FOREST DEVELOPMENT IN CANOPY GAPS OF A DIVERSE HARDWOOD FOREST OF THE SOUTHERN APPALACHIAN MOUNTAINS

In a mature hardwood forest of 15 canopy spp. [Tsuga canadensis, Acer saccharum, A. rubrum, Halesia grandifolia, Tilia heterophylla, Aesculus octandra, Betula alleghaniensis, B. lenta, Magnolia fraseri, M. acuminata, Quercus rubra, Fraxinus americana, Liriodendron tulipifera, Prunus serotina and Fagus grandifolia] (1/.SIGMA.p2 = 7.2) in Great Smoky Mountains National Park, Tennessee, tree replacement in 118 single-tree gaps and 42 multiple-tree gaps was predominantly by species which are tolerant of shading. Four species of low shade tolerance, L. tulipifera, P. serotina, Q. rubra and F. americana, were able to hold 3% of the canopy area by infrequent capture of gap space, particularly in multiple-tree gaps. Trees of lower tolerance for shade have larger crowns than very tolerant trees. Relative crown sizes were used as weighting factors to improve predictions of a Markov chain model of canopy composition. T. heterophylla tended to replace itself by basal sprouts. L. tulipifera was found as a replacement tree primarily in gaps formed by the fall of T. canadensis.