The influence of overstory trees and abiotic factors on the sapling community in an old-growth Fagus-Acer forest

We examine the influence of overstory trees and abiotic environmental factors on the patterns of spatial variation and species composition in the sapling community of an old-growth Fagus-Acer forest in southwestern Quebec, Canada Our main focus was to identify differences in the sapling distribution patterns of Fagus grandifolia and Acer saccharum, the two codominant species in the overstory, as well as the factors that determine the differences. Using canonical correspondence analysis (CCA), we show that soil moisture has the strongest influence on the spatial variation and species composition of the sapling community Acei saccharum occurred on a wide range of soil moisture conditions, while Fagus grandifolia saplings were absent in dry habitats. Another factor that differentiates the distribution patterns of Fagus grandifolia and Acer saccharum saplings is the relative dominance of Fagus grandifolia trees in the overstory, which correlates negatively with pH and Ca availability in the forest floor Acer saccharum saplings were not found on sites where Fagus grandifolia trees dominate the overstory. while Fagus grandifolia saplings are mostly limited to sites where Fagus grandifolia trees have high representation in the overstory. These findings are discussed in light of previous hypotheses on canopy tree replacement patterns in Fagus-Acer forests.