Savannas: Type Of Grassland Ecosystem

Ecosystem Lab Presentation – Savannas
The biome I will be presenting on is a savanna, also spelled savannah. Savannas are a type of grassland ecosystem. Savannas house rolling grassland scattered with shrubs and isolated trees. Savannas can be found between a tropical rainforest and desert biome. Inhabitants of the savanna are very diverse and abundant. Some of the wildlife that makes the savanna their home are lions, giraffes, elephants, and zebras just to name a few. There are also various types of reptiles in the savanna. Two of these are the Black Mamba, which is a highly poisonous snake, and the Nile Crocodile, which is also known as the Kenyan Crocodile and Madagascar Crocodile, and as its name suggests, a crocodile, which is
found in Africa and Madagascar. These animals all have their place in the food chain. The herbivores, or plant-eaters, can live well here in the savanna because they can move around and eat the plentiful grass that abounds. In turn, the carnivores, meat-eaters, eat the herbivores, who eat the grass. So, the animals go through the “circle of life” cycle to survive in a savanna just like anywhere else. Humans also inhabit savannas, and are also a food source, in some unfortunate instances, to the carnivores. The herbivores and carnivores alike are prey to the hunters among the humans, and can therefore fulfill their part as the source of nourishment for humans. The living and physical environment can be sometimes harsh and unforgiving in the savanna. One of the problems in some of the areas is the soil, which is know sometimes as “black cotton”, because of the way it becomes waterlogged and soggy during the rainy season, and then becomes dried out and cracks during the dry season. This soil makes it difficult for some insects, such as ants, to create underground nests and hives. These animals have had to adapt and some make homes in the many acacia trees or other types of vegetation.
The climate in the savanna is a wet-dry tropical climate (Aw) according to the Köppen climate classification1. These biomes have an average mean temperature around 18°C year round. Savannas have very pronounced dry and wet seasons. Some have longer dry seasons than wet seasons and others both are somewhat equal.
The plant life in the savanna has adapted to the small amount of rainfall and water sources.
The lack of water does not allow the plants and trees to grow tall as in some places. Grasses grow quickly in the wet season and turn brown in the dry months to conserve water. Grasses also stay close to the ground due to the frequent fires and grazing in the climate.2 Some examples of vegetation include shrubs, wild grasses, acacia trees, and baobab trees. The way the animals graze can actually determine the number of woody plants and grasses in the savanna.
The decomposers in the savanna include the typical list - fungi, different types of small bugs, worms, bacteria, and termites. Termites are one of the main decomposers in the savanna. It decomposes 90% of the grass biomass in the savanna. A natural decomposer is fire, which I will discuss more in the next section on the environment. This environment can be a harsh one due to frequent fires, intense heat and draught. Most of the fires in the savanna are caused by lightning strikes. Humans are now of course the greatest cause in savanna fires. The following excerpt from the Encyclopedia Britannica website lists some of the reasons for humans to set fires in the
area:
“Fires burn annually in savannas in all regions, nowhere more so than in Australia, the continent with the most fire-prone vegetation.
In Australia humans have been lighting fires in savanna regions for at least 50,000 years. These fires have traditionally been lit for many reasons: to keep the country open and easily crossed; to reveal and kill small, edible animals such as lizards, turtles, and rodents; to create areas that later will develop a cover of fresh, green grass, which will attract wallabies and other game; and to encourage plants that produce edible tubers. Fires early in the dry season are less hot and destructive than fires that occur later in the season. They are sometimes employed to provide a firebreak around patches of fire-sensitive rainforest that inhabitants may want to protect for religious or utilitarian reasons. However, early fires may have ecological drawbacks, especially in areas intended for grazing. In these areas fires that burn late in the dry season are less detrimental to new grass
growth.”3
So, in this circumstance the fires are not caused naturally, but they are caused in belief that they will prevent worse damage from the natural fires that could occur during the latter part of the dry season.
Another threat in the savanna is humans clearing land for farming or other uses. As demand increases for things such as coffee, soybeans, rice, corn, and beans, land is cleared and plant life removed and destroyed to make way for the crops to be planted and harvested. Humans herding their animals through certain areas can also cause desertification due to overgrazing from the animals.
Another problem caused by humans moving further through the biome is pollution. Pollution from exhaust fumes can make the air unclean for the wildlife and humans alike. CO2 can cause the temperature in the savanna biome to increase, and if the animals have adapted to the prior temperature already, they will be forced to again adapt. If this also causes the seasons to change their routine it can have drastic effects on the plant life, animal life, and the biome as a whole.
Humans are also a major threat to the animal population through hunting. When the human population over hunts any particular species it can become extinct and possibly never be seen again. Image of a savanna

Image which includes some of the animals of the savanna biome