Liming alone does not guarantee the success of sugar maple regeneration

Sugar maple (SM; Acer saccharum Marshall) is considered to have a high economical and ecological value in northeastern North America. Over the last few decades, dieback and regeneration failure have posed a threat to its sustainability, particularly in acidic and base-poor soils. We evaluated the status of lower regeneration and dominant regeneration in a base-poor northern hardwood stand in Québec, 20 years after a liming treatment. Liming radically increased the density of lower regeneration and the proportion of SM in this stratum, up to levels more than 7 times those of control plots for the highest doses. Dominant regeneration consisted of only 4 % SM (all in the limed plots), while 85 % was American beech (AB; Fagus grandifolia Ehrh.). However, liming had no statistically significant effect on the composition of dominant regeneration, and no effect or a negative effect on the diameter and height of SM and AB regeneration. This can probably be explained by competition for light and nutrients resulting from a greater regeneration density and canopy closure in response to lime application. Results show that 20 years after its application in an acidic and base-poor northern hardwood stand, a single lime addition can contribute to increasing the proportion of SM at the lower regeneration stage. However, sylvicultural treatments must be considered to ensure that SM lower regeneration reaches a more advanced stratum in the stand.