• Chen, Cen
  University of Maine, School of Forest Resources
  
• Weiskittel, Aaron
  University of Maine, School of Forest Resources
  
• Bataineh, Mohammad
  University of Arkansas at Monticello
  
• MacLean, David
  University of New Brunswick
  

The Forest Vegetation Simulator (FVS) is an individual-tree growth model widely used in the US and parts of Canada, which has been developed to predict stand dynamics in response to various disturbance-causing agents. In this study, we developed annualized modifiers for the Acadian variant of FVS (FVS-ACD) to account for effects of spruce budworm (SBW), Choristoneura fumiferana (Clem.), defoliation on forest development. These modifiers were developed using individual tree data collected annually from 375 permanent sample plots that covered > 40 000 km2 of varying ranges of defoliation and forest conditions during the last SBW outbreak in the 1970s-1980s in Maine. FVS-ACD refined by our modifiers consistently had smaller mean biases (predicted – observed; 64% and 79% lower in Maine and New Brunswick, respectively) and root mean squared errors (RMSE; 26% lower in both Maine and New Brunswick) of predicted stand volumes than FVS-ACD refined by STAMAN (a Canadian growth model) SBW modifiers, which was superior to FVSACD alone. Our refined FVS-ACD can be used to predict stand dynamics and support management as well as protection activities against SBW defoliation in the Acadian Region to reflect the defoliation impact relationships measured in Maine during the last SBW outbreak.