropical deciduous forests and the drier, semi-arid tropical deserts. Te savannah biome also includes treeless tracts of grasslands. Te trees of the savannah grasslands are characteristically fat-topped (Fig. 3.4). Savannah covered more than 40 per cent of Earth's land surface before human intervention but were especially modifed by humanβcaused fre. Fires occur annually throughout the savannah biome. According to ecologists, the savannah biome is the result of deforestation, frequent forest fres and overgrazing. Te Indian savannah are dominated by shrubs instead of grasses.β
Why this source?
- Notes that fires occur annually throughout the savannah biome and links frequent forest fires to the existence of savannahs.
- Implies that repeated burning (along with overgrazing/deforestation) contributes to maintaining savannah (grass-dominated) landscapes.
Statement 3
Do grazing herbivores suppress tree seedlings and prevent forest development in savannahs?
Origin: Direct from books
Fairness: Straightforward
Book-answerable
From standard books
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Explanation: > p. 438
Presence: 5/5
ββ’ Fires destroy seeds, large herds of grazing herbivores trample small plants and sprouting seeds, and seasonal rainfall leads to a long dry season that causes forest fires (mostly initiated by dry grasses which dominate the savannah ecosystem). So (c) 2, 3 and 4 is the answer.
β’ A definite dry winter and wet summer Tropical Savannah (there are a few very small regions in the world where the savannah climate is characterised by dry summers and wet winters).β
Why this source?
- Explicitly states large herds of grazing herbivores trample small plants and sprouting seeds.
- Links trampling and seed destruction to failure of plant establishment in savannah contexts.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
Presence: 4/5
βIt is one of the major biomes containing large expanses of grassland interrupted by trees and shrubs; a transitional area between the humid rainforest and tropical deciduous forests and the drier, semi-arid tropical deserts. Te savannah biome also includes treeless tracts of grasslands. Te trees of the savannah grasslands are characteristically fat-topped (Fig. 3.4). Savannah covered more than 40 per cent of Earth's land surface before human intervention but were especially modifed by humanβcaused fre. Fires occur annually throughout the savannah biome. According to ecologists, the savannah biome is the result of deforestation, frequent forest fres and overgrazing. Te Indian savannah are dominated by shrubs instead of grasses.β
Why this source?
- Identifies overgrazing as a principal factor (alongside fire) shaping the savannah biome.
- Frames savannah as a grass-dominated landscape resulting from loss or prevention of forest via overgrazing.
India and the Contemporary World - I. History-Class IX . NCERT(Revised ed 2025) > Chapter 5: Pastoralists in the Modern World > 2 Colonial Colonial Colonial Rule and ule and ule Pastoral astoral astoral Life > p. 104
Presence: 4/5
βThrough these Acts some forests which produced commercially valuable timber like deodar or sal were declared 'Reserved'. No pastoralist was allowed access to these forests. Other forests were classified as 'Protected'. In these, some customary grazing rights of pastoralists were granted but their movements were severely restricted. The colonial officials believed that grazing destroyed the saplings and young shoots of trees that germinated on the forest floor. The herds trampled over the saplings and munched away the shoots. This prevented new trees from growing. These Forest Acts changed the lives of pastoralists. They were now prevented from entering many forests that had earlier provided valuable forage for their cattle.β
Why this source?
- Records the view that herds trample saplings and eat young shoots, preventing new trees from growing.
- Provides a historical/policy rationale for restricting grazing to protect forest regeneration.
Statement 4
Does seasonal rainfall (distinct wet and dry seasons) limit forest development and contribute to the maintenance of savannah vegetation?
Origin: Direct from books
Fairness: Straightforward
Book-answerable
From standard books
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Explanation: > p. 438
Presence: 5/5
ββ’ Fires destroy seeds, large herds of grazing herbivores trample small plants and sprouting seeds, and seasonal rainfall leads to a long dry season that causes forest fires (mostly initiated by dry grasses which dominate the savannah ecosystem). So (c) 2, 3 and 4 is the answer.
