Historical forestry practices in Great Lakes northern hardwoods tended to promote the regeneration of a few, economically important tree species, a practice which has likely led to a decline in species diversity and consequently a decline in ecosystem resilience. The regeneration failure of yellow birch (Betula alleghaniensis Britton) within these forest types, for example, reflects the widespread and long-term use of single-tree selection. Microsite conditions created by this one silvicultural system give shade- and leaf litter- tolerant sugar maple (Acer saccharum Marsh) a competitive advantage over less tolerant species such as yellow birch, whose functional traits are better suited for regenerating in sites with greater light availability and less leaf litter. Using a variety of silvicultural systems to create a gradient of environmental conditions may therefore help to restore diversity in these forests. The objective of this research is to investigate plant community response across a range of timber harvesting disturbances which emulate a range of regionally-specific natural disturbance regimes, from less than 40% canopy removal (i.e. small windthrow) to 100% canopy removal (i.e. catastrophic windthrow) at the stand scale. Plant community patterns were assessed before and after treatment application and compared to environmental conditions such as light availability, soil water content, and leaf litter depth.
Results/Conclusions
In the first growing season after harvest, we found a light × soil water content × leaf litter depth interaction effect on plant community composition, but no overall effect of harvest treatment. Species such as sugar maple and black cherry (Prunus serotina (Ehrh.)) were strongly associated with greater leaf litter depth and less available light. Though not significant, yellow birch and several ruderal species were more associated with available light and less leaf litter. Continued monitoring may reveal treatment effects not detected during the first growing season following harvest. Incorporating these plant community responses and underlying competitive interactions across a broad range of disturbance severities may better inform forest managers and ecologists alike.