Caqueta River, Brazil Photograph by WWF/ Carlos Saenz   Northern South America: Northern central Brazil Tropical and Subtropical Moist Broadleaf Forests   68,500 square miles (177,500 square kilometers) -- about the size of Missouri Critical/Endangered

· Flooded Forests
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Flooded Forests

Várzea means "flooded forests" in Portuguese, a fitting name for this low-lying, seasonally inundated region of the central Amazon. The Purus Várzea ecoregion includes much of the Juruá, central Purus, and Japura/Caquetá Rivers, along with their tributaries. The confluence of the Japura and Solimões Rivers, about 370 miles (596 km) west of Manaus, marks the eastern edge of this ecoregion. River levels fluctuate as much as 20 to 40 feet (6-12 m), swelling with rainfall that averages 100 inches (2,540 mm) per year. The flooding is caused by rainwater pooling in the river basins, which fail to drain quickly because the slope of the land is not steep enough. Most of the water that does drain off is eventually forced downstream by its sheer volume.

Special Features

The annual flooding makes this area an ever-changing environment. Nutrients are replenished by the receding floodwaters, and rivers constantly change course as they form oxbows and levees. Four types of vegetation grow in this landscape. Three can be found along the floodplain meanders (one of a series of naturally occurring curves in the course of a stream or river)

that are carved out as water constantly floods and recedes: successional vegetation, forest mosaics, and, in poorly drained areas, aquatic vegetation. The fourth type is permanent swamp vegetation. These flooded forests are ecologically significant. They rapidly cycle the nutrients that are deposited in the constant floods, stabilize flooded soils, host a great diversity of plant and animal life (both terrestrial and aquatic), and perform various other functions. Many endemic orchids can be found here, along with fruit-bearing trees such as the yellow mombin and socoró, which thrive in the rich soil and humid climate.

	In some isolated areas of the várzea, no terrestrial mammals can be found because high floods make the rivers impassable.

Wild Side

An olive-spotted hummingbird flies around flowering vines in search of nectar. Here, too, in a tangle of dense vines is the favorite sleeping place of a group of titi monkeys. On the ground, a mighty jaguar stalks a capybara, the world’s largest rodent. White-collared peccaries root through the leaf litter for insects and fallen fruit, while a giant river turtle swims through the flooded forest. She might lay her eggs after the receding waters expose the riverbanks once again. High above, a bicolored hawk scans the higher ground for small mammals and lizards. Along the water’s muddy edges, an elusive wading bird called a limpkin probes for invertebrates, while a boat-billed heron rests on the fronds of a large, overhanging palm. In the canopy above, a number of green iguanas sun themselves on exposed branches.

Cause for Concern

Toxic levels of mercury used in gold-mining have seeped into the soil wherever the mines have been cut into the landscape. Expanses of deforested areas created by cattle-ranching and commercial logging scar and fragment the Purus Várzea, threatening the great diversity of species here.

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