• Weaver, Jamie K.
  University of Maine Graduate School
  

This study investigates regeneration in mixed-species stands in the Acadian Forest of Maine. We examined the effect of silvicultural intensity on available regeneration substrates and how seedling-substrates relationships may be impacted by management activities. Silvicultural treatments studied include two replicates each of 5-year selection, 20 year selection, commercial clearcutting (unregulated harvesting), and three replicates of no management (defined as no harvesting for at least 50 years). We focused on red spruce (Picea Rubens Sarg.), eastern hemlock (Tsuga canadensis (L.) Carr.), balsam fir (Abies balsamea L. Mill), and red maple (Acer rubrum L.); all four species are common within the Acadian region.

Chapter 1 presents analysis of the availability of wood as a regeneration substrate and the role that downed woody material plays in regenerating tolerant conifers and red maple, a frequent competitor. Pieces of wood > Decay Class III and >10 cm on one end were studied. Area of wood substrate was greater in unmanaged stands than commercial clearcuts (p=0.05). Seedlings <1.3 m in height were analyzed on wood and adjacent (paired) forest floor plots of equal area.  Spruce and hemlock seedlings were found at higher densities on wood than forest floor plots, regardless of treatment.  Decay Class IV and V wood supported the highest spruce seedling densities; hemlock seedlings were well distributed across all three decay classes studied. Conversely, fir and map, were less abundant on wood than forest four plots in unmanaged and selection  stands, but more abundant (fir) or equally abundant (maple) on wood relative to forest floor plots in commercial clearcuts. These findings suggest that silvicultural treatment affects wood-seedling relationships, and support the conclusion that management for hemlock and spruce in the Acadian Forest should include attention to coarse woody material. This is particularly important in light of the fact that Decay Class III through V wood represented a very small amount of available regeneration substrate.