Dynamics of Understory Biomass in Sitka Spruce-Western Hemlock Forests of Southeast Alaska

摘要: Understory vegetation undergoes successional stages during the 1st 300 yr after logging or fire disturbance in coastal Picea—Tsuga forests of southeast Alaska. Residual shrubs and tree seedlings increase their growth within 5 overstory removal. biomass peaks at Mg°ha — 1 °yr °15—25 logging. Shrubs herbs are virtually eliminated (<0.1 Mg/ha) from understory forest canopies close stand ages 25—35 yr. Bryophytes ferns dominate following century. An deciduous is reestablished 140—160 Thereafter, shrubs, herbs, continues to increase, while bryophyte productivity decline. Departures this developmental sequence related unusual types establishment, soil, microclimate, disturbance. The development duration depauperate that succeeds canopy closure Alaska closely structure shade—tolerant Tsuga with high foliar biomass. In young—growth (<100 yr), decline immediately significantly associated basal area percentage cover. old—growth forests, contrast, correlated mean diameter, age, volume. It hypothesized over chronosequence responds primarily changes induced light environment by developments canopy. Maintenance most productive aggradation (0—100 yr) through management will minimize a vascular thus deprive herbivores forage 70—80% rotation.