Igapó is the name for a blackwater-flooded forest habitat in the Amazon Basin. These forests are seasonally inundated by dark, acidic, nutrient-poor water from rivers and lakes, especially in Brazil.
The word comes from Old Tupi and is commonly translated as “root forest.” Flooding can last for months, and many trees and other organisms are specially adapted to survive prolonged submersion. Despite the low nutrient content of the water and soil, igapó forests support distinctive communities of fish, birds, reptiles, and plants, including species found nowhere else.
The most important comparison is with várzea. Both are Amazonian floodplain forests, but várzea is flooded by sediment-rich whitewater rivers, while igapó is flooded by blackwater or clearwater associated with older, more nutrient-poor landscapes. “Swamp” is too general, and “mangrove” usually refers to salt-tolerant coastal forests rather than this freshwater interior habitat.
Dams, deforestation, logging, and altered flood cycles threaten igapó ecosystems because their slow-growing trees recover poorly after disturbance.