Orinoco Delta swamp forests

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Orinoco Delta swamp forests
Deltaorinoco.jpg
Aerial view of part of the region
Ecoregion NT0147.png
Ecoregion territory (in purple)
Ecology
Realm Neotropical
Biome Tropical and subtropical moist broadleaf forests
Geography
Area27,972 km2 (10,800 sq mi)
Country Guyana, Venezuela
Coordinates 9°01′41″N61°23′46″W / 9.028°N 61.396°W / 9.028; -61.396 Coordinates: 9°01′41″N61°23′46″W / 9.028°N 61.396°W / 9.028; -61.396
Climate typeAf: equatorial, fully humid

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.

Contents

Location

The Orinoco Delta swamp forests in the lower delta plain of the Orinoco River are one of Earth's largest intact areas of wetlands. They cover an area of 27,972 square kilometres (10,800 sq mi). [1] The forests extend from the base of the Paria Peninsula in the northeast of Venezuela south across the Orinoco Delta floodplain to the Waini River of Guyana. [2]

The ecoregion is bounded on the Gulf of Paria and the Atlantic Ocean by stretches of Amazon-Orinoco-Southern Caribbean mangroves. It contains sections of Orinoco wetlands. To the northwest it adjoins the La Costa xeric shrublands. To the west it adjoins the Llanos and to the south it adjoins the Guianan moist forests. [3]

Physical

The terrain is flat, with typical elevations of 1 metre (3 ft 3 in) above sea level, but in the south there are terra firme levees up to 9 metres (30 ft) high. The soils are alluvial deposits carried by rivers from the Andes of Colombia and Venezuela. The Orinoco fans out into large and small distributaries in the delta, which wind through a landscape of permanent wetlands and marshes, oxbow lakes and levees. [2]

Climate

The Köppen climate classification is "Af": equatorial, fully humid. [4] Annual rainfall varies by location from 500 to 2,000 millimetres (20 to 79 in), and is highest in the south. A wet season generally lasts from April/May to December. [2] At a sample location at coordinates 8°45′N61°15′W / 8.75°N 61.25°W / 8.75; -61.25 the temperature is relatively stable throughout the year, slightly cooler in January and July and slightly warmer in May and October. Yearly average minimum temperature is 22 °C (72 °F) and maximum is 31 °C (88 °F) with a mean temperature of 27 °C (81 °F). Yearly total rainfall is about 1,450 millimetres (57 in). Average monthly rainfall varies from 40.5 millimetres (1.59 in) in February to 203.7 millimetres (8.02 in) in July. [4]

Ecology

The Orinoco Delta swamp forests are in the Tropical and subtropical moist broadleaf forests biome. [1] The ecoregion is part of the Guianan Moist Forests Global Ecoregion, which also includes the Guianan moist forests and the Paramaribo swamp forests. [5]

Flora

The Orinoco delta is largely covered by permanently flooded tropical ombrophilous swamp forest, which support various endemic species of plants, with areas of wetlands, mangroves and terra firma rainforest. Most of the vegetation consists of hydrophilous trees and palms, with many epiphytes and scattered herbaceous plants. Hardwood trees include Carapa guianensis , Ceiba pentandra , Dimorphandra excelsa , Hirtella triandra , Inga punctata , Manilkara bidentata , Chlorocardium rodiei , Pentaclethra macroloba , Pterocarpus officinalis , Symphonia globulifera and Terminalia obovata . Palms, often growing in stands of one species, include Astrocaryum aculeatum , açaí palm (Euterpe oleracea), Manicaria saccifera and Mauritia flexuosa . [2]

Fauna

The critically endangered Orinoco crocodile (Crocodylus intermedius) Caiman del Orinoco.JPG
The critically endangered Orinoco crocodile (Crocodylus intermedius)

The swamp forests are home to species that include Orinoco crocodile (Crocodylus intermedius), Amazon river dolphin (Inia geoffrensis), jaguar (Panthera onca), bush dog (Speothos venaticus), giant otter (Pteronura brasiliensis), Orinoco goose (Neochen jubata) and harpy eagle (Harpia harpyja). [2] Endangered species include the Orinoco crocodile, giant otter and yellow-bellied seedeater (Sporophila nigricollis). [6]

Status

The World Wildlife Fund classes the ecoregion as "Relatively Stable/Intact". [2] A flood control program in the 1960s dammed the Caño Manamo, which reduced water levels in the upper delta. This part of the delta became tidal and much more saline than before, with a drastic impact on the flora and fauna. Otherwise the swamp forests are mostly intact. [2]

The highest risk now comes from oil exploration, which would bring more people into the region and cause forest clearance for food and building materials. The way of life of the indigenous Warao people would be disturbed by the newcomers. In some areas the açaí (Euterpe oleracea) and moriche ( Mauritia flexuosa ) palm trees are over-exploited. Although the region is largely inaccessible, there is growing concern about logging. The cleared land is poor quality and cannot support farming. [2]

