Seedling Survival from Locally and Commercially Obtained Seeds on Two Semiarid Sites

Abstract

Local populations of plants are likely to be better adapted to a site than populations from elsewhere. Thus, local seeds should yield higher survival in restoration attempts than commercial seed stocks. We compared seedling survival from locally and commercially obtained seeds of seven species, Pseudoroegneria spicata (bluebunch wheatgrass), Elymus elymoides (squirreltail), Pascopyrum smithii (western wheatgrass), Stipa hymenoides (Indian ricegrass), Stipa comata (needle-and-thread), Chrysothamnus nauseosus (rubber rabbitbrush) and Ephedra nevadensis (Mormon tea) over three years on two sites in Utah (Dugway and Tintic) that were dominated by the introduced annual Bromus tectorum (cheatgrass). At the Dugway site we included burned and unburned seedbed treatments. For all species at Dugway, seedling survival to the first summer was higher on burned plots where B. tectorum densities were greatly reduced. First-year seedling survival was 20–30% for most species on the Dugway burned plots and at Tintic. At the drier Dugway site, only S. hymenoides and Ephedra had substantial third-year survival. Elymus and Pascopyrum survived to the third year only at the moister Tintic site. Survival to the third year was less than 3% for all species except S. comata (6% survival), and densities were low (0.2–1.0 plants/m²). However, third-year plants were well established and the grasses flowered. Pseudoroegneria and Ephedra at Dugway (on burned plots) and S. comata and Elymus at Tintic had higher first-year survival or higher survival based on survival curves from local than from commercial seeds. However, final survival was never significantly higher, although such a trend was suggested. Seed dormancy traits could also provide advantages to local populations, and we observed differences in dormancy between local and commercial S. comata and S. hymenoides seeds that may be an example.