Quantitative descriptions of the vegetation and maps of the pool of Bryant’s Bog are available for several years since 1917. The vegetation advanced into the bog pool in an irregular manner at an average rate of 2.1 cm/year. In 1972 the pool was 76% of its extent in 1926. The vegetation changed in a successional series from the Chamaedaphne association of 1917 to the high bog-shrub association in the dry years of the 1920’s to a bog forest which was well established in the late 1960’s. It regressed in the early 1970’s when many of the trees died and the Chamaedaphne association appeared to be re-establishing itself. The most probable cause of tree mortality was flooding caused by exceptionally high water levels due to natural weather cycles. Tree mortality was also found in Hoop Lake Bog–which, like Bryant’s Bog, lacks aboveground drainage–while none occurred in bogs with aboveground drainage.