Riparian bryophytes of the H.J. Andrews Experimental Forest in the western Cascades, Oregon

The knowledge of the distribution and habitat demands for bryophytes in the PacificNorthwest is scarce, and few published quantitative accounts of the flora are present. The presentpaper includes habitat description, elevational range, substrate preference, and frequency esti-mates for more than 130 riparian mosses and liverworts found in old-growth Pseudotsuga-Tsugaforests of the H. J. Andrews Experimental Forest, Oregon. The data are based on 360 samplesdistributed among 42 sites covering 1st to 5th order streams and 420 to 1250 m. TWINSPANanalysis resulted in 6 sample groups, representing samples from different elevations, geomorphicsurfaces, and stream sizes. The most common mosses are Eurhynchium oreganum, Isotheciumstoloniferum, Hypnum circinale, and Dicranum fuscescens. Among the hepatics Scapania bolan-deri, Cephalozia lunulifolia, and Porella navicularis are the most abundant species. Most speciesare rare at both site and sampte gtot (ever; and this is especially true for acrocarps where morethan one-third of the observed species occurred in only one or two sites orland samples. Four ofthe occurring species (i.e., Antitrichia curtipendula, Buxbaumia piperi, Douinia ovata, and Ptili-dium californicum) are listed for special management and/or regional surveys.