The COA ordination of the 17 woody species revealed one large clump of all species, except Salix nigra and Daubentonia drummondii [ILLUSTRATION FOR FIGURE 2 OMITTED], which are usually present as solitary tree species in low-elevation plots at opposite ends of each transect.
The vertical separation is suggestive, however, given the disjunct distributions (occurring in plots at opposite ends of each transect) and similar elevation ranges of Salix nigra and D.
Species are listed by median elevation: all elevations are in cm Species Min Max Mean Median Range Salix nigra -9.
2] plot data after removing Salix nigra and Daubentonia drummondii to test for additional community structure within the ridge-forest, but did not find sufficient support for the presence of nested communities despite the COA on the 171 plots and field observations; the COA ordination of the 15 species produced a group of points with no discrete separations and neither COA component significantly' correlated with elevation (2nd component: r = -0.
Salix nigra, Ilex decidua, Carya aquatica, Liquidambar styraciflua, and Diospyros virginiana) and, conversely, Crataegus spp.
Those findings generally agree with our data from BSR: Salix nigra and Daubentonia drummondii tolerate the wettest conditions, whereas Acer rubrum, Fraxinus americana and Diospyros virginiana tolerate slightly drier soils and intergrade with species such as Quercus virginiana, Celtis laevigata, Liquidambar styraciflua and Ulmus rubra (more common at "high-ridge" elevations).
Our COA indicated some influence of elevation on community formation; the ordinations revealed at least three communities: (1) Salix nigra, (2) Daubentonia drummondii and a larger community (3) the ridge forest (15 species).