A savanna is defined as a grass-land with predominantly C4 photosynthesis grass, which is slowly replacing C3 grass due to the increase of CO2 in the atmosphere (Ulfstrand). Savannas are found predominantly in four regions of the world: Africa, Australia, Asia, and South America from largest to smallest in area. I will follow this order in discussing the topic. I should note that there are some savannas in the world, including the United States, that are part of lawns and golf courses, etc. It is interesting to note that savanna in the United States is recreating the African savannas were humans originally evolved.
The African savanna is significant to human history in addition to its seemingly simple ecosystem, because the “first, homo erectus… then later our own species, Homo sapiens…” originated and spread out from there (Ulfstrand). As a direct result of Darwinian evolution, the Savanna was the soil in which the cultivation of the human species occurred. Before technological advances in weaponry saw daylight (during prehistory), the climate, various predators, the coexistence of other similar primates in the hominid group must have prehistorically given form to the first primitive religions in the savanna.
In general, savannas can be found in multiple climates, and there are three types : grass savanna, bush savanna, and woodland/forest savanna (Ulfstrand). For instance, Australia has the largest woodland/forest savanna in the world in the tropical climate zone (Savanna). The three types are dichotomized by their relative amount of grass to bushes and trees ratios, in obvious respects. The world’s continents and islands has approximately 20% savannah, and the largest chunk in any continent is in Africa (wiki). In East Africa, “’niyaka…’ is the word for bush savannah…” (Ulfstrand). With regards to the various bush species, in the niyaka, many bushes have evolved thorns and poisons to ward off bowser species or species that consume vegetation. And since at the lower ends of the food change, plants, (which “…are sitting prey,”) are able to regrow lost limbs and leaves and still reproduce after being heavily consumed by bowsers (Ulfstrand). At an even lower end of the food chain, we have grass, which as aforementioned uses C4 photosynthesis primarily.
Biologically, C4 is a more sophisticated method of photosynthesis within plants than C3, which allows for the chemical reaction of carbon dioxide to oxygen. It is interesting to note that grasses in the African savanna have evolved no defenses towards grazing, but rather, have “adapted” a means of “…regrowing bite friendly” rather than becoming chemically or physically inconsumable (Ulfstrand). This can be explained because grasses are more “concerned” with competing plant space than grazing, which they have already adapted to. In Africa, all three kinds of savannas can be found, and in woodland savannas, “miombo” is the word “…used when describing the specific vegetation type” of a certain type of tree species that is “…expansive…” (Ulfstrand). Miombo can be “found in Tanzania, Zambia, and Zimbabwe” (Ulfstrand).
The largest threat to all three savannas (that are in Africa at least) is agriculture, desertification, fires (both natural and human-made), and then bowsers. Agriculturally, Africa, “as is well known,” has many starving mouths to feed (Ker). The failure to feed their mouths has been because of excessive dry seasons, causing failed harvests (Ker). Poverty is also very high (the average GNP is $700), meaning, agricultural equipment is lacking—they still use first industrial revolution tools. So, because of this, farming isn’t as productive as it can be, and most of it is self-sustenance based anyway. Regardless, while 71% of people who live in Africa live in rural areas, the remaining few live in cities. And cities are increasing in size at the fastest rate in the world, which is 5.3% annually (Ker). While this seems to have no effect on the declining savanna, it is, because with more mouths to feed, more land is needed for agricultural purposes.
Bowsers can consist of pasture animals like cows. In North America, the Native Americans had repeatedly burned the woodland savanna down (because of the fire resistant plants that had evolved) to clear large areas for primitive farming (wiki). Fires have actually been used to created savannas, which were started by “pre-Columbian Native Americans” in the north east United States, Australia, New Guinea (by aboriginals), and India (wiki). Fires aren’t detrimental to trees in the long run, but are disruptive of other species that need trees as an environment to live in. Also, fire, which typically occurs at the beginning of a savanna’s respective dry season, is a big-time antagonist towards bushes, and is helpful towards grass (Ulfstrand).
