l8 NORTHERN HARDWOOD TYPE 



it tends to become a rich, dark loam by the disintegration of the 

 abundant leaf litter. 



While beech, yellow birch and sugar maple are the character- 

 istic species in this type there is always a generous admixture of 

 other species. On the lower edges of the type white pine, hem- 

 lock, black birch, basswood, red oak, and even occasionally white 

 oak are part of the mixture while at the upper margin spruce, 

 balsam and paper birch are the supplementary species. It is 

 seldom, indeed, that this type does not have a considerable per- 

 centage of softwood timber. In fact it is here that white pine 

 and spruce reach their best development. For example, while 

 the sand plains of northern Michigan produce the dense stands 

 of pure white pine the largest, tallest and straightest individuals 

 grew amongst the hardwoods. 



A variety of subtypes may be distinguished in this type. In 

 the first place there are the variations due to composition. These 

 are mainly the results of differences in elevation. For example, 

 a mixture of white pine and hardwoods is not common higher 

 than 2000 feet above sea level because white pine does not flourish 

 at a greater elevation. The distribution of spruce is governed 

 by the same factor, it being unable to compete successfully with 

 other species at elevations less than 2000 feet above sea level 

 except occasionally on old fields. A few of the more usual com- 

 binations which it is useful to distinguish as subtypes on account 

 of their composition are: 



Hardwoods and white pine. 

 I Pure hardwoods. 



Hardwoods and spruce. 



These are arranged in order of their occurrence starting with the 

 lower limits of the type. 



Besides the differences in composition due to elevation, lumber- 

 ing, clearing, and fire have also played an important role. Stands 

 may be virgin, culled, cutover, or burnt. Each has a different 

 composition. Culling has been the commonest form of lumbering 

 because in many places only the softwoods have been merchant- 

 able. This has naturally resulted in increasing the percentage 



