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<br />4 <br />The nitrogen and sucrose were hand broadcast annually for three <br />years, the nitrogen in three equal increments (spring, early <br />summer, and late summer) and the sucrose at eight ec,(ual increments <br />(spring to late summer). The sucrose was applied more frequently <br />to allow for a more uniform microbial uptake. <br />Sampling began in 1988 and was conducted at two dates (early- <br />and late-summer) annually for three years. Two sampling dates were <br />considered adequate (Lauenroth et al. 1987, Carpenter et al. 1990) <br />since plant growth at the study site occurs in two pulses, cool- <br />season species growing primarily from late-April to late-June and <br />warm-season species from late-May to late-August. At each sampling <br />date, 20 quadrats (0.25 mz) were randomly located within each of <br />the 12 plots. Within each quadrat canopy cover was estimated by <br />species and number of plants was recorded by species. Plant <br />numbers were counted for those species with fewer than 100 <br />individuals per quadrat and were estimated in units of 10 for those <br />over 100. <br />Canopy cover was converted to relative canopy cover for <br />statistical analysis to minimize variation due to annual <br />fluctuations in precipitation and to possible annual variations <br />between blocks. The data were analyzed by use of Student's t-tests <br />(Snedecor and Cochran 1967), and 95t confidence intervals were <br />constructed around the means of each species and each growth form <br />group (shrubs, perennial grasses, perennial forbs, annual grasses, <br />and annual forbs) by treatment for each year and overall (lour <br />separate analyses per variable per treatment). Results from <br />