Comparative Assessment of Natural Regeneration Quality in Two Northern Hardwood Stands

Selected quality aspects of natural regeneration in gaps were studied in two sugar maple-yellow birch forest stands in Quebec: a selection-cut stand (SC) and a protected old-growth stand (OG). The quality-assessment systems by Sonderman (1979) and Borner et al. (2003) were applied to saplings and poles of sugar maple (Acer saccharum Marsh.), yellow birch (Betula alleghaniensis Britton), and American beech (Fagus grandifolia Ehrh.) between 2.5-13.0 m in height to assess stem deviation, forks, the number of live branches, branch diameters, and overall quality. These individual quality parameters, the Sonderman-quality index (QI), and a modified quality index (mQI) were used to illustrate differences in sapling quality between species and stands. Saplings and poles in the OG had fewer forks and fewer live branches of smaller relative branch diameters, resulting in better overall quality compared to the SC. Gap size had no significant influence on individual quality parameters, Sonderman-QI, or mQI class. The combination of both assessment systems into the mQI class allows for a comprehensive evaluation of regeneration quality, which may be used to evaluate the success of silvicultural measures in the context of quality-oriented northern hardwoods management. ABSTRACT