Many of us do best in familiar environments, and the same is true of plants used for restoring ecosystems, according to new research in the August issue of Conservation Biology. This is the first study showing the importance of both genetic and environmental similarity when transplanting wild plants.
While many restoration projects use native plants, they fail to account for genetic and environmental differences between the transplants and local populations. “Mis-matching source populations may lower the success of restoration,” says Arlee Montalvo of the University of California at Riverside, who did this work with her colleague Norman Ellstrand.
Montalvo and Ellstrand tested the importance of the source of plants used for restoration with deerweed, a yellow-flowered member of the pea family that grows in southern California’s coastal sage scrub. They chose deerweed because, although it varies geographically (one variety grows primarily along the coast, and the other grows inland), the two varieties have been used indiscriminately for restoration projects.
The researchers collected deerweed seed from 12 areas with different climates and soils and then transplanted seedlings from each of the 12 sources into two experimental gardens within native coastal sage scrub, one coastal and the other inland (with hotter summers, cooler winters, and less rain). They measured the distance between transplant sources and experimental gardens in three ways: geographically, genetically, and environmentally. They measured the success of transplanted seedlings by factors including survival, size, and flower production.
The results showed that whereas geographic distance had little effect on transplant success, transplants did better in the experimental garden that was genetically and environmentally closer to the area they originally came from. Specifically, in the coastal garden, transplants did better when they were genetically similar to the local deerweed. In the inland garden, transplants did better when they were both genetically and environmentally similar to the local deerweed.
This study shows that the common practice of restoring ecosystems with plants from similar communities does not go far enough. To increase the success of restoration projects, Montalvo and Ellstrand recommend choosing transplant sources that are also ecologically similar.
Montalvo, A.M., and N.C. Ellstrand. 2000. Transplantation of the subshrub Lotus scoparius: testing the home-site advantage hypothesis. Conservation Biology 14(4):1034-1045.