ABNC is a complex of habitats, many of which stay wet through out all or part of the year. The ABNC wetlands complex consists of: Prairie Wetlands (Potholes), Forested Wetlands, Tidal Wetlands (Marshes), and Bayou. The Houston area wetlands, including those of ABNC, are very unique and important wetlands. They lay in-between the prairies and the forests and the salt and freshwater habitats.
Tallgrass Prairie Wetlands (Potholes) - Prairie wetlands or potholes are low areas in flat ground that collect rainwater. These wetlands can be wet several months to year round. Grass is the predominant plant in the prairie habitat. Mixed in with the grasses are many types of wildflowers. The ABNC prairies remain wet many months of the year. The ABNC prairies are also called coastal tallgrass prairies which are characterized by grass over 5 ft (1.5 m) tall.
Forested Wetlands - The ABNC forests are sometimes referred to as riparian forests or those growing along the banks of a natural waterway. The predominant trees in the ABNC forests are oaks and elms.
Tidal Wetlands (Marshes) - An area of soft wet land usually overgrown by tall marsh grasses. ABNC marshes are considered tidal wetlands because they are in Armand Bayou's tidal zone. When the tide is high, the land is covered with shallow water. When the tide is low, the land is still wet, but not flooded.
Bayou - Armand Bayou is a slow-moving stream that flows through ABNC and on to the Galveston Bay. Much of this bayou and the adjacent marshes contain a mix of salt and fresh water. Armand Bayou's fresh water is intermixed with the tidal salt water from Galveston Bay to form "brackish" water. This meeting and mixing of fresh and salt water makes much of Armand Bayou an "estuarine" bayou. An estuarine bayou or estuary is a habitat formed when a river meets tidal waters from the ocean or salt water bay.
The Armand Bayou estuary is larger than the actual stream. Approximately 64 square miles of land surrounding Armand Bayou form the Armand Bayou watershed. Rain falling in this area eventually finds its way into Armand Bayou. Thus, the fresh water in Armand Bayou comes from rainwater runoff in the Armand Bayou watershed and the salt water comes from the Galveston Bay.