Belowground traits of herbaceous species in young coniferous forests of the Olympic Peninsula, Washington

Variation in belowground traits of herbaceous species may influence their a bility to persist and spread during and after the closed-canopy period of f orest development. In 40- to 60-year-old closed-canopy, coniferous forests of the Olympic Peninsula, Washington, we excavated root and rhizome systems of 11 herbaceous species to compare morphology, vegetative spread, and pro portion of biomass in belowground structures. All species were perennial an d most were rhizomatous; four species were nonclonal. Of the seven clonal s pecies, only two (Maianthemum dilatatum and Oxalis oregana) spread extensiv ely (mean lateral spread > 50 cm) by belowground perennating structures. Th e proportion of total biomass in belowground structures varied considerably among species (21-85%) and was higher for deciduous than for evergreen spe cies. High variability in belowground traits suggests that multiple strateg ies may contribute to survival during closed-canopy conditions. For species with a high proportion of belowground biomass, we suggest that the ability to store resources or to acquire new resources through lateral spread may contribute to persistence in dense coniferous forests.