Guianan Savanna Ecoregion (South America)

Guianan Savanna Ecoregion (South America)

Tue, 12/11/2018 - 16:57
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The Guianan savanna is an ecoregion in the south of Venezuela, Guyana and Suriname and the north of Brazil. The savanna covers an area of rolling upland plains on the Guiana Shield between the Amazon and Orinoco basins.

Guianan Savanna

The Guianan savanna is an ecoregion of the Amazon biome that is found in the south of Venezuela, Guyana and Suriname as well as the north of Brazil.

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 large, relatively intact grasslands of the Guianan savanna ecoregion are embedded in a landscape of tropical rain forest and tepui sandstone peaks. These grasslands occur in three distinct patches, becoming increasingly smaller as they move south from the Guyana Shield to the mouth of the Amazon River.

All three sections adjoin the Uatuma-Trombetas moist forests ecoregion to the south. The most eastern section adjoins the Marajó várzea to the east, at the mouth of the Amazon River. The Guianan moist forest ecoregion lies to the east of the main section and to the north of the other two sections.

The main section adjoins the Guianan piedmont and lowland moist forests ecoregion to the west. The northern part of the main section adjoins areas of the Guianan Highlands moist forest and Pantepuis ecoregions.

The savanna encompasses the treeless and tree patch mosaic of the Gran Sabana and occurs as three distinct outliers:

  • the largest spanning northern Brazil, southeastern Venezuela and southeastern Guyana (also several small patches extending north along the Pakarima foothills)
  • a smaller patch bordering northern Brazil and extending into southern Suriname
  • the smallest and most elongated outlier that occurs in eastern Brazil, north of the Amazon, extending from near Macapa to near Calcoene

The Guianan savanna ecoregion is in the Neotropic ecozone and the tropical and subtropical grasslands, savannas, and shrublands biome.

The World Wildlife Fund gives the ecoregion the status of "Vulnerable". The savanna is replacing the forests as a result of frequent fires and poor soils.

The Venezuelan Gran Sabana is contained in the 30,000 sq km (12,000 sq mi) Canaima National Park. Other parts of the ecoregion are protected by Monte Roraima National Park and Tumucumaque Mountains National Park in Brazil.

Common species in the scrublands are Euphorbia guianensis, Humiria balsamifera, Clusia species Calliandra species Chamaecrista species, Bonnetia sessilis, Myrcia species and Ternstroemia pungens. Common species in the open savannas are Axonopus pruinosus, Axonopus kaietukensis, Trachypogon plumosus, Echinolaena inflexa, Bulbostylis paradoxa, Rhynchospora globosa and Hypolytrum pulchrum.

Common species in the palm savannas are Hypogynium virgatum, Andropogon species, Panicum species, Byttneria genistella, Miconia stephananthera, Mahurea exstiputata and Mauritia flexuosa. Common species in the meadows are Chalepophyllum guianense, Digomphia laurifolia, Tococa nitens and Poecilandra retusa.

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 m (2,000 ft). They include the tepui swift (Streptoprocne phelpsi), tepui golden throat (Polytmus milleri) and tepui wren (Troglodytes rufulus).

Endangered birds include the sun parakeet (Aratinga solstitialis), Rio Branco antbird (Cercomacra carbonaria), yellow-bellied seedeater (Sporophila nigricollis) and hoary-throated spinetail (Synallaxis kollari).

Endangered mammals include the black-bearded saki (Chiropotes satanas) and giant otter (Pteronura brasiliensis). There are relatively few endemic frogs when compared to the tepuis.

Most endemic species are found in the La Escalera forest, and include Anomaloglossus parkerae, Stefania scalae, Scinax danae, Tepuihyla rodriguezi, and Pristimantis pulvinatus. Rodriguez's Amazon tree frog (Tepuihyla rodriguezi) is found in savannas and some tepuis. Scinax exiguus and Leptodactylus sabanensis are found only in savannas.