The Guianan savanna (NT0707) is an ecoregion in the south of Venezuela, Guyana and Suriname and the north of Brazil. It is in the Amazon biome. The savanna covers an area of rolling upland plains on the Guiana Shield between the Amazon and Orinoco basins. It includes forested areas, but these are shrinking steadily due to the effect of frequent fires, either accidental or deliberate.[citation needed] The ecoregion includes the Gran Sabana region of Venezuela.
The ecoregion includes three large unconnected areas totaling 10,437,652 hectares (25,792,000 acres). The main section is in southeast Venezuela, the Brazilian state of Roraima and western Guyana. To the southeast a smaller section is in the north of the Brazilian state of Pará extending into the south of Suriname. The most eastern and smallest section is in the Brazilian state of Amapá, stretching north from Macapá.[2] There are small isolated fragments to the north of the main section in the Pakarima foothills in Guyana. The main section includes the Gran Sabana region of Venezuela.[3]
The grasslands are between the basins of the Amazon and Orinoco rivers.[2] This ecoregion covers gently rolling upland plains of the Roraima formation, sediments that overlay the ancient Guiana Shield basement from the Precambrian era. Soils are typically highly weathered oxisols that are low in organic matter and nutrients and often high in toxic compounds of aluminum.[3] The north part of the main section of the ecoregion is in the eastern Orinoco basin, and is drained by the upper Caroní River, known as the Kuquenán, the Yuruaní River and the Arabopó River. The south and east parts of the main section are in the Branco River basin. The rivers are blackwater rivers, acidic and very low in nutrients.[3]
Climate
The Köppen climate classification is "Am": equatorial, monsoonal.[5] Temperatures are relatively stable throughout the year, slightly cooler in July and slightly warmer in November. Average temperatures range from a minimum of 21.5°C (70.7°F) to a maximum of 31°C (88°F) with a mean temperature of 26°C (79°F). Annual rainfall averages about 2,000 millimetres (79in). Average monthly rainfall varies from 55.3 millimetres (2.18in) in November to 376.2 millimetres (14.81in) in June.[5] There are NE and SE trade winds during most of the year. Relative air humidity is generally high, with mean annual levels of 75–85%.[3]
The Guianan savanna ecoregion contains relatively intact grasslands within an area of tropical rainforest and sandstone tepuis.[2] The Guianan savanna contains the Gran Sabana mosaic of grasslands and tree patches. There are continuous forests at the base of the tepuis, and patches of forest or of shrubs in other places surrounded by broad areas of grassland that are usually free of shrubs or trees. Some areas have shrubby meadows. The streams that cross the region run through gallery forests.[3] There is a low level of endemism compared to the Guianan Tepuis. However, the ecoregion is important as a plant refuge and center for plant dispersal. 204 species have been recorded in the Venezuelan Sierra de Lema and Cerro Venamo, including endemic species in swamps in the open savanna, on dry rocky land and in the forests at different levels.[3]
Most of the endemic birds of the Guianan highland or found on the Gran Sabana. These are mostly found in the humid forest on the foothills above 600 metres (2,000ft). They include the tepui swift (Streptoprocne phelpsi), tepui goldenthroat (Polytmus milleri) and tepui wren (Troglodytes rufulus).[3] Endangered birds include the sun parakeet (Aratinga solstitialis), Rio Branco antbird (Cercomacra carbonaria), yellow-bellied seedeater (Sporophila nigricollis) and hoary-throated spinetail (Synallaxis kollari).[6]
The World Wildlife Fund gives the ecoregion the status of "Vulnerable". The savanna is replacing the forests as a result of frequent fires and the poor soils.[3] This is causing some of the small streams to become intermittent in the dry season, affecting the amphibians. The smoke from the fires may be creating a greenhouse effect, intensifying the heat and damage caused by the fires. Gold and diamond mining cause mercury pollution.[3]
50.35% of the ecoregion is in protected areas.[1] The Venezuelan Gran Sabana is contained in the 30,000 square kilometres (12,000sqmi)Canaima National Park. Other parts of the ecoregion are protected by the 1,160 square kilometres (450sqmi)Monte Roraima National Park in Brazil and the Tumucumaque Mountains National Park.[3] The Sipaliwini Savanna in Suriname borders and is an extension of the Tumucumaque National Park. It is a 1,000 square kilometres (390sqmi) protected area since 1972.[7] The 13,000 square kilometres (5,000sqmi)Rupununi savannah in Guyana does not have an official protected area status as of 2020.[8]
Notes
1 2 "Guianan savanna". DOPA Explorer. Accessed 7 March 2022.
"Guianan savanna", Global Species, Myers Enterprises II, retrieved 2017-03-31
WildFinder, WWF: World Wildlife Fund, retrieved 2017-03-25
Related Research Articles
The Guiana Shield is one of the three cratons of the South American Plate. It is a 1.7 billion-year-old Precambrian geological formation in northeast South America that forms a portion of the northern coast. The higher elevations on the shield are called the Guiana Highlands, which is where the table-like mountains called tepuis are found. The Guiana Highlands are also the source of some of the world's most well-known waterfalls such as Angel Falls, Kaieteur Falls and Cuquenan Falls.
