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.

Mass Trapping Lepidopteran Pests with Light Traps, with Focus on Tortricid Forest Pests: What If?

“…In the worst-case scenario, severe budworm defoliation and the associated massive mortality of balsam fir, combined with a limited prospect for natural regeneration due to high moose density and the consequent browsing of seedling trees [142,143], imply that the coastal forest stand in SC is at a high risk ( " R = 1) of transiting to a wetland 'ghost forest' with predominantly dead trees [144,145]. In the best-case scenario, the forest stand in SC may be at low risk ( " R ≈ 0)-noting that centuries-old coastal balsam firs have so far survived a large number of budworm immigrations.…”