Varzea

Varzea, or várzea in Portuguese, refers to the seasonally flooded tropical forests of the Amazon basin. These valleys are inundated by white-water rivers such as the Amazon and its tributaries, creating a dynamic floodplain ecosystem distinct from the adjacent terra firme, the non-flooded forest.

The varzea experiences a pronounced flood pulse driven by rainfall and river discharge. Water levels rise during the wet season and recede in the dry season, with floods lasting for months in some areas. Soils are largely alluvial and highly fertile due to sediment deposition, supporting high primary productivity. The hydrological regime shapes light availability and nutrient cycling, influencing which plant and animal communities can thrive.

Biodiversity in the varzea is high and adapted to periodic inundation. Many tree species have adaptations to waterlogged soils and nutrient-rich sediments, while the understory is seasonal in its light availability. The ecosystem supports diverse birds, mammals, reptiles, amphibians, and a rich fish fauna that often relies on the flood pulse for feeding and migration. The inundated forest also provides fruit, nuts, and other resources for local human populations.

Humans have long relied on the varzea for fishing, gathering and processing fruits, and shifting agriculture during low-water periods. The system is sensitive to changes in hydrology, so dam construction, deforestation, mining, and climate change pose conservation concerns. Efforts in protected areas and regional management aim to preserve flood regimes and the biodiversity and livelihoods they support.