Orinoco Delta Swamp Forests Ecoregion (South America)

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Orinoco Delta Swamp Forests Ecoregion (South America)

Wed, 01/02/2019 - 20:50
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The Orinoco Delta Swamp Forests occur in a diverse matrix of coastal vegetation along the river delta and surrounding regions of northwestern Venezuela and northeastern Guyana. These permanently flooded forests provide habitat to many endangered and endemic species.

Orinoco Delta Swamp Forests

The Orinoco Delta Swamp Forests ecoregion occurs in a continuous expanse of flooded forests and wetlands, occurring from the southern reaches of the Paria Peninsula in northern Venezuela, extending southwards along the Orinoco Delta to the Waini River in Guyana.

Orinoco Delta swamp forests are the dominant vegetation feature of the Orinoco Delta. The ecoregion is embedded in a complex matrix of wetlands, mangroves, and inundated terra firma moist forests. These swamp forests are characterized by permanently flooded forests and abundant waterways and canals.

The vegetation is mostly permanently flooded rainforest. These inundated forests have moderate species richness and provide habitat to many endangered and endemic species.

Geographically, this is a landscape of little relief. The soils in this ecoregion are almost entirely alluvial deposits, originating as far away as the northern Colombian Andes and Venezuelan Andes.

The Orinoco Delta swamp forests are characteristically impregnated with river systems and host many riparian features, including permanent wetlands and marshes (Orinoco wetlands ecoregion), large rivers, oxbows lakes, small gallery streams, levies, and the typical delta alluvial fan.

The delta consists of increasingly partitioned distributions, which become more confined and disjunct as they diverge from the main channel. They then come together again as they move east towards the Atlantic Ocean. In so doing, these numerous rivers form a significant number of islands.

The climate in this region is tropical, hot and humid—temperatures average 26˚C, with a relative humidity of approximately 70%. There are two distinct dry and wet seasons. Rainfall is irregular; the wet season begins in April - May and usually lasts through December.

Precipitation varies throughout the region, becoming increasingly wetter and more humid moving south. Rainfall ranges from 500 - 2,000 mm (20 - 80 in) in the north and can reach as high as 8,000 mm (300 in) south.

Flora and Fauna

The swamp forests of the Orinoco (Amacuro) Delta are essential wildlife habitats and are known to support many endemic plant species.

Common hardwood trees include Guiana chestnut, mahogany, kapok, wild pigeon plum, shimbillo, greenheart, padauk, and billygoat plum. Numerous palms also occur here, including the açaí palm, troolie palm, and moriche palm.

The delta region has a rich bird fauna, with over 175 species identified, including 39 species of aquatic birds and 13 species of wading birds, such as scarlet ibis and roseate spoonbills.

These swamp forests provide essential habitats for many threatened and endangered species, such as the Orinoco crocodile, Amazon river dolphin, jaguar, bush dog, giant river otter, Orinoco goose, and harpy eagle.

Protected Status

This region is still intact due to its inaccessibility and poor soils. However, recently oil exploration and extraction projects have encroached into these once-pristine forests.

Three protected areas protect portions of this ecoregion and are encompassed by the Delta del Orinoco Biosphere Reserve.

Map depicting the location of the Orinoco Delta swamp forests (in purple)

Map depicting the location of the Orinoco Delta swamp forests (in purple)