Biomass Dynamics in a Moose Population

From a simple model, we have calculated with a digital computer the standing crop, the gains in weight (secondary production), and the transfer of biomass by death (potential food for predators) on a monthly basis for all age and sex categories of the Isle Royale moose, a population unhunted by man and in equilibrium with its predator, the timber wolf. These estimates provide a more accurate and detailed picture than available before of biomass dynamics in a wild ungulate population. For this single—prey—single—predator system, results demonstrate that the accumulation of biomass in the prey population permits a steady flow of food to the predator, although production of food for the prey (woody and aquatic vegetation) is seasonally highly cyclic. The storage of biomass is examined in terms of the year classes of moose. Further uses of the model are discussed.