Yasuni, Ecuador Photograph by Victoria Moseley, courtesy Louisiana State Arthropod Museum   Eastern South America: Southern Colombia, eastern Venezuela, and northern Peru Tropical and Subtropical Moist Broadleaf Forests   97,200 square miles (251,700 square kilometers) -- about the size of Wyoming Vulnerable

· Water, Water Everywhere
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Water, Water Everywhere

If you ever venture to western Amazonia, be sure to bring your umbrella. This ecoregion contains some of the rainiest places in Amazonia, with rainfall averaging between 100 and 120 inches (2500 and 3000 mm) each year and reaching as high as 160 inches (4000 mm) in years with especially heavy rainfall. This is a landscape of lowlands dominated by river flood plains that alternate with hills rising only slightly above the water.

Special Features

This ecoregion is centered on the Rio Napo watershed in westernmost Amazonia, with portions in Colombia, Ecuador, and Peru. It is bounded on the west by the foothills of the Andes Mountains, on the south by the Marañon River in Peru, and on the north by the Rio Napo in Peru and the Rio Caguán in Colombia. Here, tall evergreen tropical rainforests grow to 130 feet (40 m), with some trees reaching 164 feet (50 m). Three main types of vegetation occur here: terra firme forests on the hills and above the flood levels; vársea forests that are seasonally flooded by whitewater rivers and that carry heavy sediment loads; and igapó forests that are seasonally flooded by blackwater rivers that have no sediment load. The climate is humid and tropical with a subtle dry season. In some areas, more than 310 tree species exist in a 2.5-acre (one-hectare) area.

	During the flood seasons, Amazon river dolphins frequent the flooded forests in search of fish. Because of the mud and sediment in these rivers, these freshwater dolphins can barely see, and rely, instead, on echolocation (the reflection of sound waves) to detect their prey.

Wild Side

In these flooded forests and dry hilltops, species diversity abounds. More than 210 species of mammals and 640 bird species occur here. During high water periods, a troop of longhaired spider monkeys waits out the flood atop a giant kapok tree. Below, South American river turtles sit stacked atop one another on a fallen tree trunk, while Amazon river dolphins swim carefully among the tree trunks in the flooded forests. A jaguar wades through chest-deep water to cross a small stream. Resting on an endemic Wettinia palm, a green pit viper is almost indistinguishable from the mossy leaves. Orchids attract pale-tailed barbthroats and gray-breasted sabrewing hummingbirds, while bromeliad pools provide a safe place for a poison-dart frog to release a tadpole. On dryer ground, a yellow-footed tortoise searches for fallen fruits. On a low branch, a white-browed guan watches the movements of a leaf-like katydid. A careless brown pale-fronted capuchin drops a ripe fruit from high in the canopy, but little is wasted as an agouti scampers over to eat the remains.

Cause for Concern

Ongoing human activities continue to degrade these diverse forests. Increased colonization and human settlement result in overhunting, plantation agriculture, and deforestation for subsistence, agriculture, cattle ranching, and timber. Roads constructed for oil and gas prospecting also lead to continued colonization. And wildlife trade poses a threat, too.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.