There are two indigenous reserves, which do not provide much protection, and several conservation units. The 876,500 hectares (2,166,000 acres) Delta del Orinoco Biosphere Reserve is a sustainable use unit. Part of it covers wetlands. The 3,203,250 hectares (7,915,400 acres) Imataca Forest Reserve is another sustainable use unit with a portion that covers the eastern coastal wetlands. [2] National parks in Venezuela are fully protected, and cover parts of the wetlands and surrounding ecoregions. They include the 331,000 hectares (820,000 acres) Delta del Orinoco National Park, the 72,600 hectares (179,000 acres) Turuépano National Park in the north of the ecoregion and the 265,000 hectares (650,000 acres) Mariusa National Park that protects wetlands along the Caño Macareo. [2]

Related Research Articles

Llanos Grassland

The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, savannas, and shrublands biome.

Orinoco Delta Delta region of the Orinoco River

The Orinoco Delta is a vast river delta of the Orinoco River, located in eastern Venezuela.

Maranhão mangroves Mangrove ecoregion of northern Brazil

The Maranhão mangroves is a mangrove ecoregion of northern Brazil. It supports half of the shorebird population of the country. The combination of flat land, heavy rainfall and high tides causes the mangroves to extend up to 40 kilometres (25 mi) inland, where they are interspersed with other rainforest species.

Caquetá moist forests

The Caquetá moist forests (NT0107) is an ecoregion of tropical moist broad leaf forest to the east of the Andes in the east of Colombia, with a small section in Brazil, in the Amazon biome. The forests are in the transition between the Guiana and Amazon regions, and have highly diverse flora and fauna. They are relatively intact, although they are mostly unprotected and are threatened with deforestation to create cattle pastures.

Guianan savanna

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.

Negro–Branco moist forests Tropical broadleaf forest covering portions of Venezuela, Colombia, and Brazil

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.

Marajó várzea

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.

Gurupa várzea

The Gurupa várzea (NT0126) is an ecoregion of seasonally and tidally flooded várzea forest along the Amazon River in the Amazon biome.

Monte Alegre várzea

The Monte Alegre várzea (NT0141) is an ecoregion of seasonally flooded várzea forest along the Amazon River in the Amazon biome.

Purus várzea

The Purus várzea (NT0156) is an ecoregion of seasonally flooded várzea forest in the central Amazon basin. It is part of the Amazon biome. The ecoregion is home to a vegetation adapted to floods of up to 12 metres (39 ft) that may last for eight months. There is a great variety of fish and birds, but relatively fewer mammals. Ground-dwelling mammals must migrate to higher ground during the flood season. Threats include logging, cattle farming, over-fishing and mercury pollution from gold mining.

Guianan Highlands moist forests Type of plant habitat

The Guayanan Highlands moist forests (NT0124) is an ecoregion in the south of Venezuela and the north of Brazil and in Guyana, Suriname, 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.

Guianan moist forests

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.

Amazon–Orinoco–Southern Caribbean mangroves

The Amazon–Orinoco–Southern Caribbean mangroves (NT1401) is an ecoregion along the coasts of Colombia, Venezuela, Guyana, Suriname, French Guiana and Brazil.

Guianan mangroves Coastal ecoregion of southeastern Venezuela, Guyana, Suriname and French Guiana

The Guianan mangroves (NT1411) is a coastal ecoregion of southeastern Venezuela, Guyana, Suriname and French Guiana. 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.

Orinoco wetlands

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.

Pará mangroves

The Pará mangroves (NT1427) is an ecoregion along the Atlantic coast of the state of Pará in Brazil. They constitute the western extension of the Maranhão mangroves ecoregion. The mangroves are relatively intact, although they are under some pressure from agriculture and logging.

La Costa xeric shrublands

The La Costa xeric shrublands (NT1309) is an ecoregion in Venezuela that stretches along the Caribbean coast. The dry scrub and savanna has been subject to modification since the 16th century by European colonists who replaced it by a patchwork of farm fields and pasturage. Little of the original habitat remains.

Araya and Paria xeric scrub

The Araya and Paria xeric scrub (NT1301) is an ecoregion in Venezuela that stretches along the Caribbean coast to the west of Trinidad, and that includes Margarita Island and some smaller islands. The ecoregion includes dune herbs, dry thorn scrubs and deciduous forests. The mountains on Margarita Island hold montane forests similar to those in the mainland coastal range. The beaches are used for breeding by sea turtles. Some endemic bird species are threatened with extinction by illegal capture for the pet trade. Deforestation and over-grazing by goats are also problems.

Paramaribo swamp forests

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.

References

  1. 1 2 Orinoco Delta swamp forests – Meyers, WWF Abstract.
  2. 1 2 3 4 5 6 7 8 9 10 Schipper.
  3. ↑ WildFinder – WWF.
  4. 1 2 Orinoco Delta swamp forests – Meyers, Climate Data.
  5. ↑ Guianan Moist Forests – WWF Global.
  6. ↑ Orinoco Delta swamp forests – Meyers, All Endangered.

Sources

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