Savanna

Bushfire

Savanna Vegetation

Lions in a Tree
© Flycatcher/FZS/Künkel

Savanna Vegetation

Serengeti National Park is made up of grassland and woodland, plains, kopjes, and marshes; all of which make up a savanna.
"Savanna" is a general term for any type of semi-arid land from open grassland to woodland and all mixtures of grass and trees in between. Savannas cover one quarter of the worlds land surface and can support more animals than any other land type.

One common feature of savannas is fire. Unless savanna grass is completely consumed by animals or frozen, it will occasionally burn.
With the potential to have massive numbers of resident animals and frequent fires, savannas are very dynamic landscapes and tend to change rapidly. This makes them both very interesting scientifically, and important to understand for management purposes.

The nasty trees of Africa.

Some of the Serengeti's most common plant species

Sausage tree (Kigelia africana)
This large tree is spread sparsely throughout Serengeti. It produces characteristic long (1 m), succulent, poisonous fruits that drop from the tree and release seeds as the pulp rots. The vine-like fruit stalks can be seen for months after the fruits are dropped. There is a dry bush joke that the worst place to camp is under a Sausage tree .. if the 5 kg fruits don't crush you, then the elephants will as they come to collect the fruits. There is a widespread local belief that Sausage tree fruits, when hung in your hut, will ward-off whirlwinds.

Strangle Fig (Ficus thonningii)
The Strangle Fig begins life as a small vine-like plant that climbs the nearest large tree and then thickens, produces a branching set of buttressing aerial roots, and strangles its host tree. An easy way to tell the difference between Strangle Figs and other common figs is that the bottom half of the Strangler is gnarled and twisted where it used to be attached to its host, the upper half smooth. A common tree on kopjes and along rivers in Serengeti; two massive Fig trees near Serengeti; the "Tree Where Man was Born" in southern Loliondo, and the "Ancestor Tree" near Endulin, in Ngorongoro are significant for the local Maasai peoples.

Wild Date Palm (Phoenix reclinata)
Palms are monocotyledons, the veins in their leaves are parallel and unbranched, and are thus relatives of grasses, lilies, bananas and orchids. The wild Date Palm is the most common of the native palm trees, occurring along rivers and in swamps. The fruits are edible, though horrible tasting, while the thick, sugary sap is made into Palm wine. The tree offers a pleasant, softly rustling, fragrant-smelling shade; the sort of shade you will need to rest in if you try the wine.

Candelabra Euphorbia (Euphorbia candelabrum)
(Yes, the names are supposed to reversed like that)
The Candelabra tree is a common tree in the western and Northern parts of Serengeti. Like all Euphorbias the Candelabra breaks easily and is full of white, extremely toxic latex. One drop of this latex can blind or burn the skin. Traditional people plant the tree as cattle fencing, as predators will not attempt to push their way through the dense and poisonous stems. Some circles of Candelabra can be seen in the park, where seasonal dwellings existed before the establishment of the park.

Commiphora (Commiphora africana)
Commiphoras can easily be distinguished from Acacia tree species by the Commiphora's peeling, papery blue/yellow bark. These trees occur throughout Serengeti, and are the dominant species in the eastern part of the park. Local medicine makes use of the bark, roots, and berries for a variety of treatments, including stomach complaints, liver problems, colic children, and rashes. While there are several species of Commiphora in Serengeti, Commiphora africana is the most common.

Yellow Fever tree (Acacia xanthophloea)
The Yellow Fever Tree is a common site in Serengeti in wet areas of black-cotton soil, such as along rivers. Early settlers in Kenya and India knew that malaria was more common near standing water, but blamed the Yellow Acacias there instead of mosquitoes; thus the name "Yellow Fever Tree".

Umbrella tree (Acacia tortilis)
The tree that has come to represent Africa. Acacia tortilis arches dramatically over the savanna throughout Serengeti. The seedlings of this tree are favored by elephants and cannot survive bush fires, so only twice in the past one hundred years have tortilis trees been able to grow. As such all of the tortilis trees in Serengeti are either 100 or 20 years old.

