Origin of Biomes and Succession 



253 



Fig. 111. Total distribution of five of the species of hardwood deciduous 

 trees which are dominant species in smaller areas within their total range. 

 (Modified from Munns.) 



terrain, it would undoubtedly produce the conditions found in the 

 transect across the Ohio forests mapped by Sears. 



These interlocking and overlapping aggregations of species de- 

 scribed by Whittaker undoubtedly arose from a process of splitting 

 and amalgamation which originated from a fairly simple commu- 

 nity. The result, however, no longer comes within the definition of 

 a community as "a relatively uniform area biologically." In Fig. 

 112, the combination at station 1 is a mixed Tsiiga-Tilia forest; sta- 

 tions 2 and 5 are mixed Tsuga-Tilia-Acer forest; stations 3 and 4 

 are chiefly evergreen coniferous forest with Tsuga the chief domi- 

 nant; stations 6 to 10 are deciduous hardwood forest with Querctis 

 borealis, Acer or Acer-Quercus alba as the principal dominants; 

 and stations 11 and 12 are again evergreen coniferous forest with 

 Finns species as dominants. 



Of the deciduous stations 6 to 10, each has a distinctive feature. 

 Station 6 is predominantly the black oak Quercus borealis with only 

 a scattering of many other kinds of trees; station 7 is just as pre- 

 dominantly the red maple Acer rubnim; and station 9 is a mixture 



