Abstract Vegetation changes over the past 80 years in the high elevations of Yosemite National Park were identified with 59 scenes originally photographed at the turn of the century and rephotographed in 1984 and 1985. The resulting photo pairs suggest that (1) krummholz has increased in height and density (2) forests at the upper forest line have increased in density (3) meadows have been invaded by trees (4) local patches of thin forest have increased in density and (5) trees on many domes and rock slopes have increased in number. Fire suppression, climatic fluctuations, and livestock grazing are explored as possible causes of the changes. Management programs to reverse such vegetation changes caused by modern humans are evaluated in terms of the purposes of national parks. I argue that these purposes are best met by recognizing the legitimacy of both ecological goals, which may be furthered by managing the vegetation intensively, and humanistic goals, which may be served by maintaining a landscape free of a conspicuous human presence.