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 ecoregion includes parts of southern Venezuela, western and southern Guyana and northern Brazil, with scattered portions in Suriname and French Guiana.[1] It extends into eastern Colombia.[2] It has a total area of 33,747,545 hectares (83,392,000 acres).[3] The ecoregion lies on the Guiana Shield, an ancient upland area between the Amazon and Orinoco basins. It is surrounded by lowland grassy savannas and lowland forest.[3] All areas of the ecoregion contains enclaves of the Pantepuis ecoregion on the tops of table mountains.[4]
Most areas of the ecoregion in the east are surrounded by the Guianan moist forests ecoregion, and most areas in the west are surrounded by the Guianan piedmont and lowland moist forests ecoregion. Sections of the ecoregion in the east border the Uatuma-Trombetas moist forests to the south. The central part of the ecoregion surrounds the northern part of the largest section of the Guianan savanna ecoregion The southwestern part of the ecoregion rises above the Negro-Branco moist forests ecoregion.[4] The Guayanan Highlands moist forests and the Tepuis together make up the Guayanan Highlands Forests Global 200 ecoregion.[5]
Physical
The terrain is rugged, with elevations in the ecoregion from 500 to 1,500 metres (1,600 to 4,900ft) above sea level. Taller table mountains in the region rise to elevations of 3,000 metres (9,800ft) and host the Tepui ecoregion. The Guayanan Highlands ecoregion is an "island" of higher land surrounded by lower grasslands and forests collectively known as the Guiana Shield. Most of the land drains into the Orinoco through the Ventuari, Caroní, Paragua and Caura rivers in Venezuela. In the south, it is drained by the Uraricoera and Branco rivers in Brazil into the Amazon.[2]
The upland terraces and mountains consist mainly of quartzitic or sandstone rocks, with granitic rock in some areas. The lowland plains are recent, formerly flooded by lakes or by the sea. Most of the landscape is forest-covered rolling peneplains and floodplains. The undulating peneplains between the Caura and Paragua rivers hold low hills up to 500 metres (1,600ft) high. There are scattered upland areas of undulating plains, rounded hills, low mountains and Tepuis up to 1,500 metres (4,900ft) high, and the lower slopes of the higher tepuis. Soils are mostly sandy and low in nutrients.[2]
The Köppen climate classification is "Am": equatorial, monsoonal.[6] Temperatures vary little throughout the year. Yearly average temperatures range from a minimum of 18°C (64°F) to a maximum of 29°C (84°F), with a mean of 23°C (73°F). Annual rainfall varies considerably, but in some areas averages 3,750 millimetres (148in). Monthly rainfall is lowest in January at 68.5 millimetres (2.70in) and highest in July at 537 millimetres (21.1in).[6]
The World Wildlife Fund classes the ecoregion as "Relatively Stable/Intact".[2] The interior forests have been inaccessible in the past and are generally intact, although roads are being built that open them up to logging. Logging is illegal in the state of Amazonas, Venezuela, but continues elsewhere. Legal and illegal mining for gold, diamonds, bauxite, and iron ore are a serious threat. Near urban centers in the north and northeast of the ecoregion the habitat is steadily being destroyed by large-scale agriculture, cattle ranching and mining. Planned hydroelectric dams on the Caroni and Paragua rivers would flood huge areas with devastating effect on the riparian habitats.[2]
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.
Canaima National Park 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.
Parima Tapirapecó National Park is a Venezuelan national park in the southern state of Amazonas.
The Ventuari River is the largest tributary of the Orinoco in southern Venezuela. The Ventuari flows from south-central Venezuela in the Guiana Highlands southwest into the Orinoco River. It is 520 km (320 mi) long and its major tributary is the Manapiare River.
The Paragua River is a river of Venezuela. It is part of the Orinoco River basin. It is the largest tributary of the Caroní River.
Campinarana, also called Rio Negro Campinarana, is a neotropical ecoregion in the Amazon biome of the north west of Brazil and the east of Colombia that contains vegetation adapted to extremely poor soil. It includes savanna, scrub and forest, and contains many endemic species of fauna and flora.
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. The ecoregion includes the Gran Sabana region of Venezuela.
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 Japurá–Solimões–Negro moist forests (NT0132) is an ecoregion of tropical moist broad leaf forest in the Amazon biome.
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 Alto Orinoco-Casiquiare Biosphere Reserve is a UNESCO biosphere reserve in the Venezuelan Amazon biome.
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 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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