Riparian vegetation in Oregon's western Cascade mountains: composition, biomass, and autumn phenology

Sixteen understory plant communities in the riparian zones of smallstreams are identified and described. They range from pioneer communi-ties on gravel and rock to well-developed shrub communities on floodplains and terraces. Several other vegetation types are discussed. Distribution of communities within the riparian zone is also discussed.A survey of nine small streams shows the Acer circinatum community tohave the widest distribution and highest cover, but the Rubus spectabilis/Ribes bracteosum community is somewhat more common in theactive zone. Biomass estimates are made for riparian vegetation along three streamsegments. Total foliar production for 1976 is calculated for allvegetation, for communities, and for individual species. The percentage of each type of foliage which may reach the stream directly, indirectly, ornot at all is estimated. Abscission and fall senescence for thirteen species was monitored.Leafy and herbaceous detrital input is timed. Rates of leaf fall anddecadence are related to environmental factors.