Savanna Grasslands are located next to the tropical rainforests. The savanna climate has a distinct hot, wet season and a hot, dry season. The savanna changes as you move north or south from a mix of trees and grass to just grasses. Eventually, it gradually merges into the desert ecosystem.
- There are only two layers of vegetation in the grasslands- the grasses and the trees.
- Grasses are tall and form a continuous cover, whereas trees are dotted around and there can be wide spaces between them.
- A denser covering of trees shows places where more water is available.
- During the dry season, minerals in the soil, such as calcium are drawn up to the surface by the high temperatures and high evaporation rates.
- Heavy rains in the wet season cause leaching, which washes the minerals deep into the soil.
- The main problem for the vegetation is survival during the dry season. Most plants are xerophtytic (drought resistant). Grasses turn brown and die back in the dry season.
- Trees adapt to the drought by losing their leaves to reduce water loss or the leaves are small and waxy to reduce transpiration.
- The roots are usually long to reach underground supplies of water. Some trees have very thick bark to store water during the dry season e.g. baobab tree.
Human uses of Savannah Grasslands
Local people are often nomadic and keep herds of sheep, cattle or goats. Some live in permanent villages and grow crops.
One huge problem is desertification which mean the good land is turned in desert. This has been caused by overgrazing (too many animals) and overcultivation (growing crops every year and not letting the soil recover its fertility). Soil is either blown away in the dry season (dust storms) or washed away in the heavy rains in the wet season.
Many tourists also visit the African savannas on wildlife safaris e.g. in Kenya. The wildlife is often disturbed and the people and vehicles damage the landscape.
Desertification and climate change
This video looks at the cumulative cause of desertification. The cycle begins when vegetation is removed. This vegetation would normally hold moisture, which evaporates into the atmosphere due to the warm climate. The evaporated moisture condenses to form clouds and rainfall normally occurs in the afternoons. If the vegetation is removed, the soil becomes drier and there is less moisture available for evaporation. Rainfall decreases and dry soil can easily be blown away.