California’s native grasses can be restored

A research project to restore native grasslands to a reserve in California has yielded some promising results. The native grasslands may only need to be reseeded with native seeds without having to first eradicate the invading plants from Europe, according to a presentation at the recent annual Ecological Society of America meeting by researchers from the University of California, Santa Barbara and the University of Minnesota.

The research team included Eric Seabloom, of the National Center for Ecological Analysis and Synthesis (NCEAS) at UCSB; Stan Harpole of the University of Minnesota; Jim Reichman of NCEAS at UCSB; and David Tilman, also of Minnesota.

“We used experimental seed introductions of native and exotic species to investigate one of the most dramatic plant invasions worldwide, the invasion of 23 percent of California by annual plant species introduced from Mediterranean Europe,” said Seabloom. The experiments were conducted at Santa Barbara County’s Sedgwick Reserve, part of the UC Natural Reserve System which is managed by UC Santa Barbara.

Reichman, the director of NCEAS, said that the researchers found that the “native plants are actually better competitors than the invasives, but that the seed availability of natives is extremely low – probably due to grazing and drought 150 years ago.”

He explained that when the researchers provided seeds of native grasses, they were competitively superior to the exotic species.

“This is encouraging news,” said Reichman, “because it suggests that in many places, providing seeds will be enough to re-establish native species; there may be no need to exclude the invasives first, a profoundly difficult task.”