Savanna (cerrado) biome, grassland, open woodland, saxicolous ecosystems; trees, flowers
79 images Created 13 Sep 2009
Pictures of the savanna biome (tropical grassland biome) in the Guiana Highlands in Venezuela, in the Brazilian Highlands in Central Brazil, in Africa (including swamp savanna). Savannas are called cerrado in Brazil. Three main cerrado ecosystems are represented (although there are many intermediary forms): cerrado sensu stricto or wooded savanna, campos rupestres: saxicolous vegetation (vegetation on rock outcrops) and vereda, a treeless grassland on seasonally waterlogged soil, with buriti palm (Mauritia flexuosa) along streams. Contorted (twisted) trees are characteristic of many savannas; various factors may be involved. Two explanations, probably complementing each other, explain the contorted shape of savanna trees: fires may kill the terminal bud, forcing the development of lateral shoots from the stem protected by a thick bark (Coutinho 1992 in França 2002, p. 25); and, unlike forest species, savanna species enjoy plenty of light and do not need to grow upward, which may lead to a somewhat random growth (William Hoffmann, personal communication). Experiments in fire-protected areas have shown that some savanna species naturally grow contorted (Ribeiro, personal communication), whereas even when grown if full light, forest species tend to grow upward, as they are genetically programmed to reach for light (Hoffman, personal communication). (links to contorted tree citations currently in LINKS-BOOKS page). Rock outcrops present saxicolous vegetation (vegetation on rock outcrops), called campos rupestres in Brazil. Flowers: Vellozia, Helicteres, Habenaria ground orchid, Davilla, Pterodon, Tibouchina, Mimosa, Davilla etc... Savanna fire with antelope in Africa. The savanna biome presents a high degree of biodiversity. It is one of the most threatened biomes: it was previously considered worthless for agriculture, but with modern agricultural techniques it is now widely devastated and substituted by large agribusiness plantations of soybean, sugar cane for the production of ethanol, cotton, maize... and ranching..