There are other factors to why African savannas are disappearing. Besides agricultural development and human-induced desertification (by introducing grazers that inadvertently deplete the soil’s nutrients, causing the soil to erode), climate change in general is changing the landscape. Climatically, like the sun cycle that is every eleven years, rain also has a periodic pattern to it where it can either be excessively dry or wet, which has an ecologic impact on various species that depend on rain for survival. This trend towards a warmer climate, as has been discussed in the classroom textbook before, is one that is causing the savannas to become more arid, causing desertification by non-human means.
Because trees are highly flammable due to their natural oils, they often die completely in a fire. However, they have spread their seeds so completely that the now barren landscape, which was the result of the fire, is now highly nutritious for the young seeds to flourish and there is more space for trees to grow when the old ones have died. Despite the bushes’ and tree’s seeming lack of adaptation to avoid being burnt over, they were the first vegetation to engage in chemical warfare, which is a survival mechanism for “[repelling] grazing” (Ulfstrand). In the cells of these plants, they are able to in their “normal metabolic” processes create horribly tasting and simultaneously, poisonous substances if they are eaten (Ulfstrand).
There are many species within the animal kingdom that exist in African savannas, such as the elephant, rhino, giraffe, African lion, termite (and their higher ups on the food chain such as aardvark, pangolins, aardwolfs, and honey badgers), ants, various species of grass, bushes, and trees, and unique birds. Termite eating is also an African delicacy. Unfortunately, we humans are having a detrimental effect on the count of these various species that used to live there. For instance, elephants have declined by 80% over the last 100 years due to their desirable tusks, which make good keys for pianos or good ornaments, jewelry, etc. (Ulfstrand). If one observes the elephant, one can write whole stories about them when observing their families, deaths of loved ones, and maybe even religion. Though one can’t exactly verbally communicate to one, they communicate through the touching of trunks between same genders, opposite genders, older and younger (the wiser seems to guide the younger one in most adventures). And, a cub’s mother is very protective of her children, and they always try to adhere together. Even the death of a herd member causes emotional response, one would assume; “…they seem particularly interested in the head and tusks… I would guess they are trying to recognize the individual” (Ulfstrand). One can only conclude that they have a concept of death, but not a graveyard (Ulfstrand). Although hunting them is outlawed in many countries, illegal bands still get their tusks through their murder. It is interesting to note that when an elephant makes a threat, he or she means it, and that the murder of a carnivore may result (Ulfstrand).
There are many interesting facets of our ancestors’ former home (the African savanna), which is disappearing, and radically, our original ecosystem is being preserved to some extent as awareness of their disappearance increases (Ulfstrand). Mostly, due to the forces of human development, African savannas, which are being replaced by agriculture, are slowly dwindling; we are effectively eliminating the “natural” animals and species that exist. This is due to the need to feed the mouths of a growing African population, which in Africa is growing at the fastest rate in the world. This is because of the undeveloped economies and third world status of most countries, (whereas in developed nations, people have adopted a different lifestyle, preferring a smaller family to a large one). While numbers are painting an accurate picture of how Africa lifestyle must be like, let us not forget that they, too, want a higher standard of living and that their economies are improving especially as political entities are rising from the ashes of post-European colonialism (Ulfstrand).
Bibliography
Wikipedia. 2011. 24 Nov 2011 <http://en.wikipedia.org/wiki/Savanna>
Savannas. 2011. 24 Nov 2011 <http://www.blueplanetbiomes.org/savanna.htm>
Ker, Andrew. Farming Systems of the African Savanna: A continent in Crisis. Ontario:
International Development Research Centre, November 1995.
Ulfstrand, Staffan. Savanna Lives: Animal life and Human Evolution in Africa. Oxford: Oxford University Press, 2002.
