SUCCESSION ON AN ALASKAN TUNDRA DISTURBANCE WITH AND WITHOUT ASSISTED REVEGETATION WITH GRASS

The long-term effects of planted grass on the rate and pattern of succession were evaluated on a construction-disturbed alluvial fan tundra site in the central Brooks Range of Alaska. Plots were evaluated 4 and 11 yr after the site was scarified and partially fertilized and seeded in strips with a grass mix. Cover of the surviving planted grass, Festuca rubra, was <5%. In comparison with the no-grass treatment, the grass treatment inhibited or delayed establishment and growth of native plants. Many species, particularly nonlegume forbs such as Epilobium latifolium, failed to establish on the grass treatment; establishment of other nonlegume forbs and some shrubs, including Artemisia tilesii and Salix glauca, was delayed; and growth of the dominant shrub Salix alaxensis was inhibited. In contrast, legumes such as Astragalus alpinus established and grew equally well on both treatments. Grass treatment effects were attributed to the very dense shallow root system of the planted grass and to higher moss cover, which probably reduced soil moisture in the upper portion of the soil profile, decreased the number of "safe sites" for seedling establishment, and competed for limited nutrients.