MICHIGAN ACADEMY OF SCIENCE. 207 



soil northward over the fixed dunes to the northern edge of the moraine 

 beyond Point Betsie. 



C. The Relations of the Component Parts of the Climax Forest. 



1. While the pine-oak stage is not a prominent feature of suceessions 

 of northern Michigan, there are evidences of its former existence here in 

 the oak and pine remnants found in the climax forest. These are rare, 

 and are generally located as indicated above, on the more xerophytic 

 suniniits of tlie ridges in the forest, whether on dune or glacial substratum. 



2. The conditions for germination of maple and liemlock seeds seem 

 to be rather dill'erent. The lumlock seems to be unable to germinate 

 except on decaying wood. Practically the seedlings are usually found 

 on decaying hemlock trunks, frequently as many as a dozen have reached 

 the height of several feet on a single trunk, (Plate XI). On the other 

 hand, the maple seems to need more light for successful germination, 

 and abundance of maple seedlings is a common characteristic of the 

 greater light supply produced by the fall of a large tree, and the con- 

 sequent opening up of the forest crown. 



3. Persistence in the open. When forest trees are left to grow in the 

 open, or are planted in isolated positions, the maples seem to be the 

 most successful. It is a popular saying that the hemlock will not grow 

 where people walk over its roots, which apparently indicates that it 

 needs the undisturbed conditions of the forest. The beech also is not a 

 tree of the open, and seems to die readily where exposed on the edges 

 of clearings. From these considerations it would seem as if the hemlock 

 on tlie Avliole was the more shade tolerant, and therefore likely to become 

 the final member of the climax forest, if left long enough in undisturbed 

 conditions. 



University of Chicago. 



