Total nitrogen incorporated in the shrubs of a low—fertility desert plant community (principally Acacia Gregii, Cassia armata, and Larrea divaricata) was estimated from the nitrogen content of plant parts, the total weight of plants and proportional weight of roots, stems, and leaves, and the number of plants per unit area. The average nitrogen content of shrub leaves, stems, and roots was 1.31%, .87%, and .80%, respectively. Shrub cover occupied 20% of the ground surface and contained an average of 29 kg nitrogen/ha. Legume shrubs were not significantly greater in nitrogen content than nonlegume shrubs. Soil nitrogen content decreased significantly as a function of radial distance from the center of the shrub canopy. Areas between shrubs averaged 0.19% nitrogen in the surface inch of soil. Soil nitrogen content decreased significantly from the surface to 90—cm depth and was closely related to shrub species and their root—distribution patterns.

Several species of grasses which have different ratings for seedling vigor were examined for rapidity of germination, seedling growth rates in the dark, and the ultimate length of dark grown seedlings. These are attributes which could be of importance in seedling vigor during the early, nonphotosynthetic stage of seedling growth.Extreme rapidity of germination largely accounts for the high seedling vigor of Schismus arabicus. In three species and strains of Phalaris, there were indications that rapidity of germination and mean seedling growth rates paralleled their rating for seedling vigor. No relation appeared to exist between total seedling length adjusted to a common seed weight and rating for seedling vigor.

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Basin and Wyoming big sagebrush plants growing in contiguous populations were studied to identify potential habitat differences in plant water and soil relationships. At 3 study sites, basin big sagebrush plants were growing in and adjacent to a drainage, while Wyoming big sagebrush plants occupied areas adjacent to the basin big sagebrush populations. Soil-and leaf-water potentials and leaf-transpiration resistances were measured from May to October 1980 to identify differences between basin and Wyoming big sagebrush plant-water relationships. Soil identification and plant tissue analyses were conducted to help characterize edaphic differences between the subspecies. The results of these studies showed that basin big sagebrush plants grew in a more mesic and fertile habitat than did Wyoming big sagebrush plants. Understanding the environmental differences of these two big sagebrush subspecies is important in effectively managing basin and Wyoming big sagebrush ranges. The woody sagebrushes (subgenus tridentatae (Rhdb.) E.D. McArthur of Artemisia L.) occur naturally only in western North America, ranging from southern Canada to northern Mexico (Beetle 1960, McArthur et al. I98 I). The most common, important, and widely distributed species is big sagebrush (Artemisia tridentata Nutt.). Big sagebrush plants are common on about 58,655,OOO hectares from the arid lands of the Great Basin to the moist, cool areas of mountain ranges (Beetle 1960, Hall and Clements 1923, McArthur 1979, Winward 1970). Considering the wide distribution of big sagebrush, it is not surprising to find genotypic variation among A. tridentata populations (Caldwell 1979). Presently, the big sagebrush complex consists of 3 subspecies with 2 forms (Beetle 1960, Beetle and Young Authors are range ecologist,

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