The Pacific Northwest Laboratory examined plant growth and establishment on 16 sites where severe land disturbance had taken place. The purpose of the study was to evaluate t}" relative effectiveness of the different methods in terms of their effects on establishment of native and alien plants. Disturbances ranged from 1 to 50 years in age. Revegetation using native plants had been attempted at 14 of the sites; the remainder were abandoned without any further management. Revegetation efforts variously included seeding, fertilizer application, mulching with various organic sources, compost application, application of Warden silt loam topsoil over sand and gravel soils, and moderate irrigation. The greatest benefit was derived from seeding: without seeding, abandoned sites, especially on heavier soils, were covered with a near monoculture of cheatgrass (Bromus tectorum). Cheatgrass was found to be a strong competitor with most native grasses, especially Sandberg's bluegrass (Poa sandbergit). Cheatgrass is extremely prone to fire, and supports a generally depauperate vertebrate fauna. After 50 years of such a monoculture, cheatgrass in one of the Hanford To,_ .site old fields was found to be successfully invaded by the native grass sand dropseed (Sporobolus cryptandrus). Russian thistle (Salsola kah) increased in abundance with age of site disturbance at least over the first 5 years after disturbance. In contrast to cheatgrass, Russian thistle was not found to be a significant competitor with Sandberg's bluegrass. The second greatest benefit was derived from moderate irrigation. Irrigation on the studied sites was limited to a maximum of 2.5 cm of water per month from April to July following seeding the previous October and November. Enhanced survival and growth were found among all native species on irrigated sites, including native forbs that were not introduced to the disturbed areas in the seeding mixes. Cheatgrass abundance and cover were lower on irrigated sites than on unirrigated sites. Russian thistle was more abundant on irrigated sites, but plants were smaller than on unirrigated sites. Incorporation of compost at a rate of 25% by volume produced the third greatest benefit for seeded native plants. Pure compost seedbeds, however, were totally without cover of seeded species; only Russian thistle was able to colonize such sites. Wood fiber or straw mulches were used at all revegetated sites. Different mulches had no apparent effect on Russian thistle growth. Wood fiber mulch on sands was generally more effective than straw in enhancing growth of seeded native grasses. In contrast, straw _' performed slightly better than wood fiber on loamy sand soils. Straw on silt loam sites bad a less beneficial effect on native plants than did composts. Loamy sands were the most difficult to revegetate with native plants. Silt loams, at least with the amendments used, produced the highest cover and density of seeded native species. __ Sandy soils produced intermediate success. Russian thistle density was highest on loam...