Because of its location on the rarely flooded upper parts of riverbanks or depositional bars protruding far out of the water, conditions in this natural community can be stable for years at a time. They are impacted, however, by extreme changes in the water level of the river. Significant floods may leave behind sediments such as sand, silt, and pebbles. At times, high waters may erode sediments and soil. (Ecobit: Erosion and Sediment Transport—Earth in Motion)

Trees or shrubs may sprout in this natural community, but they are typically washed away, knocked over, or buried in sediments before they can mature.

Sediments deposited by the river enrich the soil with nutrients and minerals from upstream, which act like fertilizer for the soil. The periodic influx of new nutrients and minerals influences the plants more than the chemistry of the underlying bedrock geology.