Using the University of Maine's Acadian Forest Ecosystem Research Program (AFERP) as a test case, we investigated this assumption for canopy gap-based systems by first modeling the proportion of area potentially influenced by gaps in these systems with a discrete space model, and then estimating the influence of canopy gap-induced growth increases on growth projections of a calibrated version of the Northeast variant of the Forest Vegetation Simulator (FVS-NE), a spatially implicit model commonly used by managers in this region. Results from the discrete space model showed that, across both AFERP gap-based treatments, up to 52.4%of the stand area can be within one mature tree height of a gap edge, and that the edge area could persist for multiple cutting cycles (>10 years), potentially having a dramatic impact on stand growth and yield. However, results from FVS-NE suggested the contrary, with a 20-50%increase in growth within the edge area only increasing merchantable sawtimber yields by 1-5%over the course of an entire 100-year rotation.
We conclude that edge effects are likely being severely underestimated due to limitations in the FVS model, most notably the relatively inflexible control of stand density index-based growth maximums. Short-term projections with plots not approaching these maximums suggest that a 20-50%edge effect could increase merchantable yields by 15-37%in these gap-based systems, suggesting the need for significant reworking of the underlying FVS model.