β’ A definite dry winter and wet summer Tropical Savannah (there are a few very small regions in the world where the savannah climate is characterised by dry summers and wet winters).β
Why this source?
- Explicitly links seasonal rainfall producing a long dry season to increased forest fires initiated by dry grasses in savannahs.
- Identifies fire (driven by dry-season conditions) as a mechanism that destroys seeds and prevents forest establishment.
Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 16: The Tropical Monsoon and Tropical Marine Climate > Natural Vegetation > p. 160
Presence: 4/5
βThe natural vegetation of tropical monsoon lands depends on the amount of summer rainfall. The monsoon lands with three distinct seasons, cold, hot and rainy exert great influence on the appearance of the vegetation. Trees have to be fairly tolerant of local physical and climatic conditions to survive. They grow rapidly in the rainy season, shed their leaves during the hot dry season and remain comparatively inactive in the cool season. The overall vegetation varies from dense tropical evergreen vegetation to thorny scrubland due to differences in precipitation in different parts of the monsoon lands. Where the rainfall is heavy, e.g. southern Burma, peninsular India, northern Australia and coastal regions with a tropical marine climate, the resultant vegetation is forest.β
Why this source?
- States vegetation depends on amount and seasonality of summer rainfall, with dry periods causing trees to shed leaves and remain inactive.
- Explains that differences in precipitation (including pronounced wet/dry seasons) determine whether areas support forest or more open vegetation.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 9: Indian Biodiversity Diverse Landscape > r) Peninsular trndia > p. 159
Presence: 4/5
β(r) Peninsular trndia
It is home to tropical moist deciduous to tropical dry and scrub vegetation depending upon the variation in rainfall and humidity.
Flora: Sal in north and east extends (higher rainfall) and teak in southern plateau are dominant trees. Western Chats have evergreen vegetation (flora and fauna similar to evergreen rainforests of northeastern India). In dry areas of Rajasthan and Aravalli hills, trees are scattered and thorny scrub species predominate. The forests give way to more open savannah habitat.β
Why this source?
- Describes how variation in rainfall and humidity causes forests to give way to more open savannah habitat in drier areas.
- Provides a regional example linking reduced rainfall to transition from forest to savannah vegetation.
Statement 5
Do soil properties (such as low nutrient levels, poor drainage, or shallow soils) restrict tree growth and prevent forest development in savannah ecosystems?
Origin: Direct from books
Fairness: Straightforward
Book-answerable
From standard books
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > 3.2. FOREST ECOSYSTEM > p. 24
Presence: 5/5
βThe forest ecosystem includes a complex assembly of different kinds of biotic communities. Optimum conditions such as temperature and ground moisture are responsible for the establishment of forest communities. The nature of soil, climate and local topography determine the distribution of trees and their abundance in the forest vegetation. Forests may be evergreen or deciduous. They are distinguished on the basis of leaf into broad{eafed or needle leafed coniferous forests in the case of temperate areas. The forest ecosystems have been classified into three major categories: cbniferous forest, temperate forest and tropicai forest. All these forest biomes are generally arranged on a gradient from north to south latitude or from high to lower altitude.β
Why this source?
- Explicitly links the nature of soil to the distribution of trees and their abundance in forest vegetation.
- Frames soil as a primary control on whether forest communities can establish, implying soils can limit forest development.
Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Characteristics Of Coniferous Forests > p. 469
Presence: 4/5
βThey are excessively leached and very acidic. Humus content is also low as the evergreen leaves barely fall and the rate of decomposition is slow. Under-growth is negligible because of the poor soil conditions. Absence of direct sunlight and the short duration of summer are other contributory factors.β’ Coniferous forests are also found in regions with high elevation (Example: the forests just below the snowline in Himalayas). But on very steep slopes where soils are immature or non-existent, even the conifer cannot survive (Example: Southern slopes of Greater Himalayas).β
Why this source?
