Low light availability associated with American beech is the main factor for reduced sugar maple seedling Survival and growth rates in a hardwood forest of southern Quebec

摘要

Several recent studies have reported a marked increase in American beech dominanceud(Fagus grandifolia Ehrh.) relative to sugar maple (Acer saccharum Marsh.) in late successional forestsudof North America. However, many factors have been proposed to explain this sudden shift in treeudspecies composition. We investigated the microsite factors responsible for maple regeneration failureudunder maple-beech stands, focusing on both light availability and soil conditions. The survival andudgrowth of maple seedlings planted in the natural soil and in pots with enriched soil were monitoredudfor two years, as well as foliar nutrition and herbivory damages of natural seedlings. The resultsudindicate that low light availability associated with the presence of beech is the primary factor leadingudto maple regeneration failures. Soil nutrient availability and foliar nutrition of natural seedlingsuddid not differ between forest types. Yet, the results indicate that factors such as allelopathy andudpreferential herbivory on maple seedlings under beech could be superimposed effects that hinderudmaple regeneration. Under similar forests, a control of beech sapling abundance in the understoryudfollowed by selection cutting could be one way to promote and maintain maple populations in theudlonger term.