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

Abstract

Sixteen understory plant communities in the riparian zones of small streams are identified and described. They range from pioneer communities on gravel and rock to well-developed shrub communities on flood plains 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 to have the widest distribution and highest cover, but the Rubus spectabilis/Ribes bracteosum community is somewhat more common in the active zone. Biomass estimates are made for riparian vegetation along three stream segments. Total foliar production for 1976 is calculated for all vegetation, for communities, and for individual species. The percentage of each type of foliage which may reach the stream directly, indirectly, or not at all is estimated. Abscission and fall senescence for thirteen species was monitored. Leafy and herbaceous detrital input is timed. Rates of leaf fall and decadence are related to environmental factors.