SPECIES COMPOSITION OF OLD-GROWTH AND RIPARIAN SITKA SPRUCE - WESTERNHEMLOCK FORESTS IN SOUTHEASTERN ALASKA

We studied six 1.2-ha stands, two each of three types of forest: (1) o ld-growth, riparian floodplain forest, (2) old-growth, upland forest, and (3) 40-year-old, red alder (Alnus rubra Bong.) riparian forest ori ginating after clear-cut logging of floodplain forest. Sitka spruce (P icea sitchensis (Bong.) Carriere) dominated the old-growth riparian st ands and shared dominance with western hemlock (Tsuga heterophylla (Ra f.) Sarg.) in the uplands. Regeneration was predominantly spruce in th e alder riparian, spruce and hemlock in the old-growth riparian, and h emlock in the upland stands. Total understory biomass and ground cover did not differ significantly between forest types, but species-specif ic biomasses did differ (P < 0.05). Understory of the upland forest wa s dominated by early blueberry (Vaccinium ovalifolium Sm.) and Alaska blueberry (Vaccinium alaskensis How.), while that of both riparian typ es was dominated by devilsclub (Oplopanax horridum (Sm.) Mig.). Other species-specific differences occurred in forbs (three species) and mos ses (three species). Contrary to typical stand age understory relation s in upland conifer forests of the region, the understory of the 40-ye ar-old red alder stands was very species rich and productive.