1. Tropical Savanna (Temperate Grassland Biome)

2. General Information Temperate grasslands are found mainly outside of the tropics, in temperate regions. In moist areas, short, thick, green plots of grass cover treeless, and seemingly endless, hills and plains. They can be found in Europe, Africa, Australia, and South America. They lie 15 degrees North and 15 degrees South, latitude. Some areas beyond savannas are hot deserts. Other savannas may be lined with mountains, dense forests, and seas.

3. Background History There are many different ideas of how the geologic history started. One explanation is known as the cycles of mountains and erosion, in which geologists believe it began 570 million years ago—when there was barely any oxygen, and simple bacteria reigned supreme. From some rock sequences one can find in the north, it is quite evident that the top part of Australia had once been on the edge of a plate, and so was subject to collision with others. Each collision resulted in the formation of mountains. Once the mountains were eroded to a peneplain. They were often submerged in sea water. As the sea water deepened over the land surface, these 'reefs' would die, leaving behind a sulphorous and carbonaceous black mudstone.Chronologically, an underwater avalanche, plateau sandstones, river deltas, resistant sand stones,and basalt volcanic lavas, occurred to form savannas.

4. Areas of Savannas on the Earth

5. Example of Small Food Web

6. Climatograph of Savanna

7. Animal Life The tropical savannas are home to hundreds of species of native plants, mammals, birds, reptiles and amphibians and tens of thousands of different species of invertebrates. Many species in all these groups are found nowhere else in the world. More specifically, animals like lions, zebras, elephants, and giraffes and many types of ungulates (animals with hooves) graze and hunt. Many large grass-eating mammals (herbivores) can survive here because they can move around and eat the plentiful grasses. There are also lots of carnivores (meat eaters) who eat them in turn.

8. Animal Adaptations Many animals have effective locomotion for long- distance migrations to coincide with the seasonal flush of growth--primarily mammals in Africa and birds in Australia. Many forms burrow to avoid predation (in open) and desiccation (during drought), and many others use these burrows. Savannas are perfect for birds of prey, with wide open spaces for hunting with their long- range vision and trees for perches and nest sites (even the terrestrial secretary bird uses them).

9. Plant Life The three well known types of plants found in savannas are Acacia Senegal, Baobab, and Bermuda Grass. Acacia Senegal gum is a small to average sized thorn tree of the African Savanna, which can grow up to twenty meters tall. The Baobab can be found in the savannas of India and Africa. It is a leafless tree that can grow up to twenty five meters tall and can live for several thousand years. Lastly, the Bermuda Grass is an early successional grass and grows back after grass fires, especially in Africa.

10. Plant Adaptations In trees, most savanna adaptations are to drought--long tap roots to reach the deep water table, thick bark for resistance to annual fires (thus palms are prominent in many areas), deciduousness to avoid moisture loss during the dry season, and use of the trunk as a water-storage organ (as in baobab). In grasses, most adaptations are against grazing--siliceous spicules to deter herbivores, growth from base of the plant rather than its tip to avoid damage to growing tissue, and vegetative reproduction in many types to overgrow competing forbs. Many plants have vegetative storage organs--bulbs and corms, for example--to make it through the dry (nongrowing) season.

11. Problems Due to Human Activity As the savanna is an optimal environment for ungulates, it is much used for livestock where human populations are high, as in Africa. Thus one of most significant human effects is overgrazing, primarily by cattle but also by goats in drier areas. In the past, there was much hunting for sport but with relatively minor effects. Now the illegal hunting of large animals, both for meat and salable parts such as tusks and horns, is contributing to severe population reductions and even local extinction (e.g., rhinoceroses).

12. Problems Due to Human Activity (Continued) Human-caused fires are thought to have contributed to the extent of savanna vegetation in South America. It is surprising that so little domestication has taken place in this habitat full of diverse large animals. There are also problems on the savanna which are hard to solve. Tourism has been playing a major role to extinction. Predation is also another cause of extinction because individuals are more in need of food. In addition, there have been more changes to the industry. Lastly, there are poachers who kill the wild animals on the savanna, in which they sell the tusks of elephants and the horns of rhinos.

13. Competition The competition between the tropical savanna animals is huge. Because there are decreasing numbers in space for these creatures, the huge herds of organisms like gazelles and zebras are also decreasing. The competition between cheetahs, lions, and leopards become fiercely intense. Predation also plays a huge role in this biome because it is how it functions. The antelope eat the grass, the leopards eat the antelope and the leopards eventually die and become the grass the antelope eats.

14. Competition (Continued) The process of life here is a delicate balance between animals, plants, and bacteria. Poaching can destroy this biome. All these precious animals that keep the delicate balance are just taken away, allowing for the ecosystem to be disrupted.

15. Niches There are substantial niche separations in African ungulates, even in this fairly simple environment. The primary dichotomy is between browsers and grazers, but it is not a simple one, as many species do both in different proportions. Within grazers, some species are generalists, others specialists. The proportion of grasses and forbs in the diet varies among species, as does the parts of the plant eaten, down to distinct differences in which species eat leaves, sheaths, or stems of various grasses.

16. Niches (Continued) Finally, some species are migratory, others resident, which is correlated with diet, social system (size of herd), and defense adaptations. The abundant but patchy food and the ease of keeping in contact have promoted a high degree of sociality in savanna mammals (ungulates, baboons, lions, and others). Birds are the same, also perhaps social because of the scarcity of arboreal nest sites (weavers).

17. Symbiosis In the Kenyan Savanna, symbiosis occurs in mostly mutual beneficial situations. One of which is between the antelope and the parasite eating bird. The antelope attracts many different types of parasites and the bird eats the parasite off of the antelope. Therefore, the bird gets a meal and the antelope is cleaned of the parasites and harmful bugs.

18. Diversity Savannas are quite low in tree species diversity because of stringent ecological requirements but fairly high in diversity of herbaceous plants; it would be of great interest to compare the diversity of herbs of tropical savanna, temperate grassland, and arctic tundra. Animal diversity is fairly high, although much lower overall than tropical forested areas because of fewer vegetation layers, which in turn provide environments for fewer adaptive types.

19. Overview Savannas are home to various species of both plants and animals, and as humans we should strive to protect this wonderful biome

20. Lecture Review Savannas are mainly found ______ degrees north and south latitude. One of most significant human effects is ______ Give an example of a symbiotic relationship in the savanna.