The successional studies in Sycamore Creek produced patterns of variation in diversity that differed significantly from those observed during primary succession at Glacier Bay (see fig. 20.2), old field succession on the Piedmont Plateau (see fig. 20.4), or algal and barnacle succession in the intertidal zone (see fig. 20.7). The main difference was that Fisher and colleagues (1982) observed initial increases in species diversity followed by declines. In contrast, studies of forest and intertidal succession showed increases in diversity but no obvious declines. What may have been responsible for these different results? How might have differences in the longevity of species contributed to the different patterns observed by researchers?