Whistling thorn (Acacia drepanolobium) (Ant-galled Acacia)
Tap a "drep" and you are in for a surprise. This odd-looking tree has hard, hollow spheres at the base of its thorns, filled with biting ants. The tree actually encourages these ants by both providing homes and food in special flower-like structures called "extra-floral nectaries". These tree grow in abundance wherever the soil is saturated.

Balanites (Balanites aegyptia) (Desert Date)
The Balanites tree is often confused with Acacia trees, but can easily be identified by its green thorns. This tree produces a date-like nut that is tasty both raw and roasted (with cinnamon). The green thorns are rumored to be photosynthetic, so the tree is both happy and alive even without its leaves.

Toothbrush tree (Salvadora persica)
The toothbrush tree is a low bush with characteristic long, arching shoots. These shoots, when green, are cut by locals and used as toothbrushes. First, they chew on the end until it resembles a normal toothbrush, and then they brush their teeth with it, spitting out the fragments of wood all the while. It may sound unpleasant, but their smiles tell of a job well done.

Red Grass (Themeda triandra)
Turning a dark reddish color as it dries, Themeda is one of the main grass species in the long-grass plains and woodlands of Serengeti. This grass normally grows as a dense bunch, though on the long-grass plains it can become the dominant grass and grows widely spaced like a field of wheat. Wildebeest eat Red grass, though it is consumed generally after more palatable grass species are exhausted.

Pan Dropseed (Sporobolus ioclados) (formerly marginatus)
This Sporobolus species is one of the two dominant species on the short grass plains along with Digitaria macroblephora. Both species grow in a dwarf form which can be difficult to recognize. The hard pan layer in the soil prevents grasses from growing deep roots, and very high levels of herbivory during the wet season combine to produce these smaller grass forms.

Red Dropseed (Sporobolus festivus)
The grass species is not common in Serengeti, but we included it here because it is so much fun to say: pronounce the name out loud .. "Sporololus festiiiiiiivus"! Named for its "festival-like" arrangement of seeds, the grass grows mixed in with Red Grass in the long grass plains and as a thin ring around most Kopjes.

The El-Nino Flower (Hibiscus cannabinus)
During the last El-nino rains, this plant grew in abundance throughout Serengeti, thus acquiring the local name of "El-Nino" flower. An annual, it grows most years along rivers or in wet-season boggy areas throughout East Africa. Watch out if you are taking a picture of hibiscus flowers; most of the species in the genus have poisonous hairs that break off in your skin and cause irritation and lots of grumbling.

The Mexican Poppy
This is an invasive species in Serengeti, recently introduced South West of Ngorongoro with a shipment of wheat seeds. Along with other invasives such as Prickly Pear (Opuntia sp.), and Custard Oil (Rhyciuus sp.) the Mexican Poppy may pose a very serious threat to the survival of the Serengeti Ecosystem. During the 1960's Prickly Pear ruined thousands of square kilometers of Australian savanna ranchland, while the Mexican Poppy is making some areas near Karatu unfarmable, competing with both crops and native plants. The threat of an invasive species changing the vegetation structure of Serengeti and thus the wildlife appears both real and immediate; Karatu is only eighty kilometers from the entrance gate of Serengeti National Park and individuals have already been found within the park.

References
- Trees of Kenya. 1989. T.C. Noad and A. Birnie. Self Published, Box 40034 Nairobi, Kenya. With assistance of Kul Graphics, Nairobi, Prudential Printers, Nairobi, and General Printers, Nairobi.
- Collins Guide to the Wild Flowers of East Africa. 1987. Sir Michael Blundell. William Collins Sons & Co. Ltd. London.

Please download the attached PDF-File to explore the fascinating and delicate world of savanna plant ecology in detail.

 
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