Swoope, VirginiaThe cows on Bobby Whitescarver’s farm can wander through his lush pastures pretty much as they please. But there’s one place on the farm where they’re not allowed to go.

Along the property’s stretch of the Middle River, thickets of false indigo tower overhead, their lower leaves wrapped in the thorny, protective embrace of blackberry shrubs. Native hardwoods like hickory and sycamore festoon the banks of the river, which meanders through the 40-acre cattle farm tucked into the foothills of Virginia’s Blue Ridge Mountains.

Whitescarver and his wife, Jeanne Hoffmann, have spent 15 years building this wall of vegetation—all to keep bovines at bay.

“Once you get the cows out, it’s amazing how quickly the stream can heal,” says Whitescarver, standing