Tropical+Savannah

= The Tropical Savanna  =

1. The Llanos of Venezuela is an area covering about 1,200 to 1,300 kilometers from Oriental Andes of Colombia almost to the delta of the Orinoco River. The Llanos is located in a depression surrounded by the Andes, Carribean Sea, and Guiana shield. []

2. The savannah is dominated by tropical wet and dry weather, usually consisting of a 6 to 8 month wet season and a then a dry winter season. Savannah average temperatures of around 64 degrees Farenheit and about 10 to 50 inches of precipitation annually. Crucial to Savannah's are the frequent droughts and fires which limit the tree growth, as to forbid the forming of a Tropical Rainforest. [] []

3. a) In South America, there are no savannah specific animals, but in Africa there are a large number of hoofed animals such as gazelle, Elephants, Zebras, Rhinos, and Wildebeasts. To counter these beasts, a number of car species call the savannah home including the cheetah and lion. []

b) The major invasive species in the savannahs are cows and goats introduced by humans. As herders move their cattle to new area, the stock does not graze over a large portion of land, instead they overgraze a single area, which destroys the vegitation and turns the savannah into a desert. []

c) Major indicator species in the tropical savanna are frogs. In many areas, there seems to be an ominous decline in frog population due to environmental disturbances. For example, the Australian frogs have experienced a drastic decline in population because frogs are so sensitive to environmental disturbances. http://www.savanna.org.au/all/frog_threats.html

d) Termites are one keystone species in the savannah, for they are important for their fixing of soil. They also create mounds that provide shelter for other animals and form the base of of a few food chains. []

e) Many herbivores feed on foliage in the tropical savanna. In order to avoid the competition for low-growing leaves, giraffes have evolved to have long necks, so that they can feed on foliage from the tops of trees, while other species enjoy the low-growing leaves. http://www.blueplanetbiomes.org/savanna_animal_page.htm

f) The African wild dog and the antelope have a predator-prey relationship. The African wild dog is the predator, which will use its speed to chase down the antelope. African wild dogs will hunt in packs so that they can surround the antelope and prevent its escape.



http://www.blueplanetbiomes.org/savanna_animal_page.htm

g) Nigriceps ants and the whistling thorn acacia have a relationship displaying mutualism. Whistling thorn acacias are trees in the savanna that have hollow bulbs attached to their thorns that are perfect for ant nests. The ground in the savanna does not provide a suitable home for ants because it can easily become water-logged or dried out. When any animal approaches the tree and touches a branch, whether to break off a branch or eat the tree's leaves, the ants swarm from their nests and sting the encroaching animal. The tree provides the ants with a home, and the ants provide the tree with protection.



http://www.blueplanetbiomes.org/savanna_animal_page.htm

4.Changes in local population of the Arnhem land and tradition being broken is leading to an increase in the number of large-scale fires created. About half of the region is burnt every year. Many invasive plant species have recently been introduced, such as the giant sensitive plant, and have quickly spread across the terrain. Many invasive animals, such as the red fox, have also created an imbalance of life in this ecosystem. Due to the area's low elevation, it is especially sensitive to global climate change, and large areas of floodplains have been destroyed by saltwater intrusion. http://www.eoearth.org/article/Arnhem_Land_tropical_savanna