Previous Year Question
The vegetation of Savanna 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 codes given below.
1 and 2
4 and 5
2, 3 and 4
1, 3 and 5
Correct Answer: C
Detailed Solution
Savanna is a tropical grassland containing extensive grassy plains with small and widely scattered trees. The development of dense forest is primarily controlled by fire, grazing herbivores and seasonal rainfall.
Statement 2 is correct—Fire: During the dry season, dry grasses experience frequent fires. The underground roots of grasses can regenerate after fire, but tree seedlings and young branches are destroyed. This maintains the dominance of grasses and prevents the development of dense forest.
Statement 3 is correct—Grazing herbivores: Elephants, giraffes, antelopes and other herbivores consume tree seedlings and branches. Elephants may also push down trees. Grazing and browsing therefore regulate the number and growth of trees.
Statement 4 is correct—Seasonal rainfall: Savannas have distinct wet and dry seasons. The seasonal distribution of rainfall and the prolonged dry season restrict continuous tree growth, while grasses are better adapted to this seasonal regime.
Burrowing animals, termites and soil properties can influence savanna structure locally, but the correct combination of conditions that generally keeps forest development in check is fire, grazing herbivores and seasonal rainfall.