- Gives a concrete example where immature or non-existent soils prevent conifers from surviving.
- Connects poor soil conditions and low humus to negligible undergrowth, showing soil depth/maturity can block tree establishment.
Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 10: Locational Factors of Economic Activities > Demerits of Social and Agroforestry > p. 27
Presence: 3/5
βTe negative efects of social forestry and agro-forestry are given below: β’ 1. Competition: Te major yield-decreasing efects at the tree-crop interface arise from competition for light, water and nutrients. While availability of light may be the most limiting factor in many situations, particularly those with relatively fertile soils and adequate water availability, the relative importance of light will decrease in semi-arid conditions as well as on sites with low fertility soils. Te trees exhaust the soil nutrients reducing the yield per unit area of the main crops.β’ 2. Pests and Diseases: Te efect of treeβcrop interactions on pests and disease incidence is a potentially important one, but is rather unexplored.β
Why this source?
- Notes that low fertility soils change competitive dynamics and that trees can exhaust soil nutrients, reducing growth/yields.
- Links semi-arid/low-fertility conditions to altered tree performance, supporting that low soil fertility can restrict tree growth.
Pattern takeaway:
UPSC tests the 'Why' behind the landscape, not just the 'What'. If a region is treeless, there is always a specific limiting factor (Climate, Soil, or Disturbance). Identify the dominant driver.
How you should have studied
- [THE VERDICT]: Conceptual Sitter. Source: GC Leong Chapter 17 (Savanna) & NCERT Biology (Ecology Unit) - Concept of 'Ecological Succession'.
- [THE CONCEPTUAL TRIGGER]: Biomes & Limiting Factors. Specifically, why a biome fails to reach the 'Forest' stage (Climatic Climax vs. Biotic Climax).
- [THE HORIZONTAL EXPANSION]: Memorize the 'Tree-Killers' of other biomes:
1. Tundra: Permafrost (mechanical barrier) + Physiological drought.
2. Steppe/Prairies: Continental temperature extremes + Wind.
3. Mediterranean: Summer drought (trees survive via sclerophyllous adaptations).
4. Mangroves: Salinity + Anaerobic soil (trees survive via pneumatophores).
- [THE STRATEGIC METACOGNITION]: Don't just memorize 'Savannah = Grass + Trees'. Ask 'Why not Forest?'. Always analyze biomes through the lens of 'Inhibitors': What stops the vegetation from growing taller/denser? (Is it Water? Temperature? Fire? or Animals?).
Concept hooks from this question
π Primary inhibitors of forest development in savannahs
π‘ The insight
Fire, grazing herbivores and seasonal rainfall are principal factors that check forest establishment in savannah vegetation.
High-yield for UPSC geography questions on vegetation controls: links climate (seasonal rainfall), disturbance (fire) and biotic pressure (grazers). Mastery helps answer MCQs and short-notes on savannah formation, vegetation transitions and land-use impacts.
π Reading List :
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Explanation: > p. 438
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Table 3.1 (Contd.) > p. 21
π Anchor: "Do burrowing animals and termites inhibit tree establishment and thereby limit f..."
π Biological weathering by burrowing organisms
π‘ The insight
Burrowing organisms such as earthworms, termites and rodents alter soils by exposing fresh mineral surfaces and increasing moisture and air penetration.
Important for questions on soil-vegetation interactions and ecosystem engineering: explains how fauna modify substrate properties that influence plant establishment and succession. Useful when comparing facilitative vs. inhibitory roles of fauna in vegetation dynamics.
π Reading List :
- FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 5: Geomorphic Processes > BIOLOGICAL ACTIVITY AND WEATHERING > p. 41
π Anchor: "Do burrowing animals and termites inhibit tree establishment and thereby limit f..."
π Savannah as a transitional, fire-prone biome
π‘ The insight
Savannahs are transitional zones between rainforests and deserts, prone to frequent fires and overgrazing which shape tree cover and grass dominance.
