DENVER--A group of scientists is accusing native plant advocates of going overboard and endangering habitat restoration efforts. They say the use of locally evolved plant varieties, promoted by some scientists and environmentalists, is untested and based on false assumptions. Some new research supports that claim, but other researchers are not convinced.
The private seed industry produces more than $150 million worth of native seed per year that is used to restore burned, mined, or otherwise degraded land. The federal government alone has planted this seed on more than 15 million hectares since 1985 to control erosion, create habitat, and fight alien weeds. Some environmentalists and scientists advocate using only locally evolved varieties instead of "cultivars," which are mass produced in farmlike operations. They have won over state and federal agencies, but critics say that local seed is not necessarily best suited to restoration.
To find out if tallgrass prairie plants perform better close to home, plant geneticist Kenneth Vogel of the University of Nebraska, Lincoln, and colleagues collected seed from 50 native prairie patches in a dozen states. They planted the seeds alongside mass-produced cultivars in three common plots in Nebraska, Iowa, and Indiana and measured how much each variety grew over a growing season. At every location, cultivars of three of the four species outperformed local varieties, which were highly unpredictable. And local heritage generally did not help plants--in 10 out of 12 cases, the distance between the growing site and a variety's collection site had no impact on that variety's performance, Vogel reported here on 15 February at the meeting of the American Association for the Advancement of Science, which publishes ScienceNOW.
But plant geneticist Arlee Montalvo of the University of California, Riverside, says that there are other factors to consider, such as which varieties work best in seed mixtures and which provide the best habitat for wildlife. And she says research in California, which has much greater geographic variability than the prairie, shows that local varieties often are superior.
Even though local varieties are usually more expensive to produce than cultivars, Montalvo says their use is often warranted. But some land is so degraded that any native species is better than letting invasive species take over. In such cases, she says, the cultivars may be a better option.