Tropical Grasslands

Tropical grassland biome

• BIOME: a large geographical area of distinctive plant and animal groups, adapted to that particular environment
• SAVANNA: A rolling grassland with isolated trees and shrubs, not enough rainfall to support a forest.
• LOCATION: between 5 and 23 degrees North and South of Equator. Between tropical rainforest and desert biome.
• Large expanses in central Africa such as Kenya and Tanzania.

Tropical Grassland Biome

• 
• A biome: A large geographical area spanning continents, where distinctive plants and animal groups are specially adapted to that particular environment
• Savanna: A rolling grassland scattered with shrubs and isolated trees
• Geography: not enough rainfall to support forests.
• Large expanses in Brazil and mainly Africa- Tanzania and Kenya.
• Caption: Located between desert and tropical rainforest biomes. Between 5-23 degrees north and south of equator.

Seasons and Climate

• 2 distinct seasons, WET and DRY
• Caused by ITCZ movement and it's associated rain belt.
• 1. One season of the year where ITCZ brings intense rain
• 2. For the rest of year, climate is dry and dominated by tropical high pressure air mass
• INTER-TROPICAL CONVERGENCE ZONE
• is caused by intense solar heating and when the North East and South east trade winds meet at the equator.
• This region produces high humidity, low atmospheric pressures, calm winds and high precipitation levels
• In the Dry season:
• There is an excess of evaporation> precipitation= Little percolation through the soil
• In addition, water used and stored by plants= reduces soil moisture until dry.
• No water available for plant growth= plants stop growing and enter dormant period.
• KNOWN AS PERIOD OF SOIL MOISTURE DEFICIT

Plant adaptations and characteristics

• 
• Grow quickly when there is water, in preparation for dry season
• Grasses turn brown to limit water loss
• Nutrients and water is stored in roots, in case of wildfire plant still survives.
• ACACIA TREE
• pyrophytic, long roots to reach underground water reserves, long sharp thorns and symbiotic relationship with stinging ants to discourage predators.
• Caption: ACACIA TREES

Plant adaptations and characteristics

• 
• Caption: BAOBAB TREE
• BAOBAB TREE
• Only produces leaves in wet season. Leaves are small finger like clusters to minimise water loss
• Thick trunks average 10m diameter store water (for seasonal drought)
• Can store up to 100,000 litres of water
• Pyrophytic plant- Bark is soft, fibrous and fire resistant
• Baobab can survive for more than 3000 years in the wild

Animal adaptations and characteristics

• 
• GIRAFFES
• 1. Long necks enable them to feed off high treetops, avoiding food competition from other herbivores.
• 2. Strongest tongue of any animal, well adapted to acquiring leaves from plants
• 3. Can go weeks without water, relying on morning dew and water in food
• 4. Can drink 45 litres of water at once, quick drinking helps limit time animal is vulnerable to predators
• Caption: giraffe

SERENGETI NATIONAL PARK (n.tanzania)

• 
• Africa, north Tanzania, spans 1.5 million hectares.
• UNESCO world heritage site, protected by the UNA designated NP in 1940
• Characteristics: areas of open plainland and woodland, some old and large acacia trees. Annual migration of wildebeest, zebra and gazelle.
• 4 endangered species: black rhino, elephant, cheetah, wild dog.

Geography of Serengeti

• Park is usually described as divided into 3 regions:
• 1. SERENGETI PLAINS
• South of SNP, treeless grassland breeding ground for wildebeest
• 2. WESTERN CORRIDOR
• black clay soil, swampy savannah.
• 3. NORTHERN SNP
• open woodland and hills. elephants, giraffe and migratory wildebeest/zebra

How has SNP changed? Natural factors

• 1. WEATHER
• 1970s-80s changes in weather patterns. Seasonal rains were more spread out, thus grasses didn't dry out and were therefore unable to burn in the dry season. Absence of fires and decline of elephants (peak ivory trade) = trees established
• 2. FIRES
• During May-November (dry season) previously lush green plants of the wet season acts as the perfect fuel for bush fire. Periodic natural fires combined with prolonged drought retains this ecosystem at this state, as trees and bushes are not able to establish.
• Present day: fires are monitored and controlled, to stop spread of large fires. Also ensures better growth of young grass next season.

Impact of human activity on SNP

• RINDERPEST DISEASE
• 1896 Cattle disease in East Africa, as a result from imported livestock in western europe.
• Resulted in many deaths of SNP cattle and wildebeest
• No cattle= famine= people emigrated= noone to light controlled fires
• Disease lasted many years.
• Combined with low elephant numbers as result of peak in ivory trade at the time= trees and plants flourished.
• Most of area outside SNP is lost to cultivation
• Large proportions of the park is significantly altered by poaching
• 40% natural ecosystem lost