Hill: Penobscot Vegetation 319 



graphic climax. This ecological concept, which is compara- 

 tively recent, recognizes the important role which edaphic 

 and topographic factors play in the development of vegeta- 

 tion and permits the introduction of a permanent type of 

 vegetation, different from the climax type of the region as a 

 whole, but which must not be interpreted as constituting a 

 distinct climatic formation, since, potentially at least, the 

 regional climax is capable of development. 



The characteristic jack pine country of the southern 

 peninsula of Michigan is another example of a physio- 

 graphic climax. This region has met with varied treat- 

 ment at the hands of ecologists, but Harvey has recently 

 shown (13) that it is definitely a part of the eastern decid- 

 uous forest climax, characterized locally by various physio- 

 graphic climaces ; and it should not be treated as a separate 

 formation. In this connection he makes the valuable state- 

 ment that "upon ecological grounds any region should be 

 classified upon the basis of the highest ecological type which 

 may find expression therein." 



Whitford (30) earlier showed that the pine forests of 

 northern Michigan are merely a stage in the development 

 of the maple-beech-hemlock forest; and this latter must 

 be considered the regional climax, even though it is not the 

 most characteristic type of vegetation in all cases. 



The second portion of the Transition region adjoins the 

 northeastern coniferous forest and, as would be expected, 

 shows a greater admixture of the northern coniferous spe- 

 cies. In this section, which we can call the Canadian-tran- 

 sition zone, the climax forest is still composed of maple, 

 beech, yellow birch, hemlock, and white pine, but with the 

 addition, as prominent members, of the spruce, balsam fir 

 and paper birch. This type of forest occupies much of 

 northern New England, the Adirondack region in New 

 York and the Maritime Provinces . A great part of this 

 country seems at first sight to be predominantly coniferous, 

 and has been classed as a portion of the northeastern conif- 



