Várzea forest

[9] Low várzea forests can be categorized by lower lying areas where the annual water column has an average height of more than 3 m (10 ft), where the period of flooding is greater than 50 days per year.

[1] Due to the renewal of soil nutrients caused by the annual white water flooding, várzea forests are some of the most productive areas of Amazonia[15][16] and serve as important breeding grounds for fish, birds, mammals, and reptiles.

[17] In order to grow and survive in this environment, both plants and animals must have a large range of morphological, anatomical, physiological and ethological adaptations.

[18] For example, during the flooding season, fish and other aquatic organisms take advantage of the lower density of predators, which have migrated or are confined to smaller, dryer areas, and use this time to reproduce.

[18] Both Amazonian manatees (Trichechus inunguis) and river dolphins (Inia geoffrensis) spend time in várzea areas during high water periods of the flood season.

[20] In the várzea, tree species richness, distribution and vegetation structure are influenced by a variety of characters such as topography and sedimentation dynamics.

[9] Due to the cycles of both sedimentation and erosion, habitat types of different successional stages occur simultaneously within limited areas of the várzea.

[11] This results in waterlogged or flooded conditions for up to seven months of the year, and consequently plant species numbers in the várzea are lower than the non-flooded terra firme forests.

[26] Most likely a result of the above reasoning, within Amazonia, logging has traditionally been centered in the várzea, and only in recent years has expanded into terra firme areas.

[27] It has been found that from 1976 to 1991 the areal extent of mixed species várzea had a net decrease of 25%, while other types of surrounding habitats, such as palm forest or herbaceous cover, increased.