The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature (WWF), the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species dynamics, and environmental conditions". For example, based on their levels of endemism, Madagascar gets multiple listings, ancient Lake Baikal gets one, and the North American Great Lakes get none.
A tepui, or tepuy, is a table-top mountain or mesa found in South America, especially in Venezuela and western Guyana. The word tepui means "house of the gods" in the native tongue of the Pemon, the indigenous people who inhabit the Gran Sabana.
The Pemon or Pemón (Pemong) are indigenous people living in areas of Venezuela, Brazil, and Guyana. The Pemon people are divided into many dialects and traditions, which are; Arekuna, Kamarakoto, and Taurepang.
Canaima National Park Guyana is a 30,000 km2 (12,000 sq mi) park in south-eastern Venezuela that roughly occupies the same area as the Gran Sabana region. It is located in Bolívar State, reaching the borders with Brazil and Guyana. The park was named a World Heritage Site by UNESCO.
La Gran Sabana is a region in southeastern Venezuela, part of the Guianan savanna ecoregion.
The Orinoco Delta is a vast river delta of the Orinoco River, located in eastern Venezuela.
The Amazon biome contains the Amazon rainforest, an area of tropical rainforest, and other ecoregions that cover most of the Amazon basin and some adjacent areas to the north and east. The biome contains blackwater and whitewater flooded forest, lowland and montane terra firma forest, bamboo and palm forest, savanna, sandy heath and alpine tundra. Some areas of the biome are threatened by deforestation for timber and to make way for pasture or soybean plantations.
The Negro–Branco moist forests (NT0143) is an ecoregion of tropical moist broadleaf forest to the east of the Andes in southern Venezuela, eastern Colombia and northern Brazil, in the Amazon biome. It lies on the watershed between the Orinoco and Rio Negro basins. It includes both blackwater and whitewater rivers, creating different types of seasonally flooded forest. The vegetation is more typical of the Guiana region than the Amazon.
The Marajó várzea (NT0138) is an ecoregion of seasonally and tidally flooded várzea forest in the Amazon biome. It covers a region of sedimentary islands and floodplains at the mouth of the Amazon that is flooded twice daily as the ocean tides push the river waters onto the land. The flooded forests provide food for a wide variety of fruit-eating fish, aquatic mammals, birds and other fauna. It has no protected areas and is threatened by cattle and water-buffalo ranching, logging and fruit plantations.
The Uatuma–Trombetas moist forests (NT0173) is an ecoregion in northwest Brazil in the Amazon biome. It covers the Amazon basin north of the Amazon River from close to the Atlantic Ocean to the Rio Negro west of Manaus. The ecoregion is relatively intact, although it has been damaged along the main rivers and around population centers.
The Guayanan Highlands moist forests (NT0124) is an ecoregion in the south of Venezuela, the north of Brazil, and also within Guyana, Suriname, and French Guiana. It is in the Amazon biome. It encompasses an upland region with diverse fauna and flora, which contains dramatic tepuis, or sandstone table mountains. The region has been inaccessible in the past and is generally fairly intact, apart from the north and northeast where large scale agriculture, ranching and mining operations are steadily encroaching on the ecosystem. New roads are opening the interior to logging, and planned dams will have a drastic impact on the riparian zones.
The Guianan piedmont and lowland moist forests (NT0182) is an ecoregion in the south of Venezuela and the north of Brazil. It is in the Amazon biome. The ecoregion is relatively intact, largely protected by conservation units or indigenous territories, and less threatened by global warming than flatter and more deforested regions.
The Guianan moist forests (NT0125) is an ecoregion in the east of Venezuela, north of Brazil and the Guyanas. It is in the Amazon biome. The climate is hot and humid, with two rainy seasons each year. As of 1996 the tropical rainforest habitat was relatively intact, although there were mounting threats from illegal logging and gold mining.
The Amazon–Orinoco–Southern Caribbean mangroves (NT1401) is an ecoregion along the coasts of Colombia, Venezuela, Guyana, Suriname, French Guiana and Brazil.
The Guianan mangroves (NT1411) is a coastal ecoregion of southeastern Venezuela, Guyana, Suriname, French Guiana and Brazil. The mangroves provide an important habitat for migrating birds that winter in the area. Large areas are intact, although they are threatened by destruction of the trees for timber and to make way for agriculture, and from upstream agricultural and industrial pollution.
The Orinoco Delta swamp forests (NT0147) is an ecoregion of eastern Venezuela and northern Guyana covering the large and shifting Orinoco Delta. The vegetation is mostly permanently flooded rainforest. The ecoregion is relatively intact apart from a large area that was damaged by a failed flood control program in the 1960s. It is inaccessible, so logging is difficult, and the soil is unsuitable for farming. The main threat comes from oil exploration, which would bring an influx of settlers into the delta.
The Orinoco wetlands (NT0906) is an ecoregion of northeast Venezuela within the northern Orinoco Delta. It holds areas of tall grasses in flooded land, surrounded by mangroves and swamp forest, giving way to the drier Llanos savanna in the west.
The Paramaribo swamp forests (NT0149) is an ecoregion in the coastal plain of Suriname covering a strip of land that is almost always flooded by fresh waters. It transitions into saline mangrove swamps towards the coast, and into submontane forests towards the interior.
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