Tree replacement in small canopy gaps of a Tsuga canadensis forest in the Southern Appalachians, Tennessee.

Tree species replacement was studied in 95 canopy gaps created by the fall of single trees in an undisturbed, old-growth forest in Great Smoky Mountains National Park, Tennessee. When large trees (dbh>70 cm) of the very shade tolerant species, Tsuga canadensis, die and fall, they are usually replaced by less tolerant species such as Betula alleghaniensis, Liriodendron tulipifera, and Magnolia fraseri. Species diversity of the replacement trees, measured by the index, 1/Σpi2, was 5.77 compared to a diversity of 1.66 for the fallen trees.