LACOMBE, La. (AP) - Federal crews are burning a small part of a national wildlife refuge north of New Orleans to kill invasive plants.

The US Fish and Wildlife Service on Tuesday began burning about 60 acres (24 hectares) of marsh in the Big Branch Marsh National Wildlife Refuge .

Burning the invasive plants will let native marsh grasses return.

The refuge covers 18,000 acres (nearly 7,300 hectares) of forests, marshes and wetlands on the north shore of Lake Pontchartrain.

A news release says signs have been posted along roads bordering the area where the prescribed burn is planned.

It says people may see smoke coming off the refuge, but effects on the general public are expected to be minimal.