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<br />6 <br />based on temporal position of dominance or subdominance <br />characteristic of each species (McLendon and Redente 1991). <br />RESULTS <br />Plots receiving sucrose supported seral communities that were <br />more species rich, had more perennial forbs and annual grasses, and <br />had less annual Porbs than those receiving the N treatment (Table <br />1). This pattern was consistent for each year as well as overall. <br />However, the small sample size (4) resulted in a lack of <br />significance within individual years (except for annual forbs in <br />1988). Sucrose plots also consistently had higher amounts of <br />shrubs and perennial grasses than N and control plots (Fig. 1), but <br />these differences were not significant at the 953 level because of <br />annual variation. <br />Aster canescens, a perennial forb, was the only individual <br />species to show a significant difference between sucrose and N <br />plots at the 953 level. Overall, sucrose plots had more ste <br />canescens than N plots (Table 1). However, another major species, <br />Kochia scooaria, showed a significant difference between sucrose <br />and N plots at the 903 level, sucrose plots supported less Kochia <br />(33 3) than N plots (66 3). <br />Aboveground tissue N concentrations at the termination of the <br />study displayed a pattern consistent with the seral pattern of the <br />species (Table 2). The N concentrations of both early-seral forbs <br />(Salsola iberica and Kochia sconaria) differed significantly among <br />all treatments, increasing from the low (sucrose) to the high (N) <br />treatments. Additionally, N concentration did not differ <br />