the areas of spring and fall precipitation, separated by a summer drought, galleta displays a tendency toward two separate growing seasons with a semi-dormant period in the summer. In much of Arizona and New Mexico, there is an early spring growth period then semi-dormancy in May and June with growth starting again in July or August. "Evidently galleta can tolerate a wide variety of topographic conditions. It has been reported on deserts, dry upland plains, sandy mesas, rocky benches and flats, canyons and open valleys, and rocky shale slopes (Gould, 1951; Graham, 1937; Hitchcock, 1951; Kearney and Peebles, 1960; Knight et al., 1908; McCorkle and Heerwagen, 1951; U.S. Forest Service, 1937; Vallentine, 1961; West and Ibrahim, 1968)." Indian ricegrass (Oryzopsts hymenotdes) is another valuable grass species adapted to the TTR which should be experimentally encouraged in any revegetation endeavor. Scarification requirements of seed also make it difficult to reseed naturally. Seed from this species, however, can be readily collected, scarified, and planted. Irrigation may be necessary to ensure success, since Stuart et al. (1973) failed to establish both tall wheatgrass and Indian ricegrass in a somewhat similar area to the TTR which had only 9.4 cm of rainfall. In addition to the grass species, the perennial shrubs Atriplex canescens (four winged saltbush) and Furotia lanata (winterfat) have considerable grazing advantage. If these two species are used, however, it is advisable that seed collections be made from the area since genetic variability within the species has resulted in the development of distinct ecotypes adapted especially for each local environment (Wallace et al., 1972). At present, F. lanata is rather sparse in the immediate area of the study sites at the TTR, but this species is present and can be encouraged. Once an area such as the TTR, which is primarily an Atriplex shrubland, has been disturbed by scraping or plowing, it tends to revert to a grassland until reinvaded by shrubs (Wallace and Romney, 1974). Competition for water by shrubs decreases, allowing grasses to grow. It also follows that, grasses grow first, the subsequent competition for water prevents, the establishment of new perennial shrubs. It has been postulated establishment of new shrubs from seed requires several consecutive favorable rainfall (Wallace et al., 1972). because or retards, that the years of As mentioned, native animal activity is one of the big deterrents to successful revegetation in deserts. Another is overgrazing by livestock. The existing fenced study areas at the TTR present excellent examples of what can happen. Good grassland conditions now exist inside the fences even where land had been disturbed. Outside the fences, the cattle have destroyed the grass as well as much of the ability of the land to produce grass. The ecological principles involved include nitrogen fixation processes as well as competition. The first recommendation for any mechanically disturbed land then is that it be fenced to prevent grazing for a sufficient time period to develop a grassland. The land will thus be better protected from erosion, becoming far more valuable for grazing land over a long period of time. 69