MOOSE HERBIVORY IN TAIGA - EFFECTS ON BIOGEOCHEMISTRY AND VEGETATION DYNAMICS IN PRIMARY SUCCESSION

Early successional processes in taiga forest ecosystems are believed t o be primarily under abiotic controls, with biotic factors taking on g reater importance later in the successional sequence. Here we report h ow moose (Alces alces L.), a dominant mammalian herbivore, exert major control over biogeochemical processes early in succession in the taig a of Alaska. Moose browsing affects soil chemistry and vegetation dyna mics in ways that influence subsequent plant establishment and ultimat ely forest development. Browsing significantly changed soil organic ma tter pools, the composition of soil carbon fractions, and the stable i sotope signature (delta(13)C and delta(15)N) of surface soils. These e daphic modifications were accompanied by changes in plant species comp osition that accelerate the successional trajectory. Thus, we contend that the rate of initial plant establishment and early forest successi on in taiga is under significant control by mammalian herbivores.