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<br />1z <br /> <br />annuals once the perennials have attained sufficient biomass. <br />instead, we believe that the annuals cease to dominate the site <br />because the N incorporation by the annuals (e.g., Foster et al. <br />1980) reduces the available soil N pool (Vitousek and Reinera 1975) <br />to a level insufficient to allow for the high biomass production <br />potential of the annuals to be realized. If the rate of <br />decomposition is somewhat slower than that of N incorporation in <br />litter, the reduction in available soil N may last significantly <br />long (Vitousek 1983) for herbaceous perennials, with lower N <br />requirements, to exploit the temporal dominance void and <br />successfully dominate the site until displaced by later <br />successional perennials (McLendon and Redente 1991). <br />CONCLUSIONS <br />These results indicate that the application of sucrose results <br />in a more rapid rate of secondary succession following disturbance <br />of a semiarid sagebrush community and that the application of N <br />slows secondary succession. This is consistent with a conceptual <br />model in which potential growth rate, nutrient availability, and <br />competitive displacement are important mechanisms in determining <br />the rate of secondary succession. According to this model, early <br />seral stages are dominated by rapidly growing species, primarily <br />annuals, whose high growth potential results in decreased resource <br />availability. However, these early seral species require relatively <br />high levels of available resources to support their high production <br />