The savanna biome was designed to perform several different functions within Biosphere 2. Its primary goal was to provide a hydrological transition zone between the desert and rainforest mesocosms. The objective was to learn how to balance atmospheric chemistry by varying hydrological regimes within the tropical mesocosms. The savanna was to be a scaled-down model of tropical savannas, both duplicating ecosystem processes in savannas and capturing essential features of biodiversity and aesthetics. Vegetation zones within the savanna mesocosm were created primarily from edible species, including acacias for galagos, large-seeded grasses for finches, and fruit-bearing trees for galagos and birds.
The savanna is divided into four major regions: Quartzite Slope, Upper Savanna, Granite Slope, and Lower Savanna. The northernmost section of the savanna consists of a quartzite slope made from quartzite boulders. The savanna stream waterfall is located in this area. The Upper Savanna has three sections of vegetation. The section adjacent to the stream is composed of fresh-water wetland species from the Florida Everglades including Cornus foemina, Typha domingensis, Salix caroliniana, Crinum americanum, Ludwigia octovalvis, and Cladium jamaicense. The Gallery Forest section is dominated by Acacia species with a rather sparse grass understory. Typical grass species in the gallery forest include Andropogon gayanus, Panicum maximum, Paspalum guenoarum, Setaria poiretiana, and the invasive Brachiaria mutica. Billabongs are depressions in the Upper Savanna. They were designed to be periodically flooded to produce a hyperseasonal habitat. Hyperseasonal environments alternate between waterlogged and desiccated conditions, which kill most trees and thereby favor grasses. The billabongs are dominated by a grass canopy of Brachiaria mutica and Chloris gayana, with patches of twining Vigna luteolaand Macroptilium lathyroides vines.
The Lower Savanna is southernmost, next to the Upper thornscrub. It is dominated by Brachiaria mutica. Other grasses in this area are Dichanthium annulatum, Cenchrus setigerus, Panicum maximum, Sorghum halepense, and Brachiaria decumbens.
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