OVERSTORY VEGETATION AND SUCCESSIONAL TRENDS OF LAND BETWEEN THE LAKES, USA

133 stands from the uplands of Land Between The Lakes (LBL) were sampl ed. Stand data were ordinated to identify clinal patterns in the overs tory vegetation. A coenocline, accounting for 52% of the species varia nce, was developed from the first ordination axis. Classification of s tands identified nine dominance types: Pinus echinata-Quercus spp., Q. prinus, Q. prinus-Q. alba, Q. stellata-Q. alba, Q. velutina-Q. alba, Q. alba, Q. alba-Q. rubra, Acer saccharum-Q. alba-Fagus grandifolia an d F. grandfolia-A. saccharum. Compositionally-stable (climax) and unst able (successional) stands were analyzed separately. Trajectories of u nstable stands include the succession of P. echinata to Quercus-domina ted communities on xeric sites and of Quercus types to more mesophytic communities (e.g. A. saccharum and F. grandifolia) on mesic sites. Th ese shifts indicate the nature of the future climax overstory composit ion at LBL. The first axis DCCA ordination for climax stands accounted for 45% of the vegetation variance. Factor Analysis identified two si gnificant suites of variables related to vegetation: soil chemistry/so il moisture and soil texture. Specific variables related to variation in the climax vegetation include soil pH, calcium and magnesium, effec tive soil depth, available water capacity, percent rock in the soil, s lope position, aspect, elevation and distance to the opposing slope. M odal positions of species along the direct gradient ordination were si milar in rank order to those derived from the indirect gradient ordina tion of all stands. The latter ordination represents the present fores t vegetation pattern at LBL. Climax stands showed a shift in modes of Quercus spp. toward the xeric end of the gradient and increases in hab itat width of mesophytic species. Following a reduction in disturbance , species appear to adjust to changes in competition and available hab itat. That is, the dimensions of realized niches (i.e. habitat widths) change with succession. The climax vegetation at LBL appears to show centrifugal organization.