Cobble Bars

Cobble Bar

NPS

 

 

Cobble bars, also known as “river scour prairies,” are unique plant communities that exist on open, flood-washed areas of bedrock, cobble, or gravel along large rivers. Cobble bar habitat is uncommon, with an estimated 500 acres of remaining today, worldwide. It only exists along free-flowing rivers where heavy rainfall can drastically change water levels, scouring out species not adapted to these conditions. These river scour prairies are home to many plants that are also found in the tallgrass prairies of the American Midwest. Both habitats depend on periodic disturbance to maintain their open character – fire in the tallgrass prairies and flooding on the cobble bars.

 

Cobble bar habitat on a sunny day

NPS

Cobble bars contain a number of native plant species not found anywhere else on earth. These unique plant communities are only made possible by the punishing conditions of a free-flowing river; scouring floods are crucial to the very existence of these rare habitats along the rivers’ edges. They would be greatly affected and would probably cease to exist if any portion of the river were dammed or water levels manipulated.

 

The National Park Service, state, and other federal agencies work together to monitor and care for these vulnerable communities.

NPS