175 



they attain a much larger size. Red cedars and post oaks more 

 than thirty feet high are seldom encountered, but the pignut and 

 chestnut oak commonly grow to a height of more than fifty feet. 

 While, then, both the chestnut oak and pignut may put in their 

 appearance early in the series, and while often they may be 

 conspicuous members of the pioneer tree stage, their chief im- 

 portance lies in the fact that as the trees grow larger they overtop 

 the cedar and post oak; and as they become more numerous, 

 their crowns forming a more or less continuous canopy, the red 

 cedar and post oak underneath, unable to endure the changed 

 light relations; gradually succumb. And along with the trees 

 disappear also the majority of the herbaceous and shrubby plants 

 of the pioneer tree stage. 



For a time the forest which thus originates may be dominated 

 to so marked a degree by chestnut oak and pignut as to seem to 

 warrant the recognition of a separate chestnut oak or chestnut 

 oak-pignut stage in the succession.* But on the whole it 

 seems simpler to regard this phase as merely a subdivision of a 

 larger association which may be designated the oak-hickory 

 stage. For, during the transition from the open, grove-like type 

 of woodland to the closed type, other species of oak and hickory 

 become increasingly abundant, so that the resultant forest 

 comprises an admixture of a number of species of oak and hickory, 

 together with certain other trees. The more important trees 

 present in such a society are here listed. 



Acer rubrum Quercus alba 



Carya alba Quercus coccinea 



Carya glabra Quercus Prinus 



Carya ovata Quercus rubra 



Pinus Strobus Quercus velutina 



Such a forest approximates closely the type of habitat so com- 

 monly referred to in the manuals as "dry woodlands." 



The general aspect of these oak-hickory forests at their best 



* It should be remarked, however, that the particular species of oak and hickory 

 here mentioned by no means invariably play the important role in the inaugura- 

 tion of the oak-hickory stage that is here assigned them. Quite as often other 

 species, e. g., Carya ovata, Carya alba, Quercus velutina, Quercus coccinea, are more 

 prominent at the outset. 