Crucial for synthesis-type answers linking climate, disturbance and biome distribution; helps in framing essays and answers on vegetation gradients, human impacts, and conservation challenges.
π Reading List :
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > Table 3.1 (Contd.) > p. 21
π Anchor: "Do burrowing animals and termites inhibit tree establishment and thereby limit f..."
π Fire in ecological succession
π‘ The insight
Fire interrupts successional stages and can prevent progression to forest, thereby maintaining earlier vegetation stages like grassland.
High-yield for UPSC ecology questions because it explains why some ecosystems do not progress to forest; links ecosystem dynamics with forest management and disturbance regimes, and helps answer questions on vegetation succession and biome stability.
π Reading List :
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Role of fre in terrestrial succession > p. 29
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > 3.3.4. Role of fire > p. 27
π Anchor: "Does fire (recurring wildfires) prevent forest development and maintain grasslan..."
π Fire as a maintainer of savannahs
π‘ The insight
Recurring fires favor grasses over woody plants and are a key factor sustaining savannah vegetation.
Essential for questions on biome formation and vegetation types; connects to topics such as grazing, land-use change, and climate, enabling answers about why savannahs persist and management implications.
π Reading List :
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 3: Terrestrial Ecosystems > 3.3.4. Role of fire > p. 27
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
π Anchor: "Does fire (recurring wildfires) prevent forest development and maintain grasslan..."
π Controlled burning and wildfire management
π‘ The insight
Deliberate or recurring burns are used to manage fuel loads and influence vegetation composition, affecting whether areas develop into forest or remain grassland.
Relevant for disaster management and environmental governance questions; links practical mitigation measures to ecological outcomes and frames policy debates on trade-offs between fire suppression and controlled burns.
π Reading List :
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 8: Natural Hazards and Disaster Management > Prevention of Wildfre (Forest Fire) > p. 87
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 1: BASIC CONCEPTS OF ENVIRONMENT AND ECOLOGY > Role of fre in terrestrial succession > p. 29
π Anchor: "Does fire (recurring wildfires) prevent forest development and maintain grasslan..."
π Grazing and seedling suppression
π‘ The insight
Grazing animals trampling and consuming seedlings directly reduces tree recruitment, preventing forest development in savannahs.
High-yield for questions on vegetation dynamics and land-use impacts; connects ecology with forest conservation and pastoral policy. Mastery helps answer causeβeffect questions about biome maintenance and restoration.
π Reading List :
- Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 30: Climatic Regions > Explanation: > p. 438
- India and the Contemporary World - I. History-Class IX . NCERT(Revised ed 2025) > Chapter 5: Pastoralists in the Modern World > 2 Colonial Colonial Colonial Rule and ule and ule Pastoral astoral astoral Life > p. 104
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 3: MAJOR BIOMES > 3. Tropical Savannah Biome > p. 10
π Anchor: "Do grazing herbivores suppress tree seedlings and prevent forest development in ..."
Bush Encroachment. If the 'checks' (Fire/Grazing) are removed from a Savannah, the ecosystem shifts towards a 'Thicket' or Woodland. This phenomenon is the inverse of the question and a hot topic in climate change ecology.
β‘ Elimination Cheat Code
The 'Scale & Intensity' Test. The question asks about 'extensive areas'. Ask yourself: Can 'Burrowing animals' (termites) clear forests across entire continents? Unlikely; they are localized. Can 'Soil properties' alone prevent trees globally? No, soil varies. But 'Seasonal Rainfall' (Climate) and 'Fire' (Disturbance) operate on a massive, biome-wide scale. Eliminate the niche factors (1 and 5).
Mains GS-1 (Society/Geography): Link 'Grazing Herbivores' to the 'Masai' and 'Hausa' tribes. Their pastoralist lifestyle (Overgrazing) is a human-geographic factor maintaining the Savannah landscape. It's a perfect example of 'Possibilism' in Human Geography.