The effects of moose browsing on balsam fir and forest recovery vary with bioclimatic and human use across the island of Newfoundland

Abstract

Moose present a complex management problem because they generate a mixture of benefits and costs to humans, some of which are caused by browsing of regenerating trees. We developed a Lotka-Volterra model, parameterized by moose management areas, to link moose browsing to spruce and balsam fir dynamics on the island of Newfoundland. The model predicts the distribution of moose, adult fir, and spruce well. Empirical estimates of juvenile fir biomass were variable, and our model predicted its biomass poorly. Our model predicts a small negative effect of moose on adult fir biomass (-0.06%) and juvenile fir biomass (-1.65%) and a small positive effect on spruce biomass (+0.02%) under baseline assumptions, but larger effects (±10 to 60%) if moose browse commercial softwoods preferentially. Small effects of moose on trees at steady state do not fully reflect the importance of moose because moose parameters (e.g., growth rate and harvesting rate) impacted the return time of our model from disturbance. Our model analysis demonstrates one way to add animal effects into vegetation growth models and suggests that parameterizing ecological models by management unit is useful when the data to support more detailed models are not available.