Major Plant Communities 
17 
lo place tlie 1 inus spp. communities in a separate formation (funda¬ 
mental ecological group) merely because their limits of tolerance of 
sterile soils are sufficiently broader than the broad-leaved forest elements 
to make possible their relative isolation, is not in the mind of the writer, 
adhering to the definition of the basic ecological community. Under 
the author s arrangement, Pinus palustris, tieda and others when found 
playing a successional role as they invariably do on fertile soils, con¬ 
stitute a developmental association. When these same species are 
found playing a climactic one on the humus-deficient upland soils of 
the Coastal Plain, they there constitute edaphic climax associations. It 
is thus far more logical to distinguish these two communities in such 
a manner than to attempt placing them in two formations when the 
habitat differences are minor ones and the physiogonomic differences 
are entirely lacking since the same species are involved. 
Fig. 11. Contact between developmental Pinus Association and Quercus- 
Carya Association 
A further line of argument tending to indicate the validity of the 
writer’s position is that related to the large number of mesophytic 
broad-leaved elements which actually occur associated as subdominants 
in the Coastal pine forests. The Quercus marylandica-Q. stellata asso¬ 
ciation is commonly involved in them. In old forests such distinctly 
mesophytic elements as Q. falcata and Cynoxylon florida are frequently 
seen. 
