PAPERS ON BIOLOGY AND AGRICULTLRE 95 



types and their subdivisions merge into one another by gi*a- 

 dations that are often almost imperceptible, presenting 

 degrees of difference that are quite impossible to discuss or 

 map in a preliminary sun'ey like the present study. In gen- 

 eral t«-o principal upland types may be distinguished, differ- 

 ing very considerably in response to water supply and ex- 

 pressing this response in varying degi-ees of density and 

 richness as well as in the tree species present. Distinguish- 

 ing these types by their principal trees, they may be desig- 

 nated as the upland oak and the beech-maple forests. The 

 bottomland forests may be divided into three tjiDes termed 

 respectively the streamside, the flood plain or "bottom" and 

 the cj-press swamp forests. 



UPLAND OAK FOREST 



This is developed upon the hill tops and along the more 

 exposed slopes, particularly where the soil is poor and thin. 

 It is dominated by various species of oak, the black oak, 

 Quercus velutina, being most abundant especially upon the 

 more exposed situations, while the white oak, Q. alba, 

 abounds in more favored situations. There are smaller 

 amounts of the chinquapin oak. Q. Muhlenbergii. of red oak, 

 Q. rubra, and of two or three less abundant oaks. Other 

 less important trees are the sassafras, the shagbark hick- 

 ory', and the persimmon (Fig. 2). 



BEECH-MAPLE FOREST 



Upon the sheltered slopes and in the narrower valleys, 

 particularly where the soil conditions are less severe, the oak 

 forest passes into one dominated by beech, Fagiis grandi- 

 folia, and the sugar maple, Acer sa<:charum. In the tran- 

 sition the first noticeable change is the disappearance of the 

 black oak, the increasing number of red oaks and the in- 

 vasion of the sugar maple. In addition to the species men- 

 tioned, there is also found the tulip tree, Liriodendron 

 tidipifera, the black cherry. Prunus serotbm, the red oak, 

 Q. rubra, and about two species each of hickory and ash, 

 while among trees of second size the Judas tree, Cercis 

 canadensis, the pa-v^-paw, Asimina triloba, and the hop horn- 

 beam, Ostrya virginiatm-, are most abundant. On account 

 of the extreme dissection of the upland it has been found to 

 be impossible to indicate upon the map the distinction 



