Methods for characterizing the composition, biomass, and accumulation rates of harvestable epiphytic bryophytes in the understory of temperate forests have recently been developed, but have yet to be implemented in a much wider geographical area and adapted to provide estimates at the individual mat level. In response to regulatory need, we modified and implemented these methods in 27 50 yr-old upland and riparian forest stands below 915 m to: a) characterize the composition of harvestable epiphytic bryophytes in central western Oregon, b) evaluate the compositional changes immediately following harvest, and c) retrospectively estimate minimum simple accumulation rates for harvestable bryophyte mats. Twenty-two bryophyte species, two lichens, and one vascular plant were found in a total of 433 sampled mats, dominated by Isothecium myosuroides, Neckera douglasii, Antitrichia curtipendula, Frullania tamarisci subsp. nisquallensis, and Porella navicularis. Harvest brought on significant shifts in the relative abundance of species primarily through the disproportionate removal of these species, which are commonly found in harvestable bryophyte mats throughout western Oregon. The minimum simple accumulation rate for bryophyte mats from 13 of these stands, calculated as the oven-dried mat mass per unit surface area divided by the stem age, was 22.4 (std 15.5) g/m²/yr and is approximately comparable to that previously observed in the Coast and Cascade Ranges of northwestern Oregon. This accumulation rate translates into a commercial harvest rotation period of at least 21 (std. 12) yr. This long rotation time, coupled with the scarcity of sites supporting harvestable mats, leads to our recommendation that commercial bryophyte harvest be prohibited in the study region.