Science in the Triangle | N.C. State Restoration Ecology

Chinese privet is a good example.

Brought to the U.S. in the 1800s, the shrub loves to grow in the shady understory zone beneath tall, leafy trees, where it creates a thick tangle. “Privet makes the woods completely inaccessible,” said North Carolina State University professor Ted Shear, who heads the school’s Restoration Ecology Program.

Shear and researchers from North Carolina State University’s College of Natural Resources have teamed up with the North Carolina Museum of Art to figure out the best way to restore native plants in the museum’s 164-acre forest. The goal is to preserve a patch of the state’s homegrown biodiversity.

“There is an intrinsic value to native plant communities,” Shear said. “They are a link to our natural history.”

But simply ripping out Chinese privet and other plants that don’t belong won’t bring back the natives. It takes repeated removal to control exotic species, especially in urban areas where birds and animals bring seeds from backyard gardens into the forest.

Shear and his students tested a variety of approaches for eliminating exotic plants in the museum’s forest. They also work at other North Carolina sites, such as Guilford Courthouse in Greensboro, where Shear is helping the National Park Service recreate the suite of plants that grew on the battlefield during the Civil War.

At the N.C. Museum of Art, the scientists first targeted four common exotic species. Two are shrubs: autumn olive (Elaeagnus umbellata) and Chinese privet (Ligustrum sinense). Another is a flowering vine, Japanese honeysuckle (Lonicera japonica), and the last is a grass called Japanese stilt grass (Microstegium vimineum).

In one test plot, students chopped out the exotic plants and left the ground alone, watching to see if local species grew back. At another site, Shear and his students helped the natives along by pulling any exotic seedlings that sprouted after the non-natives were cleared.

Native species were more likely to grow back in areas where the scientists cleared seedlings. But the research also shows that the forest may need further help. In areas where exotic species dominate, native seeds often lie dormant in the ground, waiting for their chance to grow. But at the N.C. Museum of Art’s forest, a young patch of woods on former farmland, there may not be enough seeds in the soil for the native plant community to completely recover, the scientists concluded.

Tia Herring, the museum’s park manager, has started growing native species for planting in the forest and on a patch of nearby prairie. “Our goal is to clear out the invasives and use only natives,” she said.

The museum has cleared more than 15 acres of exotic plants and shrubs from the forest with the help of volunteers and donations from local companies, creating trails and open areas for large pieces of art. And they’re keeping a watchful eye for any outside invaders.